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Sample records for ventricular rate control

  1. Ventricular rate control of atrial fibrillation in heart failure

    NARCIS (Netherlands)

    Rienstra, Michiel; Van Gelder, Isabelle C

    2013-01-01

    In the last few years, there has been a major shift in the treatment of atrial fibrillation (AF) in the setting of hear failure (HF), from rhythm to ventricular rate control in most patients with both conditions. In this article, the authors focus on ventricular rate control and discuss the

  2. Achieving ventricular rate control in patients taking chronic beta-blocker therapy.

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    Feeney, Megan E; Rowe, Sandra L B; Mah, Nathan D; Barton, Cassie A; Ran, Ran

    2018-01-01

    The objective of this study is to evaluate the difference in response to ventricular rate control with intravenous (IV) metoprolol compared to IV diltiazem in patients taking chronic beta-blocker therapy who present to the emergency department (ED) in atrial fibrillation (AF) with rapid ventricular rate (RVR). This was a single-center, retrospective study of adult patients taking chronic oral metoprolol. Chronic metoprolol therapy was defined as patients prescribed and taking oral metoprolol within 5days of study inclusion. Rate control was defined as either a decrease in ventricular ratebeta-blocker therapy, however the difference between groups was not statistically significant. Copyright © 2017 Elsevier Inc. All rights reserved.

  3. ORTHOSTATIC REACTIONS OF VENTRICULAR RATE IN MEDICAL CONTROL OF PERMANENT ATRIAL FIBRILLATION

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    A. N. Fomich

    2013-06-01

    Full Text Available Article is devoted to studying the Significance of orthostatic reactions of ventricular rate (OR VR in the clinical course of permanent atrial fibrillation (AF to improve the effectiveness of its control. It was found that among patients with AF there are all 3 types of OR VR as during sinus rhythm, positive OR VR predo-minate over negative and absent. It was shown, that positive OR are favorable to reduce the severity of symptoms of AF, according to European Heart Rhythm Association (EHRA, less favorable – absent, and unfavorable – negative OR VR. It was established, that the control of AF with by beta adrenergic anta-gonists (BAA is possible in any type of OR VR except qualified positive, combination of BAA and amioda-rone – for BAA inefficiency, and control of AF with amiodarone is preferable in qualified positive and ne-gative OR VR and when there are contraindications to BAA.

  4. Heart rate turbulence and variability in patients with ventricular arrhythmias

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    Diego Tarricone

    2009-08-01

    Full Text Available Background: To evaluate the changes in autonomic neural control mechanisms before malignant ventricular arrhythmias, we measured heart rate variability (HRV and heart rate turbulence (HRT in patients with ventricular tachycardia or fibrillation (Group I; n=6, non sustained ventricular tachycardia (Group II; n=32, frequent premature ventricular beats (Group III; n=26 and with ICD implantation (Group IV; n=11. Methods: Time domain parameters of HRV and turbulence onset (TO and slope (TS were calculated on 24 hour Holter recordings. Normal values were: SDNN > 70 msec for HRV, TO <0% and TS >2.5 msec/RR-I for HRT. Results: Whereas SDNN was within normal range and similar in all study groups, HRT parameters were significantly different in patients who experienced VT/VF during Holter recording. Abnormal TO and/or TS were present in 100% of Group I patients and only in about 50% of Group II and IV. On the contrary, normal HRT parameters were present in 40-70% of Group II, III and IV patients and none of Group I. Conclusions: These data suggest that HRT analysis is more suitable than HRV to detect those transient alterations in autonomic control mechanisms that are likely to play a major trigger role in the genesis of malignant cardiac arrhythmias. (Heart International 2007; 3: 51-7

  5. Sotalol vs metoprolol for ventricular rate control in patients with chronic atrial fibrillation who have undergone digitalization: a single-blinded crossover study.

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    Kochiadakis, G E; Kanoupakis, E M; Kalebubas, M D; Igoumenidis, N E; Vardakis, K E; Mavrakis, H E; Vardas, P E

    2001-01-01

    To compare the effects of sotalol and metoprolol on heart rate, during isotonic (ITE) and isometric (IME) exercise and daily activities, in digitalized patients with chronic atrial fibrillation. The study had a randomized, single-blinded, crossover design. Twenty-three patients with chronic atrial fibrillation received placebo for 4 weeks, followed by a 4-week period of treatment with sotalol and metoprolol in random order. At the end of each period, the patients were assessed with 24-h ECG monitoring, a cardiopulmonary exercise test and a handgrip manoeuvre. Both agents produced a lower heart rate than placebo at rest and at all levels of isotonic exercise (P digitalized patients with atrial fibrillation. Sotalol is superior to metoprolol at submaximal exercise, resulting in better rate control during daily activities.

  6. HEART RATE VARIABILITY IN PREGNANT WOMEN WITH VENTRICULAR EXTRASYSTOLES

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    Yevgeniya Chekashkina

    2016-03-01

    Full Text Available Frequent ventricular extrasystoles (VE can affect haemodynamic indexes and lead to negative consequences for the health of not only an expectant mother, but also a fetus. The analysis of heart rate variability (HRV is recognized as an informative method for noninvasive assessment of the impact of the autonomic nervous system on the cardiovascular system. HRV in pregnant women has been understudied. Therefore, the goal of the present research is to investigate HRV indexes in pregnant women with frequent VE in the 3-rd trimester of pregnancy and early postnatal period. Materials and Methods HRV was estimated in 40 pregnant women with frequent VE, who were divided into 2 groups: group 1– in the 3-rd trimester of pregnancy, and group 2 – in the early postnatal period. A control group included 20 normal pregnant women without any arrhythmias. In addition, HRV indexes in these groups were compared to the indexes in the group of healthy non-pregnant women at the age of 18 to 30. The investigation of HRV was conducted by using the 24-hour HM-ECG with “Valenta” cardioregistrator (Russia. SDNN, SDAN, HRVi, HF, LF, VLF and LF/HF indexes of HRV were under the study. Results The analysis of time indexes revealed the decreased of HRV during pregnancy: in the 3-rd trimester SDNN decreased. In the postnatal period SDNN increased. It was found that rMSSD decresed in pregnant women and increased in the postnatal period that is indicative of enhanced parasympathetic effects. Similar dynamics was noted in analyzing the HF index associated with vagal activity. Vagal activity tended to decrease in pregnancy as compared to its normal values and increased significantly in the early postnatal period. We sould note that the LF waves activity reflecting the sympathetic effects on the heart increased gradually in pregnant women and decreased in the postnatal period. Discussion and Conclusions The investigation of HRV allows to estimate an extent of the autonomic

  7. Effect of tunnel length on infection rate in patients with external ventricular drain.

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    Rafiq, Mirza Faisal Ahmed; Ahmed, Noor; Ali, Shafqut

    2011-01-01

    External ventricular drain involves catheter placement in ventricles of brain. It is used for various purposes. Basic theme is to drain cerebrospinal fluid so as to control intracranial pressure. This study was carried out to see the effect of tunnel length on rate of infection. This was a cross-sectional study carried out in Department of Neurosurgery, Pakistan Institute of Medical Sciences, Islamabad during 14 months from 1st December 2008 to 31 January 2010. External ventricular drain was placed in admitted patients after meticulous aseptic technique in operation theatre at right Kocher's point. It was carried out through a scalp tunnel and was connected to drainage bag through a drip set. Both long (> 5 Cm) and short (drain). All patients received prophylactic Ceftriaxone. Among 76 patients long tunnel was made in 44 (57.9%) and short in 32 (42.1%). Three patients (3.9%) with long tunnel while 6 (7.9%) patients with short tunnel had infection. The overall infection was in 9 (11.8%) patients. External ventricular drain tunnel length strongly influences the rate of infection.

  8. Influence of alterations in heart rate on left ventricular echocardiographic measurements in healthy cats.

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    Sugimoto, Keisuke; Fujii, Yoko; Ogura, Yuto; Sunahara, Hiroshi; Aoki, Takuma

    2017-08-01

    Objectives The purpose of this study was to evaluate the effect of sudden alterations in heart rate (HR) on left ventricular (LV) wall thickness and dimensions determined by echocardiography in healthy cats. Methods Six experimental cats were used. All cats were anaesthetised and HR was controlled with right atrial pacing. The interventricular septum and left ventricular free wall thickness at end diastole (IVSd and LVFWd, respectively), left ventricular end-diastolic and end-systolic diameter (LVIDd and LVIDs, respectively) and shortening fraction (FS) of each cat were assessed using echocardiography at pacing rates of 120, 130, 140, 150, 160, 170 and 180 ppm. Results There were significant relationships between HR and IVSd, LVFWd, LVIDd, LVIDs and FS. As the HR increased, LV wall thickness increased and chamber dimensions got smaller in a linear fashion. The maximum and minimum differences in wall thickness between 120 ppm and 180 ppm were 2.0 mm and 0.7 mm in single measurements, respectively. Conclusions and relevance LV wall thickness and dimensions were significantly influenced by alterations in HR.

  9. Comparison of ventricular function in atrial rate adaptive versus dual chamber rate adaptive pacing during exercise.

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    Gallik, D M; Guidry, G W; Mahmarian, J J; Verani, M S; Spencer, W H

    1994-02-01

    The hemodynamic effects of two different pacing modes--rate adaptive atrial (AAIR) versus dual chamber (DDDR) pacing--were assessed in 12 patients with DDDR pacemakers during upright bicycle exercise first-pass radionuclide angiography using a multiwire gamma camera with tantalum-178 as a tracer. All patients had sinus node disease with intact AV conduction. Patients exercised to the same heart rate in random order in these two different pacing modes, AAIR and DDDR with AV delay (of 100 msec) selected to maintain 100% ventricular capture. Cardiac output increased significantly above baseline values during exercise in both pacing modes: 154 +/- 41% (mean +/- SEM, P = 0.002) with AAIR, versus 95 +/- 24% (P = 0.004) with DDDR (P = NS between the two modes). The peak filling rate, likewise, increased in both pacing modes (2.3 +/- 0.21 end-diastolic volumes/sec to 3.8 +/- 0.31 end-diastolic volumes/sec in AAIR [P = 0.0004] and 2.2 +/- 0.18 end-diastolic volumes/sec to 3.4 +/- 0.27 end-diastolic volumes/sec in DDDR [P = 0.0008]). LV ejection fraction was normal at rest (60 +/- 4%, SEM) and did not significantly change with submaximal exercise in either pacing mode (both 56%, P = NS). No significant changes in end-diastolic volume or stroke volume indexes occurred with exercise in either pacing mode. Our study demonstrates that in patients with normal resting LV function, AAIR and DDDR pacing are equally effective in attaining appropriate increases in cardiac output and LV filling during exercise.

  10. Flecainide attenuates rate adaptation of ventricular repolarization in guinea-pig heart

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    Osadchiy, Oleg

    2016-01-01

    examined flecainide effect on adaptation of the QT interval and ventricular action potential duration (APD) to abrupt reductions of the cardiac cycle length. DESIGN: ECG and ventricular epicardial and endocardial monophasic APD were recorded in isolated, perfused guinea-pig heart preparations upon...... a sustained cardiac acceleration (rapid pacing for 30 s), and following a single perturbation of the cycle length evoked by extrasystolic stimulation. RESULTS: Sustained increase in heart rate was associated with progressive bi-exponential shortening of the QT interval and APD. Flecainide prolonged...

  11. HEART-RATE-VARIABILITY IN LEFT-VENTRICULAR DYSFUNCTION AND HEART-FAILURE - EFFECTS AND IMPLICATIONS OF DRUG-TREATMENT

    NARCIS (Netherlands)

    TUININGA, YS; VANVELDHUISEN, DJ; BROUWER, J; HAAKSMA, J; CRIJNS, HJGM; MANINTVELD, AJ; LIE, KI

    1994-01-01

    Objective-To review the importance of heart rate variability analysis in left ventricular dysfunction and heart failure and to assess the effects of drug treatment. In patients with left: ventricular dysfunction or heart failure, a low heart rate variability is a strong predictor of a low

  12. Left ventricular ejection time, not heart rate, is an independent correlate of aortic pulse wave velocity.

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    Salvi, Paolo; Palombo, Carlo; Salvi, Giovanni Matteo; Labat, Carlos; Parati, Gianfranco; Benetos, Athanase

    2013-12-01

    Several studies showed a positive association between heart rate and pulse wave velocity, a sensitive marker of arterial stiffness. However, no study involving a large population has specifically addressed the dependence of pulse wave velocity on different components of the cardiac cycle. The aim of this study was to explore in subjects of different age the link between pulse wave velocity with heart period (the reciprocal of heart rate) and the temporal components of the cardiac cycle such as left ventricular ejection time and diastolic time. Carotid-femoral pulse wave velocity was assessed in 3,020 untreated subjects (1,107 men). Heart period, left ventricular ejection time, diastolic time, and early-systolic dP/dt were determined by carotid pulse wave analysis with high-fidelity applanation tonometry. An inverse association was found between pulse wave velocity and left ventricular ejection time at all ages (heart period was also found, with the exception of the youngest subjects (P = 0.20). A significant positive correlation was also found between pulse wave velocity and dP/dt (P heart period no longer became significant. Our data demonstrate that pulse wave velocity is more closely related to left ventricular systolic function than to heart period. This may have methodological and pathophysiological implications.

  13. Left Ventricular Strain Rate is Reduced during Voluntary Apnea in Healthy Humans.

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    Smith, Joshua R; Sutterfield, Shelbi L; Baumfalk, Dryden R; Didier, Kaylin D; Hammer, Shane M; Caldwell, Jacob Troy; Ade, Carl J

    2017-09-14

    During an apneic event, sympathetic nerve activity increases resulting in subsequent increases in left ventricular afterload and myocardial work. It is unknown how cardiac mechanics are acutely impacted by the increased myocardial work during an apneic event. 10 healthy individuals (23 ± 3 yrs) performed multiple voluntary end-expiratory apnea (VEEA) maneuvers exposed to room air, while a subset (n=7) completed multiple VEEA exposed to hyperoxic air (100% FiO2). Beat-by-beat blood pressure, heart rate and stroke volume were measured continuously. Effective arterial elastance (EA) was calculated as an index of cardiac afterload and myocardial work calculated as the rate pressure product (RPP). Tissue Doppler echocardiography was used to measure left ventricular (LV) tissue velocities, and deformation via strain, and strain rate (SR). Systolic blood pressure (Δ18 ± 13 mmHg, p0.18) EA or RPP and attenuated the systolic blood pressure response compared to room air. Myocardial velocities and LV strain rate response to VEEA were unchanged (p=0.30) with hyperoxia. Consistent with our hypotheses, VEEA-induced increases in EA and myocardial work impact left ventricular mechanics, which may depend, in part, on stimulation of peripheral chemoreceptors. Copyright © 2017, Journal of Applied Physiology.

  14. Left Ventricular Wall Stress-Mass-Heart Rate Product and Cardiovascular Events in Treated Hypertensive Patients

    DEFF Research Database (Denmark)

    Devereux, Richard B; Bang, Casper N; Roman, Mary J

    2015-01-01

    randomized treatment, the triple product was reduced more by atenolol, with prevalences of elevated triple product of 39% versus 51% on losartan (both P≤0.001). In Cox regression analyses adjusting for age, smoking, diabetes mellitus, and prior stroke, MI, and heart failure, 1 SD lower triple product......In the Losartan Intervention for End Point Reduction in Hypertension (LIFE) study, 4.8 years' losartan- versus atenolol-based antihypertensive treatment reduced left ventricular hypertrophy and cardiovascular end points, including cardiovascular death and stroke. However, there was no difference...... in myocardial infarction (MI), possibly related to greater reduction in myocardial oxygen demand by atenolol-based treatment. Myocardial oxygen demand was assessed indirectly by the left ventricular mass×wall stress×heart rate (triple product) in 905 LIFE participants. The triple product was included as time...

  15. Comprehensive analyses of ventricular myocyte models identify targets exhibiting favorable rate dependence.

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    Megan A Cummins

    2014-03-01

    Full Text Available Reverse rate dependence is a problematic property of antiarrhythmic drugs that prolong the cardiac action potential (AP. The prolongation caused by reverse rate dependent agents is greater at slow heart rates, resulting in both reduced arrhythmia suppression at fast rates and increased arrhythmia risk at slow rates. The opposite property, forward rate dependence, would theoretically overcome these parallel problems, yet forward rate dependent (FRD antiarrhythmics remain elusive. Moreover, there is evidence that reverse rate dependence is an intrinsic property of perturbations to the AP. We have addressed the possibility of forward rate dependence by performing a comprehensive analysis of 13 ventricular myocyte models. By simulating populations of myocytes with varying properties and analyzing population results statistically, we simultaneously predicted the rate-dependent effects of changes in multiple model parameters. An average of 40 parameters were tested in each model, and effects on AP duration were assessed at slow (0.2 Hz and fast (2 Hz rates. The analysis identified a variety of FRD ionic current perturbations and generated specific predictions regarding their mechanisms. For instance, an increase in L-type calcium current is FRD when this is accompanied by indirect, rate-dependent changes in slow delayed rectifier potassium current. A comparison of predictions across models identified inward rectifier potassium current and the sodium-potassium pump as the two targets most likely to produce FRD AP prolongation. Finally, a statistical analysis of results from the 13 models demonstrated that models displaying minimal rate-dependent changes in AP shape have little capacity for FRD perturbations, whereas models with large shape changes have considerable FRD potential. This can explain differences between species and between ventricular cell types. Overall, this study provides new insights, both specific and general, into the determinants of

  16. Electrical remodeling and atrial dilation during atrial tachycardia are influenced by ventricular rate : Role of developing tachycardiomyopathy

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    Schoonderwoerd, BA; Van Gelder, IC; Van Veldhuisen, DJ; Tieleman, RG; Grandjean, JG; Bel, KJ; Allessie, MA; Crijns, HJGM

    2001-01-01

    Atrial Remodeling in Tachycardiomyopathy. Introduction: Atrial fibrillation (AF) and congestive heart failure (CHF) are two clinical entities that often coincide. Our aim was to establish the influence of concomitant high ventricular rate and consequent development of CHF on electrical remodeling

  17. Heart rate turbulence after ventricular premature beats in healthy Doberman pinschers and those with dilated cardiomyopathy.

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    Harris, J D; Little, C J L; Dennis, J M; Patteson, M W

    2017-10-01

    To describe the measurement of heart rate turbulence (HRT) after ventricular premature beats and compare HRT in healthy Doberman pinschers and those with dilated cardiomyopathy (DCM), with and without congestive heart failure (CHF). Sixty-five client-owned Dobermans: 20 healthy (NORMAL), 31 with preclinical DCM and 14 with DCM and CHF (DCM + CHF). A retrospective study of data retrieved from clinical records and ambulatory ECG (Holter) archives, including data collected previously for a large-scale prospective study of Dobermans with preclinical DCM. Holter data were reanalysed quantitatively, including conventional time-domain heart rate variability and the HRT parameters turbulence onset and turbulence slope. Heart rate turbulence could be measured in 58/65 dogs. Six Holter recordings had inadequate ventricular premature contractions (VPCs) and one exhibited VPCs too similar to sinus morphology. Heart rate turbulence parameter, turbulence onset, was significantly reduced in DCM dogs, whereas conventional heart rate variability measures were not. Heart rate variability and HRT markers were reduced in DCM + CHF dogs as expected. Heart rate turbulence can be measured from the majority of good quality standard canine 24-hour Holter recordings with >5 VPCs. Turbulence onset is significantly reduced in Dobermans with preclinical DCM which indicates vagal withdrawal early in the course of disease. Heart rate turbulence is a powerful prognostic indicator in human cardiac disease which can be measured from standard 24-hour ambulatory ECG (Holter) recordings using appropriate computer software. Further studies are warranted to assess whether HRT may be of prognostic value in dogs with preclinical DCM and in other canine cardiac disease. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Volume reduction rate by surgical ventricular restoration determines late outcome in ischaemic cardiomyopathy.

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    Isomura, Tadashi; Hoshino, Joji; Fukada, Yasuhisa; Kitamura, Aki; Katahira, Shintaro; Kondo, Taichi; Iwasaki, Tomoaki; Buckberg, Gerald

    2011-04-01

    Surgical ventricular restoration (SVR) effectively reduces left ventricular (LV) volume in ischaemic cardiomyopathy (ICM), but the recent Surgical Treatment of Ischemic Heart Failure (STICH) Trial questions its importance. We report 8-year SVR experience in patients with ICM. Between 2000 and 2008, 135 patients underwent SVR for ICM. This report analyses data from 90 patients who underwent accurate pre- and post-operative assessment of LV volumes by left ventriculogram or scintigram. All patients also had echocardiograms. Pre-operative LV end-systolic volume index (ESVI) was 123.5 ± 53.2 mL/m(2) (range 92-310). Overall, 63 patients were in NHYA class III and 27 were in class IV. The SVR procedure was endoventricular circular patch plasty in 33 patients, septal-anterior ventricular exclusion in 43, and 14 patients had posterior exclusion. Coronary artery bypass grafting was performed in 78 patients (87%) and 50 underwent mitral procedures. Eighteen follow-up late deaths occurred owing to chronic heart failure (n = 12) and sudden death (n = 6). Post-operative ESVI was 120 mL/m(2) (Group-L) in 20 patients. The 8-year survival rate was 82.4% in group-S following a > 33% LV volume reduction. In contrast, in Group-M and Group-L, the volume reduction was ∼ 15%, and 100% of patients died within 7 years following the SVR procedure (or 0% 8-year survival). SVR is most effective when a >33% volume reduction rate achieves an ESVI of 90 mL/m(2). This database contradicts the STICH trial findings.

  19. Detection of Left Ventricular Regional Function in Asymptomatic Children with beta-Thalassemia Major by Longitudinal Strain and Strain Rate Imaging

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    Ali Bay

    2013-09-01

    Full Text Available Objective: Cardiac failure due to iron overload remains the most common cause of death in patients with beta-thalassemia major. This study aimed to evaluate myocardial function in children with beta-thalassemia major using standard echocardiography technique and strain rate imaging. Materials and Methods: Conventional echocardiographic analysis, tissue velocity imaging, and strain/strain rate imaging of the left ventricle were evaluated in 48 children with beta thalassemia major (19 girls, 29 boys; 8.39±4.05 years and 22 healthy children (11 girls, 11 boys; 8±3.72 years. Results: Conventional echocardiographic examinations revealed that beta-thalassemia patients had larger left ventricular end-systolic diameter, end-diastolic and end-systolic volume, left ventricular mass index, and mitral early/late diastolic flow velocity ratio (p<0.05. Strain and strain rate imaging study of the basal lateral wall of the left ventricle was higher in patients than in controls, at p=0.035 and p=0.008, respectively. Conclusion: We found that superior systolic strain and strain rate imaging of the left ventricle indicated the presence of regional systolic function in the left ventricular wall. We suggest that left ventricle volume and mass index parameters might be more sensitive than the other conventional and strain/strain rate imaging parameters during childhood. However, the adulthood strain and strain rate imaging values may be lower than controls, exceeding the critical level of iron overload.

  20. Strong modulation of ectopic focus as a mechanism of repetitive interpolated ventricular bigeminy with heart rate doubling.

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    Takayanagi, Kan; Nakahara, Shiro; Toratani, Noritaka; Chida, Ryuji; Kobayashi, Sayuki; Sakai, Yoshihiko; Takeuchi, Akihiro; Ikeda, Noriaki

    2013-10-01

    Repetitive interpolated ventricular bigeminy (RIVB) can introduce a doubling of the ventricular rate. To clarify the mechanism of RIVB, we hypothesized that it was introduced by a strong modulation of the ventricular automatic focus. RIVB, defined as more than 7 bigeminy events, was detected by instantaneous heart rate and bigeminy interval (BI) tachograms in 1450 successive patients with frequent ventricular premature contractions (≥3000 per day). Postextrasystolic interval bigeminy interval curves were plotted to determine the degree of modulation. Mean sinus cycle length bigeminy interval curves were plotted for selection. RIVB was simulated by using a computer-based parasystole model. RIVB was observed in 7 patients (age 60 ± 16 years; 2 men and 5 women) with a heart rate of 58.2 ± 6.5 beats/min during a rest period both during the day and at night. The tachograms disclosed the onset of the RIVB with a doubled ventricular rate to 112.3 ± 8.5 beats/min. On the postextrasystolic interval bigeminy interval curves, compensatory bigeminy and interpolated bigeminy constituted overlapping regression lines with slopes close to 1.00 and RIVB was located in the lower left portion. RIVB lasting for up to 3 hours was quickly detected by mean sinus cycle length bigeminy interval curve. The PQ interval immediately after RIVB was prolonged in comparison with baseline (0.18 ± 0.02 to 0.21 ± 0.02 seconds; P heart rate. Our findings support the hypothesis that RIVB was introduced by strongly modulated ventricular pacemaker accelerated by an intervening normal QRS. © 2013 Heart Rhythm Society. All rights reserved.

  1. The effects of rate-adaptive atrial pacing versus ventricular backup pacing on exercise capacity in patients with left ventricular dysfunction.

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    Passman, Rod; Banthia, Smriti; Galvez, Dinita; Sheldon, Todd; Kadish, Alan

    2009-01-01

    Atrial rate-adaptive pacing may improve cardiopulmonary reserve in patients with left ventricular dysfunction. A randomized, blinded, single-crossover design enrolled dual-chamber implantable defibrillator recipients without pacing indications and an ejection fraction AAIR) and ventricular demand pacing (VVI) pacing modes. The primary endpoint was change in peak oxygen consumption (VO(2)). Secondary endpoints were changes in anaerobic threshold, perceived exertion, exercise duration, and peak blood pressure. Ten patients, nine males, eight with New York Heart Association class I, mean ejection fraction 24 +/- 7%, were analyzed. Baseline VO(2) was 3.6 +/- 0.5 mL/kg/min. Heart rate at peak exercise was significantly higher during AAIR versus VVI pacing (142 +/- 18 vs 130 +/- 23 bpm; P = 0.05). However, there was no difference in peak VO(2) (AAIR 23.7 +/- 6.1 vs VVI 23.8 +/- 6.3 mL/kg/min; P = 0.8), anaerobic threshold (AAIR 1.3 +/- 0.3 vs VVI 1.2 +/- 0.2 L/min; P = 0.11), rate of perceived exertion (AAIR 7.3 +/- 1.5 vs VVI 7.8 +/- 1.2; P = 0.46), exercise duration (AAIR 15 minutes, 46 seconds +/- 2 minutes, 54 seconds vs VVI 16 minutes, 3 seconds +/- 2 minutes, 48 seconds; P = 0.38), or peak systolic blood pressure (AAIR 155 +/- 22 vs VVI 153 +/- 21; P = 0.61) between the two pacing modes. In this study, AAIR pacing did not improve peak VO(2,) anaerobic threshold, rate of perceived exertion, or exercise duration compared to VVI backup pacing in patients with left ventricular dysfunction and no pacing indications.

  2. Arrhythmia risk assessment using heart rate variability parameters in patients with frequent ventricular ectopic beats without structural heart disease.

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    Barutçu, Ahmet; Temiz, Ahmet; Bekler, Adem; Altun, Burak; Kirilmaz, Bahadir; Aksu, Feyza Ulusoy; Küçük, Uğur; Gazi, Emine

    2014-11-01

    Ventricular ectopic beats (VEBs) are usually considered a benign condition that can be managed with conservative measures. Heart rate variability (HRV), which is one of the most important methods for assessing autonomic activity, is a noninvasive, quantitative method of analyzing autonomic effects on the heart. We aimed to investigate the risk of arrhythmia in patients with VEBs and without cardiovascular disease by using HRV parameters. Patients with frequent VEBs (more than 30 times in 1 hour, according to the Lown classification) were identified. Identified patients were evaluated by 24-hour ECG recording. Our study included 43 patients with frequent VEBs and 43 controls. General characteristics of the study population were similar. The LF (low frequency)/HF (high frequency) ratio was significantly higher in the frequent VEBs group than in the control group (P < 0.001). The rate of paroxysmal atrial fibrillation (PAF) was higher in the frequent VEB group than in the control group (P = 0.003). The number of VEBs was correlated with LF/HF ratio and PAF (r = 0.339, P = 0.001 and r = 0.294, P = 0.006, respectively). Our study showed that the sympathetic nervous system is dominant in young patients with VEBs and without significant comorbidities. There is a higher risk of atrial fibrillation in patients with VEBs and they should be monitored closely for atrial fibrillation. ©2014 Wiley Periodicals, Inc.

  3. Control of a Pediatric Pulsatile Ventricular Assist Device: A Hybrid Cardiovascular Model Study.

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    Ferrari, Gianfranco; Di Molfetta, Arianna; Zieliński, Krzysztof; Fresiello, Libera; Górczyńska, Krystyna; Pałko, Krzysztof Jakub; Darowski, Marek; Amodeo, Antonio; Kozarski, Maciej

    2017-12-01

    The aim of this work is to study pediatric pneumatic ventricle (PVAD) performance, versus VAD rate (VADR) and native heart rate (HR) ratio Rr (VADR/HR). The study uses a hybrid model of the cardiovascular system (HCS). HCS consists of a computational part (a lumped parameter model including left and right ventricles, systemic and pulmonary arterial and venous circulation) interfaced to a physical part. This permits the connection of a VAD (15 mL PVAD). Echocardiographic and hemodynamic data of a pediatric patient (average weight 14.3 kg, HR 100 bpm, systemic pressure 75/44 mm Hg, CO 1.5 L/min) assisted apically with asynchronous PVAD were used to set up a basal condition in the model. After model tuning, the assistance was started, setting VAD parameters (ejection and filling pressures, systole duration) to completely fill and empty the PVAD. The study was conducted with constant HR and variable VADR (50-120, step 10, bpm). Experiments were repeated for two additional patients' HRs, 90 and 110 bpm and for two values of systemic arterial resistance (Ras ) and Emax . Experimental data were collected and stored on disk. Analyzed data include average left and right ventricular volumes (LVV, RVV), left ventricular flow (LVF), VAD flow (VADF), and total cardiac output (COt). Data were analyzed versus Rr. LVV and RVV are sensitive to Rr and a left ventricular unloading corresponds in general to a right ventricular loading. In the case of asynchronous assistance, frequency beats are always present and the beat rate is equal to the difference between HR and VADR. In the case of pulsatile asynchronous LVAD assistance, VADR should be chosen to minimize frequency beat effects and right ventricular loading and to maximize left ventricular unloading. © 2017 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

  4. Findings from left ventricular strain and strain rate imaging in asymptomatic patients with type 2 diabetes mellitus

    NARCIS (Netherlands)

    Ng, Arnold C. T.; Delgado, Victoria; Bertini, Matteo; van der Meer, Rutger W.; Rijzewijk, Luuk J.; Shanks, Miriam; Nucifora, Gaetano; Smit, Johannes W. A.; Diamant, Michaela; Romijn, Johannes A.; de Roos, Albert; Leung, Dominic Y.; Lamb, Hildo J.; Bax, Jeroen J.

    2009-01-01

    Regional left ventricular (LV) myocardial functional changes in early diabetic cardiomyopathy have not been well documented. LV multidirectional strain and strain rate analyses by 2-dimensional speckle tracking were used to detect subtle myocardial dysfunction in 47 asymptomatic, male patients (age

  5. Systolic left ventricular function is preserved during therapeutic hypothermia, also during increases in heart rate with impaired diastolic filling

    OpenAIRE

    Kerans, Viesturs; Espinoza, Andreas; Skulstad, Helge; Halvorsen, Per S.; Edvardsen, Thor; Bugge, Jan F

    2015-01-01

    Background Systolic left ventricular function during therapeutic hypothermia is found both to improve and to decline. We hypothesized that this discrepancy would depend on the heart rate and the variables used to assess systolic function. Methods In 16 pigs, cardiac performance was assessed by measurements of invasive pressures and thermodilution cardiac output and with 2D strain echocardiography. Lef...

  6. Relationship of maximum rate of pressure rise between aorta and left ventricle in pediatric patients. Implication for ventricular-vascular interaction with the potential for noninvasive determination of left ventricular contractility.

    Science.gov (United States)

    Masutani, Satoshi; Iwamoto, Yoichi; Ishido, Hirotaka; Senzaki, Hideaki

    2009-09-01

    The maximum rate of the ventricular pressure rise (dp/dt(max)) provides a reliable measure of ventricular contractility. However, its estimation requires invasive measurement of left ventricular (LV) pressure, limiting its bedside clinical applicability. In the present study, 2 hypotheses were tested: (1)that the ratio of dp/dt(max) between the aorta (Ao) and LV is consistent among patients despite marked differences in underlying cardiac disease, contractile state and heart rate when vascular mechanical and loading properties are taken into account, and (2)that using such a relationship, LV dp/dt(max) can be estimated from Ao dp/dt(max), potentially providing a method of noninvasive determination of LV contractility. Data from 30 control children and 45 pediatric patients with various cardiovascular diseases revealed that the characteristic impedance (Zc) and mean arterial pressure were significant determinants of the Ao-LV dp/dt(max) relationship in both control and disease groups. LV dp/dt(max) estimated using the regression obtained in the control children (Ao dp/dt(max/)LV dp/dt(max) = 0.64+1.45*10(-4)*Zc-3.73*10(-3)*MAP, r=0.87) correlated well with the measured LV dp/dt(max) in the disease group, including measurements taken after dobutamine and atrial pacing (r=0.89). Ao dp/dt(max) and LV dp/dt(max) are closely correlated through the vascular loading properties and LV dp/dt(max) can be derived from Ao dp/dt(max), which has potential as a noninvasive method of determining LV contractility.

  7. Left ventricular twist is load-dependent as shown in a large animal model with controlled cardiac load

    Directory of Open Access Journals (Sweden)

    A’roch Roman

    2012-06-01

    Full Text Available Abstract Background Left ventricular rotation and twist can be assessed noninvasively by speckle tracking echocardiography. We sought to characterize the effects of acute load change and change in inotropic state on rotation parameters as a measure of left ventricular (LV contractility. Methods Seven anesthetised juvenile pigs were studied, using direct measurement of left ventricular pressure and volume and simultaneous transthoracic echocardiography. Transient inflation of an inferior vena cava balloon (IVCB catheter produced controlled load reduction. First and last beats in the sequence of eight were analysed with speckle tracking (STE during the load alteration and analysed for change in rotation/twist during controlled load alteration at same contractile status. Two pharmacological inotropic interventions were also included to examine the same hypothesis in additionally conditions of increased and decreased myocardial contractility in each animal. Paired comparisons were made for different load states using the Wilcoxon’s Signed Rank test. Results The inferior vena cava balloon occlusion (IVCBO load change compared for first to last beat resulted in LV twist increase (11.67° ±2.65° vs. 16.17° ±3.56° respectively, p  Conclusions Peak systolic LV twist and peak early diastolic untwisting rate are load dependent. Differences in LV load should be included in the interpretation when serial measures of twist are compared.

  8. Lesion dimensions during temperature-controlled radiofrequency catheter ablation of left ventricular porcine myocardium: impact of ablation site, electrode size, and convective cooling

    DEFF Research Database (Denmark)

    Høgh Petersen, H; Chen, X; Pietersen, A

    1999-01-01

    It is important to increase lesion size to improve the success rate for radiofrequency ablation of ischemic ventricular tachycardia. This study of radiofrequency ablation, with adjustment of power to approach a preset target temperature, ie, temperature-controlled ablation, explores the effect of...

  9. Right ventricular function during one-lung ventilation: effects of pressure-controlled and volume-controlled ventilation.

    Science.gov (United States)

    Al Shehri, Abdullah M; El-Tahan, Mohamed R; Al Metwally, Roshdi; Qutub, Hatem; El Ghoneimy, Yasser F; Regal, Mohamed A; Zien, Haytham

    2014-08-01

    To test the effects of pressure-controlled (PCV) and volume-controlled (VCV) ventilation during one-lung ventilation (OLV) for thoracic surgery on right ventricular (RV) function. A prospective, randomized, double-blind, controlled, crossover study. A single university hospital. Fourteen pairs of consecutive patients scheduled for elective thoracotomy. Patients were assigned randomly to ventilate the dependent lung with PCV or VCV mode, each in a randomized crossover order using tidal volume of 6 mL/kg, I: E ratio 1: 2.5, positive end-expiratory pressure (PEEP) of 5 cm H2O and respiratory rate adjusted to maintain normocapnia. Intraoperative changes in RV function (systolic and early diastolic tricuspid annular velocity (TAV), end-systolic volume (ESV), end-diastolic volume (EDV) and fractional area changes (FAC)), airway pressures, compliance and oxygenation index were recorded. The use of PCV during OLV resulted in faster systolic (10.1±2.39 vs. 5.8±1.67 cm/s, respectively), diastolic TAV (9.2±1.99 vs. 4.6±1.42 cm/s, respectively) (p<0.001) and compliance and lower ESV, EDV and airway pressures (p<0.05) than during the use of VCV. Oxygenation indices were similar during the use of VCV and PCV. The use of PCV offers more improved RV function than the use of VCV during OLV for open thoracotomy. These results apply specifically to younger patients with good ventricular and pulmonary functions. © 2014 Elsevier Inc. All rights reserved.

  10. Speed control variable rate irrigation

    Science.gov (United States)

    Speed control variable rate irrigation (VRI) is used to address within field variability by controlling a moving sprinkler’s travel speed to vary the application depth. Changes in speed are commonly practiced over areas that slope, pond or where soil texture is predominantly different. Dynamic presc...

  11. Chemical ablation of the Purkinje system causes early termination and activation rate slowing of long-duration ventricular fibrillation in dogs.

    Science.gov (United States)

    Dosdall, Derek J; Tabereaux, Paul B; Kim, Jong J; Walcott, Gregory P; Rogers, Jack M; Killingsworth, Cheryl R; Huang, Jian; Robertson, Peter G; Smith, William M; Ideker, Raymond E

    2008-08-01

    Endocardial mapping has suggested that Purkinje fibers may play a role in the maintenance of long-duration ventricular fibrillation (LDVF). To determine the influence of Purkinje fibers on LDVF, we chemically ablated the Purkinje system with Lugol solution and recorded endocardial and transmural activation during LDVF. Dog hearts were isolated and perfused, and the ventricular endocardium was exposed and treated with Lugol solution (n = 6) or normal Tyrode solution as a control (n = 6). The left anterior papillary muscle endocardium was mapped with a 504-electrode (21 x 24) plaque with electrodes spaced 1 mm apart. Transmural activation was recorded with a six-electrode plunge needle on each side of the plaque. Ventricular fibrillation (VF) was induced, and perfusion was halted. LDVF spontaneously terminated sooner in Lugol-ablated hearts than in control hearts (4.9 +/- 1.5 vs. 9.2 +/- 3.2 min, P = 0.01). After termination of VF, both the control and Lugol hearts were typically excitable, but only short episodes of VF could be reinduced. Endocardial activation rates were similar during the first 2 min of LDVF for Lugol-ablated and control hearts but were significantly slower in Lugol hearts by 3 min. In control hearts, the endocardium activated more rapidly than the epicardium after 4 min of LDVF with wave fronts propagating most often from the endocardium to epicardium. No difference in transmural activation rate or wave front direction was observed in Lugol hearts. Ablation of the subendocardium hastens VF spontaneous termination and alters VF activation sequences, suggesting that Purkinje fibers are important in the maintenance of LDVF.

  12. An optimal controller for an electric ventricular-assist device: theory, implementation, and testing

    Science.gov (United States)

    Klute, G. K.; Tasch, U.; Geselowitz, D. B.

    1992-01-01

    This paper addresses the development and testing of an optimal position feedback controller for the Penn State electric ventricular-assist device (EVAD). The control law is designed to minimize the expected value of the EVAD's power consumption for a targeted patient population. The closed-loop control law is implemented on an Intel 8096 microprocessor and in vitro test runs show that this controller improves the EVAD's efficiency by 15-21%, when compared with the performance of the currently used feedforward control scheme.

  13. Blood pressure control and left ventricular hypertrophy in ...

    African Journals Online (AJOL)

    Medicine, Federal Medical Centre, PMB 3031 Sapon, Abeokuta, Ogun State, Nigeria, 2Department of Accident and. Emergency, University ... Conclusion: Clinic blood pressure is an ineffective way of assessing BP control. Thus in apparently ..... Relationship between the level, pattern and variability of ambulatory blood.

  14. Selective heart rate reduction with ivabradine slows ischaemia-induced electrophysiological changes and reduces ischaemia–reperfusion-induced ventricular arrhythmias

    Science.gov (United States)

    Ng, Fu Siong; Shadi, Iqbal T.; Peters, Nicholas S.; Lyon, Alexander R.

    2013-01-01

    Heart rates during ischaemia and reperfusion are possible determinants of reperfusion arrhythmias. We used ivabradine, a selective If current inhibitor, to assess the effects of heart rate reduction (HRR) during ischaemia–reperfusion on reperfusion ventricular arrhythmias and assessed potential anti-arrhythmic mechanisms by optical mapping. Five groups of rat hearts were subjected to regional ischaemia by left anterior descending artery occlusion for 8 min followed by 10 min of reperfusion: (1) Control n = 10; (2) 1 μM of ivabradine perfusion n = 10; (3) 1 μM of ivabradine + 5 Hz atrial pacing throughout ischaemia–reperfusion n = 5; (4) 1 μM of ivabradine + 5 Hz pacing only at reperfusion; (5) 100 μM of ivabradine was used as a 1 ml bolus upon reperfusion. For optical mapping, 10 hearts (ivabradine n = 5; 5 Hz pacing n = 5) were subjected to global ischaemia whilst transmembrane voltage transients were recorded. Epicardial activation was mapped, and the rate of development of ischaemia-induced electrophysiological changes was assessed. HRR observed in the ivabradine group during both ischaemia (195 ± 11 bpm vs. control 272 ± 14 bpm, p hearts (27.7 ± 4.3 min vs. 14.5 ± 0.6 min, p Heart rate during ischaemia is a major determinant of reperfusion arrhythmias. Heart rate at reperfusion alone was not a determinant of reperfusion VF, as neither a bolus of ivabradine nor pacing immediately prior to reperfusion significantly altered reperfusion VF incidence. This anti-arrhythmic effect of heart rate reduction during ischaemia may reflect slower development of ischaemia-induced electrophysiological changes. PMID:23402927

  15. Temporary epicardial cardiac resynchronisation versus conventional right ventricular pacing after cardiac surgery: study protocol for a randomised control trial

    Directory of Open Access Journals (Sweden)

    Russell Stuart J

    2012-02-01

    Full Text Available Abstract Background Heart failure patients with stable angina, acute coronary syndromes and valvular heart disease may benefit from revascularisation and/or valve surgery. However, the mortality rate is increased- 5-30%. Biventricular pacing using temporary epicardial wires after surgery is a potential mechanism to improve cardiac function and clinical endpoints. Method/design A multi-centred, prospective, randomised, single-blinded, intervention-control trial of temporary biventricular pacing versus standard pacing. Patients with ischaemic cardiomyopathy, valvular heart disease or both, an ejection fraction ≤ 35% and a conventional indication for cardiac surgery will be recruited from 2 cardiac centres. Baseline investigations will include: an electrocardiogram to confirm sinus rhythm and measure QRS duration; echocardiogram to evaluate left ventricular function and markers of mechanical dyssynchrony; dobutamine echocardiogram for viability and blood tests for renal function and biomarkers of myocardial injury- troponin T and brain naturetic peptide. Blood tests will be repeated at 18, 48 and 72 hours. The principal exclusions will be subjects with permanent atrial arrhythmias, permanent pacemakers, infective endocarditis or end-stage renal disease. After surgery, temporary pacing wires will be attached to the postero-lateral wall of the left ventricle, the right atrium and right ventricle and connected to a triple chamber temporary pacemaker. Subjects will be randomised to receive either temporary biventricular pacing or standard pacing (atrial inhibited pacing or atrial-synchronous right ventricular pacing for 48 hours. The primary endpoint will be the duration of level 3 care. In brief, this is the requirement for invasive ventilation, multi-organ support or more than one inotrope/vasoconstrictor. Haemodynamic studies will be performed at baseline, 6, 18 and 24 hours after surgery using a pulmonary arterial catheter. Measurements will be

  16. Severe Sepsis Manifesting as A-Fib with Rapid Ventricular Rate

    Directory of Open Access Journals (Sweden)

    Paul Nicholson

    2018-01-01

    Full Text Available Audience: This simulation is designed to educate emergency medicine residents and medical students on the diagnosis and management of an adult patient with sepsis due to a decubitus ulcer manifesting as acute-onset atrial fibrillation (A-fib with rapid ventricular response (RVR. Introduction: Adult patients frequently present critically ill from sepsis. Proper diagnosis and management require a focused but thorough history and physical exam, as well as an appropriate diagnostic workup. Management includes aggressive care with antibiotics and intravenous fluids, and may require vasoactive agents. Objectives: Learners will be able to identify and manage atrial fibrillation with rapid ventricular response. Additionally, learners will be able to identify the concurrent infection and determine the appropriate management in the setting of A-fib with RVR. The case also provides learners with the opportunity to review principles of leadership, teamwork, and effective communication. Method: This session was conducted using high-fidelity simulation, followed by a debriefing session.

  17. Systolic left ventricular function is preserved during therapeutic hypothermia, also during increases in heart rate with impaired diastolic filling.

    Science.gov (United States)

    Kerans, Viesturs; Espinoza, Andreas; Skulstad, Helge; Halvorsen, Per Steinar; Edvardsen, Thor; Bugge, Jan Frederik

    2015-12-01

    Systolic left ventricular function during therapeutic hypothermia is found both to improve and to decline. We hypothesized that this discrepancy would depend on the heart rate and the variables used to assess systolic function. In 16 pigs, cardiac performance was assessed by measurements of invasive pressures and thermodilution cardiac output and with 2D strain echocardiography. Left ventricle (LV) volumes, ejection fraction (EF), transmitral flow, and circumferential and longitudinal systolic strain were measured. Miniaturized ultrasonic transducers were attached to the epicardium of the LV to obtain M-mode images, systolic thickening, and diastolic thinning velocities and to determine LV pressure-wall dimension relationships. Preload recruitable stroke work (PRSW) was calculated. Measurements were performed at 38 and 33°C at spontaneous and paced heart rates, successively increased in steps of 20 up to the toleration limit. Effects of temperature and heart rate were compared in a mixed model analysis. Hypothermia reduced heart rate from 87 ± 10 (SD) to 76 ± 11 beats/min without any changes in LV stroke volume, end-diastolic volume, EF, strain values, or PRSW. Systolic wall thickening velocity (S') and early diastolic wall thinning velocity decreased by approximately 30%, making systolic duration longer through a prolonged and slow contraction and changing the diastolic filling pattern from predominantly early towards late. Pacing reduced diastolic duration much more during hypo- than during normothermia, and combined with slow myocardial relaxation, incomplete relaxation occurred with all pacing rates. Pacing did not affect S' or PRSW at physiological heart rates, but stroke volume, end-diastolic volume, and strain were reduced as a consequence of reduced diastolic filling and much more accentuated during hypothermia. At the ultimate tolerable heart rate during hypothermia, S' decreased, probably as a consequence of myocardial hypoperfusion due to

  18. Modeling and control of a brushless DC axial flow ventricular assist device.

    Science.gov (United States)

    Giridharan, Guruprasad A; Skliar, Mikhail; Olsen, Donald B; Pantalos, George M

    2002-01-01

    This article presents an integrated model of the human circulatory system that incorporates circulatory support by a brushless DC axial flow ventricular assist device (VAD), and a feedback VAD controller designed to maintain physiologically sufficient perfusion. The developed integrated model combines a network type model of the circulatory system with a nonlinear dynamic model of the brushless DC pump We show that maintaining a reference differential pressure between the left ventricle and aorta leads to adequate perfusion for different pathologic cases, ranging from normal heart to left heart asystole, and widely varying physical activity scenarios from rest to exercise.

  19. Neural control of left ventricular contractility in the dog heart: synaptic interactions of negative inotropic vagal preganglionic neurons in the nucleus ambiguus with tyrosine hydroxylase immunoreactive terminals.

    Science.gov (United States)

    Massari, V J; Dickerson, L W; Gray, A L; Lauenstein, J M; Blinder, K J; Newsome, J T; Rodak, D J; Fleming, T J; Gatti, P J; Gillis, R A

    1998-08-17

    Recent physiological evidence indicates that vagal postganglionic control of left ventricular contractility is mediated by neurons found in a ventricular epicardial fat pad ganglion. In the dog this region has been referred to as the cranial medial ventricular (CMV) ganglion [J.L. Ardell, Structure and function of mammalian intrinsic cardiac neurons, in: J.A. Armour, J.L. Ardell (Eds.). Neurocardiology, Oxford Univ. Press, New York, 1994, pp. 95-114; B.X. Yuan, J.L. Ardell, D.A. Hopkins, A.M. Losier, J.A. Armour, Gross and microscopic anatomy of the canine intrinsic cardiac nervous system, Anat. Rec., 239 (1994) 75-87]. Since activation of the vagal neuronal input to the CMV ganglion reduces left ventricular contractility without influencing cardiac rate or AV conduction, this ganglion contains a functionally selective pool of negative inotropic parasympathetic postganglionic neurons. In the present report we have defined the light microscopic distribution of preganglionic negative inotropic neurons in the CNS which are retrogradely labeled from the CMV ganglion. Some tissues were also processed for the simultaneous immunocytochemical visualization of tyrosine hydroxylase (TH: a marker for catecholaminergic neurons) and examined with both light microscopic and electron microscopic methods. Histochemically visualized neurons were observed in a long slender column in the ventrolateral nucleus ambiguus (NA-VL). The greatest number of retrogradely labeled neurons were observed just rostral to the level of the area postrema. TH perikarya and dendrites were commonly observed interspersed with vagal motoneurons in the NA-VL. TH nerve terminals formed axo-dendritic synapses upon negative inotropic vagal motoneurons, however the origin of these terminals remains to be determined. We conclude that synaptic interactions exist which would permit the parasympathetic preganglionic vagal control of left ventricular contractility to be modulated monosynaptically by

  20. Computational analysis of the effect of the control model of intraaorta pump on ventricular unloading and vessel response.

    Science.gov (United States)

    Gu, Kaiyun; Chang, Yu; Gao, Bin; Liu, Youjun

    2012-01-01

    The intraaorta pump is a novel left ventricular assist device (LVAD) whose hemodynamic effects on the circulatory system is unknown. This article aims to evaluate the different effects on the circulatory system supported by the intraaorta pump. In this article, the pump is controlled by three control strategies, including the continuous flow method, the constant rotational speed, and the constant pressure head. A cardiovascular pump system, which includes cardiovascular circulation, intraaorta pump, and regulating mechanisms of systemic circulation, has been proposed. Left ventricle pressure (LVP), end-diastolic volume (EDV), and left ventricular external work (LVEW) were used to evaluate the degree of ventricular unloading. The pulsatile index (PI), which is defined as a ratio of pulse pressure and mean arterial pressure (MAP), was used to evaluate the effect of the vessel response by three control strategies. The comparison results showed that LVP and EDV were lower than those measured before the intraaorta pump was implanted. For LVEW, the constant pressure head strategy provided a superior ventricular unloading compared with other strategies. Support of the pump led to the lower pulsatility by the three models. However, the PI of the constant pressure head was the most at 0.37. In conclusion, these results indicate that the intraaorta pump controlled by constant pressure head strategy provides superior ventricular unloading and pulsatility of the vessel.

  1. Mapping correlations between ventricular expansion and CSF amyloid and tau biomarkers in 240 subjects with Alzheimer's disease, mild cognitive impairment and elderly controls.

    Science.gov (United States)

    Chou, Yi-Yu; Leporé, Natasha; Avedissian, Christina; Madsen, Sarah K; Parikshak, Neelroop; Hua, Xue; Shaw, Leslie M; Trojanowski, John Q; Weiner, Michael W; Toga, Arthur W; Thompson, Paul M

    2009-06-01

    We aimed to improve on the single-atlas ventricular segmentation method of (Carmichael, O.T., Thompson, P.M., Dutton, R.A., Lu, A., Lee, S.E., Lee, J.Y., Kuller, L.H., Lopez, O.L., Aizenstein, H.J., Meltzer, C.C., Liu, Y., Toga, A.W., Becker, J.T., 2006. Mapping ventricular changes related to dementia and mild cognitive impairment in a large community-based cohort. IEEE ISBI. 315-318) by using multi-atlas segmentation, which has been shown to lead to more accurate segmentations (Chou, Y., Leporé, N., de Zubicaray, G., Carmichael, O., Becker, J., Toga, A., Thompson, P., 2008. Automated ventricular mapping with multi-atlas fluid image alignment reveals genetic effects in Alzheimer's disease, NeuroImage 40(2): 615-630); with this method, we calculated minimal numbers of subjects needed to detect correlations between clinical scores and ventricular maps. We also assessed correlations between emerging CSF biomarkers of Alzheimer's disease pathology and localizable deficits in the brain, in 80 AD, 80 mild cognitive impairment (MCI), and 80 healthy controls from the Alzheimer's Disease Neuroimaging Initiative. Six expertly segmented images and their embedded parametric mesh surfaces were fluidly registered to each brain; segmentations were averaged within subjects to reduce errors. Surface-based statistical maps revealed powerful correlations between surface morphology and 4 variables: (1) diagnosis, (2) depression severity, (3) cognitive function at baseline, and (4) future cognitive decline over the following year. Cognitive function was assessed using the mini-mental state exam (MMSE), global and sum-of-boxes clinical dementia rating (CDR) scores, at baseline and 1-year follow-up. Lower CSF Abeta(1-42) protein levels, a biomarker of AD pathology assessed in 138 of the 240 subjects, were correlated with lateral ventricular expansion. Using false discovery rate (FDR) methods, 40 and 120 subjects, respectively, were needed to discriminate AD and MCI from normal groups

  2. Effect of Dietary Omega-3 Polyunsaturated Fatty Acids on Heart Rate and Heart Rate Variability in Animals Susceptible or Resistant to Ventricular Fibrillation

    Directory of Open Access Journals (Sweden)

    George E Billman

    2012-03-01

    Full Text Available The consumption of omega-3 polyunsaturated fatty acids (n-3 PUFAs has been reported to reduce cardiac mortality following myocardial infarction as well as to decrease resting heart rate (HR and increase heart rate variability (HRV. However, it has not been established whether n-3 PUFAs exhibit the same actions on HR and HRV in individuals known to be either susceptible or resistant to ventricular fibrillation (VF. Therefore, HR and HRV (high frequency and total R-R interval variability were evaluated before and 3 months after n-3 PUFA treatment in dogs with healed myocardial infarction that were either susceptible (VF+, n = 31 or resistant (VF-, n = 31 to ventricular tachyarrhythmias induced by a 2 min coronary artery occlusion during the last minute of a submaximal exercise test. HR and HRV were evaluated at rest, during submaximal exercise and in response to acute myocardial ischemia at rest before and after either placebo (1 g/day, corn oil, VF+, n = 9; VF- n = 8 or n-3 PUFA (docosahexaenoic acid + eicosapentaenoic acid ethyl esters, 1-4g/day, VF+, n = 22; VF-, n = 23 treatment for 3 months. The n-3 PUFA treatment elicited similar increases in red blood cell membrane, right atrial, and left ventricular n-3 PUFA levels in both the VF+ and VF- dogs. The n-3 PUFA treatment also provoked similar reductions in baseline HR and increases in baseline HRV in both groups that resulted in parallel shifts in the response to either exercise or acute myocardial ischemia (that is, the change in these variables induced by physiological challenges was not altered after n-3 PUFA treatment. These data demonstrate that dietary n-3 PUFA decreased HR and increased HRV to a similar extent in animals known to be prone to or resistant to malignant cardiac tachyarrhythmias.

  3. Left ventricular long axis tissue Doppler systolic velocity is independently related to heart rate and body size.

    Science.gov (United States)

    Peverill, Roger E; Chou, Bon; Donelan, Lesley

    2017-01-01

    The physiological factors which affect left ventricular (LV) long-axis function are not fully defined. We investigated the relationships of resting heart rate and body size with the peak velocities and amplitudes of LV systolic and early diastolic long axis motion, and also with long-axis contraction duration. Two groups of adults free of cardiac disease underwent pulsed-wave tissue Doppler imaging at the septal and lateral mitral annular borders. Group 1 (n = 77) were healthy subjects heart rate, height or body surface area (BSA) for either LV wall in either group, but SDur was inversely correlated with heart rate for both walls and both groups, and after adjustment for heart rate, males in both groups had a shorter septal SDur. Septal and lateral s` were independently and positively correlated with SExc, heart rate and height in both groups, independent of sex and age. There were no correlations of heart rate, height or BSA with either e` or EDExc for either wall in either group. Heart rate and height independently modify the relationship between s` and SExc, but neither are related to EDExc or e`. These findings suggest that s` and SExc cannot be used interchangeably for the assessment of LV long-axis contraction.

  4. ECMO Used in a Refractory Ventricular Tachycardia and Ventricular Fibrillation Patient: A National Case-Control Study.

    Science.gov (United States)

    Chen, Chih-Yu; Tsai, Ju; Hsu, Tai-Yi; Lai, Wan-Yu; Chen, Wei-Kung; Muo, Chih-Hsin; Kao, Chia-Hung

    2016-03-01

    Refractory cardiac arrhythmia, which has a poor response to defibrillation and antiarrhythmia medication, is a complicated problem for clinical physicians during resuscitation. Extracorporeal membrane oxygenation (ECMO) may be used to sustain life in this situation. ECMO is useful for cardiopulmonary resuscitation among patients suffering from cardiac arrest; the use of ECMO in this context is called E-cardiopulmonary resuscitation. However, a large-scale and nationwide survey of ECMO usage in cases involving refractory cardiac arrhythmia during resuscitation is lacking. We aimed to clarify the characteristics and efficacy of the application of ECMO in cases involving refractory cardiac arrhythmia during resuscitation by conducting a nationwide study. Using national insurance data from 1996 to 2011, 2702 patients who received defibrillation and amiodarone injections were selected. We excluded trauma patients (n = 316) and those aged1 day was higher risk of death (OR = 2.88, 95% CI = 1.27-6.53). In our retrospective case control study in refractory cardiac arrhythmia patients, ECMO supportive in high propensity score patients showed improving the overall survival rate but ECMO support for >1 day would be harmful. The evidence derived from this retrospective study using data from the national insurance system is generally of lower methodological evidence than that from randomized controlled trials because a retrospective study is subject to many biases due to lack of the necessary adjustments for possible confounding factors. Therefore, further investigation with a randomized clinical trial is needed to recommend ECMO as a routine in this specific population of patients experiencing cardiac arrest and refractory VT and VF.

  5. Clinical significance of exercise-induced left ventricular wall motion abnormality occurring at a low heart rate

    Energy Technology Data Exchange (ETDEWEB)

    Kimchi, A.; Rozanski, A.; Fletcher, C.; Maddahi, J.; Swan, H.J.; Berman, D.S.

    1987-10-01

    We studied the relationship between the heart rate at the time of onset of exercise-induced wall motion abnormality and the severity of coronary artery disease in 89 patients who underwent exercise equilibrium radionuclide ventriculography as part of their evaluation for coronary artery disease. Segmental wall motion was scored with a five-point system (3 = normal; -1 = dyskinesis); a decrease of one score defined the onset of wall motion abnormality. The onset of wall motion abnormality at less than or equal to 70% of maximal predicted heart rate had 100% predictive accuracy for coronary artery disease and higher sensitivity than the onset of ischemic ST segment depression at similar heart rate during exercise: 36% (25 of 69 patients with coronary disease) vs 19% (13 of 69 patients), p = 0.01. Wall motion abnormality occurring at less than or equal to 70% of maximal predicted heart rate was present in 49% of patients (23 of 47) with critical stenosis (greater than or equal to 90% luminal diameter narrowing), and in only 5% of patients (2 of 42) without such severe stenosis, p less than 0.001. The sensitivity of exercise-induced wall motion abnormality occurring at a low heart rate for the presence of severe coronary artery disease was similar to that of a deterioration in wall motion by more than two scores during exercise (49% vs 53%) or an absolute decrease of greater than or equal to 5% in exercise left ventricular ejection fraction (49% vs 45%).

  6. Left ventricular mechanics in humans with high aerobic fitness: adaptation independent of structural remodelling, arterial haemodynamics and heart rate

    Science.gov (United States)

    Stöhr, Eric J; McDonnell, Barry; Thompson, Jane; Stone, Keeron; Bull, Tom; Houston, Rory; Cockcroft, John; Shave, Rob

    2012-01-01

    Individuals with high aerobic fitness have lower systolic left ventricular strain, rotation and twist (‘left ventricular (LV) mechanics’) at rest, suggesting a beneficial reduction in LV myofibre stress and more efficient systolic function. However, the mechanisms responsible for this functional adaptation are not known and the influence of aerobic fitness on LV mechanics during dynamic exercise has never been studied. We assessed LV mechanics, LV wall thickness and dimensions, central augmentation index (AIx), aortic pulse wave velocity (aPWV), blood pressure and heart rate in 28 males (age: 21 ± 2 years SD) with a consistent physical activity level (no change >6 months). Individuals were examined at rest and during exercise (40% peak exercise capacity) and separated post hoc into a moderate and high aerobic fitness group (: 49 ± 5 and 63 ± 7 ml kg−1 min−1, respectively, P 0.05). However, for the same AIx, the high group had significantly lower LV apical rotation (P = 0.002) and LV twist (P = 0.003) while basal rotation and strain indices did not differ between groups (P > 0.05). We conclude that young males with high aerobic fitness have lower LV apical rotation at rest and during submaximal exercise that can occur without changes in gross LV structure, arterial haemodynamics or heart rate. The findings suggest a previously unknown type of physiological adaptation of the left ventricle that may have important implications for exercise training in older individuals and patient populations in which exercise training has previously failed to show clear benefits for LV function. PMID:22431336

  7. Verapamil induced ventricular hypertrophy in conscious dogs.

    Science.gov (United States)

    French, W J; Garner, D; Adomian, G E; Averill, W; Laks, M M

    1989-08-01

    Verapamil is used clinically in the treatment of various cardiac diseases including hypertrophic cardiomyopathy. Its long term effects on ventricular mass are not well known. In 11 conscious dogs heart rate, aortic and left ventricular pressures, cardiac output, a methoxamine induced stress ventricular function test and left ventriculography were performed. These variables were measured prior to and following a mean 7.2 month infusion of verapamil at 0.005 or 0.01 mg.kg-1.min-1 using a subcutaneously implanted pump. Resting haemodynamic variables and left ventricular ejection fraction [60(SD 6) v 55(6)%] were unchanged between baseline and chronic verapamil studies, but the slope of the methoxamine induced stress ventricular function test decreased from 3.9(0.8) to 2.1 (1.3). After verapamil was discontinued the mean slope of the stress ventricular function test returned to the baseline 4.0(1.7). Total ventricular weight increased 22% from 176.1(17.5) g.m-2 in controls to 215.6(29.5) g.m-2 (p less than 0.01) in the verapamil animals. The right ventricular weight increased 25% from 46(5.9) to 57.6(9.1) g.m-2 (p less than 0.01); the septum weight increased 26% from 42.5(4.1) to 53.7(7.2) g.m-2 (p less than 0.001); and the left ventricular free wall weight increased 19% from 87.4(9.8) to 103.9(15.7) g.m-2 (p less than 0.01). The increase in ventricular weights was not due to fibrosis or oedema since hydroxyproline contents and wet/dry ratios were not increased. In conclusion, a chronic infusion of verapamil in conscious dogs caused no change in resting haemodynamic variables but produced reversible depression of stress ventricular function and biventricular and septal hypertrophy.

  8. Heart Rate and V˙O2 Concordance in Continuous-Flow Left Ventricular Assist Devices.

    Science.gov (United States)

    Kerrigan, Dennis J; Williams, Celeste T; Brawner, Clinton A; Ehrman, Jonathan K; Saval, Matthew A; Peterson, Edward L; Lanfear, David E; Tita, Christina; Velez, Mauricio; Selektor, Yelena; Keteyian, Steven J

    2016-03-01

    The American College of Sports Medicine currently recommends the HR reserve (HRR) method to guide exercise in individuals who have heart failure with reduced ejection fraction. This recommendation is based on the known association between %HRR and percentage of V˙O2 reserve (%V˙O2R) in this population. However, to our knowledge, no studies exist regarding this relation in individuals with a left ventricular assist device (LVAD). This article aimed to describe the relation between V˙O2 and surrogate markers of exercise intensity among patients with LVAD. Patients with continuous-flow LVAD (n = 24, seven females) completed a symptom-limited graded exercise test on a treadmill. HR and V˙O2 were measured continuously and averaged every 20 s. Regression equations were determined using a generalized estimating equation to predict %V˙O2R from %HRR, Borg RPE, and LVAD flow, overall and stratified by presence of pacing. Although the association between %HRR and %V˙O2R was good (R = 0.75), the slope and y-intercept for %HRR versus %V˙O2R was different from the line of identity (P = 0.002). However, when paced subjects were excluded (n = 8) from the analysis, there was no significant difference between the slope and y-intercept (= 0.036 + 0.937 × %HRR; SEE, 2%; P = 0.052). RPE showed a strong association with %V˙O2R (R = 0.84), whereas LVAD flow showed a weak (albeit statistically significant) association (R = 0.05). Both had slopes and y-intercepts that were different from the line of identity (P intensity.

  9. Pharmacologic and nonpharmacologic treatment of ventricular arrhythmias in heart failure.

    Science.gov (United States)

    Stevenson, W G; Sweeney, M O

    1997-05-01

    Ventricular arrhythmias are common in patients with heart failure. The risk and benefits of antiarrhythmic therapies continue to be defined. Class I antiarrhythmic drugs should be avoided due to proarrhythmic and negative inotropic effects that may be responsible for increased mortality in some trials. For patients resuscitated from sustained ventricular tachycardia or ventricular fibrillation, amiodarone or an implantable cardioverter-defibrillator should be considered. Implantable cardioverter-defibrillators markedly reduce sudden death in ventricular tachycardia and ventricular fibrillation survivors, but in advanced heart failure, this may not markedly extend survival. Catheter or surgical ablation can be considered for selected patients with bundle branch reentry ventricular tachycardia or difficult to control monomorphic ventricular tachycardia. For patients who have not had sustained ventricular tachycardia or ventricular fibrillation antiarrhythmic therapy should generally be avoided, but may benefit some high risk patients. Amiodarone may be beneficial in patients with advanced heart failure and rapid resting heart rates. Implantable cardioverter-defibrillators may improve survival in selected patients with depressed ventricular function after myocardial infarction, who also have nonsustained and inducible ventricular tachycardia.

  10. A network physiology approach to the assessment of the link between sinoatrial and ventricular cardiac controls.

    Science.gov (United States)

    Porta, Alberto; Bari, Vlasta; De Maria, Beatrice; Baumert, Mathias

    2017-06-27

    A network physiology approach to evaluate the strength of the directed interactions among cardiac controls at sinoatrial and ventricular levels and respiration (R) is proposed. The network is composed of three nodes (i.e. sinoatrial and ventricular cardiac controls and R) and their activity is exemplified by the variability of heart period (HP), the variability of the duration of the electrical activity of the heart approximated as the temporal distance between Q-wave onset and T-wave end or apex (i.e. QTe or QTa) and thoracic movements respectively. Model-based transfer entropy provided the estimate of the strength of the causal link from the source to the destination conditioned on the remaining node activity. The interactions were monitored in 15 healthy subjects aged from 24 to 54 years (9 males). Increasing levels of sympathetic activity were induced by graded head-up tilt with table inclination of 0, 15, 30, 45, 60, 75°. We found that: (i) the strength of the causal link from HP to QTe gradually decreases with tilt table angle, while that in the reverse direction is weak, even though significant, and constant; (ii) the action of R on HP is stronger than that from R to QTe; (iii) the strength of the relation from R to HP is weakly related to tilt table inclination, while that from R to QTe does not depend on it; (iv) while QTe cannot affect R, a weak causal dependence of R on HP is detected; (v) the network computed over QTa is qualitatively similar to that over QTe, even though the strength of the causal relations might be different. The proposed network physiology approach provides a comprehensive picture of the directed links among relevant cardiac regulatory mechanisms and their evolution with sympathetic tone usable to identify pathological conditions.

  11. Resting Heart Rate as Predictor for Left Ventricular Dysfunction and Heart Failure: The Multi-Ethnic Study of Atherosclerosis

    Science.gov (United States)

    Opdahl, Anders; Venkatesh, Bharath Ambale; Fernandes, Veronica R. S.; Wu, Colin O.; Nasir, Khurram; Choi, Eui-Young; Almeida, Andre L. C.; Rosen, Boaz; Carvalho, Benilton; Edvardsen, Thor; Bluemke, David A.; Lima, Joao A. C.

    2014-01-01

    OBJECTIVE To investigate the relationship between baseline resting heart rate and incidence of heart failure (HF) and global and regional left ventricular (LV) dysfunction. BACKGROUND The association of resting heart rate to HF and LV function is not well described in an asymptomatic multi-ethnic population. METHODS Participants in the Multi-Ethnic Study of Atherosclerosis had resting heart rate measured at inclusion. Incident HF was registered (n=176) during follow-up (median 7 years) in those who underwent cardiac MRI (n=5000). Changes in ejection fraction (ΔEF) and peak circumferential strain (Δεcc) were measured as markers of developing global and regional LV dysfunction in 1056 participants imaged at baseline and 5 years later. Time to HF (Cox model) and Δεcc and ΔEF (multiple linear regression models) were adjusted for demographics, traditional cardiovascular risk factors, calcium score, LV end-diastolic volume and mass in addition to resting heart rate. RESULTS Cox analysis demonstrated that for 1 bpm increase in resting heart rate there was a 4% greater adjusted relative risk for incident HF (Hazard Ratio: 1.04 (1.02, 1.06 (95% CI); Pheart rate was positively associated with deteriorating εcc and decrease in EF, even in analyses when all coronary heart disease events were excluded from the model. CONCLUSION Elevated resting heart rate is associated with increased risk for incident HF in asymptomatic participants in MESA. Higher heart rate is related to development of regional and global LV dysfunction independent of subclinical atherosclerosis and coronary heart disease. PMID:24412444

  12. Resting heart rate as predictor for left ventricular dysfunction and heart failure: MESA (Multi-Ethnic Study of Atherosclerosis).

    Science.gov (United States)

    Opdahl, Anders; Ambale Venkatesh, Bharath; Fernandes, Veronica R S; Wu, Colin O; Nasir, Khurram; Choi, Eui-Young; Almeida, Andre L C; Rosen, Boaz; Carvalho, Benilton; Edvardsen, Thor; Bluemke, David A; Lima, João A C

    2014-04-01

    The objective of this study was to investigate the relationship between baseline resting heart rate and incidence of heart failure (HF) and global and regional left ventricular (LV) dysfunction. The association of resting heart rate to HF and LV function has not been well described in an asymptomatic multi-ethnic population. Resting heart rate was measured in participants in the MESA (Multi-Ethnic Study of Atherosclerosis) trial at inclusion. Incident HF was registered (n = 176) during follow-up (median 7 years) in those who underwent cardiac magnetic resonance imaging (n = 5,000). Changes in ejection fraction (ΔEF) and peak circumferential strain (Δεcc) were measured as markers of developing global and regional LV dysfunction in 1,056 participants imaged at baseline and 5 years later. Time to HF (Cox model) and Δεcc and ΔEF (multiple linear regression models) were adjusted for demographics, traditional cardiovascular risk factors, calcium score, LV end-diastolic volume, and mass in addition to resting heart rate. Cox analysis demonstrated that for 1 beat/min increase in resting heart rate, there was a 4% greater adjusted relative risk for incident HF (hazard ratio: 1.04; 95% CI: 1.02 to 1.06; p heart rate was positively associated with deteriorating εcc and decrease in EF, even when all coronary heart disease events were excluded from the model. Elevated resting heart rate was associated with increased risk for incident HF in asymptomatic participants in the MESA trial. Higher heart rate was related to development of regional and global LV dysfunction independent of subclinical atherosclerosis and coronary heart disease. (Multi-Ethnic Study of Atherosclerosis [MESA]; NCT00005487). Copyright © 2014 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

  13. Effects of carvedilol therapy on cardiac autonomic control, QT dispersion, and ventricular arrhythmias in children with dilated cardiomyopathy.

    Science.gov (United States)

    Oflaz, Mehmet Burhan; Balli, Sevket; Kibar, Ayse Esin; Ece, Ibrahim; Akdeniz, Celal; Tuzcu, Volkan

    2013-05-15

    The purpose of this study was to examine the effects of carvedilol therapy on autonomic control of the heart and QT-interval dispersion (QTd) among children with idiopathic dilated cardiomyopathy (DCM) whose symptoms were not adequately controlled with standard congestive heart failure therapy. Patients with DCM who were treated with carvedilol were enrolled in the study. All patients had undergone carvedilol therapy in addition to standard therapy for at least 6 months. Clinical, echocardiographic, and electrocardiographic parameters, and 24-h Holter records of patients were retrospectively evaluated before and after carvedilol treatment. A total 34 patients (mean age: 7.4 ± 4.3 years) with DCM were analyzed in the study. The median follow-up period was 9.5 months. After the 6 months of carvedilol therapy the clinical score significantly improved, left ventricular ejection fraction (LVEF) and fractional shortening (LVFS) significantly increased, and left ventricle end-diastolic dimensions and end-systolic dimensions significantly decreased. There were statistically significant increases in mean SDNN, SDANN, rMSSD, and pNN50 (p = 0.002, p = 0.001, p = 0.008, and p = 0.026, respectively). After the carvedilol therapy, SDNN was correlated with the clinical score, heart rate, LVEF, LVFS, and total premature ventricular contractions (PVCs). In addition, rMSSD and pNN50 were correlated with heart rate, LVEF and LVFS. A significant reduction was observed in QTc-minimum, QTc-maximum, and QTd values (434.9 ± 40.7 vs. 416.1 ± 36.5, 497.8 ± 43.6 vs. 456.3 ± 41.7, 58.6 ± 17.1 vs. 49.3 ± 15.6; p < 0.001, p = 0.001, and p = 0.008, respectively). QTd was significantly related to PVCs (r = 0.62, p = 0.02). We conclude that the addition of carvedilol to standard therapy can improve clinical symptoms and heart rate variability, and reduce in arrhythmia markers in children with DCM.

  14. Lesion dimensions during temperature-controlled radiofrequency catheter ablation of left ventricular porcine myocardium

    DEFF Research Database (Denmark)

    Høgh Petersen, H; Chen, X; Pietersen, Adrian

    1999-01-01

    the effect of catheter-tip length, ablation site, and convective cooling on lesion dimensions. METHODS AND RESULTS: In vitro strips of porcine left ventricular myocardium during different levels of convective cooling and in vivo pig hearts at 2 or 3 left ventricular sites were ablated with 2- to 12-mm...

  15. Prognostic value of heart rate variability and ventricular arrhythmias during 13-year follow-up in patients with mild to moderate heart failure

    NARCIS (Netherlands)

    Smilde, Tom D. J.; van Veldhuisen, Dirk J.; van den Berg, Maarten P.

    In contrast to patients with moderate to severe chronic heart failure (CHF), data regarding long-term outcome in patients with mild CHF are scarce. We examined the place of Holter monitoring to study the prognostic value of ventricular arrhythmias and heart rate variability (HRV) in patients with

  16. Left Ventricular Myocardial Function in Children With Pulmonary Hypertension: Relation to Right Ventricular Performance and Hemodynamics.

    Science.gov (United States)

    Burkett, Dale A; Slorach, Cameron; Patel, Sonali S; Redington, Andrew N; Ivy, D Dunbar; Mertens, Luc; Younoszai, Adel K; Friedberg, Mark K

    2015-08-01

    Through ventricular interdependence, pulmonary hypertension (PH) induces left ventricular (LV) dysfunction. We hypothesized that LV strain/strain rate, surrogate measures of myocardial contractility, are reduced in pediatric PH and relate to invasive hemodynamics, right ventricular strain, and functional measures of PH. At 2 institutions, echocardiography was prospectively performed in 54 pediatric PH patients during cardiac catheterization, and in 54 matched controls. Patients with PH had reduced LV global longitudinal strain (LS; -18.8 [-17.3 to -20.4]% versus -20.2 [-19.0 to -20.9]%; P=0.0046) predominantly because of reduced basal (-12.9 [-10.8 to -16.3]% versus -17.9 [-14.5 to -20.7]%; Pright ventricular free-wall LS (r=0.64; Pright ventricular strain, and functional PH measures. © 2015 American Heart Association, Inc.

  17. Heart rate reduction for 36 months with ivabradine reduces left ventricular mass in cardiac allograft recipients: a long-term follow-up study.

    Science.gov (United States)

    Doesch, Andreas O; Mueller, Susanne; Erbel, Christian; Gleissner, Christian A; Frankenstein, Lutz; Hardt, Stefan; Ruhparwar, Arjang; Ehlermann, Philipp; Dengler, Thomas; Katus, Hugo A

    2013-01-01

    Due to graft denervation, sinus tachycardia is a common problem after heart transplantation, underlining the importance of heart rate control without peripheral effects. However, long-term data regarding the effects of ivabradine, a novel If channel antagonist, are limited in patients after heart transplantation. In this follow-up analysis, the resting heart rate, left ventricular mass indexed to body surface area (LVMI), tolerability, and safety of ivabradine therapy were evaluated at baseline and after 36 months in 30 heart transplant recipients with symptomatic sinus tachycardia versus a matched control group. During the study period, ivabradine medication was stopped in three patients (10% of total). Further analysis was based on 27 patients with 36 months of drug intake. The mean patient age was 53.3±11.3 years and mean time after heart transplantation was 5.0±4.8 years. After 36 months, the mean ivabradine dose was 12.0±3.4 mg/day. Resting heart rate was reduced from 91.0±10.7 beats per minute before initiation of ivabradine therapy (ie, baseline) to 81.2±9.8 beats per minute at follow-up (P=0.0006). After 36 months of ivabradine therapy, a statistically significant reduction of LVMI was observed (104.3±22.7 g at baseline versus 93.4±18.4 g at follow-up, P=0.002). Hematologic, renal, and liver function parameters remained stable during ivabradine therapy. Except for a lower mycophenolate mofetil dose at follow-up (P=0.02), no statistically significant changes in immunosuppressive drug dosage or blood levels were detected. No phosphenes were observed during 36 months of ivabradine intake despite active inquiry. In line with previously published 12-month data, heart rate reduction with ivabradine remained effective and safe in chronic stable patients after heart transplantation, and also during 36-month long-term follow-up. Further, a significant reduction of LVMI was observed only during ivabradine therapy. Therefore, ivabradine may have a sustained

  18. Rate Control Efficacy in Permanent Atrial Fibrillation : Successful and Failed Strict Rate Control Against a Background of Lenient Rate Control

    NARCIS (Netherlands)

    Groenveld, Hessel F.; Tijssen, Jan G. P.; Crijns, Harry J. G. M.; Van den Berg, Maarten P.; Hillege, Hans L.; Alings, Marco; Van Veldhuisen, Dirk J.; Van Gelder, Isabelle C.

    2013-01-01

    Objectives This study sought to investigate differences in outcome between patients treated with successful strict, failed strict, and lenient rate control. Background The RACE II (Rate Control Efficacy in Permanent Atrial Fibrillation) study showed no difference in outcome between lenient and

  19. Lack of effect of nitrogen dioxide exposure on heart rate variability in patients with stable coronary heart disease and impaired left ventricular systolic function.

    Science.gov (United States)

    Scaife, Alison; Barclay, Justin; Hillis, Graham S; Srinivasan, Janaki; Macdonald, David W; Ross, John A S; Ayres, Jon G

    2012-08-01

    Epidemiological studies of air pollution on cardiovascular health show associations of cardiac mortality and admissions with exposure to nitrogen dioxide (NO(2)) at low concentrations. These associations could be causal or NO(2) could be acting as a surrogate measure for another air pollutant, most likely ultrafine particles. No studies of cardiac susceptibility to acute exposure to NO(2) have been undertaken. Randomised controlled exposures to NO(2) (400 ppb for 1 h) and air in subjects with coronary heart disease and impaired left ventricular systolic function not taking β adrenoceptor blocking drugs. There were no significant changes in heart rate, blood pressure, leucocyte coping capacity or any heart rate variability measure following NO(2) exposure compared with air. These findings suggest that NO(2) does not affect heart rate variability at these concentrations (which are high for urban background levels) and in the absence of other pollutants. While a synergistic effect has not been ruled out, these data lend support to the idea that the epidemiological data associating cardiac outcomes with NO(2) are more likely due to an associated pollutant rather than NO(2) itself.

  20. Improvement of survival rate in patients with cardiogenic shock by using nonpulsatile and pulsatile ventricular assist device.

    Science.gov (United States)

    Minami, K; el-Banayosy, A; Posival, H; Seggewiss, H; Murray, E; Körner, M M; Körfer, R

    1992-12-01

    Between January 1988 and January 1992, 65 patients (pts) had a ventricle assist device (VAD) inserted in our clinic. In 24 pts a VAD was applied because of primarily unsuccessful weaning from cardiopulmonary bypass (Group A). In a further 24 pts (Group B) a VAD was installed for the therapy of refractive cardiogenic shock (CS) after initially successful cardiac surgery (n = 21) and after acute myocardial infarction (n = 3). Twelve pts were bridged to heart transplantation (Group C) and five had a VAD inserted for various other reasons (Group D). In 36 (55.4%) of the total 65 pts a nonpulsatile VAD (Biomedicus 540) was used: 10 in Group A; 20 in B, 3 in C and 3 in D. In 29 pts (44.6%) a pulsatile VAD (Abiomed BVS 5000) was used: 14 in Group A, 4 in B, 9 in C and 2 in D. Weaning rate and long-term survival rates were 50% and 46% respectively in Group A and 38% and 42% in Group B. Seven pts from Group C were transplanted and six are long-term survivors. Two pts (40%) in Group D were discharged from hospital. Major postoperative complications were bleeding (46%), thromboembolism (14%), multiple organ failure (11%), renal failure (11%), arterial embolism (4.6%), sepsis (3%). The results indicate that application of a VAD can be recommended in pts with postcardiotomy CS to allow recovery of cardiac function and in pts with irreversible ventricular damage as bridging to HTX.

  1. Noninvasive assessment of left ventricular contractility in pediatric patients using the maximum rate of pressure rise in peripheral arteries.

    Science.gov (United States)

    Kawasaki, Hidenori; Seki, Mitsuru; Saiki, Hirofumi; Masutani, Satoshi; Senzaki, Hideaki

    2012-07-01

    The maximum rate of left ventricular pressure rise (LV dp/dt(max)) is a good indicator of ventricular contractility. However, its measurement requires invasive cardiac catheterization. By applying the relationship between the ratio of aorta (Ao) dp/dt(max) to LV dp/dt(max) and the mean artery pressure (MAP), we tested the possible noninvasive estimation of LV dp/dt(max) by the maximum rate of pressure rise in peripheral arteries, as measured by tonometry. The study subjects were 31 children with cardiovascular disease. The LV and Ao pressures were measured during cardiac catheterization, with simultaneous recording of the brachial (BrA) or radial (RaA) artery pressure. The relationships between BrA dp/dt(max) and Ao dp/dt(max) and between RaA dp/dt(max) and Ao dp/dt(max) were determined (Ao dp/dt(max) = 0.299 × BrA dp/dt(max) + 210.6, n = 17, r = 0.78, SEE = 74.0, P = 0.0002, and Ao dp/dt(max) = 1.442 × RaA dp/dt(max) + 165.9, n = 14, r = 0.87, SEE = 66.1, P = 0.0001). Using these relationships and the equation Ao dp/dt(max)/LV dp/dt(max) = 0.694 - 4.00 × 10(-3) × MAP, LV dp/dt(max) was estimated from BrA dp/dt(max) or RaA dp/dt(max). The estimated LV dp/dt(max) correlated well with the measured LV dp/dt(max) independent of the site of measurement (y = 0.912 × x + 112.9, r = 0.91, P measured and estimated LV dp/dt(max) after changes in contractility with dobutamine in 10 randomly selected patients (y = 0.86 × x + 34.2, r = 0.77, P = 0.01). It is possible to estimate LV dp/dt(max) noninvasively in children using tonometry. This procedure can be useful for bedside assessment of LV contractility and the clinical management of patients with cardiovascular disease.

  2. Effects of irregular cerebrospinal fluid production rate in human brain ventricular system

    Science.gov (United States)

    Hadzri, Edi Azali; Shamsudin, Amir Hamzah; Osman, Kahar; Abdul Kadir, Mohammed Rafiq; Aziz, Azian Abd

    2012-06-01

    Hydrocephalus is an abnormal accumulation of fluid in the ventricles and cavities in the brain. It occurs when the cerebrospinal fluid (CSF) flow or absorption is blocked or when excessive CSF is secreted. The excessive accumulation of CSF results in an abnormal widening of the ventricles. This widening creates potentially harmful pressure on the tissues of the brain. In this study, flow analysis of CSF was conducted on a three-dimensional model of the third ventricle and aqueduct of Sylvius, derived from MRI scans. CSF was modeled as Newtonian Fluid and its flow through the region of interest (ROI) was done using EFD. Lab software. Different steady flow rates through the Foramen of Monro, classified by normal and hydrocephalus cases, were modeled to investigate its effects. The results show that, for normal and hydrocephalus cases, the pressure drop of CSF flow across the third ventricle was observed to be linearly proportionally to the production rate increment. In conclusion, flow rates that cause pressure drop of 5 Pa was found to be the threshold for the initial sign of hydrocephalus.

  3. Method of controlling fusion reaction rates

    Science.gov (United States)

    Kulsrud, Russell M.; Furth, Harold P.; Valeo, Ernest J.; Goldhaber, Maurice

    1988-01-01

    A method of controlling the reaction rates of the fuel atoms in a fusion reactor comprises the step of polarizing the nuclei of the fuel atoms in a particular direction relative to the plasma confining magnetic field. Fusion reaction rates can be increased or decreased, and the direction of emission of the reaction products can be controlled, depending on the choice of polarization direction.

  4. Variable Control Charts - Linear Failure Rate Distribution

    Directory of Open Access Journals (Sweden)

    Metlapalli Chaitanya Priya

    2017-12-01

    Full Text Available The well known Linear Failure Rate Distribution (LFRD is considered. A process variate following LFRD is thought of in order to develop control charts for subgroup mean and subgroup range. In view of the limitations on LFRD the theoretical control limits are obtained through some approximations and the resulting control chart limits are worked out. Comparisons with the control limits of similar variable control charts is also presented.

  5. VENTRICULAR RATE AND BLOOD PRESSURE ORTHOSTATIC REACTIONS IN PATIENTS WITH PERMANENT ATRIAL FIBRILLATION IN GENERAL CARDIOVASCULAR RISK GROUPS

    Directory of Open Access Journals (Sweden)

    L. O. Martymianova

    2016-12-01

    Full Text Available Types and prevalence of ventricular rate (VR, systolic (SBP and diastolic (DBP blood pressure (BP orthostatic reactions (OR in patients with permanent atrial fibrillation (AF in general cardiovascular risk groups (GCVR were studied in 137 patients (73 men and 64 women, aged 66.4 ± 9.9 years. VR was measured by the electrocardiography (ECG on the computer electrocardiograph «CardioLab 2000» and BP – semi-automatic tonometer Microlife BP2BIO. Changes VR, SBP and DBP in the range of ± 5 % were classified as a lack, an increase of 5 % and more – both positive and decreased by 5 % or more – as a negative OR. GCVR calculated in accordance with the scale of SCORE. Patients were classified into groups of GCVR. Statistical evaluation of the results was performed with the parametric estimate of the mean (M and standard deviation (sd and non-parametric Student's T-test and Mann-Whitney test methods. It was found that patients with AF have all three types (positive, absent, negative OR of VR, SBP and DBP, which are stored in all classes GCVR. Optimizing the management of patients with atrial fibrillation, including with and through modification within the GCVR risk factors should take into account deviations in orthostatic reactions of VR, SBP and DBP.

  6. Hedgehog Controls Quiescence and Activation of Neural Stem Cells in the Adult Ventricular-Subventricular Zone

    Directory of Open Access Journals (Sweden)

    Mathieu Daynac

    2016-10-01

    Full Text Available Identifying the mechanisms controlling quiescence and activation of neural stem cells (NSCs is crucial for understanding brain repair. Here, we demonstrate that Hedgehog (Hh signaling actively regulates different pools of quiescent and proliferative NSCs in the adult ventricular-subventricular zone (V-SVZ, one of the main brain neurogenic niches. Specific deletion of the Hh receptor Patched in NSCs during adulthood upregulated Hh signaling in quiescent NSCs, progressively leading to a large accumulation of these cells in the V-SVZ. The pool of non-neurogenic astrocytes was not modified, whereas the activated NSC pool increased after a short period, before progressively becoming exhausted. We also showed that Sonic Hedgehog regulates proliferation of activated NSCs in vivo and shortens both their G1 and S-G2/M phases in culture. These data demonstrate that Hh orchestrates the balance between quiescent and activated NSCs, with important implications for understanding adult neurogenesis under normal homeostatic conditions or during injury.

  7. Rate Control Management of Atrial Fibrillation: May a Mathematical Model Suggest an Ideal Heart Rate?

    CERN Document Server

    Anselmino, Matteo; Camporeale, Carlo; Saglietto, Andrea; Gaita, Fiorenzo; Ridolfi, Luca

    2015-01-01

    Background. Despite the routine prescription of rate control therapy for atrial fibrillation (AF), clinical evidence demonstrating a heart rate target is lacking. Aim of the present study was to run a mathematical model simulating AF episodes with a different heart rate (HR) to predict hemodynamic parameters for each situation. Methods. The lumped model, representing the pumping heart together with systemic and pulmonary circuits, was run to simulate AF with HR of 50, 70, 90, 110 and 130 bpm, respectively. Results. Left ventricular pressure increased by 56.7%, from 33.92+-37.56 mmHg to 53.15+-47.56 mmHg, and mean systemic arterial pressure increased by 27.4%, from 82.66+-14.04 mmHg to 105.29+-7.63 mmHg, at the 50 and 130 bpm simulations, respectively. Stroke volume (from 77.45+-8.5 to 39.09+-8.08 mL), ejection fraction (from 61.1+-4.4 to 39.32+-5.42%) and stroke work (SW, from 0.88+-0.04 to 0.58+-0.09 J) decreased by 49.5, 35.6 and 34.2%, at the 50 and 130 bpm simulations, respectively. In addition, oxygen co...

  8. QT corrected for heart rate and qtc dispersion in Gujarati type 2 diabetics predominantly using preventive pharmacotherapy and with very low electrocardiogram left ventricular hypertrophy

    Directory of Open Access Journals (Sweden)

    Jayesh Dalpatbhai Solanki

    2017-01-01

    Full Text Available Background: There is a rising trend in the incidence of type 2 diabetes mellitus, and hyperglycaemia is known to cause cardiac dysautonomia, which may lead to life-threatening arrhythmias. It can be screened by simple electrocardiogram (ECG-based QTc (QT corrected for heart rate and QTd (QTc dispersion indicating cardiac repolarisation abnormality. We studied QTc and QTd intervals in treated type 2 diabetics (T2D, testing the effect of age, gender, duration and control of disease. Materials and Methods: We conducted a cross-sectional study in a tertiary care teaching hospital of Gujarat, India, on 199 T2D (67 males and 132 females. Standard 12-lead ECG was recorded to derive QTc by Bazett's formula, QTd and ECG left ventricular hypertrophy (LVH. QTc> 0.43 s in male and> 0.45 s in female, QTd> 80 msec were considered abnormal. Results: T2D (mean age 56 years, duration 6 years, coexisting hypertension 69%, glycaemic control 32% and use of β-blockers 56% had QTc and QTd abnormality prevalence 15% and 20% respectively with ECG LVH prevailing in 3%. Male gender, poor glycaemic control and increased duration had negative impact on QT parameters with statistical significance only for first two and not for all results. Conclusion: Our study showed low-to-moderate prevalence of prolonged QTc and QTd, qualitatively more than quantitatively, in T2D with very low LVH and high prevalence of preventive pharmacotherapy, associated with male gender and glycaemic control. It underscores high risk of repolarisation abnormality, though moderate, that can be further primarily prevented by early screening and strict disease control.

  9. ST segment/heart rate hysteresis improves the diagnostic accuracy of ECG stress test for coronary artery disease in patients with left ventricular hypertrophy.

    Science.gov (United States)

    Zimarino, Marco; Montebello, Elena; Radico, Francesco; Gallina, Sabina; Perfetti, Matteo; Iachini Bellisarii, Francesco; Severi, Silva; Limbruno, Ugo; Emdin, Michele; De Caterina, Raffaele

    2016-10-01

    The exercise electrocardiographic stress test (ExET) is the most widely used non-invasive diagnostic method to detect coronary artery disease. However, the sole ST depression criteria (ST-max) have poor specificity for coronary artery disease in patients with left ventricular hypertrophy. We hypothesised that ST-segment depression/heart rate hysteresis, depicting the relative behaviour of ST segment depression during the exercise and recovery phase of the test might increase the diagnostic accuracy of ExET for coronary artery disease detection in such patients. In three cardiology centres, we studied 113 consecutive patients (mean age 66 ± 2 years; 88% men) with hypertension-related left ventricular hypertrophy at echocardiography, referred to coronary angiography after an ExET. The following ExET criteria were analysed: ST-max, chronotropic index, heart rate recovery, Duke treadmill score, ST-segment depression/heart rate hysteresis. We detected significant coronary artery disease at coronary angiography in 61 patients (53%). At receiver-operating characteristic analysis, ST-segment depression/heart rate hysteresis had the highest area under the curve value (0.75, P coronary artery disease than conventional criteria in patients with hypertension-related left ventricular hypertrophy. © The European Society of Cardiology 2016.

  10. Heart Rate Reduction With Ivabradine Protects Against Left Ventricular Remodeling by Attenuating Infarct Expansion and Preserving Remote-Zone Contractile Function and Synchrony in a Mouse Model of Reperfused Myocardial Infarction.

    Science.gov (United States)

    O'Connor, Daniel M; Smith, Robert S; Piras, Bryan A; Beyers, Ronald J; Lin, Dan; Hossack, John A; French, Brent A

    2016-04-22

    Ivabradine selectively inhibits the pacemaker current of the sinoatrial node, slowing heart rate. Few studies have examined the effects of ivabradine on the mechanical properties of the heart after reperfused myocardial infarction (MI). Advances in ultrasound speckle-tracking allow strain analyses to be performed in small-animal models, enabling the assessment of regional mechanical function. After 1 hour of coronary occlusion followed by reperfusion, mice received 10 mg/kg per day of ivabradine dissolved in drinking water (n=10), or were treated as infarcted controls (n=9). Three-dimensional high-frequency echocardiography was performed at baseline and at days 2, 7, 14, and 28 post-MI. Speckle-tracking software was used to calculate intramural longitudinal myocardial strain (Ell) and strain rate. Standard deviation time to peak radial strain (SD Tpeak Err) and temporal uniformity of strain were calculated from short-axis cines acquired in the left ventricular remote zone. Ivabradine reduced heart rate by 8% to 16% over the course of 28 days compared to controls (Pleft ventricular remodeling and dyssynchrony, as well as improved mechanical performance in remote myocardium after heart rate reduction with ivabradine. © 2016 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley Blackwell.

  11. Effect of scanline orientation on ventricular flow propagation: assessment using high frame-rate color Doppler echocardiography

    Science.gov (United States)

    Greenberg, N. L.; Castro, P. L.; Drinko, J.; Garcia, M. J.; Thomas, J. D.

    2000-01-01

    Color M-mode echocardiography has recently been utilized to describe diastolic flow propagation velocity (Vp) in the left ventricle. While increasing temporal resolution from 15 to 200 Hz, this M-mode technique requires the user to select a single scanline, potentially limiting quantification of Vp due to the complex three-dimensional inflow pattern. We previously performed computational fluid dynamics simulations to demonstrate the insignificance of the scanline orientation, however geometric complexity was limited. The purpose of this study was to utilize high frame-rate 2D color Doppler images to investigate the importance of scanline selection in patients for the quantification of Vp. 2D color Doppler images were digitally acquired at 50 frames/s in 6 subjects from the apical 4-chamber window (System 5, GE/Vingmed, Milwaukee, WI). Vp was determined for a set of scanlines positioned through 5 locations across the mitral annulus (from the anterior to posterior mitral annulus). An analysis of variance was performed to examine the differences in Vp as a function of scanline position. Vp was not effected by scanline position in sampled locations from the center of the mitral valve towards the posterior annulus. Although not statistically significant, there was a trend to slower propagation velocities on the anterior side of the valve (60.8 +/- 16.7 vs. 54.4 +/- 13.6 cm/s). This study clinically validates our previous numerical experiment showing that Vp is insensitive to small perturbations of the scanline through the mitral valve. However, further investigation is necessary to examine the impact of ventricular geometry in pathologies including dilated cardiomyopathy.

  12. Biologically inspired rate control of chaos

    Science.gov (United States)

    olde Scheper, Tjeerd V.

    2017-10-01

    The overall intention of chaotic control is to eliminate chaos and to force the system to become stable in the classical sense. In this paper, I demonstrate a more subtle method that does not eliminate all traces of chaotic behaviour; yet it consistently, and reliably, can provide control as intended. The Rate Control of Chaos (RCC) method is derived from metabolic control processes and has several remarkable properties. RCC can control complex systems continuously, and unsupervised, it can also maintain control across bifurcations, and in the presence of significant systemic noise. Specifically, I show that RCC can control a typical set of chaotic models, including the 3 and 4 dimensional chaotic Lorenz systems, in all modes. Furthermore, it is capable of controlling spatiotemporal chaos without supervision and maintains control of the system across bifurcations. This property of RCC allows a dynamic system to operate in parameter spaces that are difficult to control otherwise. This may be particularly interesting for the control of forced systems or dynamic systems that are chaotically perturbed. These control properties of RCC are applicable to a range of dynamic systems, thereby appearing to have far-reaching effects beyond just controlling chaos. RCC may also point to the existence of a biochemical control function of an enzyme, to stabilise the dynamics of the reaction cascade.

  13. Rate-cost tradeoffs in control

    KAUST Repository

    Kostina, Victoria

    2017-02-13

    Consider a distributed control problem with a communication channel connecting the observer of a linear stochastic system to the controller. The goal of the controller is minimize a quadratic cost function. The most basic special case of that cost function is the mean-square deviation of the system state from the desired state. We study the fundamental tradeoff between the communication rate r bits/sec and the limsup of the expected cost b, and show a lower bound on the rate necessary to attain b. The bound applies as long as the system noise has a probability density function. If target cost b is not too large, that bound can be closely approached by a simple lattice quantization scheme that only quantizes the innovation, that is, the difference between the controller\\'s belief about the current state and the true state.

  14. Vitamin D therapy to reduce blood pressure and left ventricular hypertrophy in resistant hypertension: randomized, controlled trial.

    Science.gov (United States)

    Witham, Miles D; Ireland, Sheila; Houston, J Graeme; Gandy, Stephen J; Waugh, Shelley; Macdonald, Thomas M; Mackenzie, Isla S; Struthers, Allan D

    2014-04-01

    Low 25-hydroxyvitamin D levels are associated with higher prevalent blood pressure. We tested whether high-dose intermittent oral vitamin D therapy could reduce blood pressure and left ventricular mass in patients with hypertension resistant to conventional treatment. We conducted a parallel-group, double-blind, randomized placebo-controlled trial. Patients with supine office blood pressure >140/90 mm Hg on ≥3 antihypertensive agents received 100 000 U oral vitamin D3 or matching placebo every 2 months. Office and 24-hour ambulatory blood pressure, glucose, and cholesterol were measured at baseline, 2, 4, and 6 months; left ventricular mass index was measured by cardiac MRI on a subgroup at baseline and 6 months. The primary outcome was mean 24-hour ambulatory blood pressure at 6 months. A total of 68 participants were randomized, 34 in each group. Mean age was 63 (SD 11) years, mean baseline office blood pressure was 154/84 (13/10) mm Hg, and mean baseline 25-hydroxyvitamin D level was 42 (16) nmol/L. Treatment with vitamin D did not reduce 24-hour ambulatory blood pressure (adjusted treatment effects: systolic, +3 mm Hg; 95% confidence interval, -4 to +11; P=0.33; diastolic, -2 mm Hg; 95% confidence interval, -6 to +2; P=0.29); similar results were seen for office blood pressure. Left ventricular mass index was measured in a subgroup (n=25); no reduction was seen with vitamin D treatment (adjusted treatment effect, +4 g/m(2); 95% confidence interval, 0 to +7; P=0.04). There was no significant change in cholesterol or glucose levels. Thus, 6 months of intermittent, high-dose oral vitamin D3 did not reduce blood pressure or left ventricular mass in patients with resistant hypertension.

  15. Fixed-rate layered multicast congestion control

    Science.gov (United States)

    Bing, Zhang; Bing, Yuan; Zengji, Liu

    2006-10-01

    A new fixed-rate layered multicast congestion control algorithm called FLMCC is proposed. The sender of a multicast session transmits data packets at a fixed rate on each layer, while receivers each obtain different throughput by cumulatively subscribing to deferent number of layers based on their expected rates. In order to provide TCP-friendliness and estimate the expected rate accurately, a window-based mechanism implemented at receivers is presented. To achieve this, each receiver maintains a congestion window, adjusts it based on the GAIMD algorithm, and from the congestion window an expected rate is calculated. To measure RTT, a new method is presented which combines an accurate measurement with a rough estimation. A feedback suppression based on a random timer mechanism is given to avoid feedback implosion in the accurate measurement. The protocol is simple in its implementation. Simulations indicate that FLMCC shows good TCP-friendliness, responsiveness as well as intra-protocol fairness, and provides high link utilization.

  16. Role of circulating angiotensin converting enzyme 2 in left ventricular remodeling following myocardial infarction: a prospective controlled study.

    Directory of Open Access Journals (Sweden)

    José T Ortiz-Pérez

    Full Text Available Angiotensin-converting enzyme 2 (ACE2 cleaves Angiotensin-II to Angiotensin-(1-7, a cardioprotective peptide. Serum soluble ACE2 (sACE2 activity is raised in chronic heart failure, suggesting a compensatory role in left ventricular dysfunction. Our aim was to study the relationship between sACE2 activity, infarct size, left ventricular systolic function and remodeling following ST-elevation myocardial infarction (STEMI. A contrast-enhanced cardiac magnetic resonance study was performed acutely in 95 patients with first STEMI and repeated at 6 months to measure LV end-diastolic volume index, ejection fraction and infarct size. Baseline sACE2 activities, measured by fluorescent enzymatic assay 24 to 48 hours and at 7 days from admission, were compared to that obtained in 22 matched controls. Patients showed higher sACE2 at baseline than controls (104.4 [87.4-134.8] vs 74.9 [62.8-87.5] RFU/µl/hr, p<0.001. At seven days, sACE2 activity significantly increased from baseline (115.5 [92.9-168.6] RFU/µl/hr, p<0.01. An inverse correlation between sACE2 activity with acute and follow-up ejection fraction was observed (r = -0.519, p<0.001; r = -0.453, p = 0.001, respectively. Additionally, sACE2 directly correlated with infarct size (r = 0.373, p<0.001. Both, infarct size (β = -0.470 [95%CI:-0.691:-0.248], p<0.001 and sACE2 at 7 days (β = -0.025 [95%CI:-0.048:-0.002], p = 0.030 were independent predictors of follow-up ejection fraction. Patients with sACE2 in the upper tertile had a 4.4 fold increase in the incidence of adverse left ventricular remodeling (95% confidence interval: 1.3 to 15.2, p = 0.027. In conclusion, serum sACE2 activity rises in relation to infarct size, left ventricular systolic dysfunction and is associated with the occurrence of left ventricular remodeling.

  17. Prevalence and correlates of ventricular premature beats detected by ambulatory electrocardiography in working populations.

    Science.gov (United States)

    Green, M S; Jucha, E; Luz, J; Cocos, M; Nurynberg, M; Rosenberg, N

    1988-05-01

    The associations of ventricular premature beats detected on a one-hour ambulatory electrocardiogram with demographic, behavioral, physiologic, and anthropometric variables were examined in 2,331 factory workers aged 20-69 years. Ventricular premature beats were more prevalent with increasing age and with abnormal resting electrocardiograms. From the age of 40, they were more common among males than among females. An association with ethnicity was observed, ventricular premature beats being most common among Israelis of European origin. In univariate analysis, resting heart rate was inversely associated with the presence of ventricular premature beats for females only. Ambulatory heart rate was positively associated with ventricular premature beats only among males. No associations with smoking habits or relative weight were found. Among males and females with normal electrocardiograms, systolic and diastolic blood pressures were significant correlates of ventricular premature beats in univariate analysis and after controlling for age, resting and ambulatory heart rates, and ethnic origin.

  18. Controlling a wide range of flow rates

    Science.gov (United States)

    Perkins, G. S.

    1979-01-01

    Servo-operated valve and two flowmeters allow accurate control over 1,900:1 flow-rate range. It was developed as part of laboratory instrument for measuring properties of confined fluids under conditions analogous to those encountered in deep drilling operations.

  19. Heart rate control via vagus nerve stimulation

    NARCIS (Netherlands)

    Buschman, H.P.J.; Storm, Corstiaan J.; Duncker, Dirk J.; Verdouw, Pieter D.; van der Aa, Hans E.; van der Kemp, Peter

    2006-01-01

    Objectives: There is ample and well-established evidence that direct electrical stimulation of the vagus nerve can change heart rate in animals and humans. Since tachyarrhythmias cannot always be controlled through medication, we sought, in this pilot study, to elucidate whether a clinical

  20. Malignant ventricular tachycardia in acromegaly: a case report

    Directory of Open Access Journals (Sweden)

    Zhe An

    Full Text Available CONTEXT: In patients with acromegaly, cardiovascular complications are the main cause of death; sudden death has been associated with ventricular tachyarrhythmias. In other patients with life-threatening malignant ventricular tachyarrhythmias, surgical placement of an implantable cardioverter-defibrillator (ICD has proved highly effective in reducing sudden death rates. CASE REPORT: The present article reports the case of a 50-year-old male acromegalic patient who presented symptoms of syncope induced by ventricular tachycardia. An ICD was surgically implanted and a pituitary adenoma, which was responsible for the acromegaly, was completely removed in the same procedure. The surgery was successful and the ventricular arrhythmias were effectively terminated. During six months of follow-up, no documented arrhythmic episodes occurred. CONCLUSION: In patients with acromegaly, malignant ventricular tachyarrhythmia might be effectively controlled by implantation of an ICD and surgical removal of the pituitary adenoma.

  1. EFFECT OF FUROSEMIDE AND TORASEMIDE ON HEART RATE VARIABILITY AND VENTRICULAR RHYTHM DISORDERS IN PATIENTS WITH CHRONIC HEART FAILURE COMPLICATING ISCHEMIC HEART DISEASE: COMPARATIVE NONRANDOMIZED STUDY

    Directory of Open Access Journals (Sweden)

    H. H. Shugushev

    2010-01-01

    Full Text Available Aim. To study effect of diuretic therapy with furosemide and torasemide on heart rate variability (HRV and frequency of ventriclar rhythm disorders in patients with chronic heart failure (CHF complicating ischemic heart disease (IHD.Material and methods. Patients (n=107 with CHF III-IV functional class (NYHA complicating IHD were examined. The first group of patients received furosemide, 20-60 mg QD (n=52, the second group received torasemide, 5-20 mg QD (n=55. Analysis of heart rhythm disorders and the basic HRV indicators was performed by ECG 10-minute recordings initially and after 10 days of therapy.Results. Decrease in time and spectral HRV parameters and increase in daily number of ventricular extrasystoles was found in furosemide treated patients. Improvement of HRV parameters and reduction of daily number of ventricular rhythm disorders was found torasemide treated patients.Conclusion. Torasemide therapy improves an autonomic regulation of heart rhythm and leads to the reduction of ventricular heart rhythm disorders in patients with CHF complicating IHD.

  2. Oscillatory behaviour of ventricular action potential duration in heart failure patients at respiratory rate and low frequency

    Directory of Open Access Journals (Sweden)

    Ben eHanson

    2014-10-01

    Full Text Available Oscillations of arterial pressure occur spontaneously at a frequency of approx. 0.1Hz coupled with synchronous oscillations of sympathetic nerve activity (Mayer waves. This study investigated the extent to which corresponding oscillations may occur in ventricular action potential duration (APD.14 ambulatory (outpatient heart failure patients with biventricular pacing devices were studied while seated upright watching movie clips to maintain arousal. Activation recovery intervals (ARI as a measure of ventricular APD were obtained from unipolar electrograms recorded from the LV epicardial pacing lead during steady state RV pacing from the device. Arterial blood pressure was measured non-invasively (Finapress and respiration monitored. Oscillations were quantified using time frequency and coherence analysis.Oscillatory behaviour of ARI at the respiratory frequency was observed in all subjects. The magnitude of the ARI variation ranged from 2.2 ms to 6.9 ms (mean 5.0 ms. Coherence analysis showed a correlation with respiratory oscillation for an average of 43% of the recording time at a significance level of p < 0.05. Oscillations in systolic blood pressure in the Mayer wave frequency range were observed in all subjects for whom blood pressure was recorded (n=13. ARI oscillation in the Mayer wave frequency range was observed in 6/13 subjects (46% over a range of 2.9ms to 9.2ms. Coherence with Mayer waves at the p < 0.05 significance level was present for an average of 29 % of the recording time. In ambulatory patients with heart failure during enhanced mental arousal, left ventricular epicardial APD (ARI oscillated at the respiratory frequency (approx. 0.25Hz. In 6 patients (46% APD oscillated at the slower Mayer wave frequency (approx. 0.1 Hz. These findings may be important in understanding sympathetic activity-related arrhythmogenesis.

  3. Body position and activity, but not heart rate, affect pump flows in patients with continuous-flow left ventricular assist devices.

    Science.gov (United States)

    Muthiah, Kavitha; Gupta, Sunil; Otton, James; Robson, Desiree; Walker, Robyn; Tay, Andre; Macdonald, Peter; Keogh, Anne; Kotlyar, Eugene; Granger, Emily; Dhital, Kumud; Spratt, Phillip; Jansz, Paul; Hayward, Christopher S

    2014-08-01

    The aim of this study was to determine the contribution of pre-load and heart rate to pump flow in patients implanted with continuous-flow left ventricular assist devices (cfLVADs). Although it is known that cfLVAD pump flow increases with exercise, it is unclear if this increment is driven by increased heart rate, augmented intrinsic ventricular contraction, or enhanced venous return. Two studies were performed in patients implanted with the HeartWare HVAD. In 11 patients, paced heart rate was increased to approximately 40 beats/min above baseline and then down to approximately 30 beats/min below baseline pacing rate (in pacemaker-dependent patients). Ten patients underwent tilt-table testing at 30°, 60°, and 80° passive head-up tilt for 3 min and then for a further 3 min after ankle flexion exercise. This regimen was repeated at 20° passive head-down tilt. Pump parameters, noninvasive hemodynamics, and 2-dimensional echocardiographic measures were recorded. Heart rate alteration by pacing did not affect LVAD flows or LV dimensions. LVAD pump flow decreased from baseline 4.9 ± 0.6 l/min to approximately 4.5 ± 0.5 l/min at each level of head-up tilt (p heart rate, but they change significantly with body position and passive filling. Previously demonstrated exercise-induced changes in pump flows may be related to altered loading conditions, rather than changes in heart rate. Copyright © 2014 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

  4. Degree of Rate Control: How Much the Energies of Intermediates and Transition States Control Rates

    DEFF Research Database (Denmark)

    Stegelmann, Carsten; Andreasen, Anders; Campbell, Charles T.

    2009-01-01

    electronic or steric control on the relative energies of the key species. Since these key species are the ones whose relative energies most strongly influence the net reaction rate, they also identify the species whose energetics must be most accurately measured or calculated to achieve an accurate kinetic......For many decades, the concept of a “rate-determining step” has been of central importance in understanding chemical kinetics in multistep reaction mechanisms and using that understanding to advantage. Yet a rigorous method for identifying the rate-determining step in a reaction mechanism was only...... model for any reaction mechanism. Thus, it is very important to identify these rate-controlling transition states and rate-controlling intermediates for both applied and basic research. Here, we present a method for doing that....

  5. Distinct and flexible rates of online control.

    Science.gov (United States)

    de Grosbois, John; Tremblay, Luc

    2017-07-21

    Elliott et al. (Hum Mov Sci 10:393-418, 1991) proposed a pseudocontinuous model of online control whereby overlapping corrections lead to the appearance of smooth kinematic profiles in the presence of online feedback. More recently, it was also proposed that online control is not a singular process [see Elliott et al. (Psychol Bull 136(6):1023-1044, 2010)]. However, support for contemporary models of online control were based on methodologies that were not designed to be sensitive to different online control sub-processes. The current study sought to evaluate the possibility of multiple distinct (i.e., visual and non-visual) mechanisms contributing to the control of reaching movements completed in either a full-vision, a no-vision, or a no-vision memory-guided condition. Frequency domain analysis was applied to the acceleration traces of reaching movements. In an attempt to elicit a modulation in the online control mechanisms, these movements were completed at two levels of spatio-temporal constraint, namely with 10 and 30 cm target distances. One finding was that performance in the full-vision relative to both no-vision conditions could be distinguished via two distinct frequency peaks. Increases in the peak magnitude at the lower frequencies were associated with visuomotor mechanisms and increases in the peak magnitude at the higher frequencies were associated with non-visual mechanisms. In addition, performance to the 30-cm target led to a lower peak at a lower frequency relative to the 10 cm target, indicating that the iterative rates of visuomotor control mechanisms are flexible and sensitive to the spatio-temporal constraints of the associated movement.

  6. Left Ventricular Longitudinal Systolic Function in Septic Shock Patients with Normal Ejection Fraction: A Case-control Study.

    Science.gov (United States)

    Zhang, Hong-Min; Wang, Xiao-Ting; Zhang, Li-Na; He, Wei; Zhang, Qing; Liu, Da-Wei

    2017-05-20

    Septic cardiomyopathy is a common finding in septic shock patients. The accepted definition of septic cardiomyopathy is often based on the left ventricular ejection fraction (LVEF). The aim of this study was to determine whether the left ventricular longitudinal systolic function was more sensitive than the LVEF in heart function appraisal of septic shock patients. This was a case-control study conducted at a 40-bed Intensive Care Unit (ICU) of Peking Union Medical College Hospital. Septic shock patients admitted to the ICU were consecutively enrolled in the study group from March 1, 2016 to September 1, 2016. The control group was selected from nonsepsis patients who were admitted to the ICU and were comparable to the study group. Transthoracic echocardiography was performed to obtain the LVEF measurement, mitral annular plane systolic excursion (MAPSE), tissue Doppler velocity measurement of mitral annulus (Sa), and tricuspid annular plane systolic excursion. The study group consisted of 45 septic shock patients. Another 45 nonsepsis patients were selected as the control group. There was no difference in the LVEF between the two groups (64.6% vs. 67.2%, t= -1.426, P= 0.161). MAPSE in the study group was much lower than in the control group (1.2 cm vs. 1.5 cm, t= -4.945, Pstudy group was also lower than in the control group (10.2 cm/s vs. 11.8 cm/s, t = -2.796, P= 0.014). Compared to the LVEF, longitudinal systolic function might be more sensitive in the detection of cardiac depression in septic shock patients. In the heart function appraisal of septic shock patients with a normal ejection fraction, more attention should be given to longitudinal function parameters such as MAPSE and Sa.

  7. Electromechanically Actuated Valve for Controlling Flow Rate

    Science.gov (United States)

    Patterson, Paul

    2007-01-01

    A proposed valve for controlling the rate of flow of a fluid would include an electric-motor-driven ball-screw mechanism for adjusting the seating element of the valve to any position between fully closed and fully open. The motor would be of a type that can be electronically controlled to rotate to a specified angular position and to rotate at a specified rate, and the ball screw would enable accurate linear positioning of the seating element as a function of angular position of the motor. Hence, the proposed valve would enable fine electronic control of the rate of flow and the rate of change of flow. The uniqueness of this valve lies in a high degree of integration of the actuation mechanism with the flow-control components into a single, relatively compact unit. A notable feature of this integration is that in addition to being a major part of the actuation mechanism, the ball screw would also be a flow-control component: the ball screw would be hollow so as to contain part of the main flow passage, and one end of the ball screw would be the main seating valve element. The relationships among the components of the valve are best understood by reference to the figure, which presents meridional cross sections of the valve in the fully closed and fully open positions. The motor would be supported by a bracket bolted to the valve body. By means of gears or pulleys and a timing belt, motor drive would be transmitted to a sleeve that would rotate on bearings in the valve body. A ball nut inside the sleeve would be made to rotate with the sleeve by use of a key. The ball screw would pass through and engage the ball nut. A key would prevent rotation of the ball screw in the valve body while allowing the ball screw to translate axially when driven by the ball nut. The outer surface of the ball screw would be threaded only in a mid-length region: the end regions of the outer surface of the ball screw would be polished so that they could act as dynamic sealing surfaces

  8. Reduced Right Ventricular Native Myocardial T1 in Anderson-Fabry Disease: Comparison to Pulmonary Hypertension and Healthy Controls.

    Directory of Open Access Journals (Sweden)

    Joseph J Pagano

    Full Text Available Anderson-Fabry disease (AFD is characterized by progressive multiorgan accumulation of intracellular sphingolipids due to α-galactosidase A enzyme deficiency, resulting in progressive ventricular hypertrophy, heart failure, arrhythmias, and death. Decreased native (non-contrast left ventricular (LV T1 (longitudinal relaxation time with MRI discriminates AFD from healthy controls or other presentations of concentric hypertrophy, but the right ventricle (RV has not been studied. The aims of the current study were to evaluate native RV T1 values in AFD, with a goal of better understanding the pathophysiology of RV involvement.Native T1 values were measured in the inferior RV wall (RVI, interventricular septum (IVS, and inferior LV (LVI in patients with AFD, patients with pulmonary hypertension, who provided an alternative RV pathological process for comparison, and healthy controls. A minimum wall thickness of 4 mm was selected to minimize partial volume errors in tissue T1 analysis. T1 analysis was performed in 6 subjects with AFD, 6 subjects with PH, and 21 controls. Native T1 values were shorter (adjusted p<0.05 for all comparisons, independent of location, in subjects with AFD (RVI-T1 = 1096±49 ms, IVS-T1 = 1053±41 ms, LVI-T1 = 1072±44 ms compared to both PH (RVI-T1 = 1239±41 ms, IVS-T1 = 1280±123 ms, LVI-T1 = 1274±57 ms and HC (IVS-T1 = 1180±60 ms, LVI-T1 = 1183±45 ms. RVI measurements were not possible in controls due to insufficient wall thickness.Native T1 values appear similarly reduced in the left and right ventricles of individuals with AFD and RV wall thickening, suggesting a common pathology. In contrast, individuals with PH and thickened RVs showed increased native T1 values in both ventricles, suggestive of fibrosis.

  9. The influence of type 2 diabetes mellitus on the frequency and complexity of ventricular arrhythmias and heart rate variability in patients after myocardial infarction

    Directory of Open Access Journals (Sweden)

    Stoičkov Viktor

    2016-01-01

    Full Text Available Background/Aim. After myocardial infarction arrhythmic cardiac deaths are significantly more frequent compared to non-arrhythmic ones. The aim of the study was to investigate the influence of type 2 diabetes mellitus (T2DM on the frequency and complexity of ventricular arrhythmias after myocardial infarction. Methods. The study included 293 patients, mean age 59.5 ± 9.21 years, who were at least six months after acute myocardial infarction with the sinus rhythm, without atrioventricular blocks and branch blocks. In the clinical group 95 (32.42% patients were with T2DM, while 198 (67.57% patients were without diabetes. All of the patients were subjected to the following procedures: standard ECG according to which the corrected QT dispersion (QTdc was calculated, exercise stress test, and 24-hour holter monitoring according to which, the four parameters of time domain of heart rate variability (HRV were analyzed: standard deviation of all normal RR intervals during 24 hours (SDNN, standard deviation of the averages of normal RR intervals in all five-minute segments during 24 hours (SDANN, the square root of the mean of the sum of the squares of differences between adjacent normal (RMS-SD, and percentage of consequtive RR intervals which differed for more than 50 ms during 24 hours (NN > 50 ms. Results. In patients after myocardial infarction, patients with T2DM had significantly higher percentage of frequent and complex ventricular arrhythmias compared to the patients without diabetes (p 50 ms (p < 0.001, and significantly higher values of QTdc (p < 0.001 compared to the patients without diabetes. Conclusion. The study showed that type 2 diabetes mellitus has significant influence on ventricular arrhythmias, HRV parameters and QT dispersion in patients after myocardial infarction.

  10. Determination of aortic valve opening time and left ventricular peak filling rate from the peripheral pulse amplitude in patients with ectopic beats.

    Science.gov (United States)

    Zheng, Dingchang; Allen, John; Murray, Alan

    2008-12-01

    Ectopic beats are common in patients who have heart disease and are associated with reduced peripheral pulse amplitude. This study determined the start of the peripheral pulse increase and from it the opening of the aortic valve. The left ventricular peak filling rate was also estimated from the peripheral pulse. Results were compared with published invasive and cardiac imaging data. Twenty-five subjects with ectopic beat electrocardiograms (ECGs) were studied. The ECGs and the peripheral pulses, detected optically at the right index finger by a simple photoplethysmography (PPG) technique, were recorded for subsequent analysis. Peripheral pulse amplitudes for ectopic beats, post-ectopic sinus beats and normal sinus beats were determined. Ectopic beats induced a mean 68% decrease in pulse amplitude in comparison with sinus beats (p ectopic sinus beats increased by 20% (p ectopic beats and post-ectopic sinus beats. The range of shortest coupling interval (CI) for ectopic beats with observable pulses was from 373 to 531 ms, with the mean value equivalent to 55% of the mean sinus RR interval, comparable with the opening of the aortic valve. Finally, as the CI increased, the pulse amplitude increased quickly from zero. The average rate of increase was equivalent to 4.8 times the normal sinus amplitude in 1 s, equal to 50% filling in 208 ms, showing diastolic rapid filling, comparable with published left ventricular peak filling rate data. In conclusion, the effect of ectopic beat CI on peripheral pulse amplitude has been determined, providing useful information for developing a technique to determine the opening of the aortic valve and the peak filling rate non-invasively and peripherally in patients with frequent ectopic beats.

  11. Upgrading to biventricular pacing/defibrillation systems in right ventricular paced congestive heart failure patients: prospective assessment of procedural parameters and response rate.

    Science.gov (United States)

    Duray, Gabor Z; Israel, Carsten W; Pajitnev, Dimitrij; Hohnloser, Stefan H

    2008-01-01

    Cardiac resynchronization therapy (CRT) is indicated in patients with heart failure and bundle branch block. It is less clear whether this includes patients with pre-existing right ventricular pacemaker/defibrillator systems, particularly with respect to implantation success and clinical benefit. In consecutive patients scheduled for CRT, we prospectively compared implantation success, procedural parameters, and clinical response in 'de novo' vs. upgrade procedures of previously implanted right ventricular systems. CRT implantation was attempted in 79 consecutive patients (64 +/- 11 years, 63 male, 38 ischaemic, 41 non-ischaemic cardiomyopathy). De novo implantation was performed in 61 patients, upgrade procedures in 18 patients. Implant success (92 vs. 94%, P = 1.00), procedure duration (153 +/- 43 vs. 164 +/- 65 min, P = 0.51), fluoroscopy time (25 +/- 18 vs. 32 +/- 22 min, P = 0.18) or dose (40 +/- 31 vs. 52 +/- 49 Gy/cm(2), P = 0.35), and response rate (66 vs. 59%, P = 0.5) were comparable for both groups. Procedural aspects, implantation success, and clinical response to CRT were comparable for patients undergoing de-novo vs. upgrade procedures. Accordingly, patient selection for upgrading should be the same as for new CRT implantation.

  12. Assessment of cardiac function using global and regional left ventricular endomyocardial and epimyocardial peak systolic strain and strain rate in healthy Labrador retriever dogs.

    Science.gov (United States)

    Carnabuci, C; Hanås, S; Ljungvall, I; Tidholm, A; Bussadori, C; Häggström, J; Höglund, K

    2013-08-01

    Speckle tracking echocardiography (STE) is based on tracking of natural acoustic myocardial markers. The study aimed at quantifying global and regional endomyocardial and epimyocardial left ventricular longitudinal, circumferential and radial peak systolic strain and strain rate, including feasibility and variability; and assessing synchronicity and torsion, in healthy dogs. Cineloops were acquired from left apical 4-chamber, basal and apical right parasternal short-axis views in 22 healthy Labrador retrievers. A general epimyocardial to endomyocardial strain gradient was found. Strain was higher at apex compared to base. A strain longitudinal base to apex gradient was found. Left ventricular synchronicity could be assessed in all dogs and torsion in 1/3. Short axis apical view had highest variability. Dog and operator contributed most to overall variance. In conclusion, STE allows assessment of myocardial function in healthy Labrador retrievers. A longitudinal base to apex gradient was found and a new synchronicity index for use in dogs was introduced. Copyright © 2013 Elsevier Ltd. All rights reserved.

  13. Lenient versus Strict Rate Control in Patients with Atrial Fibrillation.

    NARCIS (Netherlands)

    Van Gelder, Isabelle C.; Groenveld, Hessel F.; Crijns, Harry J. G. M.; Tuininga, Ype S.; Tijssen, Jan G. P.; Alings, A. Marco; Hillege, Hans L.; Bergsma-Kadijk, Johanna A.; Cornel, Jan H.; Kamp, Otto; Tukkie, Raymond; Bosker, Hans A.; Van Veldhuisen, Dirk J.; Van den Berg, Maarten P.

    2010-01-01

    Background: Rate control is often the therapy of choice for atrial fibrillation. Guidelines recommend strict rate control, but this is not based on clinical evidence. We hypothesized that lenient rate control is not inferior to strict rate control for preventing cardiovascular morbidity and

  14. Implantable cardioverter-defibrillators for treatment of sustained ventricular arrhythmias in patients with Chagas' heart disease: comparison with a control group treated with amiodarone alone.

    Science.gov (United States)

    Gali, Wagner L; Sarabanda, Alvaro V; Baggio, José M; Ferreira, Luís G; Gomes, Gustavo G; Marin-Neto, J Antônio; Junqueira, Luiz F

    2014-05-01

    Evidence is inconclusive concerning the benefit of implantable cardioverter-defibrillators (ICDs) for secondary prevention of mortality in patients with Chagas' heart disease (ChHD). The aim of this study was to compare the outcomes of ChHD patients with life-threatening ventricular arrhythmias (VAs), who were treated either with ICD implantation plus amiodarone or with amiodarone alone. The ICD group [76 patients; 48 men; age, 57 ± 11 years; left ventricular ejection fraction (LVEF), 39 ± 12%] and the historical control group treated with amiodarone alone (28 patients; 18 men; age, 54 ± 10 years; LVEF, 41 ± 10%) had comparable baseline characteristics, except for a higher use of beta-blockers in the ICD group (P < 0.0001). Amiodarone was also used in 90% of the ICD group. Therapy with ICD plus amiodarone resulted in a 72% reduced risk of all-cause mortality (P = 0.007) and a 95% reduced risk of sudden death (P = 0.006) compared with amiodarone-only therapy. The survival benefit of ICD was greatest in patients with LVEF < 40% (P = 0.01) and was not significant in those with LVEF ≥ 40% (P = 0.15). Appropriate ICD therapies occurred in 72% of patients and the rates of interventions were similar across patients with LVEF < 40% and ≥40%. Compared with amiodarone-only therapy, ICD implantation plus amiodarone reduced the risk of all-cause mortality and sudden death in ChHD patients with life-threatening VAs. Patients with LVEF < 40% derived significantly more survival benefit from ICD therapy. The majority of ICD-treated patients received appropriate therapies regardless of the LV systolic function.

  15. Temperature-controlled irrigated tip radiofrequency catheter ablation: comparison of in vivo and in vitro lesion dimensions for standard catheter and irrigated tip catheter with minimal infusion rate

    DEFF Research Database (Denmark)

    Petersen, H H; Chen, X; Pietersen, A

    1998-01-01

    In patients with ventricular tachycardias due to structural heart disease, catheter ablation cures <60% partly due to the limited lesion size after conventional radiofrequency ablation. Irrigated tip radiofrequency ablation using power control and high infusion rates enlarges lesion size, but has...

  16. Heart rate changes during the Valsalva maneuver in patients with isolated aortic insufficiency

    Directory of Open Access Journals (Sweden)

    Navarro A.E.

    1997-01-01

    Full Text Available To determine the possible relationship between left ventricular dilatation and heart rate changes provoked by the Valsalva maneuver (Valsalva ratio, we studied 9 patients with isolated chronic aortic insufficiency. Left ventricular systolic function was assessed by two-dimensional echocardiography and cardiac catheterization. All patients were asymptomatic (functional class I of the New York Heart Association. The left ventricular internal diameters and volumes were significantly increased in all patients. The asymptomatic patients had either normal or slightly depressed ejection fraction (EF>0.40. The Valsalva ratio of these asymptomatic patients showed no significant correlation with the left ventricular volumes or with the left ventricular ejection fraction. In other words, parasympathetic heart rate control, as expressed by the Valsalva ratio, was normal in the asymptomatic patients with left ventricular dilatation and preserved left ventricular ejection fraction. Therefore, left ventricular dilatation may not be the major mechanism responsible for the abnormal parasympathetic heart rate control of patients with acquired heart disease

  17. Fractal analysis of heart rate dynamics as a predictor of mortality in patients with depressed left ventricular function after acute myocardial infarction. TRACE Investigators. TRAndolapril Cardiac Evaluation

    Science.gov (United States)

    Makikallio, T. H.; Hoiber, S.; Kober, L.; Torp-Pedersen, C.; Peng, C. K.; Goldberger, A. L.; Huikuri, H. V.

    1999-01-01

    A number of new methods have been recently developed to quantify complex heart rate (HR) dynamics based on nonlinear and fractal analysis, but their value in risk stratification has not been evaluated. This study was designed to determine whether selected new dynamic analysis methods of HR variability predict mortality in patients with depressed left ventricular (LV) function after acute myocardial infarction (AMI). Traditional time- and frequency-domain HR variability indexes along with short-term fractal-like correlation properties of RR intervals (exponent alpha) and power-law scaling (exponent beta) were studied in 159 patients with depressed LV function (ejection fraction function. A short-term fractal-like scaling exponent was the most powerful HR variability index in predicting mortality in patients with depressed LV function. Reduction in fractal correlation properties implies more random short-term HR dynamics in patients with increased risk of death after AMI.

  18. Ventricular Fibrillation Waveform Changes during Controlled Coronary Perfusion Using Extracorporeal Circulation in a Swine Model.

    Science.gov (United States)

    Gazmuri, Raúl J; Kaufman, Christopher L; Baetiong, Alvin; Radhakrishnan, Jeejabai

    2016-01-01

    Several characteristics of the ventricular fibrillation (VF) waveform have been found predictive of successful defibrillation and hypothesized to reflect the myocardial energy state. In an open-chest swine model of VF, we modeled "average CPR" using extracorporeal circulation (ECC) and assessed the time course of coronary blood flow, myocardial metabolism, and myocardial structure in relation to the amplitude spectral area (AMSA) of the VF waveform without artifacts related to chest compression. VF was induced and left untreated for 8 minutes in 16 swine. ECC was then started adjusting its flow to maintain a coronary perfusion pressure of 10 mmHg for 10 minutes. AMSA was calculated in the frequency domain and analyzed continuously with a 2.1 s timeframe and a Tukey window that moved ahead every 0.5 s. AMSA progressively declined during untreated VF. With ECC, AMSA increased from 7.0 ± 1.9 mV·Hz (at minute 8) to 12.8 ± 3.3 mV·Hz (at minute 14) (p coronary blood flow of borderline statistical significance (r = 0.489, p = 0.0547). Myocardial energy measurements showed marked reduction in phosphocreatine and moderate reduction in ATP with increases in ADP, AMP, and adenosine along with myocardial lactate, all indicative of ischemia. Yet, ischemia did not resolve during ECC despite a coronary blood flow of ~ 30% of baseline. AMSA increased upon return of coronary blood flow during ECC. However, the maximal level was reached after ~ 6 minutes without further change. The significance of the findings for determining the optimal timing for delivering an electrical shock during resuscitation from VF remains to be further explored.

  19. Ventricular Fibrillation Waveform Changes during Controlled Coronary Perfusion Using Extracorporeal Circulation in a Swine Model.

    Directory of Open Access Journals (Sweden)

    Raúl J Gazmuri

    Full Text Available Several characteristics of the ventricular fibrillation (VF waveform have been found predictive of successful defibrillation and hypothesized to reflect the myocardial energy state. In an open-chest swine model of VF, we modeled "average CPR" using extracorporeal circulation (ECC and assessed the time course of coronary blood flow, myocardial metabolism, and myocardial structure in relation to the amplitude spectral area (AMSA of the VF waveform without artifacts related to chest compression.VF was induced and left untreated for 8 minutes in 16 swine. ECC was then started adjusting its flow to maintain a coronary perfusion pressure of 10 mmHg for 10 minutes. AMSA was calculated in the frequency domain and analyzed continuously with a 2.1 s timeframe and a Tukey window that moved ahead every 0.5 s.AMSA progressively declined during untreated VF. With ECC, AMSA increased from 7.0 ± 1.9 mV·Hz (at minute 8 to 12.8 ± 3.3 mV·Hz (at minute 14 (p < 0.05 without subsequent increase and showing a modest correlation with coronary blood flow of borderline statistical significance (r = 0.489, p = 0.0547. Myocardial energy measurements showed marked reduction in phosphocreatine and moderate reduction in ATP with increases in ADP, AMP, and adenosine along with myocardial lactate, all indicative of ischemia. Yet, ischemia did not resolve during ECC despite a coronary blood flow of ~ 30% of baseline.AMSA increased upon return of coronary blood flow during ECC. However, the maximal level was reached after ~ 6 minutes without further change. The significance of the findings for determining the optimal timing for delivering an electrical shock during resuscitation from VF remains to be further explored.

  20. Moisture controls decomposition rate in thawing tundra

    Science.gov (United States)

    C.E. Hicks-Pries; E.A.G. Schuur; S.M. Natali; J.G. Vogel

    2013-01-01

    Permafrost thaw can affect decomposition rates by changing environmental conditions and litter quality. As permafrost thaws, soils warm and thermokarst (ground subsidence) features form, causing some areas to become wetter while other areas become drier. We used a common substrate to measure how permafrost thaw affects decomposition rates in the surface soil in a...

  1. Association of Left Ventricular Hypertrophy With a Faster Rate of Renal Function Decline in Elderly Patients With Non-End-Stage Renal Disease.

    Science.gov (United States)

    Shi, Hong-tao; Wang, Xiao-jing; Li, Jun; Song, Gui-fang; Huang, Zhe-yong; Guo, Xiang-yu; Guo, Jun-jie; Lv, Zhi-yang; Li, Hong-wei; Ge, Jun-bo; Cui, Jie; Qi, Guan-ming

    2015-11-09

    Several studies have indicated that chronic kidney disease is independently associated with the presence of left ventricular hypertrophy (LVH). However, little clinical data are currently available regarding the detailed correlation between LVH and renal function in elderly patients with non-end-stage renal disease. A total of 300 in- and outpatients (more than 60 years of age, non-end-stage renal disease), 251 with LVH and 49 without LVH, seen at Beijing Friendship Hospital from January 2000 to December 2010 were included in this retrospective study. One observation period of 12 months was used to detect rapid kidney function decline. The evaluations of cardiac structure and function were performed via echocardiography. The multivariable logistic analysis showed patients with LVH had a much higher risk of rapid kidney function decline than those without LVH. Additionally, the baseline left ventricular mass index was 140 (125-160) g/m(2) in the non-chronic kidney disease group, 152 (130-175) g/m(2) in the mild chronic kidney disease group (estimated glomerular filtration rate (eGFR)≥60 ml/min/1.73 m(2)), and 153 (133-183) g/m(2) in the severe chronic kidney disease group (eGFRrenal function decline contributes to pathological LVH in non-end-stage renal disease elderly patients and that LVH is positively associated with renal function decline followed by an increased risk of rapid kidney function decline. © 2015 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley Blackwell.

  2. Normal left ventricular torsion mechanics in healthy children: age related changes of torsion parameters are closely related to changes in heart rate.

    Science.gov (United States)

    Kim, Hye Jin; Yoon, Ji-Hong; Lee, Eun-Jung; Oh, Jin Hee; Lee, Jae Young; Lee, Soon Ju; Han, Ji Whan

    2015-03-01

    This study was aimed at assessing left ventricular torsion (LVtor) mechanics using speckle tracking echocardiography (STE), establishing normal reference values of principal LVtor parameters, and analyzing the age-related changes in normal children. Eighty children (aged 3 months to 15 years) with normal cardiac function and rhythm were recruited. LVtor parameters including rotations, twist and untwist, torsion, and their rate indices were measured using STE. Age and heart rate related changes of the parameters were analyzed. Speckle tracking echocardiography analyses for LVtor parameters had excellent reliability in 64 of 80 subjects (80%) (intraclass correlation coefficients; 0.93-0.97). Early systolic twist (EST) motions (-8.4--0.1°) were observed in all subjects during an early 20±7% of systolic time intervals. The peak systolic twist and torsion were 17.0±6.5° and 2.9±1.3°/cm, respectively. The peak twist velocity was recorded at 51±13% of systolic time and the peak untwist velocity at 13.8±11.5% of diastolic time intervals. Multivariate analysis showed that heart rate change was an independent predictor of changes in torsion parameters; significantly decreasing LV length-normalized apical and basal rotation, torsion, and twist and untwist rate with increasing age. Isovolumetric recoil rate was independent of change in age and heart rate. Left ventricle showed unique torsion mechanics in children with EST, torsion, and untwists. Heart rate was an independent predictor of the change in torsion parameters with aging.

  3. Early detection of left ventricular dysfunction in asymptomatic diabetic patient using strain and strain rate echocardiographic imaging

    Directory of Open Access Journals (Sweden)

    Rania Gaber

    2014-03-01

    Conclusion: Type 2 diabetes mellitus deteriorate both LV systolic and diastolic performance. Strain and strain rate by tissue Doppler Imaging is superior to conventional Doppler in early detection and evaluation of systolic and diastolic dysfunction in type 2 diabetic patients.

  4. Left ventricular function in endurance runners during exercise.

    Science.gov (United States)

    Jensen-Urstad, M; Bouvier, F; Nejat, M; Saltin, B; Brodin, L A

    1998-10-01

    Left ventricular function in elite runners and controls was compared by means of nuclear angiocardiography. Fifteen middle- or long-distance runners and a control group of 10 sedentary to moderately physically active subjects were studied at rest and during semi-sitting incremental exercise. Ejection fraction was higher in the runners than the controls both at rest and during exercise. At the transition from rest to exercise left ventricular end-diastolic volume initially increased similarly in runners and controls by an average of 14 and 12%, respectively, with an increase in stroke volume by approximately 25 and 23%. The parallel increase in stroke volume and left ventricular end-diastolic volume could at least partly be because of the Frank-Starling mechanism. With increasing workloads, left ventricular end-diastolic volume and ejection fraction remained fairly constant, resulting in an unchanged stroke volume from the lowest to the highest exercise intensity. This was in the runners accomplished by a 41% increase in peak filling rate and a 38% increase in peak emptying rate with similar changes observed in the controls. This has to be due to increased myocardial contractility paralleling the systolic shortening with increasing heart rate. We conclude that endurance-trained athletes have a better systolic function expressed as higher ejection fraction both at rest and during exercise than untrained subjects reflecting an enhanced myocardial contractility contributing to the maintenance of a large stroke volume during exercise. The regulatory mechanisms however, appear to be similar for athletes and healthy controls.

  5. Comparison of Metal Levels between Postmortem Brain and Ventricular Fluid in Alzheimer’s Disease and Nondemented Elderly Controls

    Science.gov (United States)

    Szabo, Steven T.; Harry, G. Jean; Hayden, Kathleen M.; Szabo, David T.; Birnbaum, Linda

    2016-01-01

    An essential metal hypothesis for neurodegenerative disease suggests an alteration in metal homeostasis contributing to the onset and progression of disease. Similar associations have been proposed for nonessential metals. To examine the relationship between metal levels in brain tissue and ventricular fluid (VF), postmortem samples of frontal cortex (FC) and VF from Alzheimer’s disease (AD) cases and nondemented elderly subjects were analyzed for arsenic (As), cadmium (Cd), chromium (Cr), cobalt (Co), copper (Cu), iron (Fe), lead (Pb), manganese (Mn), mercury (Hg), nickel (Ni), tin (Sn), vanadium (V), and zinc (Zn) using inductively coupled plasma sector field mass spectrometry. All metals, with exception of equivalent Pb levels, were lower in the VF, compared to FC. Within-subject comparisons demonstrated that VF levels were not representative of levels within brain tissue. The essential metals Cu, Fe, and Zn were found highest in both compartments. Cd, Hg, and V levels in the VF were below the limit of quantification. In AD cases, FC levels of Fe were higher and As and Cd were lower than levels in controls, while levels of As in the VF were higher. Parameter estimates for FC metal levels indicated an association of Braak stage and higher Fe levels and an association of Braak stage and lower As, Mn, and Zn levels. The data showed no evidence of an accumulation of nonessential metals within the AD brain and, with the exception of As, showed no significant shift in the ratio of FC to VF levels to indicate differential clearance. PMID:26721301

  6. Capital Controls and the Real Exchange Rate

    NARCIS (Netherlands)

    van Wijnbergen, S.J.G.

    1990-01-01

    Capital import taxes lower (raise) world (home) interest rates. This shifts home expenditure from the present to the future and foreign expenditure from the future to today. With identical home and foreign expenditure patterns, the change in the composition of world expenditure has no effects on

  7. INFLUENCE OF BRONCHOLYTIC THERAPY ON VENTRICULAR RHYTHM DISORDERS IN PATIENTS WITH CHRONIC OBSTRUCTIVE PULMONARY DISEASE

    Directory of Open Access Journals (Sweden)

    Kh. Kh. Shugushev

    2009-01-01

    Full Text Available Aim. To evaluate effects of broncholytic therapy on ventricular rhythm disorders and high resolution electrocardiogram indices in patients with chronic obstructive pulmonary disease (COPD.Material and methods. 144 patients (54 women and 90 men; aged 47,1±1,5 y.o. with COPD and 35 patients of control group without respiratory and cardiovascular diseases (23 men and 12 women; aged 42,4±2,8 y.o. were examined. 24-hour ECG monitoring and high resolution ECG with time and spectral-time mapping of ventricular ECG complex were performed in patients additionally to routine examination.Results. Reduction of ventricular rhythm disorders rate was detected during therapy with extended-release theophylline or salmeterol/fluticasone in patients with moderate and severe COPD. This effect was more significant for salmeterol/fluticasone treatment. Treatment with extended-release theophylline led to increase of a number of ventricular extra systoles in patients with severe COPD. Salmeterol/fluticasone treatment did not influence number of ventricular extrasystoles. Broncholytic therapy had positive influence on processes of ventricular depolarization. It was shown by high resolution ECG indicators improvement and by late ventricular potential rate reduction.Conclusion. Salmeterol/fluticasone combination is more reasonable than extended-release theophylline for broncholytic therapy in patients with severe COPD and ventricular rhythm disorders.

  8. INFLUENCE OF BRONCHOLYTIC THERAPY ON VENTRICULAR RHYTHM DISORDERS IN PATIENTS WITH CHRONIC OBSTRUCTIVE PULMONARY DISEASE

    Directory of Open Access Journals (Sweden)

    Kh. Kh. Shugushev

    2016-01-01

    Full Text Available Aim. To evaluate effects of broncholytic therapy on ventricular rhythm disorders and high resolution electrocardiogram indices in patients with chronic obstructive pulmonary disease (COPD.Material and methods. 144 patients (54 women and 90 men; aged 47,1±1,5 y.o. with COPD and 35 patients of control group without respiratory and cardiovascular diseases (23 men and 12 women; aged 42,4±2,8 y.o. were examined. 24-hour ECG monitoring and high resolution ECG with time and spectral-time mapping of ventricular ECG complex were performed in patients additionally to routine examination.Results. Reduction of ventricular rhythm disorders rate was detected during therapy with extended-release theophylline or salmeterol/fluticasone in patients with moderate and severe COPD. This effect was more significant for salmeterol/fluticasone treatment. Treatment with extended-release theophylline led to increase of a number of ventricular extra systoles in patients with severe COPD. Salmeterol/fluticasone treatment did not influence number of ventricular extrasystoles. Broncholytic therapy had positive influence on processes of ventricular depolarization. It was shown by high resolution ECG indicators improvement and by late ventricular potential rate reduction.Conclusion. Salmeterol/fluticasone combination is more reasonable than extended-release theophylline for broncholytic therapy in patients with severe COPD and ventricular rhythm disorders.

  9. The effects of good glycaemic control on left ventricular and coronary endothelial functions in patients with poorly controlled Type 2 diabetes mellitus.

    Science.gov (United States)

    Erdogan, Dogan; Akcay, Salaheddin; Yucel, Habil; Ersoy, I Hakkı; Icli, Atilla; Kutlucan, Ali; Arslan, Akif; Yener, Mahmut; Ozaydin, Mehmet; Tamer, M Numan

    2015-03-01

    Diabetics are at risk for developing overt heart failure and subclinical left ventricular (LV) dysfunction. Also, impaired coronary flow reserve (CFR) reflecting coronary microvascular dysfunction is common in diabetics. However, no substantial data regarding the effects of good glycaemic control on subclinical LV dysfunction and CFR are available. To investigate whether good glycaemic control had favourable effects on subclinical LV dysfunction and CFR. Prospective, open-label, follow-up study. Diabetics (n = 202) were classified based on baseline HbA1C levels: patients with good (group 1) (good glycaemic control (group 3). The groups were comparable with respect to diastolic function parameters including left atrium diameter, mitral E/A, Sm , Em /Am , E/E' and Tei index, and these parameters did not significantly change at follow-up in the groups. At baseline, CFR was slightly higher in group 1 than in group 2 and group 3, but it did not reach statistically significant level. At follow-up, CFR remained unchanged in group 1 (P = 0·58) and group 3 (P = 0·86), but increased in group 2 (P = 0·02: month 6 vs baseline and P = 0·004: month 12 vs baseline). Diabetics with poor and good glycaemic control were comparable with respect to echocardiographic parameters reflecting subclinical LV dysfunction, and good glycaemic control did not affect these parameters. However, good glycaemic control improved CFR. © 2014 John Wiley & Sons Ltd.

  10. Bundle of measures for external cerebral ventricular drainage-associated ventriculitis.

    Science.gov (United States)

    Chatzi, Maria; Karvouniaris, Marios; Makris, Demosthenes; Tsimitrea, Eleni; Gatos, Charalampos; Tasiou, Anastasia; Mantzarlis, Kostas; Fountas, Kostas N; Zakynthinos, Epaminondas

    2014-01-01

    To assess the prevalence and outcome of external cerebral ventricular drainage-associated ventriculitis in neurocritical patients before and after the implementation of a bundle of external cerebral ventricular drainage-associated ventriculitis control measures. Clinical prospective case series. University Hospital of Larissa, Greece. Consecutive patients were recruited from the ICU of the hospital. Patient inclusion criteria included presence of external ventricular drainage and ICU stay more than 48 hours. The bundle of external cerebral ventricular drainage-associated ventriculitis control measures included 1) reeducation of ICU personnel on issues of infection control related to external cerebral ventricular drainage, 2) meticulous intraventricular catheter handling, 3) cerebrospinal fluid sampling only when clinically necessary, and 4) routine replacement of the drainage catheter on the seventh drainage day if the catheter was still necessary. The bundle was applied after an initial period (preintervention) where standard policy for external cerebral ventricular drainage-associated ventriculitis was established. External cerebral ventricular drainage-associated ventriculitis prevalence, external cerebral ventricular drainage-associated ventriculitis events per 1,000 drainage days (drain-associated infection rate), length of ICU stay, Glasgow Outcome Scale at 6 months, and risk factors for external cerebral ventricular drainage-associated ventriculitis. Eighty-two patients entered the study in the preintervention period and 57 patients during the intervention period. During the preintervention and intervention period, external cerebral ventricular drainage-associated ventriculitis prevalence was 28% and 10.5% (p = 0.02) and drain-associated infection rate was 18 and 7.1, respectively (p = 0.0001); mean (95% CI) length of ICU stay in patients who presented external cerebral ventricular drainage-associated ventriculitis was 44.4 days (36.4-52.4 d), whereas mean

  11. Single axis controlled hybrid magnetic bearing for left ventricular assist device: hybrid core and closed magnetic circuit.

    Science.gov (United States)

    da Silva, Isaias; Horikawa, Oswaldo; Cardoso, Jose R; Camargo, Fernando A; Andrade, Aron J P; Bock, Eduardo G P

    2011-05-01

    In previous studies, we presented main strategies for suspending the rotor of a mixed-flow type (centrifugal and axial) ventricular assist device (VAD), originally presented by the Institute Dante Pazzanese of Cardiology (IDPC), Brazil. Magnetic suspension is achieved by the use of a magnetic bearing architecture in which the active control is executed in only one degree of freedom, in the axial direction of the rotor. Remaining degrees of freedom, excepting the rotation, are restricted only by the attraction force between pairs of permanent magnets. This study is part of a joint project in development by IDPC and Escola Politecnica of São Paulo University, Brazil. This article shows advances in that project, presenting two promising solutions for magnetic bearings. One solution uses hybrid cores as electromagnetic actuators, that is, cores that combine iron and permanent magnets. The other solution uses actuators, also of hybrid type, but with the magnetic circuit closed by an iron core. After preliminary analysis, a pump prototype has been developed for each solution and has been tested. For each prototype, a brushless DC motor has been developed as the rotor driver. Each solution was evaluated by in vitro experiments and guidelines are extracted for future improvements. Tests have shown good results and demonstrated that one solution is not isolated from the other. One complements the other for the development of a single-axis-controlled, hybrid-type magnetic bearing for a mixed-flow type VAD. © 2011, Copyright the Authors. Artificial Organs © 2011, International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

  12. Resistin and right ventricular function in children with recently diagnosed type-1 diabetes mellitus: a case control study.

    Science.gov (United States)

    Al-Biltagi, Mohammed A; Tolba, Osama A; Mawlana, Wegdan; Abd El Hamed, Abdallah; Ghazy, May

    2015-03-01

    Resistin is an adipocyte-derived signaling polypeptide described in adipose tissue, which acts as a metabolic link between inflammation and atherosclerosis. This study aimed to assess the relation between right ventricular (RV) function assessed by echocardiography and resistin levels in recently diagnosed type-1 diabetic children. The study was conducted as a prospective cohort study and it included 30 children with type-1 diabetes mellitus as a patient group and 30 healthy children matched for age and sex as controls. It evaluated RV functions by tissue Doppler imaging, speckle tracking imaging, and real-time three-dimensional echocardiography (RT3DE), as well as assessing resistin serum level using enzyme-linked immunosorbent assay. The left ventricle (LV) showed no significant difference between the two groups in E/A ratio across the mitral valve, ejection fraction, and S wave mitral annulus. However, it showed significant decrease in the E'/A' wave of mitral annulus, impairment of LV myocardial performance index (MPI), and decrease in LV EF measured by RT3DE in diabetic patients compared to the control group. Significant differences in the mean value of tricuspid annular systolic excursion (TASE), pulmonary artery pressure, longitudinal systolic strain (RV LSS), MPI, and RV ejection fraction were observed between the studied groups. Yet, no significant differences in E/A ratio and S value were observed between the two groups. Significant positive correlation of resistin level with age of studied group and significant negative correlation of resistin with both TASE and RV LSS values were also observed. We confirmed the presence of subclinical RV systolic and diastolic dysfunction in type-1 diabetic children with positive correlation between resistin level and RV dysfunction among them.

  13. The Effects of Gun Ownership Rates and Gun Control Laws on Suicide Rates

    OpenAIRE

    Mark Gius

    2011-01-01

    The purpose of the present study is to determine the effects of gun control laws and gun ownership rates on state-level suicide rates. Using the most recent data on suicide rates, gun control measures, and gun ownership rates, the results of the present study suggest that states that require handgun permits have lower gun-related suicide rates, and states that have higher gun ownership rates have higher gun-related suicide rates. Regarding non-gun suicides, results suggest that stricter gun c...

  14. 31P NMR 2D Mapping of Creatine Kinase Forward Flux Rate in Hearts with Postinfarction Left Ventricular Remodeling in Response to Cell Therapy.

    Directory of Open Access Journals (Sweden)

    Ling Gao

    Full Text Available Utilizing a fast 31P magnetic resonance spectroscopy (MRS 2-dimensional chemical shift imaging (2D-CSI method, this study examined the heterogeneity of creatine kinase (CK forward flux rate of hearts with postinfarction left ventricular (LV remodeling. Immunosuppressed Yorkshire pigs were assigned to 4 groups: 1 A sham-operated normal group (SHAM, n = 6; 2 A 60 minutes distal left anterior descending coronary artery ligation and reperfusion (MI, n = 6; 3 Open patch group; ligation injury plus open fibrin patch over the site of injury (Patch, n = 6; and 4 Cell group, hiPSCs-cardiomyocytes, -endothelial cells, and -smooth muscle cells (2 million, each were injected into the injured myocardium pass through a fibrin patch (Cell+Patch, n = 5. At 4 weeks, the creatine phosphate (PCr/ATP ratio, CK forward flux rate (Flux PCr→ATP, and k constant of CK forward flux rate (kPCr→ATP were severely decreased at border zone myocardium (BZ adjacent to MI. Cell treatment results in significantly increase of PCr/ATP ratio and improve the value of kPCr→ATP and Flux PCr→ATP in BZ myocardium. Moreover, the BZ myocardial CK total activity and protein expression of CK mitochondria isozyme and CK myocardial isozyme were significantly reduced, but recovered in response to cell treatment. Thus, cell therapy results in improvement of BZ bioenergetic abnormality in hearts with postinfarction LV remodeling, which is accompanied by significantly improvements in BZ CK activity and CK isozyme expression. The fast 2D 31P MR CSI mapping can reliably measure the heterogeneity of bioenergetics in hearts with post infarction LV remodeling.

  15. Preoperative Proteinuria and Reduced Glomerular Filtration Rate Predicts Renal Replacement Therapy in Patients Supported With Continuous-Flow Left Ventricular Assist Devices.

    Science.gov (United States)

    Topkara, Veli K; Coromilas, Ellie J; Garan, Arthur Reshad; Li, Randall C; Castagna, Francesco; Jennings, Douglas L; Yuzefpolskaya, Melana; Takeda, Koji; Takayama, Hiroo; Sladen, Robert N; Mancini, Donna M; Naka, Yoshifumi; Radhakrishnan, Jai; Colombo, Paolo C

    2016-12-01

    Renal failure requiring renal replacement therapy (RRT) has detrimental effects on quality of life and survival of patients with continuous-flow left ventricular assist devices (CF-LVADs). Current guidelines do not offer a decision-making algorithm for CF-LVAD candidates with poor baseline renal function. Objective of this study was to identify risk factors associated with RRT after CF-LVAD implantation. Three hundred and eighty-nine consecutive patients underwent contemporary CF-LVAD implantation at the Columbia University Medical Center between January 2004 and August 2015. Baseline demographics, comorbid conditions, clinical risk scores, and renal function were analyzed in patients with or without RRT after CF-LVAD implantation. Time-dependent receiver-operating characteristic curve analysis was performed to define optimal cutoffs for continuous risk factors. Forty-four patients (11.6%) required RRT during a median follow-up of 9.9 months. Patients requiring RRT had significantly worse renal function, lower hemoglobin, and increased proteinuria at baseline. Low estimated glomerular filtration rate (proteinuria (urine protein to creatinine ratio ≥0.55 mg/mg) were significant predictors of RRT after CF-LVAD support. Dipstick proteinuria was also a significant predictor of RRT after CF-LVAD implantation. Patients with both low estimated glomerular filtration rate and proteinuria had highest risk of RRT (63.6%) compared with those with either low estimated glomerular filtration rate or proteinuria (18.7%) and those with neither of these risk factors (2.7%) at 1-year follow-up (log-rank Pproteinuria are predictors RRT after CF-LVAD implantation and should be routinely assessed in CF-LVAD candidates to guide decision making. © 2016 American Heart Association, Inc.

  16. Predictors of the left ventricular dysfunction induced by ventricular arrhythmia

    Directory of Open Access Journals (Sweden)

    А. І. Vytryhovskiy

    2016-08-01

    Full Text Available The most powerful predictor of life-threatening arrhythmia risk is a combination of low heart rate variability with low ejection fraction (EF of the left ventricle. Aim. To identify predictors of left ventricle dysfunction which is induced by ventricular arrhythmia. Materials and methods. To diagnose structural changes of left ventricular functional capacity and reserves in patients with previous myocardial infarction and patients with high and very high cardiovascular risk by SCORE scale and for establishment the relationship between morphological heart changes and pathological phenomenon of heart turbulence echocardiography and study of heart rate turbulence variability were performed. 603 patients were selected for the research. All patients were divided into groups: group 1 – patients with coronary heart disease, but without associated risk factors, such as smoking, obesity, metabolic syndrome; group 2 – patients who smoke tobacco more than 2 years (very high cardiovascular risk by scale SCORE; group 3 – patients with metabolic syndrome without coronary heart disease or arterial hypertension (very high cardiovascular risk by scale SCORE. The control group consisted of 149 persons. Results. The feature of structural changes in patients with myocardial infarction and in patients with a high cardiovascular risk by SCORE with heart rate turbulence compared with cases without НRT is considerably thickening of the left interventricular septum in systole. Based on this, it can be argued that the emergence of ventricular arrhythmia and accordingly phenomenon of heart rate turbulence in patients with existing cardiovascular diseases and risk factors has both morphological and functional character. Significant difference of echocardioscopy parameters in patients with postinfarction cardiosclerosis and risk factors by the SCORE system was established by index of intraventricular septum thickness in systole, and in persons with high risk – in

  17. Cryopreservation: Vitrification and Controlled Rate Cooling.

    Science.gov (United States)

    Hunt, Charles J

    2017-01-01

    Cryopreservation is the application of low temperatures to preserve the structural and functional integrity of cells and tissues. Conventional cooling protocols allow ice to form and solute concentrations to rise during the cryopreservation process. The damage caused by the rise in solute concentration can be mitigated by the use of compounds known as cryoprotectants. Such compounds protect cells from the consequences of slow cooling injury, allowing them to be cooled at cooling rates which avoid the lethal effects of intracellular ice. An alternative to conventional cooling is vitrification. Vitrification methods incorporate cryoprotectants at sufficiently high concentrations to prevent ice crystallization so that the system forms an amorphous glass thus avoiding the damaging effects caused by conventional slow cooling. However, vitrification too can impose damaging consequences on cells as the cryoprotectant concentrations required to vitrify cells at lower cooling rates are potentially, and often, harmful. While these concentrations can be lowered to nontoxic levels, if the cells are ultra-rapidly cooled, the resulting metastable system can lead to damage through devitrification and growth of ice during subsequent storage and rewarming if not appropriately handled.The commercial and clinical application of stem cells requires robust and reproducible cryopreservation protocols and appropriate long-term, low-temperature storage conditions to provide reliable master and working cell banks. Though current Good Manufacturing Practice (cGMP) compliant methods for the derivation and banking of clinical grade pluripotent stem cells exist and stem cell lines suitable for clinical applications are available, current cryopreservation protocols, whether for vitrification or conventional slow freezing, remain suboptimal. Apart from the resultant loss of valuable product that suboptimal cryopreservation engenders, there is a danger that such processes will impose a selective

  18. Hemodynamic effects of ventricular defibrillation

    Science.gov (United States)

    Pansegrau, Donald G.; Abboud, François M.

    1970-01-01

    Hemodynamic responses to ventricular defibrillation were studied in anesthetized dogs. Observations were made on arterial, right atrial and left ventricular end-diastolic pressures, on cardiac output (dye dilution), heart rate, and right atrial electrocardiogram. Ventricular fibrillation was induced electrically with a bipolar electrode catheter placed in the right ventricle. Fibrillation was maintained for 15 or 30 sec and terminated with a 400 w sec capacitor discharge across the thoracic cage. Responses lasted 1-10 min after conversion and included a cholinergic and an adrenergic component. The cholinergic component was characterized by sinus bradycardia, periods of sinus arrest, atrioventricular block, and ventricular premature beats. The adrenergic component included increases in arterial pressure, in cardiac output, and in left ventricular stroke work at a time when left ventricular end-diastolic pressure was normal; there was no change in total peripheral resistance. The pH of arterial blood decreased slightly and pCO2 increased but pO2 and the concentration of lactate were unchanged. Bilateral vagotomy and intravenous administration of atropine blocked the cholinergic component, unmasked a sinus tachycardia, and accentuated the adrenergic component of the response. The latter was blocked by intravenous administration of propranolol and phenoxybenzamine. These responses were related primarily to conversion of ventricular fibrillation rather than to the electrical discharge of countershock because countershock without ventricular fibrillation caused more transient and smaller responses than those observed with defibrillation: furthermore, the hemodynamic effects of defibrillation were augmented by prolongation of the duration of fibrillation. The results suggest that the cholinergic component of the response may be detrimental in that it favors spontaneous recurrence of fibrillation; on the other hand, the adrenergic component may be essential for conversion

  19. Comparison of Metal Levels between Postmortem Brain and Ventricular Fluid in Alzheimer's Disease and Nondemented Elderly Controls.

    Science.gov (United States)

    Szabo, Steven T; Harry, G Jean; Hayden, Kathleen M; Szabo, David T; Birnbaum, Linda

    2016-04-01

    An essential metal hypothesis for neurodegenerative disease suggests an alteration in metal homeostasis contributing to the onset and progression of disease. Similar associations have been proposed for nonessential metals. To examine the relationship between metal levels in brain tissue and ventricular fluid (VF), postmortem samples of frontal cortex (FC) and VF from Alzheimer's disease (AD) cases and nondemented elderly subjects were analyzed for arsenic (As), cadmium (Cd), chromium (Cr), cobalt (Co), copper (Cu), iron (Fe), lead (Pb), manganese (Mn), mercury (Hg), nickel (Ni), tin (Sn), vanadium (V), and zinc (Zn) using inductively coupled plasma sector field mass spectrometry. All metals, with exception of equivalent Pb levels, were lower in the VF, compared to FC. Within-subject comparisons demonstrated that VF levels were not representative of levels within brain tissue. The essential metals Cu, Fe, and Zn were found highest in both compartments. Cd, Hg, and V levels in the VF were below the limit of quantification. In AD cases, FC levels of Fe were higher and As and Cd were lower than levels in controls, while levels of As in the VF were higher. Parameter estimates for FC metal levels indicated an association of Braak stage and higher Fe levels and an association of Braak stage and lower As, Mn, and Zn levels. The data showed no evidence of an accumulation of nonessential metals within the AD brain and, with the exception of As, showed no significant shift in the ratio of FC to VF levels to indicate differential clearance. Published by Oxford University Press on behalf of the Society of Toxicology 2015. This work is written by US Government employees and is in the public domain in the US.

  20. A Rate Control Scheme of the Even Low Bit-Rate Video Encoder

    OpenAIRE

    Bing Zhou; Shi-Mei Su; Xingjin Zhang; Xiaoqiang Li

    2009-01-01

    Rate control plays an important role in transmitting low-delay and high-quality images over the channel of very low bandwidth. The rate control algorithm in MPEG-4 or H.26X only defined the rate control model of P-frame, and did not introduce the rate control model of I-frame as it supposed that only the first frame is an I-frame, the others are all P-frames. However, in practical applications, a certain number of I-frames have to be inserted to meet the demand for fault-tolerant transmission...

  1. Arrhythmogenic right ventricular dysplasia.

    Science.gov (United States)

    Kinsara, A J; Zaman, L; Gorgels, A

    2001-01-01

    Right ventricular dysplasia (RVD) is a disease entity of unknown cause that is characterised by partial or total replacement of RV-muscle by adipose or fibrous tissue. It is a well-recognized cause of arrhythmia and premature sudden death, but usually underdiagnosed. Several noninvasive and invasive diagnostic modalities have been used, however, all may not be positive in a given case. Drug therapy with class 1c, beta-blocker, and amiodarone in variable combination produce varying success rates in preventing recurrent ventricular tachycardia. Failure of the above measures calls for insertion of implantable cardioverter defibrillator. The attention of emergency physicians is drown to this disease as they are the first medical personnel to be presented with this disease as an emergency. Hence their recognition of RVD will ensure early and proper management.

  2. Position dependent rate dampening in any active hand controller

    Science.gov (United States)

    Gregory, William W. (Inventor); Kauffman, James W. (Inventor)

    1994-01-01

    A control system for an active hand controller, for example, uses a control stick connected to and controlled by a motor. Electronics are provided to control the motor to eliminate oscillations due to motor torque and high gain due to breakout at the control stick when the control stick is at about its null position. Both hardware as well as software implementations can provide position dependent dampening to the control sticks such that when the control stick is located about a null position, a higher rate of dampening is provided than when the control stick is located outside the null position, when a lower rate of dampening is provided. The system provides a stable active hand controller control stick without degraded force and feel characteristics of the system.

  3. Clinical Characteristics and Risk Factors of Left Ventricular Thrombus after Acute Myocardial Infarction: A Matched Case-control Study

    Directory of Open Access Journals (Sweden)

    Yue-Xin Jiang

    2015-01-01

    Conclusions: This study indicated that lower LVEF, extensive anterior myocardial infarction, severe RWMA, and left ventricular aneurysm were independent risk factors of LVT after AMI. It also suggested that further efforts are needed for the LVT diagnosis after AMI in clinical practice.

  4. Improved Cerebrospinal Fluid-Based Discrimination between Alzheimer's Disease Patients and Controls after Correction for Ventricular Volumes

    NARCIS (Netherlands)

    Waalwijk van Doorn, L.L.C. van; Gispert, J.D.; Kuiperij, H.B.; Claassen, J.A.H.R.; Arighi, A.; Baldeiras, I.; Blennow, K.; Bozzali, M.; Castelo-Branco, M.; Cavedo, E.; Emek-Savas, D.D.; Eren, E.; Eusebi, P.; Farotti, L.; Fenoglio, C.; Ormaechea, J.F.; Freund-Levi, Y.; Frisoni, G.B.; Galimberti, D.; Genc, S.; Greco, V.; Hampel, H.; Herukka, S.K.; Liu, Y.; Llado, A.; Lleo, A.; Nobili, F.M.; Oguz, K.K.; Parnetti, L.; Pereira, J.; Picco, A.; Pikkarainen, M.; Oliveira, C.R.; Saka, E.; Salvadori, N.; Sanchez-Valle, R.; Santana, I.; Scarpini, E.; Scheltens, P.; Soininen, H.; Tarducci, R.; Teunissen, C.; Tsolaki, M.; Urbani, A.; Vilaplana, E.; Visser, P.J.; Wallin, A.K.; Yener, G.; Molinuevo, J.L.; Meulenbroek, O.V.; Verbeek, M.M.

    2017-01-01

    Cerebrospinal fluid (CSF) biomarkers may support the diagnosis of Alzheimer's disease (AD). We studied if the diagnostic power of AD CSF biomarker concentrations, i.e., Abeta42, total tau (t-tau), and phosphorylated tau (p-tau), is affected by differences in lateral ventricular volume (VV), using

  5. Preload dependence of color M-mode Doppler flow propagation velocity in controls and in patients with left ventricular dysfunction

    DEFF Research Database (Denmark)

    Møller, J E; Poulsen, S H; Søndergaard, E

    2000-01-01

    The purpose of this study was to assess the effects of preload alterations on color M-mode flow propagation velocity (Vp) in volunteers with normal left ventricular (LV) function and in patients with depressed LV function. Color M-mode Doppler echocardiography was performed during Valsalva maneuver...

  6. A multi-modal intervention in management of left ventricular assist device outpatients: dietary counselling, controlled exercise and psychosocial support.

    Science.gov (United States)

    Kugler, Christiane; Malehsa, Doris; Schrader, Eva; Tegtbur, Uwe; Guetzlaff, Elke; Haverich, Axel; Strueber, Martin

    2012-12-01

    Newer generation left ventricular assist devices (LVADs) are established for long-term support. The aim of this multi-modal intervention was to improve the body weight, exercise tolerance and psychosocial status in outpatients on long-term LVAD support. Seventy patients participated in this non-randomized intervention study [intervention group (IGr) n = 34; control group (CGr) n = 36] over 18 months (T1-T4); the baseline sample characteristics showed no differences between groups. Dietary counselling and weight management intervention was performed by a dietician based on a specific algorithm. Physical reconditioning followed a home ergometry protocol and was supplemented by psychosocial counselling. The outcomes were measured based on the body mass index (BMI), cardiopulmonary exercise testing and self-report [hospital anxiety and depression scale (HADS), SF-36]. The intervention showed a strong positive effect on nutrition and weight management [95% confidence interval (CI): -0.71-0.69; effect size (ES): 0.907; P = 0.02)], resulting in the normal BMI (kg/m(2)) values in the IGr (T1: 24.0 ± 0.6; T4: 24.5 ± 1.1; P = 0.35) compared with a significant BMI increase in the CGr (T1: 23.8 ± 0.6; T4: 29.7 ± 0.8; P = 0.05). Significant differences appeared regarding exercise tolerance (VO(2)max/% predicted) in favour of IGr patients (IGr: 69 ± 2.9; CGr 62 ± 3.7; P = 0.04). This increase was reflected by patients' self-reporting based on the SF-36 physical component score (IGr: P = 0.04; CGr: P = 0.54). SF-36 psychosocial component scores showed no changes for both groups. However, CGr showed a tendency for increased anxiety scores relative to their counterparts (IGr: 4.95 ± 0.4; CGr: 6.6 ± 0.9; P = 0.03). IGr patients showed a strong benefit from a multi-modal intervention, including dietary counselling, controlled exercise and psychosocial support. Dietary counselling holds potential to prevent obesity in this patient population.

  7. Controlling Rater Stringency Error in Clinical Performance Rating: Further Validation of a Performance Rating Theory.

    Science.gov (United States)

    Cason, Gerald J.; And Others

    Prior research in a single clinical training setting has shown Cason and Cason's (1981) simplified model of their performance rating theory can improve rating reliability and validity through statistical control of rater stringency error. Here, the model was applied to clinical performance ratings of 14 cohorts (about 250 students and 200 raters)…

  8. The order and volume fill rates in inventory control systems

    DEFF Research Database (Denmark)

    Thorstenson, Anders; Larsen, Christian

    2011-01-01

    This paper differentiates between an order (line) fill rate and a volume fill rate and specifies their performance for different inventory control systems. When the focus is on filling complete customer orders rather than total quantities the order fill rate would be the preferred service level...

  9. Parasympathetic neurons in the cranial medial ventricular fat pad on the dog heart selectively decrease ventricular contractility.

    Science.gov (United States)

    Dickerson, L W; Rodak, D J; Fleming, T J; Gatti, P J; Massari, V J; McKenzie, J C; Gillis, R A

    1998-05-28

    We hypothesized that selective control of ventricular contractility might be mediated by postganglionic parasympathetic neurons in the cranial medial ventricular (CMV) ganglion plexus located in a fat pad at the base of the aorta. Sinus rate, atrioventricular (AV) conduction (ventricular rate during atrial pacing), and left ventricular contractile force (LV dP/dt during right ventricular pacing) were measured in eight chloralose-anesthetized dogs both before and during bilateral cervical vagus stimulation (20-30 V, 0.5 ms pulses, 15-20 Hz). Seven of these dogs were tested under beta-adrenergic blockade (propranolol, 0.8 mg kg(-1) i.v.). Control responses included sinus node bradycardia or arrest during spontaneous rhythm, high grade AV block or complete heart block, and a 30% decrease in contractility from 2118 +/- 186 to 1526 +/- 187 mm Hg s(-1) (P 0.05) decrease in contractility but still elicited the same degree of sinus bradycardia and AV block (N = 8, P < 0.05). Five dogs were re-tested 3 h after trimethaphan fat pad injection, at which time blockade of vagally-induced negative inotropy was partially reversed, as vagal stimulation decreased LV dP/dt by 19%. The same dose of trimethaphan given either locally into other fat pads (PVFP or IVC-ILA) or systemically (i.v.) had no effect on vagally-induced negative inotropy. Thus, parasympathetic ganglia located in the CMV fat pad mediated a decrease in ventricular contractility during vagal stimulation. Blockade of the CMV fat pad had no effect on vagally-mediated slowing of sinus rate or AV conduction.

  10. Doppler-derived strain and strain rate imaging assessment of right ventricular systolic function in adults late after tetralogy of Fallot repair: an observational study.

    Science.gov (United States)

    Sadeghpour, Anita; Kyavar, Majid; Madadi, Shabnam; Ebrahimi, Leili; Khajali, Zahra; Sani, Zahra Alizadeh

    2013-09-01

    Tetralogy of Fallot (TOF) is the most common form of cyanotic congenital heart disease. Today, we are faced with an increasing number of patients with residual pulmonary regurgitation (PR) late after TOF repair. The right ventricular (RV) volumes and function are among the most important factors influencing clinical decision-making. Cardiac magnetic resonance (CMR) is the gold standard method for the quantitative assessment of the RV function; it is, however, expensive for routine clinical follow-up and sometimes is contraindicated. We sought to evaluate the RV systolic function via CMR and compare it with Doppler-derived strain(S) and strain rate (SR) imaging in patients with repaired TOF. In an observational cross-sectional study, 70 patients (22 women, mean age=22±4.9 years) late after TOF repair with severe PR were evaluated. Peak systolic strain and SR in the basal, mid, and apical segments of RV free wall (RVFW) were measured and compared with the RV function measured in the short-axis cine MR. Associations between RVEF and S/SR, investigated by ordinal logistic regression models. Significant association was observed between RV function and mean S of all the three segments of the RVFW segments [OR (CI95%): 1.17 (1.05-1.31)]. Association between RV function and mean SR of all the three segments of the RVFW segments was borderline significant [OR (CI95%): 1.7 (0.97-2.93)]. There was a significant correlation between the Doppler-derived mean strain of RVFW and the RV function measured by CMR in adults late after TOF repair. These quantitative methods improved the assessment of the RV function and served as an additional method to follow up patients with contraindications to CMR.

  11. Arrhythmogenic right ventricular dysplasia

    OpenAIRE

    Bockeria O.L.; Lе T.G.

    2015-01-01

    Arrhythmogenic right ventricular dysplasia is a hereditary cardiomyopathy characterized by structural and functional disorders in the right ventricle, which results in ventricular arrhythmias. Arrhythmogenic right ventricular dysplasia is one of the important causes of sudden cardiac death in young people and athletes. Structural disorders in arrhythmogenic right ventricular dysplasia are associated with fibrosis and fatty infiltration of the right ventricular myocardium. These changes lead t...

  12. A Novel Rate Control Scheme for Constant Bit Rate Video Streaming

    Directory of Open Access Journals (Sweden)

    Venkata Phani Kumar M

    2015-08-01

    Full Text Available In this paper, a novel rate control mechanism is proposed for constant bit rate video streaming. The initial quantization parameter used for encoding a video sequence is determined using the average spatio-temporal complexity of the sequence, its resolution and the target bit rate. Simple linear estimation models are then used to predict the number of bits that would be necessary to encode a frame for a given complexity and quantization parameter. The experimental results demonstrate that our proposed rate control mechanism significantly outperforms the existing rate control scheme in the Joint Model (JM reference software in terms of Peak Signal to Noise Ratio (PSNR and consistent perceptual visual quality while achieving the target bit rate. Furthermore, the proposed scheme is validated through implementation on a miniature test-bed.

  13. Atrial and ventricular function in thalassemic patients with supraventricular arrhythmias

    Directory of Open Access Journals (Sweden)

    Vitantonio Di Bello

    2009-04-01

    Full Text Available The aims of this study were to evaluate through Color Doppler Myocardial Imaging (CDMI echocardiography if atrial or ventricular myocardial alterations could be detectable in patients with thalassemia major (THAL and if these alterations could be considered as predictive elements for supra-ventricular arrhythmic events. Twenty-three patients with THAL underwent clinical and electrocardiographic evaluation; patients were grouped in THAL1 (9 with supra-ventricular arrhythmias and THAL2 (14 without arrhythmias; 12 healthy subjects were considered as control group (C. We examined through conventional 2D Color Doppler echocardiography some morphological and functional parameters regarding left ventricular (LV systolic and diastolic function, and through CDMI the velocities at mitral annulus level, the regional LV and left atrial (LA strain and strain rate. All THAL patients had LV dimension (pless than 0.05, LA area (p less than 0.01 and E/Em ratio (pless than 0.001 to be significantly higher than controls. The mitral annulus longitudinal velocities were significantly lower in THAL1 than in THAL2 (pless than 0.001; the E/Em ratio was higher in THAL1 than THAL2 (pless than 0.001. The THAL1 showed a lower systolic strain rate of atrial wall than THAL2 and C (pless than 0.05. The multiple regression highlighted a significantly inverse correlation among E/Em and atrial strain (pless than 0.02. CDMI showed both THAL subgroups had subtle systolic and diastolic left ventricular myocardial alterations, which could represent the onset of developing “iron cardiomyopathy” and are related to supra-ventricular arrhythmia. Monitoring these parameters in the THAL patients could contribute to decisions about follow-up and therapy.

  14. Design and Implementation of Automatic Air Flow Rate Control System

    Science.gov (United States)

    Akbar, A.; Saputra, C.; Munir, M. M.; Khairurrijal

    2016-08-01

    Venturimeter is an apparatus that can be used to measure the air flow rate. In this experiment we designed a venturimeter which equipped with a valve that is used to control the air flow rate. The difference of pressure between the cross sections was measured with the differential pressure sensor GA 100-015WD which can calculate the difference of pressures from 0 to 3737.33 Pa. A 42M048C Z36 stepper motor was used to control the valve. The precision of this motor rotation is about 0.15 °. A Graphical User Interface (GUI) was developed to monitor and set the value of flow rate then an 8-bit microcontroller was used to process the control system In this experiment- the venturimeter has been examined to get the optimal parameter of controller. The results show that the controller can set the stable output air flow rate.

  15. Comparison of Metal Levels between Postmortem Brain and Ventricular Fluid in Alzheimer?s Disease and Nondemented Elderly Controls

    OpenAIRE

    Szabo, Steven T.; Harry, G. Jean; Hayden, Kathleen M.; Szabo, David T.; Birnbaum, Linda

    2015-01-01

    An essential metal hypothesis for neurodegenerative disease suggests an alteration in metal homeostasis contributing to the onset and progression of disease. Similar associations have been proposed for nonessential metals. To examine the relationship between metal levels in brain tissue and ventricular fluid (VF), postmortem samples of frontal cortex (FC) and VF from Alzheimer?s disease (AD) cases and nondemented elderly subjects were analyzed for arsenic (As), cadmium (Cd), chromium (Cr), co...

  16. Morning surge of ventricular arrhythmias in a new arrhythmogenic canine model of chronic heart failure is associated with attenuation of time-of-day dependence of heart rate and autonomic adaptation, and reduced cardiac chaos.

    Directory of Open Access Journals (Sweden)

    Yujie Zhu

    Full Text Available Patients with chronic heart failure (CHF exhibit a morning surge in ventricular arrhythmias, but the underlying cause remains unknown. The aim of this study was to determine if heart rate dynamics, autonomic input (assessed by heart rate variability (HRV and nonlinear dynamics as well as their abnormal time-of-day-dependent oscillations in a newly developed arrhythmogenic canine heart failure model are associated with a morning surge in ventricular arrhythmias. CHF was induced in dogs by aortic insufficiency & aortic constriction, and assessed by echocardiography. Holter monitoring was performed to study time-of-day-dependent variation in ventricular arrhythmias (PVCs, VT, traditional HRV measures, and nonlinear dynamics (including detrended fluctuations analysis α1 and α2 (DFAα1 & DFAα2, correlation dimension (CD, and Shannon entropy (SE at baseline, as well as 240 days (240 d and 720 days (720 d following CHF induction. LV fractional shortening was decreased at both 240 d and 720 d. Both PVCs and VT increased with CHF duration and showed a morning rise (2.5-fold & 1.8-fold increase at 6 AM-noon vs midnight-6 AM during CHF. The morning rise in HR at baseline was significantly attenuated by 52% with development of CHF (at both 240 d & 720 d. Morning rise in the ratio of low frequency to high frequency (LF/HF HRV at baseline was markedly attenuated with CHF. DFAα1, DFAα2, CD and SE all decreased with CHF by 31, 17, 34 and 7%, respectively. Time-of-day-dependent variations in LF/HF, CD, DFA α1 and SE, observed at baseline, were lost during CHF. Thus in this new arrhythmogenic canine CHF model, attenuated morning HR rise, blunted autonomic oscillation, decreased cardiac chaos and complexity of heart rate, as well as aberrant time-of-day-dependent variations in many of these parameters were associated with a morning surge of ventricular arrhythmias.

  17. Development of normal-suction boundary control method based on inflow cannula pressure waveform for the undulation pump ventricular assist device.

    Science.gov (United States)

    Ishii, Kohei; Saito, Itsuro; Isoyama, Takashi; Nakagawa, Hidemoto; Emiko, Nakano; Ono, Toshiya; Shi, Wei; Inoue, Yusuke; Abe, Yusuke

    2012-09-01

    It is desirable to obtain the maximum assist without suction in ventricular assist devices (VADs). However, high driving power of a VAD may cause severe ventricle suction that can induce arrhythmia, hemolysis, and pump damage. In this report, an appropriate VAD driving level that maximizes the assist effect without severe systolic suction was explored. The target driving level was set at the boundary between low driving power without suction and high driving power with frequent suction. In the boundary range, intermittent mild suction may occur. Driving power was regulated by the suction occurrence. The normal-suction boundary control method was evaluated in a female goat implanted with an undulation pump ventricular assist device (UPVAD). The UPVAD was driven in a semipulsatile mode with heartbeat synchronization control. Systolic driving power was adjusted using a normal-suction boundary control method developed for this study. We confirmed that driving power could be maintained in the boundary range. Occurrences of suction were evaluated using the suction ratio. We defined this ratio as the number of suction occurrences divided by the number of heartbeats. The suction ratio decreased by 70% when the normal-suction boundary control method was used. © 2012, Copyright the Authors. Artificial Organs © 2012, International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

  18. Evaluation of left ventricular mass and function, lipid profile, and insulin resistance in Egyptian children with growth hormone deficiency: A single-center prospective case-control study

    Directory of Open Access Journals (Sweden)

    Kotb Abbass Metwalley

    2013-01-01

    Full Text Available Background: Growth hormone deficiency (GHD in adults is associated with a cluster of cardiovascular risk factors that may contribute to an increased mortality for cardiovascular disease. In children, relatively few studies have investigated the effect of GHD and replacement therapy on cardiac performance and metabolic abnormalities that may place them at a higher risk of cardiovascular disease (CVD at an early age. Aim: This study was aimed to assess the left ventricular function, lipid profile, and degree of insulin resistance in Egyptian children with GHD before and after 1 year of GH replacement therapy. Settings and Design: Prospective case-control study, single-center study. Materials and Methods: Thirty children with short stature due to GHD were studied in comparison to 20 healthy age- and sex-matched children. All subjects were subjected to history, clinical examination, auxological assessment, and echocardiography to assess the left ventricular function. Blood samples were collected for measuring IGF-1, lipid profile (Total, LDL, HDL cholesterol, triglyceride, and atherogenic index (AI, fasting blood sugar, and fasting insulin levels. In addition, basal and stimulated GH levels were measured in children with suspected GHD. Statistical Analysis Used: Student′s t-test was used for parametric data, and the Mann-Whitney U-test was used for non-parametric data. Results: Total, LDL cholesterol, triglyceride, AI, and insulin were significantly higher in children with GHD than in healthy controls at baseline. After 12 months of GH replacement therapy, total, LDL cholesterol, triglyceride, AI and insulin were significantly decreased, while homeostatic model assessment for insulin resistance index (HOMA-IR was significantly increased compared to both pre-treatment and control values. At baseline, the left ventricular mass (LVM and left ventricular mass index (LVMi were significantly lower in GHD children than in controls. After 12 months of GH

  19. Vagus nerve stimulation reverses ventricular electrophysiological changes induced by hypersympathetic nerve activity.

    Science.gov (United States)

    Huang, Jie; Qian, Jin; Yao, Wei; Wang, Neng; Zhang, Zhenjian; Cao, Chuanbin; Song, Bo; Zhang, Zhuo

    2015-03-01

    What is the central question of this study? Previous studies have shown that hypersympathetic nerve activity results in ventricular electrophysiological changes and facilitates the occurrence of ventricular arrhythmias. Vagus nerve stimulation has shown therapeutic potential for myocardial infarction-induced ventricular arrhythmias. However, the actions of vagus nerve stimulation on hypersympathetic nerve activity-induced ventricular electrophysiological changes are still unknown. What is the main finding and its importance? We show that vagus nerve stimulation is able to reverse hypersympathetic nerve activity-induced ventricular electrophysiological changes and suppress the occurrence of ventricular fibrillation. These findings further suggest that vagus nerve stimulation may be an effective treatment option for ventricular arrhythmias, especially in patients with myocardial infarction or heart failure. Vagus nerve stimulation (VNS) has shown therapeutic potential for myocardial infarction-induced ventricular arrhythmias. This study aimed to investigate the effects of VNS on ventricular electrophysiological changes induced by hypersympathetic nerve activity. Seventeen open-chest dogs were subjected to left stellate ganglion stimulation (LSGS) for 4 h to simulate hypersympathetic tone. All animals were randomly assigned to the VNS group (n = 9) or the control group (n = 8). In the VNS group, VNS was performed at the voltage causing a 10% decrease in heart rate for hours 3-4 during 4 h of LSGS. During the first 2 h of LSGS, the ventricular effective refractory period (ERP) and action potential duration (APD) were both progressively and significantly decreased; the spatial dispersion of ERP, maximal slope of the restitution curve and pacing cycle length of APD alternans were all increased. With LSGS + VNS during the next 2 h, there was a significant return of all the altered electrophysiological parameters towards baseline levels. In the eight control

  20. Long-term prognostic importance of resting heart rate in patients with left ventricular dysfunction in connection with either heart failure or myocardial infarction: the DIAMOND study

    DEFF Research Database (Denmark)

    Fosbøl, Emil Loldrup; Seibaek, Marie; Brendorp, Bente

    2010-01-01

    dysfunction in connection with either heart failure (HF) or myocardial infarction (MI). METHODS: In the Danish Investigations and Arrhythmia ON Dofetilide (DIAMOND) study; patients with left ventricular dysfunction were randomized to Dofetilide (class III antiarrhythmic drug) or placebo. One part of the study...

  1. Survival rate and factors associated with 1-month survival of witnessed out-of-hospital cardiac arrest of cardiac origin with ventricular fibrillation and pulseless ventricular tachycardia: the Utstein Osaka project.

    Science.gov (United States)

    Nishiuchi, Tatsuya; Hayashino, Yasuaki; Fukuhara, Shunichi; Iwami, Taku; Hayashi, Yasuyuki; Hiraide, Atsushi; Ikeuchi, Hisashi; Yukioka, Hidekazu; Matsuoka, Tetsuya

    2008-09-01

    We reassessed 1-month survival of patients with witnessed out-of-hospital cardiac arrest (OHCA) of cardiac origin with ventricular fibrillation (VF) or pulseless ventricular tachycardia (VT) in Osaka, Japan, and identified factors associated with 1-month survival using updated data from 1998 to 2004 collected based on the Utstein Style. Using the Utstein Osaka Project database, we analyzed 1028 cases which met the following criteria: (1) patient age 18 years or older; (2) presumed cardiac origin based on the definition of the Utstein Style; (3) witnessed by citizens; (4) VF or pulseless VT at the time of arrival of the ambulance. The main outcome measure was survival at 1 month after collapse. Variables to develop a predictive model for 1-month survival were selected by stepwise logistic regression. Survival at 1 month was 19.6%. Factors retained in the final logistic regression were age, sex, type of witness, and time interval from (a) ambulance call receipt to cardiopulmonary resuscitation (CPR) by the ambulance crew; (b) ambulance call to defibrillation; (c) CPR by the ambulance crew to hospital arrival. Area under the receiver-operating characteristic curve for the model developed with the six variables was 0.738 and Hosmer-Lemshow goodness-of-fit p-value was 0.94. We successfully developed a model to estimate the probability of 1-month survival using variables easy to collect in the early phase of resuscitation, and this model would help physicians and family members predict the likelihood of 1-month survival of OHCA patients on admission.

  2. The order and volume fill rates in inventory control systems

    DEFF Research Database (Denmark)

    Thorstenson, Anders; Larsen, Christian

    2014-01-01

    This paper differentiates between an order (line) fill rate and a volume fill rate and specifies their performance for different inventory control systems. When the focus is on filling complete customer orders rather than total demanded quantity the order fill rate would be the preferred service...... level measure. The main result shows how the order and volume fill rates are related in magnitude. Earlier results derived for a single-item, single-stage, continuous review inventory system with backordering and constant lead times controlled by a base-stock policy are extended in different directions...... extensions consider more general inventory control review policies with backordering, as well as some relations between service measures. A particularly important result in the paper concerns an alternative service measure, the customer order fill rate, and shows how this measure always exceeds the other two...

  3. Coronary artery disease, left ventricular hypertrophy and diastolic dysfunction are associated with stroke in patients affected by persistent non-valvular atrial fibrillation: a case-control study

    Directory of Open Access Journals (Sweden)

    Andrea Passantino

    2009-04-01

    Full Text Available Persistent non-valvular atrial fibrillation (NVAF is associated with an increased risk of cardiovascular events such as stroke, and its rate is expected to rise because of the ageing population. The absolute rate of stroke depends on age and comorbidity. Risk stratification for stroke in patients with NVAF derives from populations enrolled in randomized clinical trials. However, participants in clinical trials are often not representative of the general population. Many stroke risk stratification scores have been used, but they do not include transthoracic echocardiogram (TTE, pulsate wave Doppler (PWD and tissue Doppler imaging (TDI, simple and non-invasive diagnostic tools. The role of TTE, PWD and TDI findings has not been previously determined. Our study goal was to determine the association between TTE and PWD findings and stroke prevalence in a population of NVAF prone outpatients. Patients were divided into two groups: P for stroke prone and F for stroke free. There were no statistically significant differences between the two groups concerning cardiovascular risk factors, age (p=0.2, sex (p=0.2, smoking (p=0.3, diabetes (p=0.1 and hypercholesterolemia (p=0.2; hypertension was statistically significant (p less than 0.001. There were statistically significant differences concerning coronary artery disease, previous acute myocardial infarction (AMI (p less than 0.05 and non- AMI coronaropathy (p less than 0.04, a higher rate being in the P group. Concerning echo-Doppler findings, a higher statistically significant rate of left ventricular hypertrophy (LVH (p less than  0.05 and left ventricular diastolic dysfunction (p less than 0.001 was found in the P group and dilated left atrium (p Exercise, Insulin Absorption Rates, and Artificial Pancreas Control

    Science.gov (United States)

    Frank, Spencer; Hinshaw, Ling; Basu, Rita; Basu, Ananda; Szeri, Andrew J.

    2016-11-01

    Type 1 Diabetes is characterized by an inability of a person to endogenously produce the hormone insulin. Because of this, insulin must be injected - usually subcutaneously. The size of the injected dose and the rate at which the dose reaches the circulatory system have a profound effect on the ability to control glucose excursions, and therefore control of diabetes. However, insulin absorption rates via subcutaneous injection are variable and depend on a number of factors including tissue perfusion, physical activity (vasodilation, increased capillary throughput), and other tissue geometric and physical properties. Exercise may also have a sizeable effect on the rate of insulin absorption, which can potentially lead to dangerous glucose levels. Insulin-dosing algorithms, as implemented in an artificial pancreas controller, should account accurately for absorption rate variability and exercise effects on insulin absorption. The aforementioned factors affecting insulin absorption will be discussed within the context of both fluid mechanics and data driven modeling approaches.

  4. The order and volume fill rates in inventory control systems

    DEFF Research Database (Denmark)

    Thorstenson, Anders; Larsen, Christian

    2011-01-01

    . The extensions consider general continuous review policies with backordering and some related service measures. Demand is assumed to be generated by a compound renewal process. An important generalization concerns the class of customer order size distributions with increasing failure rate for which the volume......This paper differentiates between an order (line) fill rate and a volume fill rate and specifies their performance for different inventory control systems. When the focus is on filling complete customer orders rather than total quantities the order fill rate would be the preferred service level...

  5. Predictive value of the heart rate reserve in patients with permanent atrial fibrillation treated according to a strict rate-control strategy.

    Science.gov (United States)

    De Schryver, Nicolas; Scavée, Christophe; Marchandise, Sébastien; Pasquet, Agnès; de Meester, Christophe; le Polain de Waroux, Jean-Benoît

    2014-08-01

    Atrial fibrillation (AF) patients treated according to a rate-control strategy seem to have excellent outcomes as long as their ventricular response is kept low. However, the stringency of the rate control to adopt with pharmacologic agents is not clearly defined. In particular, the clinical importance of preserving a heart rate (HR) reserve (HRR) during exercise has not yet been investigated. We prospectively analysed the HR response profiles during exercise of 202 patients with permanent AF for whom a strict rate-control strategy was the preferred treatment option. Patients were asked to perform an exercise test on a cycle ergometer until exhaustion. The HRR was defined as the difference between the HR at peak exercise and the resting HR before exercise, divided by the resting HR. Patients were followed-up for at least 24 months or until death or hospitalization for heart failure. The mean resting HR was 80 ± 16 b.p.m. After a median follow-up period of 3 ± 1 years, 31 patients (15.3%) of our initial population (80% male, age 72 ± 12 years) presented either a hospitalization for heart failure (n = 13, 6.4%) or a death (n = 18, 8.9%). Using a univariate analysis, we found that these events correlated with a lower exercise capacity [hazard ratio, HR 0.98, 95% confidence interval, CI (0.96; 0.99), P heart failure was better in patients with a preserved HRR (HRR >40%, P rate-control strategy is associated with an increased risk of hospitalization for heart failure. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2014. For permissions please email: journals.permissions@oup.com.

  6. Selection of sampling rate for digital control of aircrafts

    Science.gov (United States)

    Katz, P.; Powell, J. D.

    1974-01-01

    The considerations in selecting the sample rates for digital control of aircrafts are identified and evaluated using the optimal discrete method. A high performance aircraft model which includes a bending mode and wind gusts was studied. The following factors which influence the selection of the sampling rates were identified: (1) the time and roughness response to control inputs; (2) the response to external disturbances; and (3) the sensitivity to variations of parameters. It was found that the time response to a control input and the response to external disturbances limit the selection of the sampling rate. The optimal discrete regulator, the steady state Kalman filter, and the mean response to external disturbances are calculated.

  7. Improved Bit Rate Control for Real-Time MPEG Watermarking

    Directory of Open Access Journals (Sweden)

    Pranata Sugiri

    2004-01-01

    Full Text Available The alteration of compressed video bitstream due to embedding of digital watermark tends to produce unpredictable video bit rate variations which may in turn lead to video playback buffer overflow/underflow or transmission bandwidth violation problems. This paper presents a novel bit rate control technique for real-time MPEG watermarking applications. In our experiments, spread spectrum watermarks are embedded in the quantized DCT domain without requantization and motion reestimation to achieve fast watermarking. The proposed bit rate control scheme evaluates the combined bit lengths of a set of multiple watermarked VLC codewords, and successively replaces watermarked VLC codewords having the largest increase in bit length with their corresponding unmarked VLC codewords until a target bit length is achieved. The proposed method offers flexibility and scalability, which are neglected by similar works reported in the literature. Experimental results show that the proposed bit rate control scheme is effective in meeting the bit rate targets and capable of improving the watermark detection robustness for different video contents compressed at different bit rates.

  8. Does runoff or temperature control chemical weathering rates?

    Energy Technology Data Exchange (ETDEWEB)

    Eiriksdottir, Eydis Salome, E-mail: ese@raunvis.hi.is [Institute of Earth Sciences, Sturlugata 7, 101 Reykjavik (Iceland); Gislason, Sigurdur Reynir [Institute of Earth Sciences, Sturlugata 7, 101 Reykjavik (Iceland); Oelkers, Eric H. [GET, CNRS/URM 5563-Universite Paul Sabatier, 14 Ave. Edouard Belin, 31400, Toulouse (France)

    2011-06-15

    Highlights: > The rate chemical weathering is affected by both temperature and runoff. Separating out these two factors is challenging because runoff tends to increase with increasing temperature. > In this study, natural river water samples collected on basaltic catchments over a five year period are used together with experimentally derived dissolution rate model for basaltic glass to pull apart the effects of runoff and temperature. > This study shows that the rate of chemical denudation is controlled by both temperature and runoff, but is dominated by runoff. - Abstract: The rate of chemical denudation is controlled by both temperature and runoff. The relative role of these two factors in the rivers of NE Iceland is determined through the rigorous analysis of their water chemistry over a 5-a period. River catchments are taken to be analogous to laboratory flow reactors; like the fluid in flow reactors, the loss of each dissolved element in river water is the sum of that of the original rainwater plus that added from kinetically controlled dissolution and precipitation reactions. Consideration of the laboratory determined dissolution rate behaviour of basalts and measured water chemistry indicates that the maximum effect of changing temperature on chemical denudation in the NE Icelandic rivers was 5-25% of the total change, whereas that of runoff was 75-95%. The bulk of the increased denudation rates with runoff appear to stem from an increase in reactive surface area for chemical weathering of catchment solids.

  9. Rationale and design of the Sodium Lowering In Dialysate (SoLID) trial: a randomised controlled trial of low versus standard dialysate sodium concentration during hemodialysis for regression of left ventricular mass

    Science.gov (United States)

    2013-01-01

    Background The current literature recognises that left ventricular hypertrophy makes a key contribution to the high rate of premature cardiovascular mortality in dialysis patients. Determining how we might intervene to ameliorate left ventricular hypertrophy in dialysis populations has become a research priority. Reducing sodium exposure through lower dialysate sodium may be a promising intervention in this regard. However there is clinical equipoise around this intervention because the benefit has not yet been demonstrated in a robust prospective clinical trial, and several observational studies have suggested sodium lowering interventions may be deleterious in some dialysis patients. Methods/design The Sodium Lowering in Dialysate (SoLID) study is funded by the Health Research Council of New Zealand. It is a multi-centre, prospective, randomised, single-blind (outcomes assessor), controlled parallel assignment 3-year clinical trial. The SoLID study is designed to study what impact low dialysate sodium has upon cardiovascular risk in dialysis patients. The study intends to enrol 118 home hemodialysis patients from 6 sites in New Zealand over 24 months and follow up each participant over 12 months. Key exclusion criteria are: patients who dialyse more frequently than 3.5 times per week, pre-dialysis serum sodium of <135 mM, and maintenance hemodiafiltration. In addition, some medical conditions, treatments or participation in other dialysis trials, which contraindicate the SoLID study intervention or confound its effects, will be exclusion criteria. The intervention and control groups will be dialysed using dialysate sodium 135 mM and 140 mM respectively, for 12 months. The primary outcome measure is left ventricular mass index, as measured by cardiac magnetic resonance imaging, after 12 months of intervention. Eleven or more secondary outcomes will be studied in an attempt to better understand the physiologic and clinical mechanisms by which lower dialysate sodium

  10. False discovery rate control for identifying simultaneous signals

    OpenAIRE

    Zhao, Sihai Dave

    2015-01-01

    It is frequently of interest to jointly analyze multiple sequences of multiple tests in order to identify simultaneous signals, defined as features tested in multiple independent studies whose test statistics are non-null in each. For example, researchers often wish to discover genetic variants that are significantly associated with multiple traits. This paper proposes a false discovery rate control procedure for identifying simultaneous signals in two studies. Error control is difficult due ...

  11. Non-β-blocking R-carvedilol enantiomer suppresses Ca2+ waves and stress-induced ventricular tachyarrhythmia without lowering heart rate or blood pressure

    OpenAIRE

    Zhang, Jingqun; Zhou, Qiang; Smith, Chris D.; Chen, Haiyan; Tan, Zhen; Chen, Biyi; Nani, Alma; Wu, Guogen; Song, Long-Sheng; Fill, Michael; Back, Thomas G.; Wayne Chen, S.R.

    2015-01-01

    Carvedilol is the current β-blocker of choice for suppressing ventricular tachyarrhythmia (VT). However, carvedilol’s benefits are dose-limited, attributable to its potent β-blocking activity that can lead to bradycardia and hypotension. The clinically used carvedilol is a racemic mixture of β-blocking S-carvedilol and non-β-blocking R-carvedilol. We recently reported that novel non-β-blocking carvedilol analogues are effective in suppressing arrhythmogenic Ca2+ waves and stress-induced VT wi...

  12. Heart rate variability density analysis (Dyx) for identification of appropriate implantable cardioverter defibrillator recipients among elderly patients with acute myocardial infarction and left ventricular systolic dysfunction

    DEFF Research Database (Denmark)

    Jørgensen, Rikke Mørch; Levitan, Jacob; Halevi, Zohar

    2015-01-01

    to diagnose the primary endpoint of near-fatal or fatal ventricular tachyarrhythmias likely preventable by an implantable cardioverter defibrillator (ICD), during a period of 2 years. A Dyx ≤ 1.96 was considered abnormal. The secondary endpoint was cardiovascular death. At enrolment 59 patients (24%) had...... a Dyx ≤ 1.96 and 20 experienced a primary endpoint. A Dyx ≤ 1.96 was associated with a significantly increased risk for malignant arrhythmias [hazards ratio (HR) = 4.36 (1.81-10.52), P = 0.001] and cardiovascular death [HR = 3.47 (1.38-8.74), P = 0.008]. Compared with important clinical risk parameters...

  13. Subclinical left ventricular systolic dysfunction in patients with metabolic syndrome: A case-control study using two-dimensional speckle tracking echocardiography.

    Science.gov (United States)

    Moaref, Alireza; Faraji, Majid; Tahamtan, Maryam

    2016-11-01

    The dramatic increase in the prevalence of metabolic syndrome is associated with more increased cardiovascular morbidity and mortality in this group. Some recent studies suggested that metabolic syndrome is associated with increased risk of subclinical left ventricular (LV) systolic dysfunction. In the present cross-sectional case-control study, the utility of two-dimensional speckle tracking echocardiography (STE) was examined to detect early LV systolic dysfunction in this population. A total of 75 clinically asymptomatic subjects with left ventricular ejection fraction (LVEF) ≥ 55%, 39 without metabolic syndrome and 36 with metabolic syndrome, matched for gender and age, were enrolled in this case-control study. Metabolic syndrome was diagnosed using the National Cholesterol Education Program/Adult Treatment Panel III criteria. LV systolic function was assessed by STE-derived global and segmental longitudinal strain (εLL). Global εLL was significantly lower in patients with metabolic syndrome compared with normal population (-18.41 ± 2.20% vs. -21.2 ± 2.1%, P metabolic syndrome in comparison to control group except for basal anteroseptal (-19.95 ± 2.90% vs. -21.15 ± 3.30%, P = 0.106), basal anterolateral (-17.5 ± 5.0% vs. -18.3 ± 4.1%, P = 0.437), and basal inferolateral segments (-18.1 ± 6.3% vs. -18.9 ± 4.1%, P = 0.526). STE-derived longitudinal LV strain (εLL), a marker of subclinical cardiovascular disease, is impaired in asymptomatic individuals with metabolic syndrome and normal LVEF.

  14. Parallel efficient rate control methods for JPEG 2000

    Science.gov (United States)

    Martínez-del-Amor, Miguel Á.; Bruns, Volker; Sparenberg, Heiko

    2017-09-01

    Since the introduction of JPEG 2000, several rate control methods have been proposed. Among them, post-compression rate-distortion optimization (PCRD-Opt) is the most widely used, and the one recommended by the standard. The approach followed by this method is to first compress the entire image split in code blocks, and subsequently, optimally truncate the set of generated bit streams according to the maximum target bit rate constraint. The literature proposes various strategies on how to estimate ahead of time where a block will get truncated in order to stop the execution prematurely and save time. However, none of them have been defined bearing in mind a parallel implementation. Today, multi-core and many-core architectures are becoming popular for JPEG 2000 codecs implementations. Therefore, in this paper, we analyze how some techniques for efficient rate control can be deployed in GPUs. In order to do that, the design of our GPU-based codec is extended, allowing stopping the process at a given point. This extension also harnesses a higher level of parallelism on the GPU, leading to up to 40% of speedup with 4K test material on a Titan X. In a second step, three selected rate control methods are adapted and implemented in our parallel encoder. A comparison is then carried out, and used to select the best candidate to be deployed in a GPU encoder, which gave an extra 40% of speedup in those situations where it was really employed.

  15. Very high rate programming in primary prevention patients with reduced ejection fraction implanted with a defibrillator: Results from a large multicenter controlled study.

    Science.gov (United States)

    Clementy, Nicolas; Challal, Farid; Marijon, Eloi; Boveda, Serge; Defaye, Pascal; Leclercq, Christophe; Deharo, Jean-Claude; Sadoul, Nicolas; Klug, Didier; Piot, Olivier; Gras, Daniel; Bordachar, Pierre; Algalarrondo, Vincent; Fauchier, Laurent; Babuty, Dominique

    2017-02-01

    Programming implantable cardioverter-defibrillators (ICDs) with a high-rate therapy strategy has proven to be effective in reducing shocks and is associated with a reduced mortality. We sought to determine the impact of a very high rate cutoff programming strategy on outcomes in patients with a primary indication for an ICD due to reduced left ventricular ejection fraction. Using data from the multicenter French DAI-PP registry, this cohort-controlled study compared outcomes in 500 patients programmed with a very high rate cutoff (VH-RATE group: monitor zone 170-219 beats/min; ventricular fibrillation zone ≥220 beats/min with 13 ± 4 detection intervals) with 1500 matched control patients programmed with 1 or 2 therapy zone. All ICDs were implanted for primary prevention in patients with systolic dysfunction. Risks of events were compared after propensity score matching of sex, age, ejection fraction, New York Heart Association class, cardiomyopathy, atrial fibrillation, and type of device. After a mean follow-up of 3.6 ± 2.3 years, VH-RATE programming was associated with a reduction of appropriate therapy risk (hazard ratio [HR] 0.40; 95% confidence interval [CI] 0.31-0.51; P programmed with 2 therapy zones. There was no significant difference in overall survival between the groups. In patients implanted with an ICD in primary prevention with left ventricular dysfunction, very high rate cutoff programming (single therapy zone ≥220 beats/min) was associated with a 60% reduction of appropriate therapies as well as inappropriate shocks, without affecting mortality. Copyright © 2016 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

  16. QT dispersion and ventricular arrhythmias in children with primary mitral valve prolapse.

    Science.gov (United States)

    İmamoğlu, Ebru Yalın; Eroğlu, Ayşe Güler

    2016-09-01

    To investigate ventricular arrhythmias in children with primary mitral valve prolapse and to evaluate its relation with QT length, QT dispersion, autonomic function tests and heart rate variability measurements. Fourty two children with mitral valve prolapse and 32 healthy children were enrolled into the study. Twelve-lead electrocardiograms, autonomic function tests, echocardiography and 24-hour rhythm Holter tests were performed. Electrocardiograms were magnified digitally. The QT length was corrected according to heart rate. The patients were grouped according to the number of premature ventricular contractions and presence of complex ventricular arhythmia in the 24-hour rhythm Holter monitor test. Heart rate variability measurements were calculated automatically from the 24-hour rhythm Holter monitor test. Orthostatic hypotension and resting heart rate were used as autonomic function tests. The mean age was 13.9±3.3 years in the patient group and 14.6±3.1 years in the control group (p>0.05). Thirty four of the patients (81%) were female and eight (19%) were male. Twenty five of the control subjects (78%) were female and seven (22%) were male. The QT dispersion and heart rate corrected QT interval were found to be significantly increased in the children with primary mitral valve prolapse when compared with the control group (56±16 ms vs. 43±11 ms, p=0.001; 426±25 ms vs. 407±26 ms, p=0.002, respectively). In 24-hour rhythm Holter monitor tests, ventricular arrhythmias were found in 21 out of 42 patients (50%) and 6 out of 32 control subjects (18.8%) (p=0.006). QT dispersion was found to be significantly increased in patients with premature ventricular contractions ≥ 10/day and/or complex ventricular arrhythmias compared to the control group without ventricular premature beats (p=0.002). There was no significant difference in autonomic function tests and heart rate variability measurements between the patient and control groups. The noted increase in QT

  17. Controlled rate cooling of fungi using a stirling cycle freezer.

    Science.gov (United States)

    Ryan, Matthew J; Kasulyte-Creasey, Daiva; Kermode, Anthony; San, Shwe Phue; Buddie, Alan G

    2014-01-01

    The use of a Stirling cycle freezer for cryopreservation is considered to have significant advantages over traditional methodologies including N2 free operation, application of low cooling rates, reduction of sample contamination risks and control of ice nucleation. The study assesses the suitability of an 'N2-free' Stirling Cycle controlled rate freezer for fungi cryopreservation. In total, 77 fungi representing a broad taxonomic coverage were cooled using the N2 free cooler following a cooling rate of -1 degrees C min(-1). Of these, 15 strains were also cryopreserved using a traditional 'N2 gas chamber' controlled rate cooler and a comparison of culture morphology and genomic stability against non-cryopreserved starter cultures was undertaken. In total of 75 fungi survived cryopreservation, only a recalcitrant Basidiomycete and filamentous Chromist failed to survive. No changes were detected in genomic profile after preservation, suggesting that genomic function is not adversely compromised as a result of using 'N2 free' cooling. The results demonstrate the potential of 'N2-free' cooling for the routine cryopreservation of fungi in Biological Resource Centres.

  18. Amiodarone in patients with congestive heart failure and asymptomatic ventricular arrhythmia. Survival Trial of Antiarrhythmic Therapy in Congestive Heart Failure.

    Science.gov (United States)

    Singh, S N; Fletcher, R D; Fisher, S G; Singh, B N; Lewis, H D; Deedwania, P C; Massie, B M; Colling, C; Lazzeri, D

    1995-07-13

    Asymptomatic ventricular arrhythmias in patients with congestive heart failure are associated with increased rates of overall mortality and sudden death. Amiodarone is now used widely to prevent ventricular tachycardia and fibrillation. We conducted a trial to determine whether amiodarone can reduce overall mortality in patients with congestive heart failure and asymptomatic ventricular arrhythmias. We used a double-blind, placebo-controlled protocol in which 674 patients with symptoms of congestive heart failure, cardiac enlargement, 10 or more premature ventricular contractions per hour, and a left ventricular ejection fraction of 40 percent or less were randomly assigned to receive amiodarone (336 patients) or placebo (338 patients). The primary end point was overall mortality, and the median follow-up was 45 months (range, 0 to 54). There was no significant difference in overall mortality between the two treatment groups (P = 0.6). The two-year actuarial survival rate was 69.4 percent (95 percent confidence interval, 64.2 to 74.6) for the patients in the amiodarone group and 70.8 percent (95 percent confidence interval, 65.7 to 75.9) for those in the placebo group. At two years, the rate of sudden death was 15 percent in the amiodarone group and 19 percent in the placebo group (P = 0.43). There was a trend toward a reduction in overall mortality among the patients with nonischemic cardiomyopathy who received amiodarone (P = 0.07). Amiodarone was significantly more effective in suppressing ventricular arrhythmias and increased the left ventricular ejection fraction by 42 percent at two years. Although amiodarone was effective in suppressing ventricular arrhythmias and improving ventricular function, it did not reduce the incidence of sudden death or prolong survival among patients with heart failure, except for a trend toward reduced mortality among those with nonischemic cardiomyopathy.

  19. FMO-based H.264 frame layer rate control for low bit rate video transmission

    Science.gov (United States)

    Cajote, Rhandley D.; Aramvith, Supavadee; Miyanaga, Yoshikazu

    2011-12-01

    The use of flexible macroblock ordering (FMO) in H.264/AVC improves error resiliency at the expense of reduced coding efficiency with added overhead bits for slice headers and signalling. The trade-off is most severe at low bit rates, where header bits occupy a significant portion of the total bit budget. To better manage the rate and improve coding efficiency, we propose enhancements to the H.264/AVC frame layer rate control, which take into consideration the effects of using FMO for video transmission. In this article, we propose a new header bits model, an enhanced frame complexity measure, a bit allocation and a quantization parameter adjustment scheme. Simulation results show that the proposed improvements achieve better visual quality compared with the JM 9.2 frame layer rate control with FMO enabled using a different number of slice groups. Using FMO as an error resilient tool with better rate management is suitable in applications that have limited bandwidth and in error prone environments such as video transmission for mobile terminals.

  1. FMO-based H.264 frame layer rate control for low bit rate video transmission

    Directory of Open Access Journals (Sweden)

    Miyanaga Yoshikazu

    2011-01-01

    Full Text Available Abstract The use of flexible macroblock ordering (FMO in H.264/AVC improves error resiliency at the expense of reduced coding efficiency with added overhead bits for slice headers and signalling. The trade-off is most severe at low bit rates, where header bits occupy a significant portion of the total bit budget. To better manage the rate and improve coding efficiency, we propose enhancements to the H.264/AVC frame layer rate control, which take into consideration the effects of using FMO for video transmission. In this article, we propose a new header bits model, an enhanced frame complexity measure, a bit allocation and a quantization parameter adjustment scheme. Simulation results show that the proposed improvements achieve better visual quality compared with the JM 9.2 frame layer rate control with FMO enabled using a different number of slice groups. Using FMO as an error resilient tool with better rate management is suitable in applications that have limited bandwidth and in error prone environments such as video transmission for mobile terminals.

  2. The effects of rhythm control strategies versus rate control strategies for atrial fibrillation and atrial flutter

    DEFF Research Database (Denmark)

    Sethi, Naqash J; Feinberg, Joshua; Nielsen, Emil E

    2017-01-01

    strategies versus rate control strategies for atrial fibrillation and atrial flutter. METHODS: We searched CENTRAL, MEDLINE, Embase, LILACS, Web of Science, BIOSIS, Google Scholar, clinicaltrials.gov, TRIP, EU-CTR, Chi-CTR, and ICTRP for eligible trials comparing any rhythm control strategy with any rate...

  3. Efficacy of amiodarone in patients with atrial fibrillation with and without left ventricular dysfunction: a pooled analysis of AFFIRM and AF-CHF trials.

    Science.gov (United States)

    Cadrin-Tourigny, Julia; Wyse, D G; Roy, Denis; Blondeau, Lucie; Levesque, Sylvie; Talajic, Mario; Andrade, Jason G; Dubuc, Marc; Thibault, Bernard; Guerra, Peter G; Macle, Laurent; Rivard, Lena; Khairy, Paul

    2014-12-01

    Despite amiodarone's established safety profile in the setting of heart failure, it is unknown whether its impact on cardiovascular outcomes in patients with atrial fibrillation is modulated by left ventricular function. A pooled analysis of 3,307 patients (age 68.0 ± 0.2 years; 31.1% female) enrolled in AFFIRM and AF-CHF trials was conducted to assess the effect of rhythm control with amiodarone on cardiovascular outcomes, according to left ventricular systolic function. In amiodarone-treated patients (N = 1,107), freedom from recurrent atrial fibrillation was 84% and 45% at 1 and 5 years, respectively, with no differences according to left ventricular function (P = 0.8754). Similarly, the adjusted proportion of time spent in atrial fibrillation (15.0 ± 1.8%) did not vary according to ventricular function (P = 0.6094). Over 40.0 ± 0.3 months of follow-up, 1,963 (59.4%) patients required at least one hospitalization, 1,401 (42.6%) of whom had cardiovascular-related hospitalizations. Adjusted all-cause and cardiovascular hospitalization rates were similar with amiodarone versus rate control in all patients and in subgroups with and without severe left ventricular dysfunction. A total of 729 (22.0%) patients died, 498 (15.1%) from cardiovascular causes. Adjusted all-cause and cardiovascular mortality rates were similar with amiodarone versus rate control overall and in subgroups with and without severe left ventricular dysfunction. Amiodarone's efficacy in maintaining sinus rhythm and reducing the burden of atrial fibrillation is similar in the presence or absence of severe left ventricular dysfunction. Rhythm control with amiodarone is associated with comparable hospitalization and mortality rates to rate control in patients with and without left ventricular dysfunction. © 2014 Wiley Periodicals, Inc.

  4. Seismic behaviour of mountain belts controlled by plate convergence rate

    Science.gov (United States)

    Dal Zilio, Luca; van Dinther, Ylona; Gerya, Taras V.; Pranger, Casper C.

    2018-01-01

    The relative contribution of tectonic and kinematic processes to seismic behaviour of mountain belts is still controversial. To understand the partitioning between these processes we developed a model that simulates both tectonic and seismic processes in a continental collision setting. These 2D seismo-thermo-mechanical (STM) models obtain a Gutenberg-Richter frequency-magnitude distribution due to spontaneous events occurring throughout the orogen. Our simulations suggest that both the corresponding slope (b value) and maximum earthquake magnitude (MWmax) correlate linearly with plate convergence rate. By analyzing 1D rheological profiles and isotherm depths we demonstrate that plate convergence rate controls the brittle strength through a rheological feedback with temperature and strain rate. Faster convergence leads to cooler temperatures and also results in more larger seismogenic domains, thereby increasing both MWmax and the relative number of large earthquakes (decreasing b value). This mechanism also predicts a more seismogenic lower crust, which is confirmed by a transition from uni- to bi-modal hypocentre depth distributions in our models. This transition and a linear relation between convergence rate and b value and MWmax is supported by our comparison of earthquakes recorded across the Alps, Apennines, Zagros and Himalaya. These results imply that deformation in the Alps occurs in a more ductile manner compared to the Himalayas, thereby reducing its seismic hazard. Furthermore, a second set of experiments with higher temperature and different orogenic architecture shows the same linear relation with convergence rate, suggesting that large-scale tectonic structure plays a subordinate role. We thus propose that plate convergence rate, which also controls the average differential stress of the orogen and its linear relation to the b value, is the first-order parameter controlling seismic hazard of mountain belts.

  5. Procedure for determining the rate of organizational control.

    Directory of Open Access Journals (Sweden)

    Omar Mar Cornelio

    2014-06-01

    Full Text Available For a company to be productive, requires high cohesion in the elements involved in the system of internal control. In order to analyze trends of control that the organizations have, the Controller General of the Republic of Cuba, provides a guide to self control where each entity in certain periods checks the behavior of these indicators. However, it takes time and consistency in work control to achieve compliance with all elements not to mention that the current model does not identify the critical components to prioritize work in that direction. This paper describes a solution to the problem created by performing a procedure that applies multicriteria techniques of expert consensus to establish ranking indicators to guide self-control, and inference process using the addition operator to assign weights, weight indicators index gaining control of an organization. It was performed as a validation process using a case study applied to a real organization where it was possible to obtain the rate of organizational control demonstrating the applicability and possible degree generalization of the proposal.

  6. Left Ventricular Speckle Tracking-Derived Cardiac Strain and Cardiac Twist Mechanics in Athletes: A Systematic Review and Meta-Analysis of Controlled Studies.

    Science.gov (United States)

    Beaumont, Alexander; Grace, Fergal; Richards, Joanna; Hough, John; Oxborough, David; Sculthorpe, Nicholas

    2017-06-01

    The athlete's heart is associated with physiological remodeling as a consequence of repetitive cardiac loading. The effect of exercise training on left ventricular (LV) cardiac strain and twist mechanics are equivocal, and no meta-analysis has been conducted to date. The objective of this systematic review and meta-analysis was to review the literature pertaining to the effect of different forms of athletic training on cardiac strain and twist mechanics and determine the influence of traditional and contemporary sporting classifications on cardiac strain and twist mechanics. We searched PubMed/MEDLINE, Web of Science, and ScienceDirect for controlled studies of aged-matched male participants aged 18-45 years that used two-dimensional (2D) speckle tracking with a defined athlete sporting discipline and a control group not engaged in training programs. Data were extracted independently by two reviewers. Random-effects meta-analyses, subgroup analyses, and meta-regressions were conducted. Our review included 13 studies with 945 participants (controls n = 355; athletes n = 590). Meta-analyses showed no athlete-control differences in LV strain or twist mechanics. However, moderator analyses showed greater LV twist in high-static low-dynamic athletes (d = -0.76, 95% confidence interval [CI] -1.32 to -0.20; p mechanics between athletes and healthy controls. Differences in speckle tracking echocardiography-derived parameters can be identified using suitable sporting categorizations.

  7. Echocardiographic left ventricular masses in distance runners and weight lifters

    Science.gov (United States)

    Longhurst, J. C.; Gonyea, W. J.; Mitchell, J. H.; Kelly, A. R.

    1980-01-01

    The relationships of different forms of exercise training to left ventricular mass and body mass are investigated by echocardiographic studies of weight lifters, long-distance runners, and comparatively sized untrained control subjects. Left ventricular mass determinations by the Penn convention reveal increased absolute left ventricular masses in long-distance runners and competitive weight lifters with respect to controls matched for age, body weight, and body surface area, and a significant correlation between ventricular mass and lean body mass. When normalized to lean body mass, the ventricular masses of distance runners are found to be significantly higher than those of the other groups, suggesting that dynamic training elevates left ventricular mass compared to static training and no training, while static training increases ventricular mass only to the extent that lean body mass is increased.

  8. Chemical control of rate and onset temperature of nadimide polymerization

    Science.gov (United States)

    Lauver, R. W.

    1985-01-01

    The chemistry of norbornenyl capped imide compounds (nadimides) is briefly reviewed with emphasis on the contribution of Diels-Alder reversion in controlling the rate and onset of the thermal polymerization reaction. Control of onset temperature of the cure exotherm by adjusting the concentration of maleimide is demonstrated using selected model compounds. The effects of nitrophenyl compounds as free radical retarders on nadimide reactivity are discussed. A simple copolymerization model is proposed for the overall nadimide cure reaction. An approximate numerical analysis is carried out to demonstrate the ability of the model to simulate the trends observed for both maleimide and nitrophenyl additions.

  9. Degree of rate control approach to computational catalyst screening

    Energy Technology Data Exchange (ETDEWEB)

    Wolcott, Christopher A.; Medford, Andrew J.; Studt, Felix; Campbell, Charles T.

    2015-10-01

    A new method for computational catalyst screening that is based on the concept of the degree of rate control (DRC) is introduced. It starts by developing a full mechanism and microkinetic model at the conditions of interest for a reference catalyst (ideally, the best known material) and then determines the degrees of rate control of the species in the mechanism (i.e., all adsorbed intermediates and transition states). It then uses the energies of the few species with the highest DRCs for this reference catalyst as descriptors to estimate the rates on related materials and predict which are most active. The predictions of this method regarding the relative rates of twelve late transition metals for methane steam reforming, using the Rh(2 1 1) surface as the reference catalyst, are compared to the most commonly-used approach for computation catalyst screening, the Nørskov–Bligaard (NB) method which uses linear scaling relationships to estimate the energies of all adsorbed intermediates and transition states. It is slightly more accurate than the NB approach when the metals are similar to the reference metal (<0.5 eV different on a plot where the axes are the bond energies to C and O adatoms), but worse when too different from the reference. It is computationally faster than the NB method when screening a moderate number of materials (<100), thus adding a valuable complement to the NB approach. It can be implemented without a microkinetic model if the degrees of rate control are already known approximately, e.g., from experiments.

  10. Controlling type-1 error rates in whole effluent toxicity testing

    Energy Technology Data Exchange (ETDEWEB)

    Smith, R.; Johnson, S.C. [EcoAnalysis, Inc., Ojai, CA (United States)

    1995-12-31

    A form of variability, called the dose x test interaction, has been found to affect the variability of the mean differences from control in the statistical tests used to evaluate Whole Effluent Toxicity Tests for compliance purposes. Since the dose x test interaction is not included in these statistical tests, the assumed type-1 and type-2 error rates can be incorrect. The accepted type-1 error rate for these tests is 5%. Analysis of over 100 Ceriodaphnia, fathead minnow and sea urchin fertilization tests showed that when the test x dose interaction term was not included in the calculations the type-1 error rate was inflated to as high as 20%. In a compliance setting, this problem may lead to incorrect regulatory decisions. Statistical tests are proposed that properly incorporate the dose x test interaction variance.

  11. Circadian variation in ventricular electrical instability associated with coronary artery disease.

    Science.gov (United States)

    McClelland, J; Halperin, B; Cutler, J; Kudenchuk, P; Kron, J; McAnulty, J

    1990-06-01

    Although sudden cardiac deaths and ischemic cardiac events clearly occur in a circadian pattern, such a pattern has not been shown for primary arrhythmic events. Because primary arrhythmic events are thought to play an important role in sudden cardiac death, a large series of ventricular stimulation studies was analyzed to determine whether circadian variation in ventricular electrical instability exists. If such a circadian variation could be shown, it could have implications for the conduct and interpretation of electrophysiologic testing and the etiology of circadian variation in sudden cardiac death. Results of 2 drug-free ventricular stimulation studies performed 4 to 28 hours apart in each of 162 patients with coronary artery disease were analyzed. Rate and duration of induced arrhythmia, number of extrastimuli required to induce arrhythmia and changes in these factors between the 2 tests in each patient were analyzed. Comparisons were made by half-day, by hour and in a temporally continuous manner to eliminate errors associated with any single method. No significant circadian variation was found in any electrophysiologic measure of ventricular electrical instability despite adequate statistical power. These findings show that the time of day during which ventricular stimulation tests are performed does not affect test results, and therefore does not need to be controlled during electrophysiologic studies. If these findings are parallel to those in ambulatory patients with coronary artery disease, then circadian changes in ventricular electrical instability may not play as important a role in the circadian pattern of sudden cardiac death as had been previously thought.

  12. Effect of obesity on left ventricular structure and myocardial systolic function: assessment by tissue Doppler imaging and strain/strain rate imaging.

    Science.gov (United States)

    Tumuklu, Mustafa Murat; Etikan, Ilker; Kisacik, Bunyamin; Kayikcioglu, Meral

    2007-09-01

    Obesity is associated with heart failure, cardiovascular morbidity, and mortality. A direct effect of weight on left ventricle (LV) structure and myocardial function is not well-established. The aim of our study is to determine the effect of obesity on LV morphology and systolic function by using LV standard Doppler echocardiographic indices, myocardial Doppler imaging and strain/strain rate imaging indices. We studied 33 obese and 34 age, sex-adjusted control subjects who had no other pathological conditions. Standard transthoracic Doppler echocardiographical measurements, reconstructed spectral pulsed wave tissue Doppler velocities, strain and strain rate imaging of six different myocardial regions were obtained. Peak systolic velocity (SR), peak systolic strain (I), peak systolic strain rate (SR) for each region and as a global systolic longitidunal LV function mean of peak systolic strain of six myocardial regions (glsca) were compared. Age, body surface area, blood pressure, and heart rate were comparable between the two groups. Obese subjects had significantly increased LV end-diastolic volume, septal wall thickness, left atrial diameter, and decreased transmitral early to late diastolic velocity ratio. In obese subjects, reconstructed spectral pulsed-wave tissue Doppler analysis showed significantly decreased basal lateral peak systolic (Sm) velocity (6.68 +/- 1.89 vs. 8.08 +/- 2.50, P < 0.05), mid lateral Sm (5.01 +/- 2.17 vs. 6.78 +/- 3.22, P < 0.05). Differences in regional strain rate (mid septal SR, 1.45 +/- 0.23 vs. 1.63 +/- 0.18, P < 0.05), regional strain (basal septum I, 19.13 +/- 3.83 vs. 22.09 +/- 4.60, P < 0.05; mid-septum I, 18.03 +/- 2.91 vs. 20.25 +/- 4.77, P < 0.05; radial I, 27.50 +/- 7.32 vs. 35.53 +/- 9.48, P < 0.05), and global strain (glsca, 19.38 +/- 1.34 vs. 21.24 +/- 2.82, P < 0.05) were identified between obese and the referent subjects. Obesity is associated with morphologic alterations in left ventricle and left atrium and

  13. Antiarrhythmic effect of carvedilol after acute myocardial infarction: results of the Carvedilol Post-Infarct Survival Control in Left Ventricular Dysfunction (CAPRICORN) trial

    DEFF Research Database (Denmark)

    McMurray, John; Køber, Lars; Robertson, Michele

    2005-01-01

    OBJECTIVES: Whether beta-blockers reduce atrial arrhythmias and, when added to an angiotensin-converting enzyme (ACE) inhibitor, ventricular arrhythmia is unknown. BACKGROUND: Ventricular and atrial arrhythmias are common after acute myocardial infarction (AMI) and are associated with a poor prog...

  14. chronic sleep deprevation and ventricular arrhythmias: effect of symphatic nervous system

    Directory of Open Access Journals (Sweden)

    Samira Choopani

    2016-04-01

    Full Text Available Introduction: We assessed the effect of chronic sleep deprivation on incidence of ischemia/reperfusion-induced ventricular arrhythmias (ventricular tachycardia and ventricular fibrillation and the role of the sympathetic nervous system in this respect. Material and methods: Rats were randomly divided into four groups; 1 ischemia/reperfusion group (IR: 30 minutes ischemia followed by 60 minutes reperfusion was induced, 2 control group (CON: rats has been placed in large multiple platforms for 72h prior to ischemia and reperfusion, 3 Chronic sleep deprivation group( SD: 72h sleep deprivation was induced by using small  multiple platform prior to ischemia and reperfusion, 4 Sympathectomy group (SYM: chemical sympathectomy was done 24h before to chronic sleep deprivation and then underwent ischemia and reperfusion. The heart isolated and perfused by langendorff apparatus. After thoracotomy and aorta cannulation, the hearts perfused in the langendorff apparatus using krebs-Henseleit buffer. Hearts were allowed to recovery for 15 min. After recovery period, 15 minutes was considered as baseline prior to 30 minutes ischemia followed by 60 minutes reperfusion.Tow thin stainless stell electrodes fixed on the ventricular apex and right atrium for recording the lead II of electrocardiogram (ECG.Results: There were no significant differences between heart rates between groups, and ventricular tachycardia significantly increased in chronic sleep deprivation group As compared with IR group in ischemia period. Sympathectomy significantly reduced ventricular tachycardia incidence when compared with SD. There is no difference in incidence of ventricular tachycardia between control group and IR group. The incidence of ventricular fibrillation during early reperfusion was significantly augmented (P<0.05 in sleep deprivation group as compared with IR group and Sympathectomy significantly could reverse ventricular fibrillation incidence to IR group level as

  15. Rate Control versus Rhythm Control for Atrial Fibrillation after Cardiac Surgery.

    Science.gov (United States)

    Gillinov, A Marc; Bagiella, Emilia; Moskowitz, Alan J; Raiten, Jesse M; Groh, Mark A; Bowdish, Michael E; Ailawadi, Gorav; Kirkwood, Katherine A; Perrault, Louis P; Parides, Michael K; Smith, Robert L; Kern, John A; Dussault, Gladys; Hackmann, Amy E; Jeffries, Neal O; Miller, Marissa A; Taddei-Peters, Wendy C; Rose, Eric A; Weisel, Richard D; Williams, Deborah L; Mangusan, Ralph F; Argenziano, Michael; Moquete, Ellen G; O'Sullivan, Karen L; Pellerin, Michel; Shah, Kinjal J; Gammie, James S; Mayer, Mary Lou; Voisine, Pierre; Gelijns, Annetine C; O'Gara, Patrick T; Mack, Michael J

    2016-05-19

    Atrial fibrillation after cardiac surgery is associated with increased rates of death, complications, and hospitalizations. In patients with postoperative atrial fibrillation who are in stable condition, the best initial treatment strategy--heart-rate control or rhythm control--remains controversial. Patients with new-onset postoperative atrial fibrillation were randomly assigned to undergo either rate control or rhythm control. The primary end point was the total number of days of hospitalization within 60 days after randomization, as assessed by the Wilcoxon rank-sum test. Postoperative atrial fibrillation occurred in 695 of the 2109 patients (33.0%) who were enrolled preoperatively; of these patients, 523 underwent randomization. The total numbers of hospital days in the rate-control group and the rhythm-control group were similar (median, 5.1 days and 5.0 days, respectively; P=0.76). There were no significant between-group differences in the rates of death (P=0.64) or overall serious adverse events (24.8 per 100 patient-months in the rate-control group and 26.4 per 100 patient-months in the rhythm-control group, P=0.61), including thromboembolic and bleeding events. About 25% of the patients in each group deviated from the assigned therapy, mainly because of drug ineffectiveness (in the rate-control group) or amiodarone side effects or adverse drug reactions (in the rhythm-control group). At 60 days, 93.8% of the patients in the rate-control group and 97.9% of those in the rhythm-control group had had a stable heart rhythm without atrial fibrillation for the previous 30 days (P=0.02), and 84.2% and 86.9%, respectively, had been free from atrial fibrillation from discharge to 60 days (P=0.41). Strategies for rate control and rhythm control to treat postoperative atrial fibrillation were associated with equal numbers of days of hospitalization, similar complication rates, and similarly low rates of persistent atrial fibrillation 60 days after onset. Neither

  16. Synchronous temperature rate control for refrigeration with reduced energy consumption

    Science.gov (United States)

    Gomes, Alberto Regio; Keres, Stephen L.; Kuehl, Steven J.; Litch, Andrew D.; Richmond, Peter J.; Wu, Guolian

    2015-09-22

    Methods of operation for refrigerator appliance configurations with a controller, a condenser, at least one evaporator, a compressor, and two refrigeration compartments. The configuration may be equipped with a variable-speed or variable-capacity compressor, variable speed evaporator or compartment fans, a damper, and/or a dual-temperature evaporator with a valve system to control flow of refrigerant through one or more pressure reduction devices. The methods may include synchronizing alternating cycles of cooling each compartment to a temperature approximately equal to the compartment set point temperature by operation of the compressor, fans, damper and/or valve system. The methods may also include controlling the cooling rate in one or both compartments. Refrigeration compartment cooling may begin at an interval before or after when the freezer compartment reaches its lower threshold temperature. Freezer compartment cooling may begin at an interval before or after when the freezer compartment reaches its upper threshold temperature.

  17. Synchronous temperature rate control for refrigeration with reduced energy consumption

    Energy Technology Data Exchange (ETDEWEB)

    Gomes, Alberto Regio; Keres, Stephen L.; Kuehl, Steven J.; Litch, Andrew D.; Richmond, Peter J.; Wu, Guolian

    2017-11-07

    Methods of operation for refrigerator appliance configurations with a controller, a condenser, at least one evaporator, a compressor, and two refrigeration compartments. The configuration may be equipped with a variable-speed or variable-capacity compressor, variable speed evaporator or compartment fans, a damper, and/or a dual-temperature evaporator with a valve system to control flow of refrigerant through one or more pressure reduction devices. The methods may include synchronizing alternating cycles of cooling each compartment to a temperature approximately equal to the compartment set point temperature by operation of the compressor, fans, damper and/or valve system. The methods may also include controlling the cooling rate in one or both compartments. Refrigeration compartment cooling may begin at an interval before or after when the freezer compartment reaches its lower threshold temperature. Freezer compartment cooling may begin at an interval before or after when the freezer compartment reaches its upper threshold temperature.

  18. Wind Turbine Contingency Control Through Generator De-Rating

    Science.gov (United States)

    Frost, Susan; Goebel, Kai; Balas, Mark

    2013-01-01

    Maximizing turbine up-time and reducing maintenance costs are key technology drivers for wind turbine operators. Components within wind turbines are subject to considerable stresses due to unpredictable environmental conditions resulting from rapidly changing local dynamics. In that context, systems health management has the aim to assess the state-of-health of components within a wind turbine, to estimate remaining life, and to aid in autonomous decision-making to minimize damage to the turbine. Advanced contingency control is one way to enable autonomous decision-making by providing the mechanism to enable safe and efficient turbine operation. The work reported herein explores the integration of condition monitoring of wind turbines with contingency control to balance the trade-offs between maintaining system health and energy capture. The contingency control involves de-rating the generator operating point to achieve reduced loads on the wind turbine. Results are demonstrated using a high fidelity simulator of a utility-scale wind turbine.

  19. Remote magnetic navigation for mapping and ablation of right and left ventricular outflow tract arrhythmias.

    Science.gov (United States)

    Parreira, Leonor; Cavaco, Diogo; Reis-Santos, Katya; Carmo, Pedro; Cabrita, David; Scanavacca, Mauricio; Adragão, Pedro

    2013-06-01

    The aim of this study was to assess the efficacy and potential complications of a remote-controlled magnetic navigation system (Niobe II, Stereotaxis) for mapping and ablation of right or left ventricular outflow tract ventricular tachycardia or premature ventricular contractions. We studied 32 consecutive patients, mean age 43±11 years, 24 female. Mapping of the arrhythmia was performed using the CARTO RMT mapping system, remotely guided by the Niobe II. Radiofrequency ablation was performed at the site of earliest ventricular activation with pacemapping of at least 11/12 leads. Acute success was defined as suppression and non-inducibility of the arrhythmia after stimulation with isoprenaline. After a minimum 3-month follow-up, we assessed clinical success (absence of symptoms and suppression of the arrhythmia on Holter recording), defined as less than 50 premature ventricular contractions/24 hours. The origin of the arrhythmia was in the right ventricular outflow tract in 28 patients (88%), in the left in three, and in the epicardium in one. Acute success was achieved in 26 patients (81%). Two patients underwent a second successful procedure, in one of which an epicardial approach was necessary. The overall clinical success rate, after two repeat procedures, was 88%. No complications occurred. There were two recurrences during a mean follow-up of 307±204 days. The Niobe II remote control system for mapping and ablation of ventricular outflow tract arrhythmias is effective and safe, and provides precise mapping and a high success rate, with no complications. Copyright © 2012 Sociedade Portuguesa de Cardiologia. Published by Elsevier España. All rights reserved.

  20. Pharmacologic Rhythm Control versus Rate Control in Heart Failure and Atrial Fibrillation

    Directory of Open Access Journals (Sweden)

    Gladys Gladys

    2017-01-01

    Full Text Available Heart failure (HF with atrial fibrillation (AF is correlated with worse prognosis requiring special approach.Rate control has been the first line of treatment in cases of HF and HF. On the other hand, rhythm controlhas been proven to be effective in returning sinus rhythm resulting in better prognosis for patients with HFbut not HF. Its role in cocurring cases of HF and AF is not fully understood. Thus, this study aims to analysewhether pharmacologic rhythm control can be applied to cases of HF and AF to reduce mortality. A searchwas conducted via PubMed, Medline, ProQuest, and Cochrane Database on January 2016. One study wasselected after filtering process by inclusion and exclusion criteria and critical appraisal was performed. It wasfound that there was rhythm control and rate control do no have favouring effect towards mortality shown byRR 1.03 (95% CI 0.90-1.17, p=0.69. Rate control has protective effect towards hospitalizations by RR of 0.92(95% CI 0.86 – 0.98, p=0.008, NNT=19. To conclude, rhythm control is not superior to rate control in reducingmortality and rate control should be still be considered as first line treatment of HF and AF. Keywords: heart failure, pharmacologic rhythm control, rate control, atrial fibrillation   Farmakologis Rhythm Control Dibandingkan dengan Rate Control padaKasus Gagal Jantung dan Atrial Fibrilasi Abstrak Gagal jantung dengan atrial fibrilasi berhubungan dengan prognosis yang lebih buruk dan membutuhkanpenanganan khusus. Saat ini strategi rate control merupakan terapi lini pertama pada kasus gagal jantungdan atrial fibrilasi. Rhythm control memberikan prognosis yang lebih baik pada pasien gagal jantung denganmengembalikan sinus ritme. Kegunaan rhythm control pada kasus gagal jantung dan atrial fibrilasi sampaisaat ini belum sepenuhnya dimengerti. Tujuan studi ini adalah menelaah apakah terapi farmakologis rhythmcontrol dapat menurunkan mortalitas gagal jantung dan atrial fibrilasi. Pencarian data

  1. Respiratory modulation and baroreflex control of heart rate in space

    Science.gov (United States)

    Verheyden, Bart; Couckuyt, Kurt; Liu, Jiexin; Aubert, Andre

    During everyday life, gravity constantly stresses the human circulation by diminishing venous return in the upright position. This induces baroreflex-mediated cardiovascular adjustments that are aimed to prevent the blood pressure from falling. In weightlessness, gravitational pressure gradients do not arise in the circulation so that baroreflex function remains chronically unchallenged. This may contribute to the development of post spaceflight orthostatic intolerance. The purpose of this study was to evaluate respiratory modulation and baroreflex control of heart rate after a week of weightlessness in space. We tested the hypothesis that cardiovascular control in space will be similar to the baseline supine condition on Earth. We studied nine male cosmonauts during seven different space missions aboard the ISS (age 40 - 52 yrs, height 1.69 - 1.85 m, weight 67 - 90 kg). Data collection was performed between 30 and 45 days before launch in the standing and supine positions, and after 8 days in space. Cosmonauts were carefully trained to perform in-flight data collection by themselves. They were instructed to pace their breathing to a fixed rate of 12 breaths per minute (0.2 Hz) for a total duration of 3 minutes. The electrocardiogram and beat-by-beat finger arterial blood pressure were recorded at 1-kHz sample rate. Respiratory rate was evaluated using an abdominal pressure sensor. We used power spectral analysis to calculate respiratory sinus arrhythmia (RSA) as well as the low-frequency (0.04 - 0.15 Hz) powers of spontaneous oscillations in heart rate and systolic blood pressure. Baroreflex sensitivity (BRS) was estimated in the time domain using cross-correlation analysis. As expected, there was a rise in heart rate upon assuming the standing position before space- flight (59 ± 6 to 79 ± 11 beats per min; p ¡ 0.001). This was accompanied by an increase in mean arterial blood pressure (84 ± 6 to 93 ± 6 mmHg; p ¡ 0.001). Standing up further induced a marked

  2. Coronary artery disease, left ventricular hypertrophy and diastolic dysfunction are associated with stroke in patients affected by persistent non-valvular atrial fibrillation: a case-control study.

    Science.gov (United States)

    Palmiero, Pasquale; Maiello, Maria; Passantino, Andrea

    2009-06-30

    Persistent non-valvular atrial fibrillation (NVAF) is associated with an increased risk of cardiovascular events such as stroke, and its rate is expected to rise because of the ageing population. The absolute rate of stroke depends on age and comorbidity. Risk stratification for stroke in patients with NVAF derives from populations enrolled in randomized clinical trials. However, participants in clinical trials are often not representative of the general population. Many stroke risk stratification scores have been used, but they do not include transthoracic echocardiogram (TTE), pulsate wave Doppler (PWD) and tissue Doppler imaging (TDI), simple and non- invasive diagnostic tools. The role of TTE, PWD and TDI findings has not been previously determined. Our study goal was to determine the association between TTE and PWD findings and stroke prevalence in a population of NVAF prone outpatients.PATIENTS WERE DIVIDED INTO TWO GROUPS: P for stroke prone and F for stroke free. There were no statistically significant differences between the two groups concerning cardiovascular risk factors, age (p=0.2), sex (p=0.2), smoking (p=0.3), diabetes (p=0.1) and hypercholesterolemia (p=0.2); hypertension was statistically significant (pdisease, previous acute myocardial infarction (AMI) (pdisease, with and without AMI, LVH and left ventricular diastolic dysfunction, but not left atrial dilatation. M-B mode echocardiography and PWD examination help to identify high-risk stroke patients among NVAF subjects; therefore, they may help in the selection of appropriate therapy for each patient.

  3. Hospitalization Rates and Reasons Among HIV Elite Controllers and Persons With Medically Controlled HIV Infection.

    Science.gov (United States)

    Crowell, Trevor A; Gebo, Kelly A; Blankson, Joel N; Korthuis, P Todd; Yehia, Baligh R; Rutstein, Richard M; Moore, Richard D; Sharp, Victoria; Nijhawan, Ank E; Mathews, W Christopher; Hanau, Lawrence H; Corales, Roberto B; Beil, Robert; Somboonwit, Charurut; Edelstein, Howard; Allen, Sara L; Berry, Stephen A

    2015-06-01

    Elite controllers spontaneously suppress human immunodeficiency virus (HIV) viremia but also demonstrate chronic inflammation that may increase risk of comorbid conditions. We compared hospitalization rates and causes among elite controllers to those of immunologically intact persons with medically controlled HIV. For adults in care at 11 sites from 2005 to 2011, person-years with CD4 T-cell counts ≥350 cells/mm(2) were categorized as medical control, elite control, low viremia, or high viremia. All-cause and diagnostic category-specific hospitalization rates were compared between groups using negative binomial regression. We identified 149 elite controllers (0.4%) among 34 354 persons in care. Unadjusted hospitalization rates among the medical control, elite control, low-viremia, and high-viremia groups were 10.5, 23.3, 12.6, and 16.9 per 100 person-years, respectively. After adjustment for demographic and clinical factors, elite control was associated with higher rates of all-cause (adjusted incidence rate ratio, 1.77 [95% confidence interval, 1.21-2.60]), cardiovascular (3.19 [1.50-6.79]) and psychiatric (3.98 [1.54-10.28]) hospitalization than was medical control. Non-AIDS-defining infections were the most common reason for admission overall (24.1% of hospitalizations) but were rare among elite controllers (2.7%), in whom cardiovascular hospitalizations were most common (31.1%). Elite controllers are hospitalized more frequently than persons with medically controlled HIV and cardiovascular hospitalizations are an important contributor. © The Author 2014. Published by Oxford University Press on behalf of the Infectious Diseases Society of America. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  4. Deformation pattern and predictive value of right ventricular longitudinal strain in children with pulmonary arterial hypertension.

    Science.gov (United States)

    Muntean, Iolanda; Benedek, Theodora; Melinte, Mihaela; Suteu, Carmen; Togãnel, Rodica

    2016-07-29

    Right ventricular function has been identified as an important prognostic factor in children with pulmonary arterial hypertension. The aim of the study was to assess the deformation pattern and prognostic value of right ventricular longitudinal strain in children with pulmonary arterial hypertension. We prospectively evaluated 46 children (25 with pulmonary arterial hyperetension and 21 age and sex matched controls) using conventional and speckle-tracking echocardiography, brain natriuretic peptide levels and clinical status expressed by WHO functional class and 6-min walking test. According to the clinical status after 12 months of follow-up, the pulmonary arterial hypertension patients were divided in two groups: non-worsening (13) and worsening (12). Right ventricular free wall longitudinal strain and strain rate were significantly lower in children with PAH compared with controls (-24.72 ± 3.48 vs -15.60 ± 3.40, p = 0.0001 and -1.44 ± 0.09 vs -1.09 ± 0.15, p = 0.0001, respectively). There was a more expressed decrease of basal than apical region of right ventricular free wall longitudinal strain/strain rate in pulmonary arterial hypertension patients compared with controls (strain: p = 0.0001 vs p = 0.07 and strain rate: p = 0.0001 vs p = 0.002). Comparing worsening and non-worsening pulmonary arterial hypertension patients there was a significant difference in Mid right ventricular free wall longitudinal strain (-14.00 ± 3.13 vs. -20.76 ± 4.62, p = 0.0001). In multivariable logistic regression analysis Mid right ventricular free wall longitudinal strain was an independent predictor of worsening in pulmonary arterial hypertension children (OR 0.45; 95 % CI: 0.21-0.96, p = 0.041). In ROC curve analysis a cut-off value of Mid right ventricular free wall longitudinal strain of -18.50 % predicted clinical worsening in pulmonary arterial hypertension children, with a sensitivity and specificity of 91

  5. Efficacy and effects on cardiac function of radiofrequency catheter ablation vs. direct current cardioversion of persistent atrial fibrillation with left ventricular systolic dysfunction.

    Directory of Open Access Journals (Sweden)

    Maojing Wang

    Full Text Available To evaluate the effect of catheter ablation vs. direct current synchronized cardioversion (DCC in patients with persistent atrial fibrillation (AF and left ventricular systolic dysfunction, and to define baseline features of patients that will get more benefit from ablation.From July 2013 to October 2014, 97 consecutive single-center patients with persistent AF and symptomatic heart failure (left ventricular ejection fraction (LVEF 20% or to over 55% in 31 (54.39% patients with worse baseline cardiac function and ventricular rate control.Catheter ablation relative to cardioversion of persistent AF with symptomatic heart failure yielded better 12-month SR maintenance and cardiac function. Compared with non-responders, patients with improved LVEF post-ablation had poorer ventricular rate control and cardiac function at baseline, suggesting a significant component of tachycardia-induced cardiomyopathy in this group.

  6. Assessment of cardiac blood pool imaging in patients with left ventricular outflow tract stenosis

    Energy Technology Data Exchange (ETDEWEB)

    Nakamura, Yutaka (Tajimi City Hospital, Gifu (Japan)); Ono, Yasuo; Kohata, Tohru; Tsubata, Shinichi; Kamiya, Tetsuroh

    1993-09-01

    We performed cardiac blood pool imagings with Tc-99m at rest and during supine ergometer exercise to evaluate left ventricular performance in 14 patients with left ventricular outflow tract stenosis. All catheterized patients were divided into two subgroups: 8 patients with peak systolic left ventricular to descending aortic pressure gradients of less than 50 mmHg (LPG group) and 6 patients with peak systolic gradients of more than 50 mmHg (HPG group). Control group included 10 patients without stenotic coronary lesions after Kawasaki disease. Left ventricular ejection fraction (LVEF) was obtained as systolic index; both filling fraction during the first third of diastole (1/3FF) and mean filling rate during the first third of diastole (1/3FR mean) were obtained as diastolic indices. None of the patients had abnormal findings on [sup 201]Tl imaging. LVEF at rest in HPG group was significantly higher than those in control group, but LVEF in HPG group did not increase after exercise. It increased significantly in control group and LPG group. 1/3 FF in HPG group was significantly lower not only at rest but also during exercise. 1/3 FR mean at rest was not different significantly among the 3 groups. However, 1/3FR mean during exercise in LPG group was significantly lower; and 1/3 FR mean during exercise was significantly lower in HPG group than LPG group. The ratio of left ventricular muscular mass to left ventricular end-diastolic volume (M/V) calculated from left ventricular cineangiograms was different significantly among the 3 groups. The M/V ratio showed a correlation with LVEF and 1/3 FF both at rest and during exercise. These results would indicate that systolic function was impaired on exercise in severe left ventricular outflow tract stenosis and diastolic function was impaired on exercise in mild and severe left ventricular outflow tract stenosis. This may correlate with left ventricular hypertrophy and interaction of systolic function. (author).

  7. Induction of ventricular fibrillation predicts sudden death in patients treated with amiodarone because of ventricular tachyarrhythmias after a myocardial infarction.

    Science.gov (United States)

    Rodríguez, L. M.; Sternick, E. B.; Smeets, J. L.; Timmermans, C.; den Dulk, K.; Oreto, G.; Wellens, H. J.

    1996-01-01

    OBJECTIVE--To examine the value of programmed electrical stimulation of the heart in predicting sudden death in patients receiving amiodarone to treat ventricular tachyarrhythmias after myocardial infarction. DESIGN--Consecutive patients; retrospective study. SETTING--Referral centre for cardiology, academic hospital. PATIENTS--106 patients with ventricular tachycardia (n = 77) or ventricular fibrillation (n = 29) late after myocardial infarction. INTERVENTIONS--Programmed electrical stimulation was performed while on amiodarone treatment for at least one month. MEASUREMENTS AND MAIN RESULTS--In 80/106 patients either ventricular fibrillation (n = 15) or sustained monomorphic ventricular tachycardia (n = 65) was induced. After a mean follow up of 50 (SD 40) months (1-144), 11 patients died suddenly and two used their implantable cardioverter debfibrillator. By multivariate analysis two predictors for sudden death were found: (1) inducibility of ventricular fibrillation under amiodarone treatment (P rate at one, two, three, and five years was 70%, 62%, 62%, and 40% respectively for patients in whom ventricular fibrillation was induced, and 98%, 96%, 94%, 94% for patients with induced sustained monomorphic ventricular tachycardia. Where there was no sustained arrhythmia, five year survival was 100%. CONCLUSIONS--In patients receiving amiodarone because of life threatening ventricular arrhythmias after myocardial infarction, inducibility of ventricular fibrillation, but not of sustained monomorphic ventricular tachycardia, indicates a high risk of sudden death. PMID:8624866

  8. Control of serpentinisation rate by reaction-induced cracking

    Science.gov (United States)

    Malvoisin, Benjamin; Brantut, Nicolas; Kaczmarek, Mary-Alix

    2017-10-01

    Serpentinisation of mantle rocks requires the generation and maintenance of transport pathways for water. The solid volume increase during serpentinisation can lead to stress build-up and trigger cracking, which ease fluid penetration into the rock. The quantitative effect of this reaction-induced cracking mechanism on reactive surface generation is poorly constrained, thus hampering our ability to predict serpentinisation rate in geological environments. Here we use a combined approach with numerical modelling and observations in natural samples to provide estimates of serpentinisation rate at mid-ocean ridges. We develop a micromechanical model to quantify the propagation of serpentinisation-induced cracks in olivine. The maximum crystallisation pressure deduced from thermodynamic calculations reaches several hundreds of megapascals but does not necessary lead to crack propagation if the olivine grain is subjected to high compressive stresses. The micromechanical model is then coupled to a simple geometrical model to predict reactive surface area formation during grain splitting, and thus bulk reaction rate. Our model reproduces quantitatively experimental kinetic data and the typical mesh texture formed during serpentinisation. We also compare the model results with olivine grain size distribution data obtained on natural serpentinised peridotites from the Marum ophiolite and the Papuan ultramafic belt (Papua New Guinea). The natural serpentinised peridotites show an increase of the number of olivine grains for a decrease of the mean grain size by one order of magnitude as reaction progresses from 5 to 40%. These results are in agreement with our model predictions, suggesting that reaction-induced cracking controls the serpentinisation rate. We use our model to estimate that, at mid-ocean ridges, serpentinisation occurs up to 12 km depth and reaction-induced cracking reduces the characteristic time of serpentinisation by one order of magnitude, down to values

  9. Arrhythmogenic right ventricular cardiomyopathy in a dog : case report

    Directory of Open Access Journals (Sweden)

    A.J. Möhr

    2000-07-01

    Full Text Available An 8-month-old Labrador retriever bitch was evaluated for sudden-onset, progressive abdominal distension. Physical examination revealed an exaggerated inspiratory effort, severe ascites, bilateral jugular vein distension, and hypokinetic femoral arterial pulses. Thoracic auscultation detected tachycardia with muffled heart sounds, without audible cardiac murmurs. Thoracic radiographs identified severe right ventricular enlargement and pleural effusion. The electrocardiogram was consistent with incomplete right bundle branch block or right ventricular enlargement. Echocardiography demonstrated severe right ventricular and atrial dilation, secondary tricuspid regurgitation, and thinning and hypocontractility of the right ventricular myocardium. Left heart chamber sizes were slightly decreased, with normal left ventricular contractility. Adiagnosis of arrhythmogenic right ventricular cardiomyopathy was reached, based on the characteristic clinical, electrocardiographic, radiographic and echocardiographic findings, and the exclusion of other causes of isolated right ventricular failure. Treatment effected good control of clinical signs, until acutely decompensated congestive right heart failure led to euthanasia after 4 months. Arrhythmogenic right ventricular cardiomyopathy is a well-described clinical entity in humans, and has previously been documented in 3 male dogs. The condition is characterised by progressive fibro-adipose replacement of right ventricular myocardium, while the left ventricle usually remains unaffected. It should be considered a differential diagnosis in any young dog presented with isolated right heart failure, syncope, or unexplained ventricular tachyarrhythmias. This article reports the 1st case of arrhythmogenic right ventricular cardiomyopathy in a female dog, and highlights its echocardiographic features.

  10. Unsteady Flows Control Hydrologic Turnover Rates in Antarctic Hyporheic Zones

    Science.gov (United States)

    Wlostowski, A. N.; Gooseff, M. N.; McKnight, D. M.; Lyons, W. B.; Saelens, E.

    2016-12-01

    Hydrologic turnover of the hyporheic zone (HZ) is the process of HZ flowpaths receiving water and solutes from the stream channel while simultaneously contributing water and solutes from the HZ back to the stream channel. The influence of hydrologic turnover on HZ solute storage depends on the relative magnitude of hyporheic exchange rates (i.e. physical transport) and biogeochemical reaction rates. Because both exchange rates and reaction rates are unsteady in natural systems, the availability of solutes in the HZ is controlled by the legacy of hydraulic and biological conditions. In this study, we quantify the influence of unsteady flows on hydrologic turnover of the HZ. We study a glacial melt stream in the McMurdo Dry Valleys of Antarctica (MDVs). The MDVs provide an ideal setting for investigating hydrologic and chemical storage characteristics of HZs, because nearly all streamflow is generated from glacier melt and the HZ is vertically bounded by continuous permafrost. A dense network of shallow groundwater wells and piezometers was installed along a 60-meter reach of Von Guerard Stream. 12 days of continuous water level data in each well was used to compute the magnitude and direction of 2D hydraulic gradients between the stream channel and lateral hyporheic aquifer. Piezometers were sampled daily for stable isotope abundances. The direction and magnitude of the cross-valley (CV), perpendicular to the thalweg, component of hydraulic gradients is sensitive to daily flood events and exhibits significant spatial heterogeneity. CV gradients are consistently oriented from the hyporheic aquifer towards the stream channel on 2 sections of the study reach, whereas CV gradients are consistently oriented from the stream channel towards the hyporheic aquifer on 1 section. Three sections show diel changes in orientation of CV gradients, coincident with the passage of daily flood events. During a 4-day period of low flows, the HZ is isotopically distinct from the stream

  11. Double-blind, randomized, placebo-controlled study of high-dose HMG CoA reductase inhibitor therapy on ventricular remodeling, pro-inflammatory cytokines and neurohormonal parameters in patients with chronic systolic heart failure.

    Science.gov (United States)

    Krum, Henry; Ashton, Emma; Reid, Christopher; Kalff, Victor; Rogers, Jim; Amarena, John; Singh, Bhuwan; Tonkin, Andrew

    2007-02-01

    Statins decrease mortality in patients with coronary artery disease. However, chronic heart failure (CHF) patients were often excluded in such trials. Statins possess pharmacologic properties (independent of cholesterol lowering) that may be beneficial on ventricular remodeling in such patients. We conducted a 6-month randomized placebo (PBO)-controlled study of rosuvastatin (ROS) in patients with systolic (left ventricular ejection fraction [LVEF] ventriculogram. Secondary end points included change in echocardiographic parameters, neurohormonal and inflammatory markers, Packer composite score, death, and heart failure hospitalization. Patients were well matched for baseline values. Compared with PBO (n = 46), ROS patients (n = 40) had a decrease in low-density lipoprotein cholesterol (PBO +3, ROS -54%, P ventriculogram (PBO +5.3, ROS +3.2%), fractional shortening by echocardiographic (PBO +2.7, ROS +1.8%), left ventricular end-diastolic diameter (PBO -1.7, ROS +0.8 mm), left ventricular end-systolic diameter (PBO -1.9, ROS +0.1 mm). Plasma norepinephrine, endothelin-1, brain natriuretic peptide, hsCRP, tumor necrosis factor-alpha and interleukin-6, patient global assessment, Packer composite, death/heart failure hospitalization, and adverse events were similar between PBO and ROS. Despite being safe and effective at decreasing plasma cholesterol, high-dose ROS did not beneficially alter parameters of LV remodeling. Reasons for absence of benefit are uncertain, but may include patient population studied, high dose of ROS used or high use of effective background CHF medications.

  12. Risk factors in the origin of congenital left-ventricular outflow-tract obstruction defects of the heart: a population-based case-control study.

    Science.gov (United States)

    Csáky-Szunyogh, Melinda; Vereczkey, Attila; Kósa, Zsolt; Gerencsér, Balázs; Czeizel, Andrew E

    2014-01-01

    The aim of our project was to study possible etiological factors in the origin of congenital heart defects (CHDs) because in the majority of patients the underlying causes are unclear. Cases with different CHD entities as homogeneously as possible were planned for evaluation in the population-based large data set of the Hungarian Case Control Surveillance of Congenital Abnormalities. Dead or surgically corrected 302 live-born cases with different types of left-ventricular outflow tract obstructive defects (LVOT, i.e., valvular aortic stenosis 76, hypoplastic left heart syndrome 76, coarctation of the aorta 113, and other congenital anomalies of aorta 32) were compared with 469 matched controls, 38,151 controls without any defects, and 20,750 malformed controls with other isolated defects. Medically recorded pregnancy complications and chronic diseases were evaluated based on prenatal maternity logbooks, whereas acute diseases, drug treatments, and folic acid/multivitamin supplementation were analyzed both on the basis of retrospective maternal information and medical records. The results of the study showed the role of maternal diabetes in the origin of LVOT in general, while panic disorder was associated with a higher risk of hypoplastic left heart syndrome and ampicillin treatment with a higher risk of coarctation of the aorta (COA). High doses of folic acid had a protective effect regarding the manifestation of LVOT, particularly COA. In conclusion, only a minor portion of causes was shown in our study; thus, further studies are needed to understand better the underlying causal factors in the origin of LVOT.

  13. Reduced contraction and altered frequency response of isolated ventricular myocytes from patients with heart failure.

    Science.gov (United States)

    Davies, C H; Davia, K; Bennett, J G; Pepper, J R; Poole-Wilson, P A; Harding, S E

    1995-11-01

    Previous work has failed to demonstrate reduced maximal contraction of isolated ventricular myocytes from failing human hearts compared with nonfailing control hearts. The effect of alterations in stimulation frequency and temperature on the contraction of isolated ventricular myocytes has been investigated. Left ventricular myocytes were isolated from the hearts of patients with severe heart failure undergoing heart transplantation and compared with myocytes isolated from myocardial biopsies from patients with coronary disease but preserved left ventricular systolic function or from myocytes from rejected donor hearts. Myocytes were exposed to either a maximally activating level of extracellular calcium at 37 degrees C or to 2 mmol/L calcium at 32 degrees C. There was no significant difference in the contraction amplitude between myocytes from failing and nonfailing hearts at 0.2 Hz. With increasing stimulation frequency, there was a reduction in contraction amplitude in cells from failing hearts relative to control hearts in both maximal calcium from 0.33 Hz (4.5% versus 6.6%) to 1.4 Hz (3.9% versus 8.8%) (ANCOVA, P contraction and the times to 50% and 90% relaxation were prolonged in myocytes from failing hearts at stimulation rate of 0.2 Hz (P contraction, slowed relaxation, and impaired frequency response occurring at the level of the individual ventricular myocyte can be demonstrated in human heart failure. This demonstrates that disruption of myocyte function can contribute to both the systolic and the diastolic abnormalities that occur in the failing human heart.

  14. Can using a peel-away sheath in shunt implantation prevent ventricular catheter obstruction?

    Science.gov (United States)

    Camlar, Mahmut; Ersahin, Yusuf; Ozer, Fusun Demirçivi; Sen, Fatih; Orman, Mehmet

    2011-02-01

    Shunt obstruction is the most common shunt complication. In 2003, Kehler et al. used peel-away sheath while implanting the ventricular catheter in 20 patients. They found less revision rate in the peel-away sheath group. We aimed to test the efficacy of this technique in cadavers. We used 100 fresh brains obtained from medicolegal autopsies. Posterior parietal and frontal approaches were used to puncture the lateral ventricle in each cerebral hemisphere. The ventricle is punctured with a peel-away sheath system. After the ventricle is reached, the mandarin is retracted and the ventricular catheter is introduced through the opening. The ventricular catheter was removed from the ventricle, the opening at the tip of the ventricular catheter was checked out for obstruction, and the number of patent and plugged openings was recorded. This procedure was repeated four times for each location with and without using peel-away sheath. The control group consisted of the procedures done without using peel-away sheath. The number of the plugged openings in the peel-away sheath group was significantly smaller than the control group. There was no significant difference between the two groups in terms of gender and left and right cerebral hemispheres. The obstruction rate was significantly lower in the posterior parietal approach. Pearson's correlation showed that increasing age was associated with less obstruction rate. Peel-away sheath decreases the number of plugged openings of the ventricular catheter. A clinical cooperative study is needed to prove that a peel-away sheath should be included in the ventricular shunt systems in the market.

  15. Failure to Treat Life-Threatening Ventricular Tachyarrhythmias in Contemporary Implantable Cardioverter-Defibrillators

    DEFF Research Database (Denmark)

    Thøgersen, Anna Margrethe; Larsen, Jacob Moesgaard; Johansen, Jens Brock

    2017-01-01

    BACKGROUND: In clinical trials, manufacturer-specific, strategic programming of implantable cardioverter-defibrillators (ICDs), including faster detection rates, reduces unnecessary therapy but permits therapy for ventricular tachycardia/ventricular fibrillation (VF). Present consensus recommends...

  16. False discovery rate control in two-stage designs

    Directory of Open Access Journals (Sweden)

    Zehetmayer Sonja

    2012-05-01

    Full Text Available Abstract Background For gene expression or gene association studies with a large number of hypotheses the number of measurements per marker in a conventional single-stage design is often low due to limited resources. Two-stage designs have been proposed where in a first stage promising hypotheses are identified and further investigated in the second stage with larger sample sizes. For two types of two-stage designs proposed in the literature we derive multiple testing procedures controlling the False Discovery Rate (FDR demonstrating FDR control by simulations: designs where a fixed number of top-ranked hypotheses are selected and designs where the selection in the interim analysis is based on an FDR threshold. In contrast to earlier approaches which use only the second-stage data in the hypothesis tests (pilot approach, the proposed testing procedures are based on the pooled data from both stages (integrated approach. Results For both selection rules the multiple testing procedures control the FDR in the considered simulation scenarios. This holds for the case of independent observations across hypotheses as well as for certain correlation structures. Additionally, we show that in scenarios with small effect sizes the testing procedures based on the pooled data from both stages can give a considerable improvement in power compared to tests based on the second-stage data only. Conclusion The proposed hypothesis tests provide a tool for FDR control for the considered two-stage designs. Comparing the integrated approaches for both selection rules with the corresponding pilot approaches showed an advantage of the integrated approach in many simulation scenarios.

  17. The effects of nocturnal hemodialysis compared to conventional hemodialysis on change in left ventricular mass: Rationale and study design of a randomized controlled pilot study

    Directory of Open Access Journals (Sweden)

    Klarenbach Scott

    2006-02-01

    Full Text Available Abstract Background Nocturnal hemodialysis (NHD is an alternative to conventional three times per week hemodialysis (CvHD and has been reported to improve several health outcomes. To date, no randomized controlled trial (RCT has compared NHD and CvHD. We have undertaken a multi-center RCT in hemodialysis patients comparing the effect of NHD to CvHD on left ventricular (LV mass, as measured by cardiac magnetic resonance imaging (cMR. Methodology/design All patients in Alberta, Canada, expressing an interest in performing NHD are eligible for the study. Patients enrolled in the study will be randomized to either NHD or CvHD for a six month period. All patients will have a full clinical assessment, including collection of biochemical and cMR data at baseline and at 6 months. Both groups of patients will be monitored biweekly to optimize blood pressure (BP to a goal of Discussion To our knowledge, this study will be the first RCT evaluating health outcomes in NHD. The impact of NHD on LV mass represents a clinically important outcome which will further elucidate the potential benefits of NHD and guide future clinical endpoint studies.

  18. Does intensity of rate control influence outcome in persistent atrial fibrillation? : Data of the RACE study

    NARCIS (Netherlands)

    Groenveld, Hessel F.; Crijns, Harry J. G. M.; Rienstra, Michiel; van den Berg, Maarten P.; van Veldhuisen, Dirk J.; van Gelder, Isabelle C.

    2009-01-01

    Background Large trials have demonstrated that rate control is an acceptable alternative for rhythm control. However, optimal heart rate during atrial fibrillation (AF) remains unknown. Aim of this analysis was to compare outcome between rate control >= 80 and Methods In the RAte Control versus

  19. Early evaluation of cerebral metabolic rate of glucose (CMRglu) with {sup 18}F-FDG PET/CT and clinical assessment in idiopathic normal pressure hydrocephalus (INPH) patients before and after ventricular shunt placement: preliminary experience

    Energy Technology Data Exchange (ETDEWEB)

    Calcagni, Maria Lucia; Lavalle, Mariadea; Leccisotti, Lucia; Giordano, Alessandro [Universita Cattolica del Sacro Cuore, Institute of Nuclear Medicine, Rome (Italy); Mangiola, Annunziato; De Bonis, Pasquale; Anile, Carmelo [Universita Cattolica del Sacro Cuore, Institute of Neurosurgery, Rome (Italy); Indovina, Luca [Universita Cattolica del Sacro Cuore, Institute of Physics, Rome (Italy); Marra, Camillo [Universita Cattolica del Sacro Cuore, Institute of Neurology, Rome (Italy); Pelliccioni, Armando [Istituto Nazionale per l' Assicurazione contro gli Infortuni sul Lavoro (INAIL), Rome (Italy)

    2012-02-15

    We evaluated the relationships between the cerebral metabolic rate of glucose (CMRglu) measured by dynamic {sup 18}F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) and the clinical and neuropsychological assessment before and after the surgical procedure in idiopathic normal pressure hydrocephalus (INPH) patients. Eleven selected INPH patients underwent clinical assessment (modified Rankin scale, Krauss scale, Larsson categorization system and Stein-Langfitt scale), cognitive evaluation (Mini-Mental State Examination, MMSE) and dynamic {sup 18}F-FDG PET/CT scan 3 days before and 1 week after ventricular shunt placement. After shunting, the global CMRglu significantly increased (2.95 {+-} 0.44 vs 4.38 {+-} 0.68, p = 10{sup -7}) in all INPH patients with a mean percentage value of 48.7%. After shunting, no significant change was found in the Evans ratio whereas a significant decrease in all clinical scale scores was observed. Only a slight reduction in the MMSE was found. After shunting, a significant correlation between the global CMRglu value and clinical assessment was found (R {sup 2} = 0.75, p = 0.024); indeed all clinical scale scores varied (decreasing) and the CMRglu value also varied (increasing) in all INPH patients. Our preliminary data show that changes in the CMRglu are promptly reversible after surgery and that there is a relationship between the early metabolic changes and clinical symptoms, independently from the simultaneous changes in the ventricular size. The remarkable and prompt improvement in the global CMRglu and in symptoms may also have important implications for the current concept of ''neuronal plasticity'' and for the cells' reactivity in order to recover their metabolic function. (orig.)

  20. Isoflurane depresses baroreflex control of heart rate in decerebrate rats.

    Science.gov (United States)

    Lee, Jong S; Morrow, Don; Andresen, Michael C; Chang, Kyoung S K

    2002-05-01

    Isoflurane inhibits baroreflex control of heart rate (HR) by poorly understood mechanisms. The authors examined whether suprapontine central nervous system cardiovascular regulatory sites are required for anesthetic depression. The effects of isoflurane (1 and 2 rat minimum alveolar concentration [MAC]) on the baroreflex control of HR were determined in sham intact and midcollicular-transected decerebrate rats. Intravenous phenylephrine (0.2-12 microg/kg) and nitroprusside (1-60 microg/kg) were used to measure HR responses to peak changes in mean arterial pressure (MAP). Sigmoidal logistic curve fits to HR-MAP data assessed baroreflex sensitivity (HR/MAP), HR range, lower and upper HR plateau, and MAP at half the HR range (BP50). Four groups (two brain intact and two decerebrate) were studied before, during, and after isoflurane. To assess sympathetic and vagal contributions to HR baroreflex, beta-adrenoceptor (1 mg/kg atenolol) or muscarinic (0.5 mg/kg methyl atropine) antagonists were administered systemically. Decerebration did not alter resting MAP and HR or baroreflex parameters. Isoflurane depressed baroreflex slope and HR range in brain-intact and decerebrate rats. In both groups, 1 MAC reduced HR range by depressing peak reflex tachycardia. Maximal reflex bradycardia during increases in blood pressure was relatively preserved. Atenolol during 1 MAC did not alter maximum reflex tachycardia. In contrast, atropine during 1 MAC fully blocked reflex bradycardia. Therefore, 1 MAC predominantly depresses sympathetic components of HR baroreflex. Isoflurane at 2 MAC depressed both HR plateaus and decreased BP50 in both groups. Isoflurane depresses HR baroreflex control by actions that do not require suprapontine central nervous system sites. Isoflurane actions seem to inhibit HR baroreflex primarily by the sympathetic nervous system.

  1. Left Ventricular Hypertrophy

    Science.gov (United States)

    ... need to restrict certain physical activities, such as weightlifting, which may temporarily raise your blood pressure. The ... Accessed April 6, 2015. Chatterjee S, et al. Meta-analysis of left ventricular hypertrophy and sustained arrhythmias. American ...

  2. Premature Ventricular Contractions (PVCs)

    Science.gov (United States)

    ... Premature ventricular contractions (PVCs) Symptoms & causes Diagnosis & treatment Advertisement Mayo Clinic does not endorse companies or products. ... a Job Site Map About This Site Twitter Facebook Google YouTube Pinterest Mayo Clinic is a not- ...

  3. Right ventricular dysfunction affects survival after surgical left ventricular restoration.

    Science.gov (United States)

    Couperus, Lotte E; Delgado, Victoria; Palmen, Meindert; van Vessem, Marieke E; Braun, Jerry; Fiocco, Marta; Tops, Laurens F; Verwey, Harriëtte F; Klautz, Robert J M; Schalij, Martin J; Beeres, Saskia L M A

    2017-04-01

    Several clinical and left ventricular parameters have been associated with prognosis after surgical left ventricular restoration in patients with ischemic heart failure. The aim of this study was to determine the prognostic value of right ventricular function. A total of 139 patients with ischemic heart failure (62 ± 10 years; 79% were male; left ventricular ejection fraction 27% ± 7%) underwent surgical left ventricular restoration. Biventricular function was assessed with echocardiography before surgery. The independent association between all-cause mortality and right ventricular fractional area change, tricuspid annular plane systolic excursion, and right ventricular longitudinal peak systolic strain was assessed. The additive effect of multiple impaired right ventricular parameters on mortality also was assessed. Baseline right ventricular fractional area change was 42% ± 9%, tricuspid annular plane systolic excursion was 18 ± 3 mm, and right ventricular longitudinal peak systolic strain was -24% ± 7%. Within 30 days after surgery, 15 patients died. Right ventricular fractional area change (hazard ratio, 0.93; 95% confidence interval, 0.88-0.98; P right ventricular longitudinal peak systolic strain (hazard ratio, 1.15; 95% confidence interval, 1.05-1.26; P Right ventricular function was impaired in 21%, 20%, and 27% of patients on the basis of right ventricular fractional area change, tricuspid annular plane systolic excursion, and right ventricular longitudinal peak systolic strain, respectively. Any echocardiographic parameter of right ventricular dysfunction was present in 39% of patients. The coexistence of several impaired right ventricular parameters per patient was independently associated with increased 30-day mortality (hazard ratio, 2.83; 95% confidence interval, 1.64-4.87, P right ventricular systolic dysfunction is independently associated with increased mortality in patients with ischemic heart failure undergoing surgical left

  4. The effect of raloxifene on left ventricular hypertrophy in postmenopausal women: A prospective, randomized, and controlled study.

    Science.gov (United States)

    Bal, Uğur Abbas; Atar, İlyas; Öktem, Mesut; Zeyneloğlu, Hulusi B; Yıldırır, Aylin; Kuşcu, Esra; Müderrisoğlu, Haldun

    2015-06-01

    In healthy women, there is a progressive age-related increase in myocardial mass that is not seen in their male counterparts and occurs primarily in postmenopausal women. Raloxifene is a selective estrogen receptor modulator that has estrogenic actions on bone and the cardiovascular system. The aim of this study was to investigate the effect of raloxifene on myocardial hypertrophy in postmenopausal patients. A total of 22 postmenopausal osteoporotic women were included in this open-label, randomized, prospective, controlled study. Patients were randomized into two groups: 11 of the patients (group 1) were treated with raloxifene 60 mg/day, and the other 11 patients
(group 2) were defined as the control group. Quantitative 2-dimensional and M-mode echocardiographic examination was performed in all patients at the beginning and repeated at the end of the 6-month follow-up period. Left ventricle mass (LVM) and left ventricle mass index (LVMI) were calculated for all patients. The mean age of the patients was 57.2±3.9 years, and baseline clinical characteristics and echocardiographic parameters were similar between the two groups. After 6 months of raloxifene treatment, there was no difference in echocardiographic parameters of LVM and LVMI compared with the control group (201.2±25.9 gr vs. 169.7±46.2 gr, p=0.14 and 120.4±25.9 gr/m2 vs. 105.5±26.3 gr/m2, p=0.195, respectively). There was also no significant difference in LVM and LVMI in the within-group analysis of both groups. Raloxifene therapy does not affect myocardial hypertrophy in postmenopausal women after 6 months of treatment.

  5. Effectiveness of quality control methods for glomerular filtration rate calculation.

    Science.gov (United States)

    McMeekin, Helena; Wickham, Fred; Barnfield, Mark; Burniston, Maria

    2016-07-01

    In this work, we aimed to identify the types of errors encountered in glomerular filtration rate (GFR) measurement and test the effectiveness of all published quality control (QC) methods for detection of clinically significant errors. A total of 412 GFR tests were carried out on adults and children. The three-point slope-intercept glomerular filtration rate (SI-GFR) was compared with the nine-point 'area under curve' calculation as a gold standard to determine the error in SI-GFR. The Durbin-Watson test was used to characterize the nature of the errors. The sensitivity, specificity and positive predictive value (PPV) of QC methods for detecting clinically significant errors were calculated and receiver operating characteristic curves were constructed. The QC methods were also applied to a dataset of 100 four-point GFR tests from different institutions. Model failure is the dominant cause of clinically significant error in this dataset, with individual point measurement errors only giving rise to clinically significant errors in a small number of cases. No QC test had an acceptable combination of sensitivity, PPV and specificity. The correlation coefficient QC test had the largest area under the receiver operating characteristic curve (0.73). No other QC test had an area greater than 0.57. All the QC methods have poor sensitivity and PPV for detecting clinically significant errors and so cannot be relied on to ensure a robust measurement of GFR, underlining the need for careful working practices and a thorough system of measurement checks. We found no evidence for the value of multiple sampling with respect to QC; until such evidence is published, their clinical utility is unproven.

  6. Altered ventricular stretch contributes to initiation of cardiac memory.

    Science.gov (United States)

    Sosunov, Eugene A; Anyukhovsky, Evgeny P; Rosen, Michael R

    2008-01-01

    Cardiac memory is a change in T-wave morphology induced by ventricular pacing or arrhythmias that persist after resumption of normal AV conduction. Changing the pacemaker site from atrium to ventricle alters ventricular activation and the mechanical pattern of ventricular contraction. Either or both alterations affect T-wave configuration. The purpose of this study was to study the role of altered contractile patterns on initiation of cardiac memory. Isolated rabbit hearts were immersed in Tyrode's solution (37 degrees C) and aortically perfused at a constant pressure of 70 mmHg. Three orthogonal quasi-ECG leads were recorded via six Ag-AgCl electrodes located on the walls of the bath. Hearts were paced at a constant cycle length from either the right atrial appendage or left ventricle lateral wall. The pulmonary artery was sealed, and both ventricles contracted isovolumetrically. Cardiac memory was quantified as T-wave vector displacement expressed as distance between T-wave vector peaks during atrial pacing before and after ventricular pacing. Five minutes of ventricular pacing induced significant T-wave vector displacement that returned to control in 5 to 10 minutes. No significant changes in intraventricular pressure occurred during and after ventricular pacing. Interventions that decreased ventricular load (shunting both ventricles to the bath) or contractility (excitation-contraction uncoupler blebbistatin) significantly decreased developed pressure and eliminated T-wave vector displacement. Neither intervention affected ventricular activation during ventricular pacing. Locally applied left ventricular epicardial stretch induced T-wave vector displacement similar to that induced by ventricular pacing. Altered ventricular activation during ventricular pacing initiates cardiac memory via induction of altered contractile patterns and altered stretch.

  7. The effects of rhythm control strategies versus rate control strategies for atrial fibrillation and atrial flutter

    DEFF Research Database (Denmark)

    Sethi, Naqash; Safi, Sanam; Nielsen, Emil E

    2017-01-01

    by Jakobsen and colleagues. We plan to include all relevant randomised clinical trials assessing the effects of any rhythm control strategy versus any rate control strategy. We plan to search the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, LILACS, Science Citation Index Expanded...... and Trial Sequential Analysis. For both our primary and secondary outcomes, we will create a 'Summary of Findings' table and use GRADE assessment to assess the quality of the evidence. DISCUSSION: The results of this systematic review have the potential to benefit thousands of patients worldwide as well...

  8. Transformation Invariant Control of Voxel-Wise False Discovery Rate

    Science.gov (United States)

    Li, Junning; Shi, Yonggang; Toga, Arthur W.

    2016-01-01

    Multiple testing for statistical maps remains a critical and challenging problem in brain mapping. Since the false discovery rate (FDR) criterion was introduced to the neuroimaging community a decade ago, many variations have been proposed, mainly to enhance detection power. However, a fundamental geometrical property known as transformation invariance has not been adequately addressed, especially for the voxel-wise FDR. Correction of multiple testing applied after spatial transformation is not necessarily equivalent to transformation applied after correction in the original space. Without the invariance property, assigning different testing spaces will yield different results. We find that normalized residuals of linear models with Gaussian noises are uniformly distributed on a unit high-dimensional sphere, independent of t-statistics and F-statistics. By defining volumetric measure in the hyper-spherical space mapped by normalized residuals, instead of the image’s Euclidean space, we can achieve invariant control of the FDR under diffeomorphic transformation. This hyper-spherical measure also reflects intrinsic “volume of randomness” in signals. Experiments with synthetic, semi-synthetic and real images demonstrate that our method significantly reduces FDR inconsistency introduced by the choice of testing spaces. PMID:27101602

  9. Cross-Layer Design of Source Rate Control and Congestion Control for Wireless Video Streaming

    Directory of Open Access Journals (Sweden)

    Peng Zhu

    2007-01-01

    Full Text Available Cross-layer design has been used in streaming video over the wireless channels to optimize the overall system performance. In this paper, we extend our previous work on joint design of source rate control and congestion control for video streaming over the wired channel, and propose a cross-layer design approach for wireless video streaming. First, we extend the QoS-aware congestion control mechanism (TFRCC proposed in our previous work to the wireless scenario, and provide a detailed discussion about how to enhance the overall performance in terms of rate smoothness and responsiveness of the transport protocol. Then, we extend our previous joint design work to the wireless scenario, and a thorough performance evaluation is conducted to investigate its performance. Simulation results show that by cross-layer design of source rate control at application layer and congestion control at transport layer, and by taking advantage of the MAC layer information, our approach can avoid the throughput degradation caused by wireless link error, and better support the QoS requirements of the application. Thus, the playback quality is significantly improved, while good performance of the transport protocol is still preserved.

  10. Valor clínico de la utilización del strain rate sistólico en el estudio de distintas formas de hipertrofia ventricular izquierda

    OpenAIRE

    Norberto Marani; Carol Kotliar; Jorge Bilbao; Fabián E. Ferroni; Horacio Fernández; Demián Chejtman; Sergio Baratta; Domingo Turri; Alejandro Hita

    2007-01-01

    IntroducciónLa hipertrofia del ventrículo izquierdo (HVI) incluye diferentes etiologías, estados evolutivos y pronóstico. El strain rate sistólico (SRS) o estudio de la deformación miocárdica permite analizar la función sistólica regional al evaluar la velocidad de acortamiento miocárdico en función del tiempo, con independencia del movimiento traslativo del corazón o del tironeamiento de estructuras vecinas.ObjetivoDeterminar la utilidad del strain rate sistólico para diferenciar formas de h...

  11. The mitochondrial uniporter controls fight or flight heart rate increases.

    Science.gov (United States)

    Wu, Yuejin; Rasmussen, Tyler P; Koval, Olha M; Joiner, Mei-Ling A; Hall, Duane D; Chen, Biyi; Luczak, Elizabeth D; Wang, Qiongling; Rokita, Adam G; Wehrens, Xander H T; Song, Long-Sheng; Anderson, Mark E

    2015-01-20

    Heart rate increases are a fundamental adaptation to physiological stress, while inappropriate heart rate increases are resistant to current therapies. However, the metabolic mechanisms driving heart rate acceleration in cardiac pacemaker cells remain incompletely understood. The mitochondrial calcium uniporter (MCU) facilitates calcium entry into the mitochondrial matrix to stimulate metabolism. We developed mice with myocardial MCU inhibition by transgenic expression of a dominant-negative (DN) MCU. Here, we show that DN-MCU mice had normal resting heart rates but were incapable of physiological fight or flight heart rate acceleration. We found that MCU function was essential for rapidly increasing mitochondrial calcium in pacemaker cells and that MCU-enhanced oxidative phoshorylation was required to accelerate reloading of an intracellular calcium compartment before each heartbeat. Our findings show that MCU is necessary for complete physiological heart rate acceleration and suggest that MCU inhibition could reduce inappropriate heart rate increases without affecting resting heart rate.

  12. Impact of continuous positive airway pressure treatment on left ventricular ejection fraction in patients with obstructive sleep apnea: a meta-analysis of randomized controlled trials.

    Directory of Open Access Journals (Sweden)

    Hao Sun

    Full Text Available BACKGROUND: It has been known for a long time that obstructive sleep apnea (OSA is associated with a decreased left ventricular ejection fraction (LVEF. Continuous positive airway pressure (CPAP is the gold standard treatment for OSA; however, it is unknown whether or not CPAP treatment will improve the LVEF. The aim of the current study was to assess whether or not CPAP treatment improves the LVEF. A meta-analysis was conducted to determine the effect of CPAP treatment on the LVEF among patients with OSA. METHODS: A literature search of PubMed, the Web of Science, and Cochrane Collaboration's database were utilized to identify eligible reports for this trial. Ten randomized controlled trails were examined and the meta-analysis was performed using STATA 11. RESULTS: A significant improvement in the LVEF was observed after CPAP treatment (weighted mean difference(WMD = 3.59, 95% CI = 1.74-5.44; P<0.001. Subgroup analysis revealed that patients with OSA and heart failure had a significant improvement in the LVEF after CPAP treatment (WMD = 5.18, 95% CI = 3.27-7.08; P<0.001; however, the LVEF of patients with OSA only increased 1.11% and there was no statistical significance (WMD = 1.11, 95% CI = -1.13-3.35; P = 0.331. Furthermore, based on univariate meta-regression analysis, only the baseline AHI had a statistically significant correlation with the LVEF. CONCLUSIONS: Our meta-analysis supports the notion that CPAP may improve the LVEF among patients with OSA.

  13. Fractal analysis of heart rate dynamics as a predictor of mortality in patients with depressed left ventricular function after acute myocardial infarction. TRACE Investigators. TRAndolapril Cardiac Evaluation

    DEFF Research Database (Denmark)

    Mäkikallio, T H; Høiber, S; Køber, L

    1999-01-01

    A number of new methods have been recently developed to quantify complex heart rate (HR) dynamics based on nonlinear and fractal analysis, but their value in risk stratification has not been evaluated. This study was designed to determine whether selected new dynamic analysis methods of HR...

  14. Risk stratification and management of patients with recurrent ventricular tachycardia and other malignant ventricular arrhythmias.

    Science.gov (United States)

    Hargrove, W C; Miller, J M

    1989-06-01

    Clinical results are reviewed in 269 patients who underwent subendocardial resection for recurrent sustained ventricular tachycardia secondary to ischemic heart disease. Operative mortality is 15%. Factors increasing operative mortality rates are ejection fraction less than 20%, emergency operation, and history of previous heart operation. Use of amiodarone preoperatively does not alter operative risk. Clinical control of ventricular tachycardia is achieved in 93% of operative survivors. Two thirds of these patients do not need antiarrhythmic agents. Five-year actuarial survival is approximately 60%. Patient results with the automatic internal cardioverter defibrillator at the Hospital of the University of Pennsylvania and nationwide are also reviewed. As of June 1987, almost 1,500 patients had one or more devices implanted. Most patients had a prior documented cardiac arrest. Coronary artery disease is the cause of heart disease in over 70% of patients. Operative mortality is low (0.8-3.9%). Approximately 50% of patients have had therapeutic discharge of the device; however, asymptomatic discharge occurs in up to 45% of patients. Incidence of sudden death is 1.5% at 1 year and 5% at 5 years. Five-year actuarial survival is approximately 60%. Long-term mortality is primarily from heart failure.

  15. Influence of deep breathing exercise on spontaneous respiratory rate and heart rate variability: a randomised controlled trial in healthy subjects.

    Science.gov (United States)

    Tharion, Elizabeth; Samuel, Prasanna; Rajalakshmi, R; Gnanasenthil, G; Subramanian, Rajam Krishna

    2012-01-01

    Studies show that yogic type of breathing exercises reduces the spontaneous respiratory rate. However, there are no conclusive studies on the effects of breathing exercise on heart rate variability. We investigated the effects of non-yogic breathing exercise on respiratory rate and heart rate variability. Healthy subjects (21-33 years, both genders) were randomized into the intervention group (n=18), which performed daily deep breathing exercise at 6 breaths/min (0.1 Hz) for one month, and a control group (n=18) which did not perform any breathing exercise. Baseline respiratory rate and short-term heart rate variability indices were assessed in both groups. Reassessment was done after one month and the change in the parameters from baseline was computed for each group. Comparison of the absolute changes [median (inter-quartile ranges)] of the parameters between the intervention and control group showed a significant difference in the spontaneous respiratory rate [intervention group -2.50 (-4.00, -1.00), control group 0.00 (-1.00, 1.00), cycles/min, Prate and cardiac autonomic modulation of the intervention group were significant, when compared to the changes in the control group. Thus practice of deep slow breathing exercise improves heart rate variability in healthy subjects, without altering their cardiac autonomic balance. These findings have implications in the use of deep breathing exercises to improve cardiac autonomic control in subjects known to have reduced heart rate variability.

  16. Ventricular Tachycardia Ablation versus Escalation of Antiarrhythmic Drugs.

    Science.gov (United States)

    Sapp, John L; Wells, George A; Parkash, Ratika; Stevenson, William G; Blier, Louis; Sarrazin, Jean-Francois; Thibault, Bernard; Rivard, Lena; Gula, Lorne; Leong-Sit, Peter; Essebag, Vidal; Nery, Pablo B; Tung, Stanley K; Raymond, Jean-Marc; Sterns, Laurence D; Veenhuyzen, George D; Healey, Jeff S; Redfearn, Damian; Roux, Jean-Francois; Tang, Anthony S L

    2016-07-14

    Recurrent ventricular tachycardia among survivors of myocardial infarction with an implantable cardioverter-defibrillator (ICD) is frequent despite antiarrhythmic drug therapy. The most effective approach to management of this problem is uncertain. We conducted a multicenter, randomized, controlled trial involving patients with ischemic cardiomyopathy and an ICD who had ventricular tachycardia despite the use of antiarrhythmic drugs. Patients were randomly assigned to receive either catheter ablation (ablation group) with continuation of baseline antiarrhythmic medications or escalated antiarrhythmic drug therapy (escalated-therapy group). In the escalated-therapy group, amiodarone was initiated if another agent had been used previously. The dose of amiodarone was increased if it had been less than 300 mg per day or mexiletine was added if the dose was already at least 300 mg per day. The primary outcome was a composite of death, three or more documented episodes of ventricular tachycardia within 24 hours (ventricular tachycardia storm), or appropriate ICD shock. Of the 259 patients who were enrolled, 132 were assigned to the ablation group and 127 to the escalated-therapy group. During a mean (±SD) of 27.9±17.1 months of follow-up, the primary outcome occurred in 59.1% of patients in the ablation group and 68.5% of those in the escalated-therapy group (hazard ratio in the ablation group, 0.72; 95% confidence interval, 0.53 to 0.98; P=0.04). There was no significant between-group difference in mortality. There were two cardiac perforations and three cases of major bleeding in the ablation group and two deaths from pulmonary toxic effects and one from hepatic dysfunction in the escalated-therapy group. In patients with ischemic cardiomyopathy and an ICD who had ventricular tachycardia despite antiarrhythmic drug therapy, there was a significantly lower rate of the composite primary outcome of death, ventricular tachycardia storm, or appropriate ICD shock among

  17. Mechanisms linking electrical alternans and clinical ventricular arrhythmia in human heart failure.

    Science.gov (United States)

    Bayer, J D; Lalani, G G; Vigmond, E J; Narayan, S M; Trayanova, N A

    2016-09-01

    Mechanisms of ventricular tachycardia (VT) and ventricular fibrillation (VF) in patients with heart failure (HF) are undefined. The purpose of this study was to elucidate VT/VF mechanisms in HF by using a computational-clinical approach. In 53 patients with HF and 18 control patients, we established the relationship between low-amplitude action potential voltage alternans (APV-ALT) during ventricular pacing at near-resting heart rates and VT/VF on long-term follow-up. Mechanisms underlying the transition of APV-ALT to VT/VF, which cannot be ascertained in patients, were dissected with multiscale human ventricular models based on human electrophysiological and magnetic resonance imaging data (control and HF). For patients with APV-ALT k-score >1.7, complex action potential duration (APD) oscillations (≥2.3% of mean APD), rather than APD alternans, most accurately predicted VT/VF during long-term follow-up (+82%; -90% predictive values). In the failing human ventricular models, abnormal sarcoplasmic reticulum (SR) calcium handling caused APV-ALT (>1 mV) during pacing with a cycle length of 550 ms, which transitioned into large magnitude (>100 ms) discordant repolarization time alternans (RT-ALT) at faster rates. This initiated VT/VF (cycle length <400 ms) by steepening apicobasal repolarization (189 ms/mm) until unidirectional conduction block and reentry. Complex APD oscillations resulted from nonstationary discordant RT-ALT. Restoring SR calcium to control levels was antiarrhythmic by terminating electrical alternans. APV-ALT and complex APD oscillations at near-resting heart rates in patients with HF are linked to arrhythmogenic discordant RT-ALT. This may enable novel physiologically tailored, bioengineered indices to improve VT/VF risk stratification, where SR calcium handling and spatial apicobasal repolarization are potential therapeutic targets. Copyright © 2016 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

  18. Impact of an Educational Intervention Implanted in a Neurological Intensive Care Unit on Rates of Infection Related to External Ventricular Drains

    Science.gov (United States)

    Camacho, Eduardo Fernandes; Boszczowski, Ícaro; Freire, Maristela Pinheiro; Pinto, Fernando Campos Gomes; Guimaraes, Thais; Teixeira, Manuel Jacobsen; Costa, Silvia Figueiredo

    2013-01-01

    Background Studies on the implantation of care routines showed reduction on EVD catheter-related infections rates; however zero tolerance is difficult to be achieved. The objective of this study was to assess the impact of an educational intervention on the maximal reduction on rates of EVD-related infections. Methodology/Principal Findings The quasi-experimental (before-after intervention) study occurred in two phases: pre-intervention, from April 2007 to July 2008, and intervention, from August 2008 to July 2010. Patients were followed for 30 days after the removal of the EVD, and EVD-related infections were considered as only those with laboratorial confirmation in the CSF. Observations were made of the care of the EVD and compliance with Hygiene of the Hands (HH), a routine of care was drawn up, training was given, and intervention was made to reduce the time the EVD catheter remained in place. Results during the study, 178 patients were submitted to 194 procedures, corresponding to 1217 EVD catheters-day. Gram-negative agents were identified in 71.4% of the infections during the pre-intervention period and in 60% during the intervention period. During the study, EVD-related infection rates were reduced from 9.5% to 4.8% per patient, from 8.8% to 4.4% per procedure, and the incidence density dropped from 14.0 to 6.9 infections per 1000 catheters-day (p = 0.027). The mortality reduced 12% (from 42% to 30%). Conclusions/Significance During one year after the fourth intervention, no microbiologically identified infection was documented. In light of these results, educational intervention proved to be a useful tool in reducing these rates and showed also impact on mortality. PMID:23390486

  19. Molecular and electrical characterization of the canine cardiac ventricular septum

    NARCIS (Netherlands)

    Ramakers, Christian; Stengl, Milan; Spätjens, Roel L. H. M. G.; Moorman, Antoon F. M.; Vos, Marc A.

    2005-01-01

    Electrophysiological heterogeneity in the ventricular septum (VS) has been poorly addressed. In this study we investigated the electrophysiological and molecular composition of the VS in control sinus rhythm (SR) and chronic, complete atrio-ventricular block (CAVB) dogs. In the latter model, we

  20. Thrombolysis for non-traumatic intra-ventricular hemorrhage in adults: a critical reappraisal.

    Science.gov (United States)

    Starnoni, Daniele; Oddo, Mauro; Maduri, Rodolfo; Messerer, Mahmoud; Daniel, Roy T

    2017-09-01

    Intra-ventricular hemorrhage (IVH) is a critical condition with high rate of morbidity and mortality due to acute hydrocephalus and secondary brain injury. Mechanisms underlying the clinical deterioration are not only related to the appearance of an acute hydrocephalus but also to blood-clot mass effect and the inflammatory effects of blood break-down products which impede local blood flow and exert a direct toxic effect on the peri-ventricular structures leading to chronic hydrocephalus. An effective treatment strategy should aim at IVH fast removal and reduction of blood-clot mass effect. Although external ventricular drainage placement is an intuitive treatment for obstructive hydrocephalus this treatment does not address in total the aforementioned pathophysiological mechanisms underlying secondary brain damage. Intra-ventricular fibrinolysis, with tissue plasminogen activator or urokinase, is a level of evidence B, class IIB treatment which has proved to be beneficial in lowering the mortality rates. Its effectiveness on functional outcome has been assessed on three large meta-analysis and a recent large randomized control trial (CLEAR III). Results from the CLEAR III multicenter trial suggest that a routine extra-ventricular drain, irrigation with alteplase reduced mortality but did not substantially improve functional outcomes compared with irrigation with saline. Protocol-based use of alteplase with extra-ventricular drain seemed safe, therefore such approach may be a potential option in individual cases. Currently no consensus has been reached and extrapolation of data from the literature does not permit to identify a uniform therapeutic approach but merely to outline some rational procedural modalities. Further research and studies are needed to compare the efficacy of the different fibrinolytic agents and protocols on functional outcome.

  1. Testing the Control of Mineral Supply Rates on Chemical Erosion Rates in the Klamath Mountains

    Science.gov (United States)

    West, N.; Ferrier, K.

    2016-12-01

    The relationship between rates of chemical erosion and mineral supply is central to many problems in Earth science, including how tightly Earth's climate should be coupled to tectonics, how strongly nutrient supply to soils and streams depends on soil production, and how much lithology affects landscape evolution. Despite widespread interest in this relationship, there remains no consensus on how closely coupled chemical erosion rates should be to mineral supply rates. To address this, we have established a network of field sites in the Klamath Mountains along a latitudinal transect that spans an expected gradient in mineral supply rates associated with the geodynamic response to the migration of the Mendocino Triple Junction. Here, we present new measurements of regolith geochemistry and topographic analyses that will be compared with cosmogenic 10Be measurements to test hypotheses about supply-limited and kinetically-limited chemical erosion on granodioritic ridgetops. Previous studies in this area suggest a balance between rock uplift rates and basin wide erosion rates, implying the study ridgetops may have adjusted to an approximate steady state. Preliminary data are consistent with a decrease in chemical depletion fraction (CDF) with increasing ridgetop curvature. To the extent that ridgetop curvature reflects ridgetop erosion rates, this implies that chemical erosion rates at these sites are influenced by both mineral supply rates and dissolution kinetics.

  2. Atrial fibrillation is an independent risk factor for ventricular fibrillation: a large-scale population-based case-control study

    NARCIS (Netherlands)

    Bardai, Abdennasser; Blom, Marieke T.; van Hoeijen, Daniel A.; van Deutekom, Hanneke W. M.; Brouwer, Henk J.; Tan, Hanno L.

    2014-01-01

    Atrial fibrillation (AF) is associated with sudden cardiac death. We aimed to study whether AF is associated with ventricular fibrillation (VF), the most common cause of sudden cardiac death and whether this association is independent of confounders, ie, concomitant disease, use of antiarrhythmic or

  3. Controlling the Type I Error Rate in Stepwise Regression Analysis.

    Science.gov (United States)

    Pohlmann, John T.

    1979-01-01

    The type I error rate in stepwise regression analysis deserves serious consideration by researchers. The problem-wide error rate is the probability of selecting any variable when all variables have population regression weights of zero. Appropriate significance tests are presented and a Monte Carlo experiment is described. (Author/CTM)

  4. Delayed seismicity rate changes controlled by static stress transfer

    Science.gov (United States)

    Kroll, Kayla A.; Richards-Dinger, Keith B.; Dieterich, James H.; Cochran, Elizabeth S.

    2017-01-01

    On 15 June 2010, a Mw5.7 earthquake occurred near Ocotillo, California, in the Yuha Desert. This event was the largest aftershock of the 4 April 2010 Mw7.2 El Mayor-Cucapah (EMC) earthquake in this region. The EMC mainshock and subsequent Ocotillo aftershock provide an opportunity to test the Coulomb failure hypothesis (CFS). We explore the spatiotemporal correlation between seismicity rate changes and regions of positive and negative CFS change imparted by the Ocotillo event. Based on simple CFS calculations we divide the Yuha Desert into three subregions, one triggering zone and two stress shadow zones. We find the nominal triggering zone displays immediate triggering, one stress shadowed region experiences immediate quiescence, and the other nominal stress shadow undergoes an immediate rate increase followed by a delayed shutdown. We quantitatively model the spatiotemporal variation of earthquake rates by combining calculations of CFS change with the rate-state earthquake rate formulation of Dieterich (1994), assuming that each subregion contains a mixture of nucleation sources that experienced a CFS change of differing signs. Our modeling reproduces the observations, including the observed delay in the stress shadow effect in the third region following the Ocotillo aftershock. The delayed shadow effect occurs because of intrinsic differences in the amplitude of the rate response to positive and negative stress changes and the time constants for return to background rates for the two populations. We find that rate-state models of time-dependent earthquake rates are in good agreement with the observed rates and thus explain the complex spatiotemporal patterns of seismicity.

  5. The effect of 1 year of Alagebrium and moderate-intensity exercise training on left ventricular function during exercise in seniors: a randomized controlled trial.

    Science.gov (United States)

    Carrick-Ranson, Graeme; Fujimoto, Naoki; Shafer, Keri M; Hastings, Jeffrey L; Shibata, Shigeki; Palmer, M Dean; Boyd, Kara; Levine, Benjamin D

    2016-08-01

    Sedentary aging leads to left ventricular (LV) and vascular stiffening due in part to advanced glycation end-products (AGEs) cross-linking of extracellular matrix proteins. Vigorous lifelong exercise ameliorates age-related cardiovascular (CV) stiffening and enhances exercise LV function, although this effect is limited when exercise is initiated later in life. We hypothesized that exercise training might be more effective at improving the impact of age-related CV stiffening during exercise when combined with an AGE cross-link breaker (Alagebrium). Sixty-two seniors (≥60 yr) were randomized into four groups: sedentary + placebo, sedentary + Alagebrium, exercise + placebo, and exercise + Alagebrium for 1 yr. Moderate-intensity aerobic exercise was performed 3-4 sessions/wk; controls underwent similar frequency of yoga/balance training. Twenty-four similarly-aged, lifelong exercisers (4-5 sessions/wk) served as a comparator for the effect of lifelong exercise on exercising LV function. Oxygen uptake (Douglas bags), stroke index (SI; acetylene rebreathing), and effective arterial elastance (Ea) were collected at rest and submaximal and maximal exercise. Maximum O2 uptake (23 ± 5 to 25 ± 6 ml·kg(-1)·min(-1)) increased, while SI (35 ± 11 to 39 ± 12 ml/m(2)) and Ea (4.0 ± 1.1 to 3.7 ± 1.2 mmHg·ml(-1)·m(-2)) were improved across all conditions with exercise, but remained unchanged in controls (exercise × time, P ≤ 0.018). SI or Ea were not affected by Alagebrium (medication × time, P ≥ 0.468) or its combination with exercise (interaction P ≥ 0.252). After 1 yr of exercise plus Alagebrium, exercise SI and Ea remained substantially below that of lifelong exercisers (15-24 and 9-22%, respectively, P ≤ 0.415). In conclusion, Alagebrium plus exercise had no synergistic effect on exercise LV function and failed to achieve levels associated with lifelong exercise, despite a similar exercise frequency.

  6. Left ventricular pressure and volume data acquisition and analysis using LabVIEW.

    Science.gov (United States)

    Cassidy, S C; Teitel, D F

    1997-03-01

    To automate analysis of left ventricular pressure-volume data, we used LabVIEW to create applications that digitize and display data recorded from conductance and manometric catheters. Applications separate data into cardiac cycles, calculate parallel conductance, and calculate indices of left ventricular function, including end-systolic elastance, preload-recruitable stroke work, stroke volume, ejection fraction, stroke work, maximum and minimum derivative of ventricular pressure, heart rate, indices of relaxation, peak filling rate, and ventricular chamber stiffness. Pressure-volume loops can be graphically displayed. These analyses are exported to a text-file. These applications have simplified and automated the process of evaluating ventricular function.

  7. Valor clínico de la utilización del strain rate sistólico en el estudio de distintas formas de hipertrofia ventricular izquierda

    Directory of Open Access Journals (Sweden)

    Norberto Marani

    2007-01-01

    Full Text Available IntroducciónLa hipertrofia del ventrículo izquierdo (HVI incluye diferentes etiologías, estados evolutivos y pronóstico. El strain rate sistólico (SRS o estudio de la deformación miocárdica permite analizar la función sistólica regional al evaluar la velocidad de acortamiento miocárdico en función del tiempo, con independencia del movimiento traslativo del corazón o del tironeamiento de estructuras vecinas.ObjetivoDeterminar la utilidad del strain rate sistólico para diferenciar formas de hipertrofia del ventrículo izquierdo.Material y métodosLa población del estudio estuvo conformada por cuatro grupos: Grupo 1: (G1, n = 10: voluntarios sanos sedentarios; grupo 2 (G2, n = 21: atletas de alto rendimiento con aumento del índice de masa del ventrículo izquierdo (IMVI > 125 g/m2; grupo 3 (G3, n = 15: pacientes hipertensos según VII JNC con IMVI > 125 g/m2 y grupo 4 (G4, n = 12: pacientes con miocardiopatía hipertrófica (MCH, septum > 15 mm y/o relación septum/pared posterior > 1,5:1, sin causa que lo justifique.ResultadosEn los grupos con IMVI incrementado no hubo diferencia en la fracción de acortamiento mesoparietal (p = 0,3 o el IMVI (p = 0,6.SRS 01 seg (G1 0,75 1/s, (G2 0,87 1/s, (G3 0,57 1/s, (G4 0,29 1/s (p < 0,001.SRS 02 seg (G1 0,67 1/s, (G2 0,52 1/s, (G3 0,49 1/s (G4 0,18 1/s (p < 0,001.SRS 03 seg (G1 0,57 1/s, (G2 0,38 1/s, (G3 0,25 1/s (G4 0,11 1/s (p < 0,002.EL SRS permitió diferenciar MCH en deportistas durante toda la sístole.ConclusiónEl acortamiento sistólico regional determinado por SRS está disminuido en la MCH. La utilización de esta técnica permite diferenciar formas de hipertrofia patológica de la hipertrofia fisiológica.

  8. Climatic Controls on Alpine Rockwall Erosion: Current Rates Versus Long-Term Rates

    Science.gov (United States)

    Matsuoka, N.

    2002-12-01

    Seasonal, interannual and long-term variations in rates of alpine rockwall retreat are evaluated on the basis of field measurements in the Swiss and Japanese Alps and extant data in other humid high mountains. Observations of rock joint widening, rockfall activity and rock temperatures indicate that freeze-thaw action dominates current erosion of hard but highly jointed rockwalls. Diurnal freeze-thaw alternations occur within the outermost few decimeters of bedrock, producing pebble falls and granular weathering. These processes contribute to retreat rates of the order of 0.1 mm/a or smaller, which depend on the freeze-thaw frequency, moisture availability and rock mass strength. Boulder falls following seasonal thaw penetration (permafrost and seasonal frost regimes or (3) in seasonal freeze-thaw depth. In the first case, whereas the retreat rate during the glacial regime (the rate of cirque wall erosion) is rarely understood, paraglacial unloading, which enhances rockfalls and rockslides following the glacier retreat, would raise the rate significantly. In the second case, melting of permafrost may detach a large block that temporary raises the retreat rate. Intensive segregation freezing in the basal active layer may also promote boulder falls during the permafrost regime. The third case is important where the rockwall currently undergoes shallow diurnal freezing but have experienced deep seasonal freezing during a past cold period.

  9. Rationale and design of a multi-centre randomised controlled trial of individualised cooled dialysate to prevent left ventricular systolic dysfunction in haemodialysis patients

    Directory of Open Access Journals (Sweden)

    Odudu Aghogho

    2012-06-01

    Full Text Available Abstract Background The main hypothesis of this study is that patients having regular conventional haemodialysis (HD will have a smaller decline in cardiac systolic function by using cooler dialysate. Cooler dialysate may also be beneficial for brain function. Methods/Design The trial is a multicentre, prospective, randomised, un-blinded, controlled trial. Patients will be randomised 1:1 to use a dialysate temperature of 37°C for 12 months or an individualised cooled dialysate. The latter will be set at 0.5°C less than the patient’s own temperature, determined from the mean of 6 prior treatment sessions with a tympanic thermometer, up to a maximum of 36°C. Protocol adherence will be regularly checked. Inclusion criteria are incident adult HD patients within 180 days of commencing in-centre treatment 3 times per week with capacity to consent for the trial and without contra-indications for magnetic resonance imaging. Exclusion criteria include not meeting inclusion criteria, inability to tolerate magnetic resonance imaging and New York Heart Association Grade IV heart failure. During the study period, resting cardiac and cerebral magnetic resonance imaging will be performed at baseline and 12 months on an inter-dialytic day. Cardiovascular performance during HD will also be assessed by continuous cardiac output monitors, intra-dialytic echocardiography and biomarkers at baseline and 12 months. The primary outcome measure is a 5% between-group difference in left ventricular ejection fraction measured by cardiac magnetic resonance imaging at 12 months compared to baseline. Analysis will be by intention-to-treat. Secondary outcome measures will include changes in cerebral microstructure and changes in cardiovascular performance during HD. A total of 73 patients have been recruited into the trial from four UK centres. The trial is funded by a Research for Patient Benefit Grant from the National Institute of Healthcare Research. AO is

  10. Carvedilol's antiarrhythmic properties: therapeutic implications in patients with left ventricular dysfunction.

    Science.gov (United States)

    Naccarelli, Gerald V; Lukas, Mary Ann

    2005-04-01

    Carvedilol is a beta- and alpha-adrenergic-blocking drug with clinically important antiarrhythmic properties. It possesses anti-ischemic and antioxidant activity and inhibits a number of cationic channels in the cardiomyocyte, including the HERG-associated potassium channel, the L-type calcium channel, and the rapid-depolarizing sodium channel. The electrophysiologic properties of carvedilol include moderate prolongation of action potential duration and effective refractory period; slowing of atrioventricular conduction; and reducing the dispersion of refractoriness. Experimentally, carvedilol reduces complex and repetitive ventricular ectopy induced by ischemia and reperfusion. In patients, carvedilol is effective in controlling the ventricular rate response in atrial fibrillation (AF), with and without digitalis, and is useful in maintaining sinus rhythm after cardioversion, with and without amiodarone. In patients with AF and heart failure (HF), carvedilol reduces mortality risk and improves left ventricular (LV) function. Large-scale clinical trials have demonstrated that combined carvedilol and angiotensin-converting enzyme inhibitor therapy significantly reduces sudden cardiac death, mortality, and ventricular arrhythmia in patients with LV dysfunction (LVD) due to chronic HF or following myocardial infarction (MI). Despite intensive neurohormonal blockade, mortality rates remain relatively high in patients with post-MI and nonischemic LVD. Recent trials of implantable cardioverter-defibrillators added to pharmacologic therapy, especially beta blockers, have shown a further reduction in arrhythmic deaths in these patients.

  11. Left and right ventricular diastolic function in hemodialysis patients

    Directory of Open Access Journals (Sweden)

    Rudhani Ibrahim

    2010-01-01

    Full Text Available The aim of this prospective study was the assessment of left ventricular and right ventricular diastolic function in patients on hemodialysis (HD and the correlation of this func-tion with the duration of HD. The study included 42 patients (22 females and 20 males with chro-nic renal failure (CRF, treated with HD, and 40 healthy subjects (24 females and 16 males with no history of cardiovascular disease and with normal renal function, who constituted the control group. The groups were matched for age and sex. All study patients and control subjects under-went detailed history taking and physical examination. They also underwent electrocardiogram, echocardiography and biochemical and hematological blood analyses. Significant differences were noted between the two groups in the two-dimensional and M-mode echocardiography findings concerning aortic root dimension, transverse diameter of the left atrium, thickness of the inter-ventricular septum, thickness of the left ventricular posterior wall, left ventricular diastolic diameter, left ventricular systolic diameter, shortening fraction, ejection fraction as well as findings from the pulse Doppler study, including E wave, A wave, E/A ratio, deceleration time of E wave (DT-E, acceleration time of E wave (AT-E, tricuspid E and A waves (E tr and A tr and E tr /A tr , ratio. There were significant changes in HD patients without arterial hypertension as well in the control group subjects. Our study suggests that the left ventricular and left atrial dimensions as well as the left ventricular wall thickness are augmented in patients with CRF treated with HD compared with the control group. Additionally, the left and right ventricular diastolic function is also reduced in these patients. These differences were also noted in patients with CRF without arterial hypertension. Left ventricular diastolic dysfunction had no correlation with the duration of HD.

  12. An overview of zinc addition for BWR dose rate control

    Energy Technology Data Exchange (ETDEWEB)

    Marble, W.J. [GE Nuclear Energy, San Jose, CA (United States)

    1995-03-01

    This paper presents an overview of the BWRs employing feedwater zinc addition to reduce primary system dose rates. It identifies which BWRs are using zinc addition and reviews the mechanical injection and passive addition hardware currently being employed. The impact that zinc has on plant chemistry, including the factor of two to four reduction in reactor water Co-60 concentrations, is discussed. Dose rate results, showing the benefits of implementing zinc on either fresh piping surfaces or on pipes with existing films are reviewed. The advantages of using zinc that is isotopically enhanced by the depletion of the Zn-64 precursor to Zn-65 are identified.

  13. Correlation of Ventricular Arrhythmogenesis with Neuronal Remodeling of Cardiac Postganglionic Parasympathetic Neurons in the Late Stage of Heart Failure after Myocardial Infarction

    Science.gov (United States)

    Zhang, Dongze; Tu, Huiyin; Wang, Chaojun; Cao, Liang; Muelleman, Robert L.; Wadman, Michael C.; Li, Yu-Long

    2017-01-01

    Introduction: Ventricular arrhythmia is a major cause of sudden cardiac death in patients with chronic heart failure (CHF). Our recent study demonstrates that N-type Ca2+ currents in intracardiac ganglionic neurons are reduced in the late stage of CHF rats. Rat intracardiac ganglia are divided into the atrioventricular ganglion (AVG) and sinoatrial ganglion. Only AVG nerve terminals innervate the ventricular myocardium. In this study, we tested the correlation of electrical remodeling in AVG neurons with ventricular arrhythmogenesis in CHF rats. Methods and Results: CHF was induced in male Sprague-Dawley rats by surgical ligation of the left coronary artery. The data from 24-h continuous radiotelemetry ECG recording in conscious rats showed that ventricular tachycardia/fibrillation (VT/VF) occurred in 3 and 14-week CHF rats but not 8-week CHF rats. Additionally, as an index for vagal control of ventricular function, changes of left ventricular systolic pressure (LVSP) and the maximum rate of left ventricular pressure rise (LV dP/dtmax) in response to vagal efferent nerve stimulation were blunted in 14-week CHF rats but not 3 or 8-week CHF rats. Results from whole-cell patch clamp recording demonstrated that N-type Ca2+ currents in AVG neurons began to decrease in 8-week CHF rats, and that there was also a significant decrease in 14-week CHF rats. Correlation analysis revealed that N-type Ca2+ currents in AVG neurons negatively correlated with the cumulative duration of VT/VF in 14-week CHF rats, whereas there was no correlation between N-type Ca2+ currents in AVG neurons and the cumulative duration of VT/VF in 3-week CHF. Conclusion: Malignant ventricular arrhythmias mainly occur in the early and late stages of CHF. Electrical remodeling of AVG neurons highly correlates with the occurrence of ventricular arrhythmias in the late stage of CHF. PMID:28533740

  14. Correlation of Ventricular Arrhythmogenesis with Neuronal Remodeling of Cardiac Postganglionic Parasympathetic Neurons in the Late Stage of Heart Failure after Myocardial Infarction

    Directory of Open Access Journals (Sweden)

    Dongze Zhang

    2017-05-01

    Full Text Available Introduction: Ventricular arrhythmia is a major cause of sudden cardiac death in patients with chronic heart failure (CHF. Our recent study demonstrates that N-type Ca2+ currents in intracardiac ganglionic neurons are reduced in the late stage of CHF rats. Rat intracardiac ganglia are divided into the atrioventricular ganglion (AVG and sinoatrial ganglion. Only AVG nerve terminals innervate the ventricular myocardium. In this study, we tested the correlation of electrical remodeling in AVG neurons with ventricular arrhythmogenesis in CHF rats.Methods and Results: CHF was induced in male Sprague-Dawley rats by surgical ligation of the left coronary artery. The data from 24-h continuous radiotelemetry ECG recording in conscious rats showed that ventricular tachycardia/fibrillation (VT/VF occurred in 3 and 14-week CHF rats but not 8-week CHF rats. Additionally, as an index for vagal control of ventricular function, changes of left ventricular systolic pressure (LVSP and the maximum rate of left ventricular pressure rise (LV dP/dtmax in response to vagal efferent nerve stimulation were blunted in 14-week CHF rats but not 3 or 8-week CHF rats. Results from whole-cell patch clamp recording demonstrated that N-type Ca2+ currents in AVG neurons began to decrease in 8-week CHF rats, and that there was also a significant decrease in 14-week CHF rats. Correlation analysis revealed that N-type Ca2+ currents in AVG neurons negatively correlated with the cumulative duration of VT/VF in 14-week CHF rats, whereas there was no correlation between N-type Ca2+ currents in AVG neurons and the cumulative duration of VT/VF in 3-week CHF.Conclusion: Malignant ventricular arrhythmias mainly occur in the early and late stages of CHF. Electrical remodeling of AVG neurons highly correlates with the occurrence of ventricular arrhythmias in the late stage of CHF.

  15. Correlation of Ventricular Arrhythmogenesis with Neuronal Remodeling of Cardiac Postganglionic Parasympathetic Neurons in the Late Stage of Heart Failure after Myocardial Infarction.

    Science.gov (United States)

    Zhang, Dongze; Tu, Huiyin; Wang, Chaojun; Cao, Liang; Muelleman, Robert L; Wadman, Michael C; Li, Yu-Long

    2017-01-01

    Introduction: Ventricular arrhythmia is a major cause of sudden cardiac death in patients with chronic heart failure (CHF). Our recent study demonstrates that N-type Ca(2+) currents in intracardiac ganglionic neurons are reduced in the late stage of CHF rats. Rat intracardiac ganglia are divided into the atrioventricular ganglion (AVG) and sinoatrial ganglion. Only AVG nerve terminals innervate the ventricular myocardium. In this study, we tested the correlation of electrical remodeling in AVG neurons with ventricular arrhythmogenesis in CHF rats. Methods and Results: CHF was induced in male Sprague-Dawley rats by surgical ligation of the left coronary artery. The data from 24-h continuous radiotelemetry ECG recording in conscious rats showed that ventricular tachycardia/fibrillation (VT/VF) occurred in 3 and 14-week CHF rats but not 8-week CHF rats. Additionally, as an index for vagal control of ventricular function, changes of left ventricular systolic pressure (LVSP) and the maximum rate of left ventricular pressure rise (LV dP/dtmax) in response to vagal efferent nerve stimulation were blunted in 14-week CHF rats but not 3 or 8-week CHF rats. Results from whole-cell patch clamp recording demonstrated that N-type Ca(2+) currents in AVG neurons began to decrease in 8-week CHF rats, and that there was also a significant decrease in 14-week CHF rats. Correlation analysis revealed that N-type Ca(2+) currents in AVG neurons negatively correlated with the cumulative duration of VT/VF in 14-week CHF rats, whereas there was no correlation between N-type Ca(2+) currents in AVG neurons and the cumulative duration of VT/VF in 3-week CHF. Conclusion: Malignant ventricular arrhythmias mainly occur in the early and late stages of CHF. Electrical remodeling of AVG neurons highly correlates with the occurrence of ventricular arrhythmias in the late stage of CHF.

  16. Electrophysiological characteristics of pressure overload-induced cardiac hypertrophy and its influence on ventricular arrhythmias.

    Science.gov (United States)

    Chen, Xiaowei; Qin, Mu; Jiang, Weifeng; Zhang, Yu; Liu, Xu

    2017-01-01

    To explore the cardiac electrophysiological characteristics of cardiac hypertrophy and its influence on the occurrence of ventricular tachyarrhythmias. Adult C57BL6 mice were randomly divided into a surgery group and a control group. Thoracic aortic constriction was performed on mice in the surgery group, and cardiac anatomical and ultrasonic evaluations were performed to confirm the success of the cardiac hypertrophy model 4 weeks after the operation. Using the Langendorff method of isolated heart perfusion, monophasic action potentials (MAPs) and the effective refractory period (ERP) at different parts of the heart (including the epi- and endo-myocardium of the left and right ventricles) were measured, and the induction rate of ventricular tachyarrhythmias was observed under programmed electrical stimulus (PES) and burst stimulus. Whole-cell patch-clamp was used to obtain the I-V characteristics of voltage-gated potassium channels in cardiomyocytes of different parts of the heart (including the epi- and endo-myocardium of the left and right ventricles) as well as the channels' properties of steady-state inactivation and recovery from inactivation. The ratio of heart weight to body weight and the ratio of left ventricular weight to body weight in the surgery group were significantly higher than those in the control group (P cardiac hypertrophy, and the spatially heterogeneous changes of the channels may increase the occurrence of ventricular arrhythmias that accompany cardiac hypertrophy.

  17. Noradrenaline: Central inhibitory control of blood pressure and heart rate

    NARCIS (Netherlands)

    Jong, Wybren de

    1974-01-01

    Noradrenaline injected bilaterally into the brainstem in the area of the nucleus tractus solitarii decreased systemic arterial blood pressure and heart rate of anesthetized rats. The effect of noradrenaline was prevented by a preceding injection of the α-adrenergic blocking agent phentolamine, at

  18. Drugs or implantable cardioverter-defibrillators in patients with poor left ventricular function?

    Science.gov (United States)

    Block, M; Hammel, D; Böcker, D; Borggrefe, M; Breithardt, G

    1996-09-12

    Poor left ventricular function is a predictor of sudden death. Both antiarrhythmic drugs and implantable cardioverter-defibrillators (ICDs) promise to reduce the sudden death rate in these patients and consequently improve survival. In patients without spontaneous ventricular tachyarrhythmias, only beta-blocking agents and amiodarone have been shown to reduce sudden death and improve survival in some studies, whereas class I antiarrhythmic drugs increased mortality. For patients with documented ventricular tachyarrhythmias, protection against sudden death by serially tested class I antiarrhythmic drugs is at best moderate. There is some evidence suggesting that therapy with class III antiarrhythmic drugs, either amiodarone or dl-sotalol, may reduce sudden death rates and improve overall mortality in comparison to therapy with class I antiarrhythmic drugs. ICDs have been shown to prevent sudden death reliably. In published patient cohorts in which only patients who were not inducible off antiarrhythmic drugs or still inducible on antiarrhythmic drugs received an ICD, the ICD seemed to improve overall survival in comparison to class I antiarrhythmic drugs. A small prospective randomized study that compared a conventional therapy strategy to primary ICD implantations showed an improved outcome with ICDs as therapy of first choice. However, these studies included many patients treated with class I antiarrhythmic drugs considered to be less effective. In matched control studies comparing the ICD to amiodarone or dl-sotalol, less sudden deaths and an improved overall survival could be shown for the ICD in general without stratification for left ventricular function. Thus, in patients with hemodynamically nontolerated ventricular tachyarrhythmias, the ICD seems to improve survival in comparison to class I antiarrhythmic drugs, dl-sotalol, or amiodarone. However, in patients with poor left ventricular function, therapy with ICDs seems to be less cost-effective than in

  19. Control of Rate-Bounded Hybrid Systems with Liveness Specifications

    Science.gov (United States)

    Heymann, Michael; Lin, Feng; Meyer, George

    1998-01-01

    In the present paper we examine the control problem for a class of composite hybrid machines (CHMs) that consist of concurrent operation (employing synchronous composition) of elementary hybrid machines (EHMs), that allows both signal sharing and event synchronization. A controller can then be coupled with the plant by means of synchronous composition. We confine our attention to controllers that interact with the system only through event synchronization. We present an initial investigation of synthesis of liveness controllers for hybrid machines. To this end we define open hybrid machines as systems that can interact with the environment through event synchronization and can be therefor be "driven" to their marked configuration by user (controller). Liveness specifications must be associated with timing constraints. We may require that for a specified time limit, every run reach a marked configuration within that time limit. Alternatively, a more relaxed specification may be that, for some (unspecified) global time bound, every run of the system reach a marked configuration within that time bound. Finally, the least restrictive liveness requirement is that every run reach a marked configuration within a finite time limit (but we do not insist on the existence of a global time bound for all runs).

  20. A novel practical control approach for rate independent hysteretic systems.

    Science.gov (United States)

    Goforth, Frank J; Zheng, Qing; Gao, Zhiqiang

    2012-05-01

    A disturbance rejection based control approach, active disturbance rejection control (ADRC), is proposed for hysteretic systems with unknown characteristics. It is an appealing alternative to hysteresis compensation because it does not require a detailed model of hysteresis, by treating the nonlinear hysteresis as a common disturbance and actively rejecting it. The stability characteristic of the ADRC is analyzed. It is shown that, in the face of the inherent dynamic uncertainties, the estimation and closed-loop tracking errors of ADRC are bounded, with their bounds monotonously decreasing with the observer and controller bandwidths, respectively. Simulation results on a typical hysteretic system further demonstrate the effectiveness of the proposed approach. Copyright © 2012 ISA. Published by Elsevier Ltd. All rights reserved.

  1. Fragmented QRS and Left Ventricular Geometry in Hypertensive Patients

    Directory of Open Access Journals (Sweden)

    Lütfü Bekar

    2013-08-01

    Full Text Available Introduction: Fragmented QRS is a depolarization abnormality detected with routin ECG recording. It is related with conduction defect which occurs after myocardial fibrosis. In the left ventricular hypertrophy, an excessive amount of collagen accumulates in the interstitium when the myocytes became hypertrophied, resulting in myocardial fibrosis. In this study, we aimed to investigate the relationship of fragmented QRS which was detected on ECG recordings of the hypertensive patients with the left ventricular geometry.Patients and Methods: Essential hypertension patients referred to our hospital on outpatient bases were included in the study. 12-lead resting ECG was taken in all the patients. Left ventricular geometry defined using left ventricular mass index and relative wall thickness with transthorasic echocardiography.Results: Sixy seven patients with fragmented QRS and 63 patients without fragmented QRS included the study. We found that patients in the group with fragmented QRS detected have a wider mean left atrium diameter, greater left ventricular mass and left ventricular mass index compared with the group without fragmented QRS. Concentric and eccentric hypertrophy were more common in fragmented QRS group, while normal geometry and concentric remodelling have greater rates in the normal group.Conclusion: Left ventricular hypertrophy is observed more frequently in the patients with fragmented QRS than without fragmented QRS. This may be associated with the increased myocardial fibrosis in the left ventricular hypertrophy. Existence of fragmented QRS can be used for risk stratification in the hypertensive patients.

  2. Rate vs. rhythm control and adverse outcomes among European patients with atrial fibrillation.

    Science.gov (United States)

    Purmah, Yanish; Proietti, Marco; Laroche, Cecilé; Mazurek, Michal; Tahmatzidis, Dimitrios; Boriani, Giuseppe; Novo, Salvatore; Lip, Gregory Y H

    2017-02-04

    The impact of rate and rhythm control strategies on outcomes in patients with atrial fibrillation (AF) remains controversial. Our aims were: to report use of rate and rhythm control strategies in European patients from the EURObservational Research Program AF General Pilot Registry. Secondly, to evaluate outcomes according to assigned strategies. Use of pure rate and rhythm control agents was described according to European regions. 1-year follow-up data were reported. Among rate control strategies, beta-blockers were the most commonly used drug. Proportions of patients assigned to rhythm control varied greatly between countries, and amiodarone was the most used rhythm control drug. Of the original 3119 patients, 1036 (33.2%) were assigned to rate control only and 355 (11.4%) to rhythm control only. Patients assigned to a rate control strategy were older (P rate control strategy had higher rates for any thrombo-embolic event (P = 0.0245), cardiovascular death (P = 0.0437), and all-cause death (P rate control strategy was associated with a higher risk for all-cause death (P rate control strategy was independently associated with all-cause death (P = 0.0256). A propensity matched analysis only found a trend for the association between rate control and all-cause death (P = 0.0664). In a European AF patients' cohort, a pure rate control strategy was associated with a higher risk for adverse events at 1-year follow-up, and partially adjusted analysis suggested that rate control independently increased the risk for all-cause death. A fully adjusted propensity score matched analysis found that this association was no longer statistically significant, suggesting an important role of comorbidities in determining the higher risk for all-cause death.

  3. Convergence rate controls seismicity styles in collision orogens

    Science.gov (United States)

    Dal Zilio, Luca; van Dinther, Ylona; Gerya, Taras

    2016-04-01

    The 25 April 2015 Mw 7.8 Gorkha earthquake in Nepal resulted from the unzipping of the previously locked Main Himalayan Thrust (MHT) fault, along which the Himalayan wedge is thrust over India. Strong ground shaking caused the collapse of more than half a million homes, killing more than 8500 people. Can such a large magnitude event also occur within the populated European Alps? Or is there a distinctly different seismicity pattern in different orogens? We show that their long-term seismicity patterns are indeed different and that their differences can be explained by a single parameter: their convergence rate. To do so we present the first self-consistent seismic cycle model for continental collisional margins. We use the viscoelastoplastic continuum Seismo-Thermo-Mechanical model (STM) validated for seismic cycle applications against a laboratory model (van Dinther et al., 2013a) and natural observations (van Dinther et al., 2013b), which includes Drucker-Prager plasticity and spontaneous rupture events governed by strongly rate-dependent friction. The 2-D model setup consists of two continental plates separated by an oceanic plate, in which the incipient subduction phase is followed by collisional orogeny. Results show the physically consistent spontaneous emergence of complex rupture paths, both on and off the main frontal thrust. These off-main frontal thrust events within the upper and lower plate complement the main frontal thrust seismicity leading to a Gutenberg-Richter frequency-magnitude distribution. This is a key observational feature of seismicity, which is typically not reproduced in seismic cycle models. The range of simulated b-values agrees with natural ranges, as we observe values from 0.97 up to 1.25 for convergence rates decreasing from 5 to 1 cm/yr. Decreasing convergence rates thus lead to relatively larger amounts of smaller earthquakes (increasing b-value) and lower maximum magnitudes. This change in b-value also observed to corresponds to

  4. Control of specific growth rate in Saccharomyces cerevisiae

    NARCIS (Netherlands)

    Snoep, J.L.; Mrwebi, M; Schuurmans, J.M.; Rohwer, J.M.; Teixeira De Mattos, M.J.

    2009-01-01

    In this contribution we resolve the long-standing dispute whether or not the Monod constant (KS), describing the overall affinity of an organism for its growth-limiting substrate, can be related to the affinity of the transporter for that substrate (KM). We show how this can be done via the control

  5. A Distributed Flow Rate Control Algorithm for Networked Agent System with Multiple Coding Rates to Optimize Multimedia Data Transmission

    Directory of Open Access Journals (Sweden)

    Shuai Zeng

    2013-01-01

    Full Text Available With the development of wireless technologies, mobile communication applies more and more extensively in the various walks of life. The social network of both fixed and mobile users can be seen as networked agent system. At present, kinds of devices and access network technology are widely used. Different users in this networked agent system may need different coding rates multimedia data due to their heterogeneous demand. This paper proposes a distributed flow rate control algorithm to optimize multimedia data transmission of the networked agent system with the coexisting various coding rates. In this proposed algorithm, transmission path and upload bandwidth of different coding rate data between source node, fixed and mobile nodes are appropriately arranged and controlled. On the one hand, this algorithm can provide user nodes with differentiated coding rate data and corresponding flow rate. On the other hand, it makes the different coding rate data and user nodes networked, which realizes the sharing of upload bandwidth of user nodes which require different coding rate data. The study conducts mathematical modeling on the proposed algorithm and compares the system that adopts the proposed algorithm with the existing system based on the simulation experiment and mathematical analysis. The results show that the system that adopts the proposed algorithm achieves higher upload bandwidth utilization of user nodes and lower upload bandwidth consumption of source node.

  6. Effect of acute subendocardial ischemia on ventricular refractory periods.

    Science.gov (United States)

    Ma, Longle; Wang, Lexin

    2007-01-01

    To investigate the impact of acute subendocardial ischemia on the dispersion of ventricular refractory periods. Acute subendocardial ischemia was induced in sheep by partial ligation of the left circumflex coronary artery and rapid pacing of the left atrium. The ventricular effective refractory period (ERP) was measured in five areas of the left ventricle by a programmed premature stimulation technique. The average ERP and ERP dispersion remained unchanged in the control group (n=5, P>0.05). In the study group (n=5), the ERP was shortened following subendocardial ischemia. ERP dispersion decreased significantly from 48+/-9 ms to 36+/-13 ms 30 min after the ischemia (P=0.02). There was neither spontaneous nor stimulation-induced ventricular arrhythmia after ischemia. Acute subendocardial ischemia leads to a homogenous reduction of ventricular ERP. This may partially explain why subendocardial ischemia is associated with a low incidence of ventricular arrhythmia.

  7. Wireless Power Control for Tactical MANET: Power Rate Bounds

    Science.gov (United States)

    2016-09-01

    and Sayed is a masterful exposition of this approach [73]. Gunnarsson, Guustafsson, and Blom produced a superb analysis of time-delay (TD) effects and...function, the analytic properties of the function may force the image to be its own Pareto front. Lemma 2 Let h : X ⊆ R→ R be continuous and strictly...Motorola, Inc. [1995] Final Text for PACS Licensed Air Interface (TAG 3) J-STD014. 60. Muqattash, A. & M. Krunz [2002] Power-Controlled Dual Channel

  8. Ivabradine for patients with stable coronary artery disease and left-ventricular systolic dysfunction (BEAUTIFUL): a randomised, double-blind, placebo-controlled trial

    DEFF Research Database (Denmark)

    Fox, Kim; Ford, Ian; Steg, P Gabriel

    2008-01-01

    .9) beats per minute (bpm). Median follow-up was 19 months (IQR 16-24). Ivabradine reduced heart rate by 6 bpm (SE 0.2) at 12 months, corrected for placebo. Most (87%) patients were receiving beta blockers in addition to study drugs, and no safety concerns were identified. Ivabradine did not affect...... the primary composite endpoint (hazard ratio 1.00, 95% CI 0.91-1.1, p=0.94). 1233 (22.5%) patients in the ivabradine group had serious adverse events, compared with 1239 (22.8%) controls (p=0.70). In a prespecified subgroup of patients with heart rate of 70 bpm or greater, ivabradine treatment did not affect...... disease outcomes in a subgroup of patients who have heart rates of 70 bpm or greater....

  9. Left ventricular mural thrombus

    Energy Technology Data Exchange (ETDEWEB)

    Nixon, J.V.

    1983-08-01

    The identification of mural thrombus in patients with left ventricular aneurysm and mural thrombus probably warrants consideration of long-term anticoagulation. In patients with acute, large, anterior or anteroapical, transmural myocardial infarctions, serial noninvasive examinations are warranted to define a group of patients at high risk for the development of left ventricular aneurysm and/or mural thrombus. Anticoagulants should be considered in patients in whom mural thrombi develop as a complication of their infarction. Patients with congestive cardiomyopathy should be considered for long-term anticoagulation. These recommendations are all tempered by the realization that the use of anticoagulant therapy is not without its own risks. The decision to anticoagulate must be balanced against each individual patient's suitability for such therapy and the individual likelihood of the development of side effects.

  10. Arrhythmogenic right ventricular cardiomyopathy.

    Science.gov (United States)

    Soni, Roopali; Oade, Yvette

    2011-08-24

    Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a rare inherited disease of the heart muscle that causes ventricular tachyarrhythmias and sudden death in young people and athletes. It results in fibrofatty replacement of the right ventricle, and the subepicardial region of the left ventricle. It is the most common cause of sudden cardiac death in young people after hypertrophic heart disease. Diagnosis can be difficult and at present there is no cure for ARVC. Prevention of sudden death is the most important management strategy. Paediatricians need to be aware of the possibility of ARVC in adolescents and young adults presenting with palpitations, fatigue, syncope or cardiac arrest. The authors present two cases of apparently healthy teenage boys who died suddenly and unexpectedly. Postmortem examination of the myocardium was strongly suggestive of ARVC in both cases.

  11. Effects of telmisartan combined with nifedipine controlled release tablet on inflammatory factors, vascular endothelial function and left ventricular function in patients with coronary heart disease with mild to moderate hypertension

    Directory of Open Access Journals (Sweden)

    Feng Guo

    2017-10-01

    Full Text Available Objective: To investigate the effect of telmisartan combined with Nifedipine Controlled Release Tablet on inflammatory factors, vascular endothelial function and left ventricular function in patients with coronary heart disease with mild to moderate hypertension. Methods: A total of 92 cases of patients with coronary heart disease with mild to moderate hypertension were selected as the object of observation, according to the random data table, they were divided into the control group (n=46 and observation group (n=46, and patients in the control group were treated with Nifedipine Controlled Release Table therapy, on this basis, the observation group patients were given telmisartan treatment, two groups were treated for 6 months. The levels of the blood pressure, inflammatory factors, vascular endothelial function and left ventricular function compared between the two groups before and after treatment. Results: There were no significant differences in the levels of SBP, DBP, hs-CRP, TNF-α, NO, ET-1, LVEF, LVEDD and LVESD in the two groups before treatment. After treatment, two groups of SBP, DBP, hs-CRP, TNF-α, ET-1, LVEDD and LVESD levels were significantly lower than those in the same group before treatment, and after treatment, the levels of SBP, DBP, hs-CRP, TNF-α, ET-1 and LVESD in the observation group were significantly lower than those in the control group, while there were no significant difference in the level of LVEDD between the two groups after treatment; Compared with level in the group before treatment, the levels of NO and LVEF in the two groups were significantly increased, and the observation group [(82.13±19.01 µmol/L, (52.83±7.45%] was significantly higher than the control group [(67.37±13.08 µmol/L, (49.47±6.96%]. Conclusion: Telmisartan combined with Nifedipine Controlled Release Table in treating coronary heart disease with mild to moderate hypertension, can effectively control blood pressure, reduce the

  12. Idiopathic Fascicular Ventricular Tachycardia

    Directory of Open Access Journals (Sweden)

    Johnson Francis

    2004-07-01

    Full Text Available Idiopathic fascicular ventricular tachycardia is an important cardiac arrhythmia with specific electrocardiographic features and therapeutic options. It is characterized by relatively narrow QRS complex and right bundle branch block pattern. The QRS axis depends on which fascicle is involved in the re-entry. Left axis deviation is noted with left posterior fascicular tachycardia and right axis deviation with left anterior fascicular tachycardia. A left septal fascicular tachycardia with normal axis has also been described. Fascicular tachycardia is usually seen in individuals without structural heart disease. Response to verapamil is an important feature of fascicular tachycardia. Rare instances of termination with intravenous adenosine have also been noted. A presystolic or diastolic potential preceding the QRS, presumed to originate from the Purkinje fibers can be recorded during sinus rhythm and ventricular tachycardia in many patients with fascicular tachycardia. This potential (P potential has been used as a guide to catheter ablation. Prompt recognition of fascicular tachycardia especially in the emergency department is very important. It is one of the eminently ablatable ventricular tachycardias. Primary ablation has been reported to have a higher success, lesser procedure time and fluoroscopy time

  13. Left and right ventricular diastolic function in hemodialysis patients.

    Science.gov (United States)

    Rudhani, Ibrahim Destan; Bajraktari, Gani; Kryziu, Emrush; Zylfiu, Bejtush; Sadiku, Shemsedin; Elezi, Ymer; Rexhepaj, Nehat; Vitia, Arber; Emini, Merita; Abazi, Murat; Berbatovci-Ukimeraj, M; Kryeziu, Kaltrina; Hsanagjekaj, Venera; Korca, Hajrije; Ukimeri, Aferdita

    2010-11-01

    The aim of this prospective study was the assessment of left ventricular and right ventricular diastolic function in patients on hemodialysis (HD) and the correlation of this function with the duration of HD. The study included 42 patients (22 females and 20 males) with chronic renal failure (CRF), treated with HD, and 40 healthy subjects (24 females and 16 males) with no history of cardiovascular disease and with normal renal function, who constituted the control group. The groups were matched for age and sex. All study patients and control subjects underwent detailed history taking and physical examination. They also underwent electrocardiogram, echocardiography and biochemical and hematological blood analyses. Significant differences were noted between the two groups in the two-dimensional and M-mode echocardiography findings concerning aortic root dimension, transverse diameter of the left atrium, thickness of the interventricular septum, thickness of the left ventricular posterior wall, left ventricular diastolic diameter, left ventricular systolic diameter, shortening fraction, ejection fraction as well as findings from the pulse Doppler study, including E wave, A wave, E/A ratio, deceleration time of E wave (DT-E), acceleration time of E wave (AT-E), tricuspid E and A waves (E tr and A tr ) and E tr /A tr , ratio. There were significant changes in HD patients without arterial hypertension as well in the control group subjects. Our study suggests that the left ventricular and left atrial dimensions as well as the left ventricular wall thickness are augmented in patients with CRF treated with HD compared with the control group. Additionally, the left and right ventricular diastolic function is also reduced in these patients. These differences were also noted in patients with CRF without arterial hypertension. Left ventricular diastolic dysfunction had no correlation with the duration of HD.

  14. [Ventricular pump function under ectopic excitation of the frog heart].

    Science.gov (United States)

    Kibler, N A; Belogolova, A S; Vaĭkshnoraĭte, M A; Azarov, Ia E; Shmakov, D N

    2008-02-01

    The ventricular pump function under ectopic excitation of the heart was studied in decapitated and pithed adult frogs Rana temporaria (n = 21) at 18-19 degrees C. The intraventricular pressure was recorded with a catheter via ventricular wall. During pacing of the ventricular base and apex, the systolic pressure decreased (6.1 +/- 4.5 mm Hg and 8.9 +/- 5.0 mm Hg, respectively) as compared to the supraventricular rhythm (8.9 +/- 5.0 mm Hg, p < 0.05). The end-diastolic pressure decreased insignificantly both under basal and apical pacing. The systolic rate of pressure rise during dP/dtmax decreased under ventricular pacing, especially during pacing of the ventricular apex, as compared to the supraventricular rhythm (14.4 +/- 6/9 mm Hg/s and 22.1 +/- 11.2 mm Hg/s, respectively, p < 0.003). The isovolumetric relaxation (dP/dtmin) slowed during apical pacing as compared to the supraventricular rhythm (-25.1 +/- 13.6 and -35.6 +/- 18.3 mm Hg/s, respectively, p < 0.03). Ectopic excitation of the ventricular base and apex resulted in increase of the QRS duration (93 +/- 33 ms and 81 +/- 30 ms, respectively) as compared to the supraventricular rhythm (63 +/- 13 ms, p < 0.05). Thus, pacing of different ventricular areas ventricular myocardium with the ventricular pump function being reduced more obviously during the apical pacing compared to the pacing of ventricular base.

  15. Practical Rate-Based Congestion Control for Wireless Mesh Networks

    Science.gov (United States)

    Elrakabawy, Sherif M.; Lindemann, Christoph

    We introduce an adaptive pacing scheme to overcome the drawbacks of TCP in wireless mesh networks with Internet connectivity. The pacing scheme is implemented at the wireless TCP sender as well as at the mesh gateway, and reacts according to the direction of TCP flows running across the wireless network and the Internet. TCP packets are transmitted rate-based within the TCP congestion window according to the current out-of-interference delay and the coefficient of variation of recently measured round-trip times. Opposed to the majority of previous work which builds on simulations, we implement a Linux prototype of our approach and evaluate its feasibility in a real 20-node mesh testbed. In an experimental performance study, we compare the goodput and fairness of our approach against the widely deployed TCP NewReno. Experiments show that our approach, which we denote as Mesh Adaptive Pacing (MAP), can achieve up to 150% more goodput than TCP NewReno and significantly improves fairness between competing flows. MAP is incrementally deployable since it is TCP-compatible, does not require cross-layer information from intermediate nodes along the path, and requires no modifications in the wired domain.

  16. Controlling the local false discovery rate in the adaptive Lasso

    KAUST Repository

    Sampson, J. N.

    2013-04-09

    The Lasso shrinkage procedure achieved its popularity, in part, by its tendency to shrink estimated coefficients to zero, and its ability to serve as a variable selection procedure. Using data-adaptive weights, the adaptive Lasso modified the original procedure to increase the penalty terms for those variables estimated to be less important by ordinary least squares. Although this modified procedure attained the oracle properties, the resulting models tend to include a large number of "false positives" in practice. Here, we adapt the concept of local false discovery rates (lFDRs) so that it applies to the sequence, λn, of smoothing parameters for the adaptive Lasso. We define the lFDR for a given λn to be the probability that the variable added to the model by decreasing λn to λn-δ is not associated with the outcome, where δ is a small value. We derive the relationship between the lFDR and λn, show lFDR =1 for traditional smoothing parameters, and show how to select λn so as to achieve a desired lFDR. We compare the smoothing parameters chosen to achieve a specified lFDR and those chosen to achieve the oracle properties, as well as their resulting estimates for model coefficients, with both simulation and an example from a genetic study of prostate specific antigen.

  17. Wear rate control of peek surfaces modified by femtosecond laser

    Science.gov (United States)

    Hammouti, S.; Pascale-Hamri, A.; Faure, N.; Beaugiraud, B.; Guibert, M.; Mauclair, C.; Benayoun, S.; Valette, S.

    2015-12-01

    This paper presents the effect of laser texturing on the tribological properties of PEEK surfaces under a ball-on-flat contact configuration. Thus, surfaces with circular dimples of various diameters and depth were created. Tests were conducted with a normal load of 5 N and a sliding velocity of 0.01 m s-1, using bovine calf serum at 37.5 °C as a lubricant. The tribological conditions including the sliding frequency and the lubricant viscosity indicate that tests were performed under boundary lubrication regime. Results showed that discs with higher dimple depth exhibited higher friction coefficient and caused more abrasive wear on the ball specimen. Nevertheless, tribosystems (ball and disc) with dimpled disc surfaces showed a higher wear resistance. In the frame of our experiments, wear rates obtained for tribosystems including dimpled surfaces were 10 times lower than tribosystems including limited patterned or untextured surfaces. Applications such as design of spinal implants may be concerned by such a surface treatment to increase wear resistance of components.

  18. Kinematic equations for resolved-rate control of an industrial robot arm

    Science.gov (United States)

    Barker, L. K.

    1983-01-01

    An operator can use kinematic, resolved-rate equations to dynamically control a robot arm by watching its response to commanded inputs. Known resolved-rate equations for the control of a particular six-degree-of-freedom industrial robot arm and proceeds to simplify the equations for faster computations are derived. Methods for controlling the robot arm in regions which normally cause mathematical singularities in the resolved-rate equations are discussed.

  19. Macrosomia Rates in Women with Diet-Controlled Gestational Diabetes: A Retrospective Study

    OpenAIRE

    Fatima Vally; Jeffrey Presneill; Thomas Cade

    2017-01-01

    Background. Current data on the rates of macrosomia in women with gestational diabetes mellitus (GDM) are heterogenous. No study has specifically examined macrosomia rates in women with diet-controlled gestational diabetes. Aims. To compare the rates of macrosomia between mothers with diet-controlled GDM to mothers without diabetes mellitus. Methods. A retrospective study in which all patients with diet-controlled GDM and singleton pregnancies in 2014 were considered for inclusion in the stud...

  20. Ventricular hypertrophy in cardiomyopathy.

    Science.gov (United States)

    Oakley, C

    1971-01-01

    Semantic difficulties arise when hypertrophic obstructive cardiomyopathy is seen without obstruction and with congestive failure, and also when congestive cardiomyopathy is seen with gross hypertrophy but without heart failure. Retention of a small left ventricular cavity and a normal ejection fraction characterizes hypertrophic cardiomyopathy at all stages of the disorder. Congestive cardiomyopathy is recognized by the presence of a dilated left ventricular cavity and reduced ejection fraction regardless of the amount of hypertrophy and the presence or not of heart failure. Longevity in congestive cardiomyopathy seems to be promoted when hypertrophy is great relative to the amount of pump failure as measured by increase in cavity size. Conversely, death in hypertrophic cardiomyopathy is most likely when hypertrophy is greatest at a time when outflow tract obstruction has been replaced by inflow restriction caused by diminishing ventricular distensibility. Hypertrophy is thus beneficial and compensatory in congestive cardiomyopathy, whereas it may be the primary disorder and eventual cause of death in hypertrophic cardiomyopathy. Reasons are given for believing that hypertension may have been the original cause of left ventricular dilatation in some case of congestive cardiomyopathy in which loss of stroke output thenceforward is followed by normotension. Development of severe hypertension in these patients after recovery from a prolonged period of left ventricular failure with normotension lends weight to this hypothesis. No fault has been found in the large or small coronary arteries in either hypertrophic cardiomyopathy or congestive cardiomyopathy when they have been examined in life by selective coronary angiography, or by histological methods in biopsy or post-mortem material. Coronary blood supply may be a limiting factor in the compensatory hypertrophy of congestive cardiomyopathy, and the ability to hypertrophy may explain the better prognosis of some

  1. Comparison of the rhythm control treatment strategy versus the rate control strategy in patients with permanent or long-standing persistent atrial fibrillation and heart failure treated with cardiac resynchronization therapy - a pilot study of Cardiac Resynchronization in Atrial Fibrillation Trial (Pilot-CRAfT): study protocol for a randomized controlled trial.

    Science.gov (United States)

    Ciszewski, Jan; Maciag, Aleksander; Kowalik, Ilona; Syska, Pawel; Lewandowski, Michal; Farkowski, Michal M; Borowiec, Anna; Chwyczko, Tomasz; Pytkowski, Mariusz; Szwed, Hanna; Sterlinski, Maciej

    2014-10-04

    The only subgroups of patients with heart failure and atrial fibrillation in which the efficacy of cardiac resynchronization therapy has been scientifically proven are patients with indications for right ventricular pacing and patients after atrioventricular junction ablation. However it is unlikely that atrioventricular junction ablation would be a standard procedure in the majority of the heart failure patients with cardiac resynchronization therapy and concomitant atrial fibrillation due to the irreversible character of the procedure and a spontaneous sinus rhythm resumption that occurs in about 10% of these patients. Pilot-CRAfT is the first randomized controlled trial evaluating the efficacy of a rhythm control strategy in atrial fibrillation patients with cardiac resynchronization therapy devices. The aim of this prospective, single center randomized controlled pilot study is to answer the question whether the patients with cardiac resynchronization therapy and permanent atrial fibrillation would benefit from a strategy to restore and maintain sinus rhythm (that is 'rhythm control' strategy) in comparison to rate control strategy. The study population consists of 60 patients with heart failure and concomitant long-standing persistent or permanent atrial fibrillation who underwent a cardiac resynchronization therapy device implantation at least 3 months before qualification. Study participants are randomly assigned to the rhythm control strategy (including electrical cardioversion and pharmacotherapy) or to the rate control group whose goal is to control ventricular rate. The follow-up time is 12 months. The primary endpoint is the ratio of effectively captured biventricular beats. The secondary endpoints include peak oxygen consumption, six-minute walk test distance, heart failure symptom escalation, reverse remodelling of the heart on echo and quality of life. NCT01850277 registered on 22 April 2013 (ClinicalTrials.gov).

  2. Quality control of high-dose-rate brachytherapy: treatment delivery analysis using statistical process control.

    Science.gov (United States)

    Able, Charles M; Bright, Megan; Frizzell, Bart

    2013-03-01

    Statistical process control (SPC) is a quality control method used to ensure that a process is well controlled and operates with little variation. This study determined whether SPC was a viable technique for evaluating the proper operation of a high-dose-rate (HDR) brachytherapy treatment delivery system. A surrogate prostate patient was developed using Vyse ordnance gelatin. A total of 10 metal oxide semiconductor field-effect transistors (MOSFETs) were placed from prostate base to apex. Computed tomography guidance was used to accurately position the first detector in each train at the base. The plan consisted of 12 needles with 129 dwell positions delivering a prescribed peripheral dose of 200 cGy. Sixteen accurate treatment trials were delivered as planned. Subsequently, a number of treatments were delivered with errors introduced, including wrong patient, wrong source calibration, wrong connection sequence, single needle displaced inferiorly 5 mm, and entire implant displaced 2 mm and 4 mm inferiorly. Two process behavior charts (PBC), an individual and a moving range chart, were developed for each dosimeter location. There were 4 false positives resulting from 160 measurements from 16 accurately delivered treatments. For the inaccurately delivered treatments, the PBC indicated that measurements made at the periphery and apex (regions of high-dose gradient) were much more sensitive to treatment delivery errors. All errors introduced were correctly identified by either the individual or the moving range PBC in the apex region. Measurements at the urethra and base were less sensitive to errors. SPC is a viable method for assessing the quality of HDR treatment delivery. Further development is necessary to determine the most effective dose sampling, to ensure reproducible evaluation of treatment delivery accuracy. Copyright © 2013 Elsevier Inc. All rights reserved.

  3. CASE REPORT Arrythmogenic right ventricular dysplasia ...

    African Journals Online (AJOL)

    RBBB: right bundle-branch block. RV: right ventricular. RVEDV: right ventricular end diastolic volume. RVEF: right ventricular ejection fraction. RVOT: right ventricular outflow tract. SAECG: signal averaged electrocardiogram. VT: ventricular tachycardia. 'Modifications of the orginal criteria have been proposed to facilitate ...

  4. The cardiomyocyte molecular clock regulates the circadian expression of Kcnh2 and contributes to ventricular repolarization.

    Science.gov (United States)

    Schroder, Elizabeth A; Burgess, Don E; Zhang, Xiping; Lefta, Mellani; Smith, Jennifer L; Patwardhan, Abhijit; Bartos, Daniel C; Elayi, Claude S; Esser, Karyn A; Delisle, Brian P

    2015-06-01

    Sudden cardiac death (SCD) follows a diurnal variation. Data suggest the timing of SCD is influenced by circadian (~24-hour) changes in neurohumoral and cardiomyocyte-specific regulation of the heart's electrical properties. The basic helix-loop-helix transcription factors brain muscle arnt-like1 (BMAL1) and circadian locomotor output control kaput (CLOCK) coordinate the circadian expression of select genes. We sought to test whether Bmal1 expression in cardiomyocytes contributes to K(+) channel expression and diurnal changes in ventricular repolarization. We used transgenic mice that allow for the inducible cardiomyocyte-specific deletion of Bmal1 (iCSΔBmal1(-/-)). We used quantitative polymerase chain reaction, voltage clamping, promoter-reporter bioluminescence assays, and electrocardiographic telemetry. Although several K(+) channel gene transcripts were downregulated in iCSΔBmal1(-/-)mouse hearts, only Kcnh2 exhibited a robust circadian pattern of expression that was disrupted in iCSΔBmal1(-/-) hearts. Kcnh2 underlies the rapidly activating delayed-rectifier K(+) current, and the rapidly activating delayed-rectifier K(+) current recorded from iCSΔBmal1(-/-) ventricular cardiomyocytes was ~50% smaller than control ventricular myocytes. Promoter-reporter assays demonstrated that the human Kcnh2 promoter is transactivated by the coexpression of BMAL1 and CLOCK. Electrocardiographic analysis showed that iCSΔBmal1(-/-) mice developed a prolongation in the heart rate-corrected QT interval during the light (resting) phase. This was secondary to an augmented circadian rhythm in the uncorrected QT interval without a corresponding change in the RR interval. The molecular clock in the heart regulates the circadian expression of Kcnh2, modifies K(+) channel gene expression, and is important for normal ventricular repolarization. Disruption of the cardiomyocyte circadian clock mechanism likely unmasks diurnal changes in ventricular repolarization that could contribute

  5. Risk Factors for Asymptomatic Ventricular Dysfunction in Rheumatoid Arthritis Patients

    Science.gov (United States)

    Garza-García, Carlos; Rocío, Sánchez-Santillán; Orea-Tejeda, Arturo; Castillo-Martínez, Lilia; Eduardo, Canseco; López-Campos, José Luis; Keirns-Davis, Candace

    2013-01-01

    Objective. The aim of the study was to describe echocardiographic abnormalities in patients with rheumatoid arthritis, concurrent systemic comorbidities, rheumatologic clinical activity, serologic markers of rheumatoid arthritis, and inflammatory activity. Methods. In an observational, cross-sectional study, rheumatoid arthritis outpatients were included (n = 105). Conventional transthoracic echocardiographic variables were compared between patients with arthritis and non-RA controls (n = 41). For rheumatoid arthritis patients, articular activity and rheumatologic and inflammatory markers were obtained. Results. Ventricular dysfunction was found in 54.3% of the population: systolic (18.1%), diastolic (32.4%), and/or right (24.8%), with lower ejection fraction (P < 0.0001). Pulmonary hypertension was found in 46.9%. Other echocardiographic findings included increased left atrial diameter (P = 0.01), aortic diameter (P = 0.01), ventricular septum (P = 0.01), left ventricular posterior wall (P = 0.013), and right ventricular (P = 0.01) and atrial diameters compared to control subjects. Rheumatoid factor and anti-CCP antibodies levels were significantly elevated in cases with ventricular dysfunction. Angina and myocardial infarction, diabetes, and dyslipidemia were the main risk factors for ventricular dysfunction. Conclusions. Ventricular dysfunction is common in rheumatoid arthritis and associated with longer disease duration and increased serologic markers of rheumatoid arthritis. Screening for cardiac abnormalities should be considered in this kind of patients. PMID:24368945

  6. Effects of Vildagliptin on Ventricular Function in Patients With Type 2 Diabetes Mellitus and Heart Failure: A Randomized Placebo-Controlled Trial.

    Science.gov (United States)

    McMurray, John J V; Ponikowski, Piotr; Bolli, Geremia B; Lukashevich, Valentina; Kozlovski, Plamen; Kothny, Wolfgang; Lewsey, James D; Krum, Henry

    2017-10-11

    This study sought to examine the safety of the dipeptidyl peptidase-4 inhibitor, vildagliptin, in patients with heart failure and reduced ejection fraction. Many patients with type 2 diabetes mellitus have heart failure and it is important to know about the safety of new treatments for diabetes in these individuals. Patients 18 to 85 years of age with type 2 diabetes and heart failure (New York Heart Association functional class I to III and left ventricular ejection fraction [LVEF] <0.40) were randomized to 52 weeks treatment with vildagliptin 50 mg twice daily (50 mg once daily if treated with a sulfonylurea) or matching placebo. The primary endpoint was between-treatment change from baseline in echocardiographic LVEF using a noninferiority margin of -3.5%. A total of 254 patients were randomly assigned to vildagliptin (n = 128) or placebo (n = 126). Baseline LVEF was 30.6 ± 6.8% in the vildagliptin group and 29.6 ± 7.7% in the placebo group. The adjusted mean change in LVEF was 4.95 ± 1.25% in vildagliptin treated patients and 4.33 ± 1.23% in placebo treated patients, a difference of 0.62 (95% confidence interval [CI]: -2.21 to 3.44; p = 0.667). This difference met the predefined noninferiority margin of -3.5%. Left ventricular end-diastolic and end-systolic volumes increased more in the vildagliptin group by 17.1 ml (95% CI: 4.6 to 29.5 ml; p = 0.007) and 9.4 ml (95% CI: -0.49 to 19.4 ml; p = 0.062), respectively. Decrease in hemoglobin A1c from baseline to 16 weeks, the main secondary endpoint, was greater in the vildagliptin group: -0.62% (95% CI: -0.93 to -0.30%; p < 0.001; -6.8 mmol/mol; 95% CI: -10.2 to -3.3 mmol/mol). Compared with placebo, vildagliptin had no major effect on LVEF but did lead to an increase in left ventricular volumes, the cause and clinical significance of which is unknown. More evidence is needed regarding the safety of dipeptidyl peptidase-4 inhibitors in patients with heart failure and left ventricular

  7. Modeling and Model Predictive Power and Rate Control of Wireless Communication Networks

    Directory of Open Access Journals (Sweden)

    Cunwu Han

    2014-01-01

    Full Text Available A novel power and rate control system model for wireless communication networks is presented, which includes uncertainties, input constraints, and time-varying delays in both state and control input. A robust delay-dependent model predictive power and rate control method is proposed, and the state feedback control law is obtained by solving an optimization problem that is derived by using linear matrix inequality (LMI techniques. Simulation results are given to illustrate the effectiveness of the proposed method.

  8. Control of Chaos in Rate-Dependent Friction-Induced Vibration Using Adaptive Sliding Mode Control and Impulse Damper

    Directory of Open Access Journals (Sweden)

    Ehsan Maani Miandoab

    2013-01-01

    Full Text Available Two different control methods, namely, adaptive sliding mode control and impulse damper, are used to control the chaotic vibration of a block on a belt system due to the rate-dependent friction. In the first method, using the sliding mode control technique and based on the Lyapunov stability theory, a sliding surface is determined, and an adaptive control law is established which stabilizes the chaotic response of the system. In the second control method, the vibration of this system is controlled by an impulse damper. In this method, an impulsive force is applied to the system by expanding and contracting the PZT stack according to efficient control law. Numerical simulations demonstrate the effectiveness of both methods in controlling the chaotic vibration of the system. It is shown that the settling time of the controlled system using impulse damper is less than that one controlled by adaptive sliding mode control; however, it needs more control effort.

  9. [Efficacy of rate and rhythm control strategy in patients with atrial fibrillation: meta-analysis].

    Science.gov (United States)

    Chen, Shao-jie; Yin, Yue-hui; Dong, Ying; Fan, Jin-qi; Su, Li

    2012-01-01

    The efficacy of rate and rhythm control strategies for treating atrial fibrillation (AF) patients was analyzed in this meta-analysis. Eligible trials were searched in MEDLINE, the Cochrane Library, the Clinical Trials, the Chinese VIP database up to May 31, 2010. Ten prospective randomized control trials with 7876 patients (rate control n = 3932, rhythm control n = 3944) were included for final analysis. All cause mortality (5.3% vs. 5.0%; OR: 1.03; 95%CI: 0.84 - 1.26; I(2) control group than in rhythm control group in patients with age control and rate control groups while rehospitalization rate was significantly lower in rate control group than in rhythm control group (17.56% vs. 22.98%; OR: 0.37, 95%CI: 0.19 - 0.71). This meta-analysis shows that rhythm control strategy is superior to rate control strategy for AF patients with age < 65 years in terms of reducing all cause mortality and incidence of worsening heart failure.

  10. Endothelin-1 signalling controls early embryonic heart rate in vitro and in vivo.

    Science.gov (United States)

    Karppinen, S; Rapila, R; Mäkikallio, K; Hänninen, S L; Rysä, J; Vuolteenaho, O; Tavi, P

    2014-02-01

    Spontaneous activity of embryonic cardiomyocytes originates from sarcoplasmic reticulum (SR) Ca(2+) release during early cardiogenesis. However, the regulation of heart rate during embryonic development is still not clear. The aim of this study was to determine how endothelin-1 (ET-1) affects the heart rate of embryonic mice, as well as the pathway through which it exerts its effects. The effects of ET-1 and ET-1 receptor inhibition on cardiac contraction were studied using confocal Ca(2+) imaging of isolated mouse embryonic ventricular cardiomyocytes and ultrasonographic examination of embryonic cardiac contractions in utero. In addition, the amount of ET-1 peptide and ET receptor a (ETa) and b (ETb) mRNA levels were measured during different stages of development of the cardiac muscle. High ET-1 concentration and expression of both ETa and ETb receptors was observed in early cardiac tissue. ET-1 was found to increase the frequency of spontaneous Ca(2+) oscillations in E10.5 embryonic cardiomyocytes in vitro. Non-specific inhibition of ET receptors with tezosentan caused arrhythmia and bradycardia in isolated embryonic cardiomyocytes and in whole embryonic hearts both in vitro (E10.5) and in utero (E12.5). ET-1-mediated stimulation of early heart rate was found to occur via ETb receptors and subsequent inositol trisphosphate receptor activation and increased SR Ca(2+) leak. Endothelin-1 is required to maintain a sufficient heart rate, as well as to prevent arrhythmia during early development of the mouse heart. This is achieved through ETb receptor, which stimulates Ca(2+) leak through IP3 receptors. © 2013 Scandinavian Physiological Society. Published by John Wiley & Sons Ltd.

  11. Estimating the impact of birth control on fertility rate in Sub-Saharan ...

    African Journals Online (AJOL)

    Using a cross-country data drawn from 40 countries and a multiple regression analysis, this paper examines the impact of birth control devices on the rate of fertility in sub-Saharan Africa. Our a-priori expectations are that the more women used birth control devices, the less will be the fertility rate in sub-Saharan Africa.

  12. Constant specific growth rate in fed-batch cultivation of Bordetella pertussis using adaptive control

    NARCIS (Netherlands)

    Soons, Z.I.T.A.; Voogt, J.A.; Straten, van G.; Boxtel, van A.J.B.

    2006-01-01

    Monitoring and control of production processes for biopharmaceuticals have become standard requirements to support consistency and quality. In this paper, a constant specific growth rate in fed-batch cultivation of Bordetella pertussis is achieved by a newly designed specific growth rate controller.

  13. Left Ventricular Hypertrophy: Major Risk Factor in Patients with Hypertension: Update and Practical Clinical Applications

    Directory of Open Access Journals (Sweden)

    Richard E. Katholi

    2011-01-01

    Full Text Available Left ventricular hypertrophy is a maladaptive response to chronic pressure overload and an important risk factor for atrial fibrillation, diastolic heart failure, systolic heart failure, and sudden death in patients with hypertension. Since not all patients with hypertension develop left ventricular hypertrophy, there are clinical findings that should be kept in mind that may alert the physician to the presence of left ventricular hypertrophy so a more definitive evaluation can be performed using an echocardiogram or cardiovascular magnetic resonance. Controlling arterial pressure, sodium restriction, and weight loss independently facilitate the regression of left ventricular hypertrophy. Choice of antihypertensive agents may be important when treating a patient with hypertensive left ventricular hypertrophy. Angiotensin-converting enzyme inhibitors or angiotensin II receptor blockers followed by calcium channel antagonists most rapidly facilitate the regression of left ventricular hypertrophy. With the regression of left ventricular hypertrophy, diastolic function and coronary flow reserve usually improve, and cardiovascular risk decreases.

  14. Power flow controller with a fractionally rated back-to-back converter

    Science.gov (United States)

    Divan, Deepakraj M.; Kandula, Rajendra Prasad; Prasai, Anish

    2016-03-08

    A power flow controller with a fractionally rated back-to-back (BTB) converter is provided. The power flow controller provide dynamic control of both active and reactive power of a power system. The power flow controller inserts a voltage with controllable magnitude and phase between two AC sources at the same frequency; thereby effecting control of active and reactive power flows between the two AC sources. A transformer may be augmented with a fractionally rated bi-directional Back to Back (BTB) converter. The fractionally rated BTB converter comprises a transformer side converter (TSC), a direct-current (DC) link, and a line side converter (LSC). By controlling the switches of the BTB converter, the effective phase angle between the two AC source voltages may be regulated, and the amplitude of the voltage inserted by the power flow controller may be adjusted with respect to the AC source voltages.

  15. Active random noise control using adaptive learning rate neural networks with an immune feedback law

    Science.gov (United States)

    Sasaki, Minoru; Kuribayashi, Takumi; Ito, Satoshi

    2005-12-01

    In this paper an active random noise control using adaptive learning rate neural networks with an immune feedback law is presented. The adaptive learning rate strategy increases the learning rate by a small constant if the current partial derivative of the objective function with respect to the weight and the exponential average of the previous derivatives have the same sign, otherwise the learning rate is decreased by a proportion of its value. The use of an adaptive learning rate attempts to keep the learning step size as large as possible without leading to oscillation. In the proposed method, because of the immune feedback law change a learning rate of the neural networks individually and adaptively, it is expected that a cost function minimize rapidly and training time is decreased. Numerical simulations and experiments of active random noise control with the transfer function of the error path will be performed, to validate the convergence properties of the adaptive learning rate Neural Networks with the immune feedback law. Control results show that adaptive learning rate Neural Networks control structure can outperform linear controllers and conventional neural network controller for the active random noise control.

  16. Ventricular septal defect.

    Science.gov (United States)

    Giboney, G S

    1983-05-01

    This article has discussed the ventricular septal defect, its occurrence, physiology, and therapy, and nursing concerns. The VSD, a communication allowing left-to-right shunting of blood at the ventricular level, is the most common congenital heart defect. Surgical correction is often required for large defects before the age of 12 months, and primary correction is now considered standard procedure. Small defects usually close spontaneously, and moderate defects are closely monitored for signs indicating the need for surgical intervention. Nursing care begins with child and family assessment and evaluation of the strengths and weaknesses of the family system. The child's developmental level is a major consideration in formulating interventions for his benefit. Play therapy is a useful vehicle in relating to the child in a nonthreatening manner preoperatively and in allowing the child to work through his hospitalization postoperatively. Maintaining the physical integrity of a child just out of the operating room is a challenge. Continuing support of the family system is a significant aspect of nursing's responsibility toward child and family. Discharge planning and intervention strive to prepare the family for the transition from hospital to home both physically and emotionally.

  17. Adaptive Rate-Scheduling with Reactive Delay Control for Next Generation CDMA Wireless Mobile Systems

    Directory of Open Access Journals (Sweden)

    Yu Oliver

    2006-01-01

    Full Text Available To minimize QoS degradations during nonstationary packet loadings, predictive rate schedulers adapt the operation according to anticipated packet arrival rates deduced via specified estimation algorithm. Existing predictive rate schedulers are developed under the assumption of perfect estimation, which may not be possible in future CDMA-based cellular networks characterized with highly nonstationary and bursty traffic. Additional shortcoming of existing rate schedulers is the coupling of delay and bandwidth, that is, close interdependence of delay and bandwidth (rate, whereby controlling one is accomplished solely by changing the other. In order to mitigate for the arrival rate estimation errors and delay-bandwidth coupling, this paper presents the feedback-enhanced target-tracking weighted fair queuing (FT-WFQ rate scheduler. It is an adaptive rate scheduler over multiclass CDMA systems with predictive adaptation control to adapt to nonstationary loadings; and feedback-enhanced reactive adaptation control to counteract arrival rate estimation errors. When the predictive adaptation control is not able to maintain long-term delay targets, feedback information will trigger reactive adaptation control. The objective of FT-WFQ scheduler is to minimize deviations from delay targets subject to maximum throughput utilization. Analytical and simulation results indicate that FT-WFQ is able to substantially reduce degradations caused by arrival rate estimation errors and to minimize delay degradations during nonstationary loading conditions.

  18. Right ventricular metastasis of leiomyosarcoma

    Directory of Open Access Journals (Sweden)

    Stagmo Martin

    2009-05-01

    Full Text Available Abstract Metastatic presentation of leiomyosarcoma in the heart is very rare. We present transthoracic echocardiography and combined PET/CT images of a case with a large right ventricular metastasis of leiomyosarcoma. The patient was placed on cytostatic drugs for palliative purposes, but passed away one month later because of an untreatable ventricular tackycardia.

  19. Idiopathic Fascicular Left Ventricular Tachycardia.

    Science.gov (United States)

    Alahmad, Yaser; Asaad, Nidal Ahmad; Arafa, Salaheddin Omran; Ahmad Khan, Shahul Hameed; Mahmoud, Alsayed

    2017-01-01

    Idiopathic left fascicular ventricular tachycardia (ILFVT) is characterized by right bundle branch block morphology and left axis deviation. We report a case of idiopathic left ventricular fascicular tachycardia in a young 31-year-old male patient presenting with a narrow complex tachycardia.

  20. Idiopathic Fascicular Left Ventricular Tachycardia

    OpenAIRE

    Alahmad, Yaser; Asaad, Nidal Ahmad; Arafa, Salaheddin Omran; Ahmad Khan, Shahul Hameed; Mahmoud, Alsayed

    2017-01-01

    Idiopathic left fascicular ventricular tachycardia (ILFVT) is characterized by right bundle branch block morphology and left axis deviation. We report a case of idiopathic left ventricular fascicular tachycardia in a young 31-year-old male patient presenting with a narrow complex tachycardia.

  1. Canadian Cardiovascular Society atrial fibrillation guidelines 2010: rate and rhythm management.

    Science.gov (United States)

    Gillis, Anne M; Verma, Atul; Talajic, Mario; Nattel, Stanley; Dorian, Paul

    2011-01-01

    The goals of atrial fibrillation (AF) and atrial flutter (AFL) arrhythmia management are to alleviate patient symptoms, improve patient quality of life, and minimize the morbidity associated with AF and AFL. Arrhythmia management usually commences with drugs to slow the ventricular rate. The addition of class I or class III antiarrhythmic drugs for restoration or maintenance of sinus rhythm is largely determined by patient symptoms and preferences. For rate control, treatment of persistent or permanent AF and AFL should aim for a resting heart rate of myocardial infarction or left ventricular dysfunction. Digoxin is not recommended as monotherapy for rate control in active patients. Digoxin and dronedarone may be used in combination with other agents to optimize rate control. The first-choice antiarrhythmic drug for maintenance of sinus rhythm in patients with non structural heart disease can be any one of dronedarone, flecainide, propafenone, or sotalol. In patients with abnormal ventricular function but left ventricular ejection fraction >35%, dronedarone, sotalol, or amiodarone is recommended. In patients with left ventricular ejection fraction <35%, amiodarone is the only drug usually recommended. Intermittent antiarrhythmic drug therapy ("pill in the pocket") may be considered in symptomatic patients with infrequent, longer-lasting episodes of AF or AFL as an alternative to daily antiarrhythmic therapy. Referral for ablation of AF may be considered for patients who remain symptomatic after adequate trials of antiarrhythmic drug therapy and in whom a rhythm control strategy remains desired. Copyright © 2011 Canadian Cardiovascular Society. Published by Elsevier Inc. All rights reserved.

  2. The control of self-propelled microjets inside a microchannel with time-varying flow rates

    NARCIS (Netherlands)

    Khalil, I.S.M.; Magdanz, Veronika; Sanchez, Samuel; Schmidt, Oliver S.; Misra, Sarthak

    We demonstrate the closed-loop motion control of self-propelled microjets inside a fluidic microchannel. The motion control of the microjets is achieved in hydrogen peroxide solution with time-varying flow rates, under the influence of the controlled magnetic fields and the self-propulsion force.

  3. Right ventricular hydatid cyst ruptured to pericardium

    Directory of Open Access Journals (Sweden)

    Feridoun Sabzi

    2015-01-01

    Full Text Available Cardiac hydatidosis is rare presentation of body hydatidosis. Incidence of cardiac involvements range from 5% to 5% of patients with hydatid disease. Most common site of hydatid cyst in heart is interventricular septum and left ventricular free wall. Right ventricular free wall involvement by cyst that ruptured to pericardial cavity is very rare presentation of hydatid cyst. Cardiac involvement may have serious consequences such as rupture to blood steam or pericardial cavity. Both the disease and its surgical treatment carry a high complication rate, including rupture leading to cardiac tamponade, anaphylaxis and also death. In the present report, a 43-year-old man with constrictive pericarditis secondary to a pericardial hydatid cyst is described.

  4. Improving arachidonic acid fermentation by Mortierella alpina through multistage temperature and aeration rate control in bioreactor.

    Science.gov (United States)

    Gao, Min-Jie; Wang, Cheng; Zheng, Zhi-Yong; Zhu, Li; Zhan, Xiao-Bei; Lin, Chi-Chung

    2016-05-18

    Effective production of arachidonic acid (ARA) using Mortierella alpina was conducted in a 30-L airlift bioreactor. Varying the aeration rate and temperature significantly influenced cell morphology, cell growth, and ARA production, while the optimal aeration rate and temperature for cell growth and product formation were quite different. As a result, a two-stage aeration rate control strategy was constructed based on monitoring of cell morphology and ARA production under various aeration rate control levels (0.6-1.8 vvm). Using this strategy, ARA yield reached 4.7 g/L, an increase of 38.2% compared with the control (constant aeration rate control at 1.0 vvm). Dynamic temperature-control strategy was implemented based on the fermentation performance at various temperatures (13-28°C), with ARA level in total cellular lipid increased by 37.1% comparing to a constant-temperature control (25°C). On that basis, the combinatorial fermentation strategy of two-stage aeration rate control and dynamic temperature control was applied and ARA production achieved the highest level of 5.8 g/L.

  5. One year of high-intensity interval training improves exercise capacity, but not left ventricular function in stable heart transplant recipients: a randomised controlled trial.

    Science.gov (United States)

    Rustad, Lene A; Nytrøen, Kari; Amundsen, Brage H; Gullestad, Lars; Aakhus, Svend

    2014-02-01

    Heart transplant recipients have lower exercise capacity and impaired cardiac function compared with the normal population. High-intensity interval training (HIIT) improves exercise capacity and cardiac function in patients with heart failure and hypertension, but the effect on cardiac function in stable heart transplant recipients is not known. Thus, we investigated whether HIIT improved cardiac function and exercise capacity in stable heart transplant recipients by use of comprehensive rest- and exercise-echocardiography and cardiopulmonary exercise testing. Fifty-two clinically stable heart transplant recipients were randomised either to HIIT (4 × 4 minutes at 85-95% of peak heart rate three times per week for eight weeks) or to control. Three such eight-week periods were distributed throughout one year. Echocardiography (rest and submaximal exercise) and cardiopulmonary exercise testing were performed at baseline and follow-up. One year of HIIT increased VO 2peak from 27.7 ± 5.5 at baseline to 30.9 ± 5.0 ml/kg/min at follow-up, while the control group remained unchanged (28.5 ± 7.0 vs. 28.0 ± 6.7 ml/kg per min, p cardiac systolic and diastolic function significantly. Thus, the observed augmentation in exercise capacity is best explained by extra-cardiac adaptive mechanisms.

  6. Improved recovery of regional left ventricular function after PCI of chronic total occlusion in STEMI patients: a cardiovascular magnetic resonance study of the randomized controlled EXPLORE trial.

    Science.gov (United States)

    Elias, Joëlle; van Dongen, Ivo M; Hoebers, Loes P; Ouweneel, Dagmar M; Claessen, Bimmer E P M; Råmunddal, Truls; Laanmets, Peep; Eriksen, Erlend; van der Schaaf, René J; Ioanes, Dan; Nijveldt, Robin; Tijssen, Jan G; Hirsch, Alexander; Henriques, José P S

    2017-07-19

    The Evaluating Xience and left ventricular function in PCI on occlusiOns afteR STEMI (EXPLORE) trial did not show a significant benefit of percutaneous coronary intervention (PCI) of the concurrent chronic total occlusion (CTO) in ST-segment elevation myocardial infarction (STEMI) patients on global left ventricular (LV) systolic function. However a possible treatment effect will be most pronounced in the CTO territory. Therefore, we aimed to study the effect of CTO PCI compared to no-CTO PCI on the recovery of regional LV function, particularly in the CTO territory. Using cardiovascular magnetic resonance (CMR) we studied 180 of the 302 EXPLORE patients with serial CMR (baseline and 4 months follow-up). Segmental wall thickening (SWT) was quantified on cine images by an independent core laboratory. Dysfunctional segments were defined as SWT < 45%. Dysfunctional segments were further analyzed by viability (transmural extent of infarction (TEI) ≤50%.). All outcomes were stratified for randomization treatment. In the dysfunctional segments in the CTO territory recovery of SWT was better after CTO PCI compared to no-CTO PCI (ΔSWT 17 ± 27% vs 11 ± 23%, p = 0.03). This recovery was most pronounced in the dysfunctional but viable segments(TEI < 50%) (ΔSWT 17 ± 27% vs 11 ± 22%, p = 0.02). Furthermore in the CTO territory, recovery of SWT was significantly better in the dysfunctional segments in patients with Rentrop grade 2-3 collaterals compared to grade 0-1 collaterals to the CTO (16 ± 26% versus 11 ± 24%, p = 0.04). CTO PCI compared with no-CTO PCI is associated with a greater recovery of regional systolic function in the CTO territory, especially in the dysfunctional but viable segments. Further research is needed to evaluate the use of CMR in selecting post-STEMI patients for CTO PCI and the effect of regional LV function recovery on clinical outcome. Trialregister.nl NTR1108 , Date registered NTR: 30-okt-2007.

  7. Compatibility of Astragalus and Salvia extract inhibits myocardial fibrosis and ventricular remodeling by regulation of protein kinase D1 protein

    Science.gov (United States)

    Mao, Bingyu; Nuan, Liu; Yang, Lei; Zeng, Xiaotao

    2015-01-01

    Aims: This study is to determine the effect of astragalus and salvia extract on the alteration of myocardium in a rat model of myocardial infarction. Methods: A total of 40 male Sprague-Dawley rats were randomly divided into the sham-operated group, the control group, the Astragalus group, the Salvia group, and the compatibility of Astragalus and Salvia and group. The cardiac functions were determined at 8 weeks after treatment. Hematoxylin-eosin staining was performed to observe the morphology and arrangement of cardiomyocytes. Masson’s trichrome staining was performed to investigate the distribution of myocardial interstitial collagen. Immunohistochemical staining was performed to determine the expression ofprotein kinase D1 in myocardial tissues. Results: In the sham-operated group, the Astragalus group, the Salvia group, and the compatibility of Astragalus and Salvia group, the left ventricular systolic pressure and the maximum rate of left ventricular pressure were significantly increased while the left ventricular end diastolic pressure were significantly decreased when compared with those in the control group (P Salvia group. Contents of collagen fibers in myocardial tissues were decreased in the compatibility of Astragalus and Salvia group (P Salvia group. Conclusions: Compatibility of Astragalus and Salvia extract may inhibit myocardial fibrosis and ventricular remodeling by regulation of protein kinase D1 protein in a rat model of myocardial infarction. PMID:26064267

  8. [Late potentials and ventricular arrhythmia].

    Science.gov (United States)

    Adamec, R; Zimmermann, M

    1986-04-01

    When electrodes are placed at the surface of the thorax, high-amplification electrocardiography (HA-ECG) combined with signal summation as a function of time provides a non-invasive method for detecting electric potentials occurring after the QRS complex of the clinical electrocardiogram. These potentials are called late, and can probably be likened to the "divided" or "fragmented" potentials recorded directly on the heart or in its ventricles near zones of ischemia, infarction or aneurysm. The prevalence of late potentials of ventricular activation (LPVA) and their association with the occurrence of ventricular arrhythmias seems well established, notably in the presence of ventricular aneurysm and anamnesis of severe ventricular arrhythmia. Some studies have shown that detection of LPVAs is of value in identifying heart patients at risk of ventricular arrhythmia or sudden death. Heart disease aside, the presence of LPVAs has been demonstrated in arrhythmogenic right ventricular dysplasia and reported in Fallot's tetralogy after complete correction. A standardization of recordings and a more precise definition of LPVAs are necessary before HA-ECG can become a routine clinical method. Further, the possibility of "beat by beat" recordings with "spatial" summation will allow detection of LPVAs which vary with time and in nature and hence provide a better understanding of the genesis of ventricular arrhythmias.

  9. The efficacy of centralized flow rate control in 802.11-based wireless mesh networks

    KAUST Repository

    Jamshaid, K.

    2013-06-13

    Commodity WiFi-based wireless mesh networks (WMNs) can be used to provide last mile Internet access. These networks exhibit extreme unfairness with backlogged traffic sources. Current solutions propose distributed source-rate control algorithms requiring link-layer or transport-layer changes on all mesh nodes. This is often infeasible in large practical deployments. In wireline networks, router-assisted rate control techniques have been proposed for use alongside end-to-end mechanisms. We wish to evaluate the feasibility of establishing similar centralized control via gateways in WMNs. In this paper, we focus on the efficacy of this control rather than the specifics of the controller design mechanism. We answer the question: Given sources that react predictably to congestion notification, can we enforce a desired rate allocation through a single centralized controller? The answer is not obvious because flows experience varying contention levels, and transmissions are scheduled by a node using imperfect local knowledge. We find that common router-assisted flow control schemes used in wired networks fail in WMNs because they assume that (1) links are independent, and (2) router queue buildups are sufficient for detecting congestion. We show that non-work-conserving, rate-based centralized scheduling can effectively enforce rate allocation. It can achieve results comparable to source rate limiting, without requiring any modifications to mesh routers or client devices. 2013 Jamshaid et al.; licensee Springer.

  10. Closed-Loop Control of Chemical Injection Rate for a Direct Nozzle Injection System

    Directory of Open Access Journals (Sweden)

    Xiang Cai

    2016-01-01

    Full Text Available To realize site-specific and variable-rate application of agricultural pesticides, accurately metering and controlling the chemical injection rate is necessary. This study presents a prototype of a direct nozzle injection system (DNIS by which chemical concentration transport lag was greatly reduced. In this system, a rapid-reacting solenoid valve (RRV was utilized for injecting chemicals, driven by a pulse-width modulation (PWM signal at 100 Hz, so with varying pulse width the chemical injection rate could be adjusted. Meanwhile, a closed-loop control strategy, proportional-integral-derivative (PID method, was applied for metering and stabilizing the chemical injection rate. In order to measure chemical flow rates and input them into the controller as a feedback in real-time, a thermodynamic flowmeter that was independent of chemical viscosity was used. Laboratory tests were conducted to assess the performance of DNIS and PID control strategy. Due to the nonlinear input–output characteristics of the RRV, a two-phase PID control process obtained better effects as compared with single PID control strategy. Test results also indicated that the set-point chemical flow rate could be achieved within less than 4 s, and the output stability was improved compared to the case without control strategy.

  11. Methane conversion efficiency as a simple control parameter for an anaerobic digester at high loading rates.

    Science.gov (United States)

    Charles, W; Carnaje, N P; Cord-Ruwisch, R

    2011-01-01

    The anaerobic digestion process is globally applied to the treatment of highly concentrated wastes such as industrial and rural effluents, and sewage sludge. However, it is known to be relatively unstable. When loaded with high concentrations of organic material, unwanted volatile fatty acids (VFA) are often produced rather than methane (CH4) gas which can lead to digester acidification and failure. This study investigated digester behaviour under high loading rates, testing the usefulness of stoichiometric methane conversion efficiency as a digester control parameter at high loading rates. Our results show that, in general, the CH4 production rate was proportional to the feed rate (loading rate). However, at very high loading rates, the CH4 production rate was not proportional to the increase in the feeding rate. Consequently, VFA accumulated and the H2 partial pressure increased. The proportionality of the loading rate and gas production rate is stoichiometrically expressed as the conversion efficiency. We found that conversion efficiency was a useful indicator as an early warning of digester imbalance. The digester remained stable at conversion efficiencies above 75%. Dropping below 70% signified the onset of digester failure. As loading rate and methane production data are readily available on-line in most anaerobic digestion plants, the conversion efficiency can be monitored on-line and used as an efficient control technique to maintain safe operation of anaerobic digesters at high loading rates.

  12. Simultaneous control of error rates in fMRI data analysis.

    Science.gov (United States)

    Kang, Hakmook; Blume, Jeffrey; Ombao, Hernando; Badre, David

    2015-12-01

    The key idea of statistical hypothesis testing is to fix, and thereby control, the Type I error (false positive) rate across samples of any size. Multiple comparisons inflate the global (family-wise) Type I error rate and the traditional solution to maintaining control of the error rate is to increase the local (comparison-wise) Type II error (false negative) rates. However, in the analysis of human brain imaging data, the number of comparisons is so large that this solution breaks down: the local Type II error rate ends up being so large that scientifically meaningful analysis is precluded. Here we propose a novel solution to this problem: allow the Type I error rate to converge to zero along with the Type II error rate. It works because when the Type I error rate per comparison is very small, the accumulation (or global) Type I error rate is also small. This solution is achieved by employing the likelihood paradigm, which uses likelihood ratios to measure the strength of evidence on a voxel-by-voxel basis. In this paper, we provide theoretical and empirical justification for a likelihood approach to the analysis of human brain imaging data. In addition, we present extensive simulations that show the likelihood approach is viable, leading to "cleaner"-looking brain maps and operational superiority (lower average error rate). Finally, we include a case study on cognitive control related activation in the prefrontal cortex of the human brain. Copyright © 2015 Elsevier Inc. All rights reserved.

  13. Prevalence, Treatment, and Control Rates of Conventional and Ambulatory Hypertension Across 10 Populations in 3 Continents

    DEFF Research Database (Denmark)

    Melgarejo, Jesus D.; Maestre, Gladys E; Thijs, Lutgarde

    2017-01-01

    and ambulatory hypertension. In conclusion, high rates of hypertension in all cohorts examined demonstrate the need for improvements in prevention, treatment, and control. Strategies for the management of hypertension should continue to not only focus on preventable and modifiable risk factors but also consider......Hypertension is a major global health problem, but prevalence rates vary widely among regions. To determine prevalence, treatment, and control rates of hypertension, we measured conventional blood pressure (BP) and 24-hour ambulatory BP in 6546 subjects, aged 40 to 79 years, recruited from 10.......2%-66.5%) for ambulatory hypertension (ambulatory BP ≥130/80 mm Hg). Treatment and control rates for conventional hypertension were 48.0% (33.5%-74.1%) and 38.6% (10.1%-55.3%) respectively. The corresponding rates for ambulatory hypertension were 48.6% (30.5%-71.9%) and 45.6% (18.6%-64.2%). Among 1677 untreated subjects...

  14. Metabolic control analysis of biochemical pathways based on a thermokinetic description of reaction rates

    DEFF Research Database (Denmark)

    Nielsen, Jens Bredal

    1997-01-01

    of the thermokinetic description of reaction rates to include the influence of effecters. Here the reaction rate is written as a linear function of the logarithm of the metabolite concentrations. With this type of rate function it is shown that the approach of Delgado and Liao [Biochem. J. (1992) 282, 919-927] can......Metabolic control analysis is a powerful technique for the evaluation of flux control within biochemical pathways. Its foundation is the elasticity coefficients and the flux control coefficients (FCCs). On the basis of a thermokinetic description of reaction rates it is here shown...... that the elasticity coefficients can be calculated directly from the pool levels of metabolites at steady state. The only requirement is that one thermodynamic parameter be known, namely the reaction affinity at the intercept of the tangent in the inflection point of the curve of reaction rate against reaction...

  15. The Power of Exercise-Induced T-wave Alternans to Predict Ventricular Arrhythmias in Patients with Implanted Cardiac Defibrillator

    Directory of Open Access Journals (Sweden)

    Laura Burattini

    2013-01-01

    Full Text Available The power of exercise-induced T-wave alternans (TWA to predict the occurrence of ventricular arrhythmias was evaluated in 67 patients with an implanted cardiac defibrillator (ICD. During the 4-year follow-up, electrocardiographic (ECG tracings were recorded in a bicycle ergometer test with increasing workload ranging from zero (NoWL to the patient's maximal capacity (MaxWL. After the follow-up, patients were classified as either ICD_Cases (n = 29, if developed ventricular tachycardia/fibrillation, or ICD_Controls (n = 38. TWA was quantified using our heart-rate adaptive match filter. Compared to NoWL, MaxWL was characterized by faster heart rates and higher TWA in both ICD_Cases (12-18 μ V vs. 20-39 μ V; P < 0.05 and ICD_Controls (9-15 μ V vs. 20-32 μ V; P < 0.05. Still, TWA was able to discriminate the two ICD groups during NoWL (sensitivity = 59-83%, specificity = 53-84% but not MaxWL (sensitivity = 55-69%, specificity = 39-74%. Thus, this retrospective observational case-control study suggests that TWA's predictive power for the occurrence of ventricular arrhythmias could increase at low heart rates.

  16. Embedded computer controlled premixing inline injection system for air-assisted variable-rate sprayers

    Science.gov (United States)

    Improvements to reduce chemical waste and environmental pollution for variable-rate sprayers used in orchards and ornamental nurseries require inline injection techniques. A microprocessor controlled premixing inline injection system implementing a ceramic piston chemical metering pump and two small...

  17. Heart rate variability during sleep in detoxified alcohol-dependent males: A comparison with healthy controls.

    Science.gov (United States)

    Ganesha, Suhas; Thirthalli, Jagadisha; Muralidharan, Kesavan; Benegal, Vivek; Gangadhar, Bangalore N

    2013-04-01

    Alcohol dependence can lead to autonomic neuropathy resulting in increased cardiac morbidity and mortality. This has previously been evaluated using heart-rate variability. We compared sleep heart-rate variability of alcohol-dependent patients with that of healthy controls in this study. This study was conducted at NIMHANS, Bangalore. A case control study design was adopted. Sleep heart-rate variability of 20 male alcohol-dependent inpatients was recorded on the 5(th) day after detoxification. Sleep heart-rate variability was also recorded in 18 age- and gender-matched healthy controls. The groups were compared using t-test for continuous variables and Chi-squared test for discrete variables. Both time and frequency domain measures were significantly lower in the patients as compared to the controls, indicating decreased HRV in alcohol-dependent individuals. Decreased HRV in alcohol dependence indicates potential autonomic neuropathy.

  18. Interactions among temperature, moisture, and oxygen concentrations in controlling decomposition rates in a boreal forest soil

    OpenAIRE

    Sierra, Carlos A.; Malghani, Saadatullah; Henry W Loescher

    2017-01-01

    Determining environmental controls on soil organic matter decomposition is of importance for developing models that predict the effects of environmental change on global soil carbon stocks. There is uncertainty about the environmental controls on decomposition rates at temperature and moisture extremes, particularly at high water content levels and high temperatures. It is uncertain whether observed declines in decomposition rates at high temperatures are due to declines ...

  19. Heart Rate Variability as a Measure of Airport Ramp-Traffic Controllers Workload

    Science.gov (United States)

    Hayashi, Miwa; Dulchinos, Victoria Lee

    2016-01-01

    Heart Rate Variability (HRV) has been reported to reflect the person's cognitive and emotional stress levels, and may offer an objective measure of human-operator's workload levels, which are recorded continuously and unobtrusively to the task performance. The present paper compares the HRV data collected during a human-in-the-loop simulation of airport ramp-traffic control operations with the controller participants' own verbal self-reporting ratings of their workload.

  20. Control of Variable Speed Variable Pitch Wind Turbine at Above and Below Rated Wind Speed

    Directory of Open Access Journals (Sweden)

    Saravanakumar Rajendran

    2014-01-01

    Full Text Available The paper presents a nonlinear approach to wind turbine (WT using two-mass model. The main aim of the controller in the WT is to maximize the energy output at varying wind speed. In this work, a combination of linear and nonlinear controllers is adapted to variable speed variable pitch wind turbines (VSVPWT system. The major operating regions of the WT are below (region 2 and above rated (region 3 wind speed. In these regions, generator torque control (region 2 and pitch control (region 3 are used. The controllers in WT are tested for below and above rated wind speed for step and vertical wind speed profile. The performances of the controllers are analyzed with nonlinear FAST (Fatigue, Aerodynamics, Structures, and Turbulence WT dynamic simulation. In this paper, two nonlinear controllers, that is, sliding mode control (SMC and integral sliding mode control (ISMC, have been applied for region 2, whereas for pitch control in region 3 conventional PI control is used. In ISMC, the sliding manifold makes use of an integral action to show effective qualities of control in terms of the control level reduction and sliding mode switching control minimization.

  1. Model Reference Adaptive Control of the Air Flow Rate of Centrifugal Compressor Using State Space Method

    Energy Technology Data Exchange (ETDEWEB)

    Han, Jaeyoung; Jung, Mooncheong; Yu, Sangseok [Chungnam Nat’l Univ., Daejeon (Korea, Republic of); Yi, Sun [North Carolina A and T State Univ., Raleigh (United States)

    2016-08-15

    In this study, a model reference adaptive controller is developed to regulate the outlet air flow rate of centrifugal compressor for automotive supercharger. The centrifugal compressor is developed using the analytical based method to predict the transient behavior of operating and the designed model is validated with experimental data to confirm the system accuracy. The model reference adaptive control structure consists of a compressor model and a MRAC(model reference adaptive control) mechanism. The feedback control do not robust with variation of system parameter but the applied adaptive control is robust even if the system parameter is changed. As a result, the MRAC was regulated to reference air flow rate. Also MRAC was found to be more robust control compared with the feedback control even if the system parameter is changed.

  2. [Significance of Tp-Te interval for risk stratification of ventricular premature contractions in children].

    Science.gov (United States)

    Wei, Li; Lu, Yong-Yi; Qiao, Li-Na; Hua, Yi-Min; Wang, Yi-Bin; Wang, Xiao; Li, Xin-Hui

    2013-11-01

    To investigate the significance of Tp-Te interval for risk stratification of ventricular premature contractions (VPC) in children. A total of 120 children with VPC were divided into benign VPC (n=40), organic disease (n=40) and ventricular parasystole groups (n=40) according to the etiology of VPC; another 40 children who underwent physical examination were selected as the normal control group. The four groups were compared in terms of Tp-Te intervals and Tp-Te/QT ratios in leads V3, V4 and V5. The Tp-Te interval in lead V3 was significantly longer in the organic disease group than in the other groups (PTe interval in lead V4 than the normal control and organic disease groups (PTe interval in lead V5 than the benign VPC group (PTe/QT ratios in leads V3-V5 were significantly higher in the organic disease group than in the other groups (PTe/QT ratios in leads V4 and V5 showed significant differences between the ventricular parasystole and benign VPC groups (PTe interval is susceptible to changes in heart rate, and it is of little value for the risk stratification of VPC in children. Tp-Te/QT ratio, however, may be used as an important non-invasive index for clinical risk stratification of VPC in children and is worthy of further study.

  3. Systolic left ventricular function according to left ventricular concentricity and dilatation in hypertensive patients

    DEFF Research Database (Denmark)

    Bang, Casper; Gerdts, Eva; Aurigemma, Gerard P

    2013-01-01

    Left ventricular hypertrophy [LVH, high left ventricular mass (LVM)] is traditionally classified as concentric or eccentric based on left ventricular relative wall thickness. We evaluated left ventricular systolic function in a new four-group LVH classification based on left ventricular dilatatio...

  4. Heritability of cardiac vagal control in 24-h heart rate variability recordings: influence of ceiling effects at low heart rates.

    Science.gov (United States)

    Neijts, Melanie; Van Lien, Rene; Kupper, Nina; Boomsma, Dorret; Willemsen, Gonneke; de Geus, Eco J C

    2014-10-01

    This study estimated the heritability of 24-h heart rate variability (HRV) measures, while considering ceiling effects on HRV at low heart rates during the night. HRV was indexed by the standard deviation of all valid interbeat intervals (SDNN), the root mean square of differences between valid, successive interbeat intervals (RMSSD), and peak-valley respiratory sinus arrhythmia (pvRSA). Sleep and waking levels of cardiac vagal control were assessed in 1,003 twins and 285 of their non-twin siblings. Comparable heritability estimates were found for SDNN (46%-53%), RMSSD (49%-54%), and pvRSA (48%-57%) during the day and night. A nighttime ceiling effect was revealed in 10.7% of participants by a quadratic relationship between mean pvRSA and the interbeat interval. Excluding these participants did not change the heritability estimates. The genetic factors influencing ambulatory pvRSA, RMSSD, and SDNN largely overlap. These results suggest that gene-finding studies may pool the different cardiac vagal indices and that exclusion of participants with low heart rates is not required. Copyright © 2014 Society for Psychophysiological Research.

  5. Control of skin blood flow, sweating, and heart rate - Role of skin vs. core temperature

    Science.gov (United States)

    Wyss, C. R.; Brengelmann, G. L.; Johnson, J. M.; Rowell, L. B.; Niederberger, M.

    1974-01-01

    A study was conducted to generate quantitative expressions for the influence of core temperature, skin temperature, and the rate of change of skin temperature on sweat rate, skin blood flow, and heart rate. A second goal of the study was to determine whether the use of esophageal temperature rather than the right atrial temperature as a measure of core temperature would lead to different conclusions about the control of measured effector variables.

  6. Efeitos hemodinâmicos da sobrecarga ventricular direita aguda experimental Efectos hemodinámicos de la sobrecarga ventricular derecha aguda experimental Hemodynamic effects of experimental acute right ventricular overload

    Directory of Open Access Journals (Sweden)

    Flávio Brito Filho

    2011-04-01

    Full Text Available FUNDAMENTO: A sobrecarga ventricular direita aguda está associada a situações clínicas de elevada morbimortalidade, tais como: ressecções pulmonares extensas, tromboembolismo pulmonar, transplante pulmonar e edema pulmonar das altitudes. Alguns pontos de sua fisiopatologia permanecem obscuros. OBJETIVO: Avaliar os efeitos hemodinâmicos da sobrecarga ventricular direita aguda experimental em suínos. MÉTODOS: A sobrecarga ventricular direita foi induzida pela oclusão das artérias pulmonares através de ligaduras. Vinte porcos foram utilizados no estudo, sendo alocados em 04 grupos: um controle, não submetido à oclusão vascular pulmonar, e três de sobrecarga ventricular direita submetidos à oclusão das seguintes artérias pulmonares: SVD1 (artéria pulmonar esquerda; SVD2 (artéria pulmonar esquerda e do lobo inferior direito e SVD3 (artéria pulmonar esquerda, do lobo inferior direito e do lobo mediastinal, obstruindo a vasculatura pulmonar em 42, 76 e 82,0% respectivamente. Variáveis de hemodinâmica foram medidas a cada 15 minutos durante a uma hora do estudo. Na análise estatística, foram utilizados ajustes de modelos lineares mistos com estrutura de variâncias e covariâncias. RESULTADOS: Nas comparações intergrupais, houve aumento significativo da frequência cardíaca (p = 0,004, pressão arterial pulmonar média (p = 0,001 e pressão capilar pulmonar (p FUNDAMENTO: La sobrecarga ventricular derecha aguda está asociada a situaciones clínicas de elevada morbimortalidad, tales como: resecciones pulmonares extensas, tromboembolismo pulmonar, transplante pulmonar y edema pulmonar de las alturas. Algunos puntos de su fisiopatología permanecen obscuros. OBJETIVO:Evaluar los efectos hemodinámicos de la sobrecarga ventricular derecha aguda experimental en porcinos. MÉTODOS:La sobrecarga ventricular derecha fue inducida por la oclusión de las arterias pulmonares a través de ligaduras. Veinte cerdos fueron utilizados en

  7. Case-control study of blink rate in Parkinson's disease under different conditions.

    Science.gov (United States)

    Fitzpatrick, Emily; Hohl, Norman; Silburn, Peter; O'Gorman, Cullen; Broadley, Simon A

    2012-04-01

    Standard neurology texts list a reduced blink rate as one of the clinical features of Parkinson's disease. However, there are few clinical studies which have quantified this clinical sign. Here we present the results of a quantified study in a cohort of cases and controls using a standard protocol. Cases meeting standard criteria for a diagnosis of Parkinson's disease were studied together with age- and sex-matched controls. Baseline data included age, sex, duration of disease, Hoehn and Yahr stage, mini-mental state examination and treatment. Subjects were videoed undertaking three different tasks: being interviewed, watching a video, and reading from a book. Blink rates were calculated as a mean 'per minute' figure for each of the three tasks. A meta-analysis of previous studies of blink rate was undertaken. A total of 20 cases and 41 controls were studied. A decline in blink rate with increasing age was seen for cases but not controls. A significant reduction in blink rate was seen in cases when compared with controls for each of the test conditions. Blink rates were highest in subjects when being interviewed and were lowest whilst reading a passage in both cases and controls. No effect of disease duration, severity or treatment was observed. We have quantified the reduction in blink rate which has long been recognised as a feature of Parkinson's disease. We have identified factors which determine blink rate within individuals. We have also been able to define normal and abnormal levels for blink rate which may be of value clinically and for future research.

  8. [Ventricular tachycardia and cardiac hemochromatosis].

    Science.gov (United States)

    Luis Moríñigo, J; Martín Luengo, C; Ledesma, C; Arribas, A; Nieto, A A; Rodríguez, J

    2001-11-01

    Hemochromatosis is characterized by an excessive iron deposit in different tissues. Cardiac involvement may be observed in one third of the patients due to hemochromatosis and occurs as a consequence of ferritin accumulation in the heart which on one hand induces alterations in systolic and diastolic ventricular function and on the other hand, an arrythmogenic substrate. The clinical manifestations can be indistinctly related to atrial tachyarrhythmia, ventricular tachyarrhythmia, atrio-ventricular blockade and congestive heart failure, with the first being the most frequent. We present the case of one patient with secondary hemochromatosis to repeated transfusions due to sideroblastic anemia with cardiac involvement, whose initial heart manifestations were recurrent atrial tachyarrhythmia and sustained ventricular tachycardia with syncope for which an automatic defibrillator was implanted.

  9. Packetized Predictive Control for Rate-Limited Networks via Sparse Representation

    DEFF Research Database (Denmark)

    Nagahara, Masaaki; Quevedo, Daniel; Østergaard, Jan

    2012-01-01

    controller and the plant input. To achieve robustness with respect to dropouts, the controller transmits data packets containing plant input predictions, which minimize a finite horizon cost function. In our formulation, we design sparse packets for rate-limited networks, by adopting an an ℓ0 optimization...

  10. Determinants of left ventricular mass in obesity; a cardiovascular magnetic resonance study

    Directory of Open Access Journals (Sweden)

    Clarke Kieran

    2009-04-01

    Full Text Available Abstract Background Obesity is linked to increased left ventricular mass, an independent predictor of mortality. As a result of this, understanding the determinants of left ventricular mass in the setting of obesity has both therapeutic and prognostic implications. Using cardiovascular magnetic resonance our goal was to elucidate the main predictors of left ventricular mass in severely obese subjects free of additional cardiovascular risk factors. Methods 38 obese (BMI 37.8 ± 6.9 kg/m2 and 16 normal weight controls subjects, (BMI 21.7 ± 1.8 kg/m2, all without cardiovascular risk factors, underwent cardiovascular magnetic resonance imaging to assess left ventricular mass, left ventricular volumes and visceral fat mass. Left ventricular mass was then compared to serum and anthropometric markers of obesity linked to left ventricular mass, i.e. height, age, blood pressure, total fat mass, visceral fat mass, lean mass, serum leptin and fasting insulin level. Results As expected, obesity was associated with significantly increased left ventricular mass (126 ± 27 vs 90 ± 20 g; p 2 = 0.77. Conclusion The left ventricular hypertrophic response to obesity in the absence of additional cardiovascular risk factors is mainly attributable to increases in lean body mass, LV stroke volume and visceral fat mass. In view of the well documented link between obesity, left ventricular hypertrophy and mortality, these findings have potentially important prognostic and therapeutic implications for primary and secondary prevention.

  11. Right ventricular remodeling in restrictive ventricular septal defect

    Science.gov (United States)

    Monreal, Gretel; Youtz, Dane J.; Phillips, Alistair B.; Eyman, Mahala E.; Gorr, Matthew W.; Velten, Christina; Lucchesi, Pamela A.; Wold, Loren E.; Gerhardt, Mark A.

    2014-01-01

    Restrictive ventricular septal defect (rVSD) presents with little/no hemodynamic aberrations despite a patent septal defect. Clinically, these patients are observed with the hope that the defect will functionally close over time without the need for surgical repair and development of heart failure. Without evidence supporting a definitive therapeutic strategy, rVSD patients may have increased risk of a poor outcome. We tested the hypothesis that rVSD results in subclinical RV diastolic dysfunction and molecular remodeling. Five pigs underwent surgical rVSD creation. Echocardiography, hemodynamics, myocyte contractility experiments, and proteomics/Western blot were performed 6-weeks post-rVSD and in controls. *p < 0.05. LV and RV hemodynamics in rVSD were comparable to controls. The tricuspid valve early/late diastolic inflow velocity ratio (TV E/A ratio) decreased from 1.6 ± 0.05 in controls to 1.0 ± 0.08* in rVSD, indicating RV diastolic dysfunction. rVSD RV myocytes showed abnormalities in contraction (departure velocity (Vd) − 51%*, Vd time +55%*) and relaxation (return velocity (Vr) −50%*, Vr time +62%*). Mitochondrial proteins (fatty acid, TCA cycle) increased 2-fold*, indicating heightened RV work. Desmin protein upregulated 285%* in rVSD RV myocardium, suggesting cytoskeletal remodeling. rVSD causes RV diastolic dysfunction, myocyte functional impairment, and mitochondrial/cytoskeletal protein upregulation in our model. Desmin upregulation may hinder sarcomeric organization/relaxation, representing a key subclinical early marker for future RV dysfunction. TV E/A measurements are a non-invasive modality to assess rVSD patients for diastolic dysfunction. Translational research applications may lead to fundamental changes in the clinical management of rVSD by providing evidence for early repair of the defect. PMID:20637777

  12. Nonlinear dynamics in ventricular fibrillation.

    Science.gov (United States)

    Hastings, H M; Evans, S J; Quan, W; Chong, M L; Nwasokwa, O

    1996-09-17

    Electrogram recordings of ventricular fibrillation appear complex and possibly chaotic. However, sequences of beat-to-beat intervals obtained from these recordings are generally short, making it difficult to explicitly demonstrate nonlinear dynamics. Motivated by the work of Sugihara on atmospheric dynamics and the Durbin-Watson test for nonlinearity, we introduce a new statistical test that recovers significant dynamical patterns from smoothed lag plots. This test is used to show highly significant nonlinear dynamics in a stable canine model of ventricular fibrillation.

  13. Distinguishing between overdrive excited and suppressed ventricular beats in guinea pig ventricular myocardium

    Directory of Open Access Journals (Sweden)

    Amara eGreer-Short

    2015-02-01

    Full Text Available Rapid ventricular pacing rates induces two types of beats following pacing cessation: recovery cycle length (RCL prolongation (overdrive suppression and RCL shortening (overdrive excitation. The goals of this study were to compare common experimental protocols for studying triggered activity in whole-heart preparations and differentiate between recovery beats using a new methodology. Post-pacing recovery beat cycle length (RCL and QRS were normalized to pre-paced R-R and QRS intervals and analyzed using a K-means clustering algorithm. Control hearts only produced suppressed beats: RCL ratio increased with rapid pacing (25±4.0%, n=10 without changing QRS duration. Rapid pacing during hypercalcemia + hypothermia (5.5 mM and 34°C produced significantly earlier excited beats (53±14%, n=5 with wider QRS durations (58±6.3%, n=5 than suppressed beats. Digoxin + hypothermia (0.75 M produced the most excited beats with significantly earlier RCL (44±3.2%, n=6 and wider QRS (60±3.1%, n=6 ratios relative to suppressed beats. Increasing pacing further shortened RCL (30±7.8%, n=6. In a prospective study, TTX (100 nM increased RCL ratio (15±6.0%, n=10 without changing the QRS duration of excited beats. The algorithm was compared to a cross-correlation analysis with 93% sensitivity and 94% specificity. This ECG based algorithm distinguishes between triggered and automatic activity.

  14. Effect of control activity on blade fatigue damage rate for a small horizontal axis wind turbine

    Energy Technology Data Exchange (ETDEWEB)

    Riddle, A.F.; Freris, L.L.; Graham, J.M.R. [Imperial College, London (United Kingdom)

    1996-09-01

    An experiment into the effect of control activity on blade fatigue damage rate for a 5 kW, two bladed, teetered HAWT has been performed. It has been shown that control activity influences the distribution of strain in the blade but that in a high rotor speed, high cycle fatigue regime this has little influence on damage rate. The experiment was conducted on a small test turbine by implementing variable speed stall, pitch and yaw control strategies and measuring blade flapwise strain response at root and midspan locations. A full description of the investigation is provided. (au)

  15. Dynamic neural networking as a basis for plasticity in the control of heart rate.

    Science.gov (United States)

    Kember, G; Armour, J A; Zamir, M

    2013-01-21

    A model is proposed in which the relationship between individual neurons within a neural network is dynamically changing to the effect of providing a measure of "plasticity" in the control of heart rate. The neural network on which the model is based consists of three populations of neurons residing in the central nervous system, the intrathoracic extracardiac nervous system, and the intrinsic cardiac nervous system. This hierarchy of neural centers is used to challenge the classical view that the control of heart rate, a key clinical index, resides entirely in central neuronal command (spinal cord, medulla oblongata, and higher centers). Our results indicate that dynamic networking allows for the possibility of an interplay among the three populations of neurons to the effect of altering the order of control of heart rate among them. This interplay among the three levels of control allows for different neural pathways for the control of heart rate to emerge under different blood flow demands or disease conditions and, as such, it has significant clinical implications because current understanding and treatment of heart rate anomalies are based largely on a single level of control and on neurons acting in unison as a single entity rather than individually within a (plastically) interconnected network. Copyright © 2012 Elsevier Ltd. All rights reserved.

  16. Optimal control of vaccination rate in an epidemiological model of Clostridium difficile transmission.

    Science.gov (United States)

    Stephenson, Brittany; Lanzas, Cristina; Lenhart, Suzanne; Day, Judy

    2017-12-01

    The spore-forming, gram-negative bacteria Clostridium difficile can cause severe intestinal illness. A striking increase in the number of cases of C. difficile infection (CDI) among hospitals has highlighted the need to better understand how to prevent the spread of CDI. In our paper, we modify and update a compartmental model of nosocomial C. difficile transmission to include vaccination. We then apply optimal control theory to determine the time-varying optimal vaccination rate that minimizes a combination of disease prevalence and spread in the hospital population as well as cost, in terms of time and money, associated with vaccination. Various hospital scenarios are considered, such as times of increased antibiotic prescription rate and times of outbreak, to see how such scenarios modify the optimal vaccination rate. By comparing the values of the objective functional with constant vaccination rates to those with time-varying optimal vaccination rates, we illustrate the benefits of time-varying controls.

  17. Ventricular arrhythmias in Chagas disease

    Directory of Open Access Journals (Sweden)

    Marco Paulo Tomaz Barbosa

    2015-02-01

    Full Text Available Sudden death is one of the most characteristic phenomena of Chagas disease, and approximately one-third of infected patients develop life-threatening heart disease, including malignant ventricular arrhythmias. Fibrotic lesions secondary to chronic cardiomyopathy produce arrhythmogenic substrates that lead to the appearance and maintenance of ventricular arrhythmias. The objective of this study is to discuss the main clinical and epidemiological aspects of ventricular arrhythmias in Chagas disease, the specific workups and treatments for these abnormalities, and the breakthroughs needed to determine a more effective approach to these arrhythmias. A literature review was performed via a search of the PubMed database from 1965 to May 31, 2014 for studies of patients with Chagas disease. Clinical management of patients with chronic Chagas disease begins with proper clinical stratification and the identification of individuals at a higher risk of sudden cardiac death. Once a patient develops malignant ventricular arrhythmia, the therapeutic approach aims to prevent the recurrence of arrhythmias and sudden cardiac death by the use of implantable cardioverter defibrillators, antiarrhythmic drugs, or both. In select cases, invasive ablation of the reentrant circuit causing tachycardia may be useful. Ventricular arrhythmias are important manifestations of Chagas cardiomyopathy. This review highlights the absence of high-quality evidence regarding the treatment of ventricular arrhythmias in Chagas disease. Recognizing high-risk patients who require specific therapies, especially invasive procedures such as the implantation of cardioverter defibrillators and ablative approaches, is a major challenge in clinical practice.

  18. Decentralized control of transmission rates in energy-critical wireless networks

    KAUST Repository

    Xia, Li

    2013-06-01

    In this paper, we discuss the decentralized optimization of delay and energy consumption in a multi-hop wireless network. The goal is to minimize the energy consumption of energy-critical nodes and the overall packet transmission delay of the network. The transmission rates of energy-critical nodes are adjustable according to the local information of nodes, i.e., the length of packets queued. The multi-hop network is modeled as a queueing network.We prove that the system performance is monotone w.r.t. (with respect to) the transmission rate, thus the “bang-bang” control is an optimal control. We also prove that there exists a threshold type control policy which is optimal. We propose a decentralized algorithm to control transmission rates of these energy-critical nodes. Some simulation experiments are conducted to demonstrate the effectiveness of our approach.

  19. Relation of right ventricular mechanics to exercise tolerance in children after tetralogy of Fallot repair.

    Science.gov (United States)

    Friedberg, Mark K; Fernandes, Fernanda P; Roche, Susan L; Slorach, Cameron; Grosse-Wortmann, Lars; Manlhiot, Cedric; Fackoury, Cheryl; McCrindle, Brian W; Mertens, Luc; Kantor, Paul F

    2013-04-01

    Progressive right ventricular (RV) dysfunction and exercise intolerance are common problems after tetralogy of Fallot (TOF) repair. We investigated RV myocardial deformation and dyssynchrony in children after TOF repair and their association with exercise capacity. Asymptomatic children after TOF repair were investigated by 2-dimensional speckle tracking echocardiography, magnetic resonance, and metabolic exercise study. Patients with RV outflow obstruction were excluded. Peak RV longitudinal strain and strain rate (SR) and dyssynchrony (RV intraventricular delay) were compared with healthy controls. Associations between RV strain, dyssynchrony, and exercise capacity were analyzed. Thirty-nine (81%) of 48 TOF patients and 40 healthy controls had adequate RV strain imaging. The TOF patients had moderately dilated RVs and normal RV ejection fraction. Right ventricular peak systolic strain (-23.2% ± 5.1% vs -28.5% ± 8.5%, P Right ventricular intraventricular delay was higher in TOF patients (146.0 ± 159 vs 71.0 ± 92 milliseconds, P = .008). Decreased RV strain and SR were associated with increased RV dyssynchrony (strain parameter estimate [PE] 6.31 [2.30], P = .007; SR [PE] 11.32 [3.84], P = .004). Increased RV-left ventricular delay was associated with prolonged QRS duration (PE 0.13 [0.058], P = .03) and reduced RV ejection fraction (PE -2.95 [1.275], P = .02). Reduced RV peak SR was associated with decreased exercise peak oxygen uptake (PE 0.14 [0.07], P = .04). After repair of TOF, asymptomatic children have reduced RV deformation in association with RV dyssynchrony and reduced exercise tolerance. Copyright © 2013 Mosby, Inc. All rights reserved.

  20. Left ventricular noncompaction.

    Science.gov (United States)

    Ichida, Fukiko

    2009-01-01

    Left ventricular noncompaction (LVNC) is a recently defined cardiomyopathy characterized by a pattern of prominent trabecular meshwork and deep intertrabecular recesses, and is thought to be caused by arrest of normal endomyocardial morphogenesis. Although LVNC has been classified as a primary cardiomyopathy of genetic origin, its definition and diagnostic criteria are still being debated. Isolated LVNC was thought to be rare; however, heightened awareness has resulted in an increased detection of the morphological features of LVNC in routine clinical practice, especially in the adult population. Clinical manifestations are highly variable, ranging from no symptoms to disabling congestive heart failure, arrhythmias, and systemic thromboemboli. LVNC, like other forms of inherited cardiomyopathy, is genetically heterogeneous and can be inherited as an autosomal-dominant or X-linked recessive disorder. It has been linked to mutations in several genes, including LIM domain binding protein 3 (ZASP), alpha-dystrobrevin (DTNA), tafazzin (TAZ/G4.5) and those encoding sarcomeric proteins. However, the relatively small contribution of known mutations to the disease, compared with the higher proportion of familial cases suggests that other elusive genes remain to be identified.

  1. Soybean oil increases SERCA2a expression and left ventricular contractility in rats without change in arterial blood pressure

    Directory of Open Access Journals (Sweden)

    Vassallo Dalton

    2010-05-01

    Full Text Available Abstract Background Our aim was to evaluate the effects of soybean oil treatment for 15 days on arterial and ventricular pressure, myocardial mechanics and proteins involved in calcium handling. Methods Wistar rats were divided in two groups receiving 100 μL of soybean oil (SB or saline (CT i.m. for 15 days. Ventricular performance was analyzed in male 12-weeks old Wistar rats by measuring left ventricle diastolic and systolic pressure in isolated perfused hearts according to the Langendorff technique. Protein expression was measured by Western blot analysis. Results Systolic and diastolic arterial pressures did not differ between CT and SB rats. However, heart rate was reduced in the SB group. In the perfused hearts, left ventricular isovolumetric systolic pressure was higher in the SB hearts. The inotropic response to extracellular Ca2+ and isoproterenol was higher in the soybean-treated animals than in the control group. Myosin ATPase and Na+-K+ATPase activities, the expression of sarcoplasmic reticulum calcium pump (SERCA2a and sodium calcium exchanger (NCX were increased in the SB group. Although the phosfolamban (PLB expression did not change, its phosphorylation at Ser16 was reduced while the SERCA2a/PLB ratio was increased. Conclusions In summary, soybean treatment for 15 days in rats increases the left ventricular performance without affecting arterial blood pressure. These changes might be associated with an increase in the myosin ATPase activity and SERCA2a expression.

  2. Epicardial radiofrequency ablation for left ventricular aneurysm related ventricular arrhythmias during off-pump coronary artery bypass surgery.

    Science.gov (United States)

    Yu, Yang; Gao, Ming-Xin; Li, Hai-Tao; Zhang, Fan; Gu, Cheng-Xiong

    2012-11-01

    Left ventricular aneurysm (LVA) is one of the serious complications after acute myocardial infarction. We attempted to evaluate the preliminary efficacy of LVA repair combined with epicardial radiofrequency ablation for ventricular arrhythmia during off-pump coronary artery bypass grafting (OPCAB). From June 2009 to April 2011, 31 patients with LVA had angina symptoms and ventricular arrhythmia. In all patients, circular and cross-shaped radiofrequency epicardial ablations were performed using unipolar ablation pen along the border between the aneurysm wall and normal cardiac tissue and in the central zone of the aneurysms, followed by a linear placation of ventricular aneurysms on beating heart. All the patients showed complete recovery. The average number of grafted vessels was 2.7 ± 1.3. Intraoperative examinations revealed that the ventricular arrhythmia was effectively controlled by radiofrequency ablation. All cases had been followed up for one year. Holter monitoring revealed a significant reduction in ventricular arrhythmias (P aneurysm and preoperative malignant arrhythmia, aneurysm repair plus epicardial radiofrequency ablation in OPCAB was found to be an effective and feasible therapeutic technique. However, medium- to long-term therapeutic efficacy of this method remains to be determined by future studies and observations.

  3. The overloaded right heart and ventricular interdependence.

    Science.gov (United States)

    Naeije, Robert; Badagliacca, Roberto

    2017-10-01

    The right and the left ventricle are interdependent as both structures are nested within the pericardium, have the septum in common and are encircled with common myocardial fibres. Therefore, right ventricular volume or pressure overloading affects left ventricular function, and this in turn may affect the right ventricle. In normal subjects at rest, right ventricular function has negligible interaction with left ventricular function. However, the right ventricle contributes significantly to the normal cardiac output response to exercise. In patients with right ventricular volume overload without pulmonary hypertension, left ventricular diastolic compliance is decreased and ejection fraction depressed but without intrinsic alteration in contractility. In patients with right ventricular pressure overload, left ventricular compliance is decreased with initial preservation of left ventricular ejection fraction, but with eventual left ventricular atrophic remodelling and altered systolic function. Breathing affects ventricular interdependence, in healthy subjects during exercise and in patients with lung diseases and altered respiratory system mechanics. Inspiration increases right ventricular volumes and decreases left ventricular volumes. Expiration decreases both right and left ventricular volumes. The presence of an intact pericardium enhances ventricular diastolic interdependence but has negligible effect on ventricular systolic interdependence. On the other hand, systolic interdependence is enhanced by a stiff right ventricular free wall, and decreased by a stiff septum. Recent imaging studies have shown that both diastolic and systolic ventricular interactions are negatively affected by right ventricular regional inhomogeneity and prolongation of contraction, which occur along with an increase in pulmonary artery pressure. The clinical relevance of these observations is being explored. Published on behalf of the European Society of Cardiology. All rights

  4. Growth rate and resource imbalance interactively control biomass stoichiometry and elemental quotas of aquatic bacteria.

    Science.gov (United States)

    Godwin, Casey M; Whitaker, Emily A; Cotner, James B

    2017-03-01

    The effects of resource stoichiometry and growth rate on the elemental composition of biomass have been examined in a wide variety of organisms, but the interaction among these effects is often overlooked. To determine how growth rate and resource imbalance affect bacterial carbon (C): nitrogen (N): phosphorus (P) stoichiometry and elemental content, we cultured two strains of aquatic heterotrophic bacteria in chemostats at a range of dilution rates and P supply levels (C:P of 100:1 to 10,000:1). When growing below 50% of their maximum growth rate, P availability and dilution rate had strong interactive effects on biomass C:N:P, elemental quotas, cell size, respiration rate, and growth efficiency. In contrast, at faster growth rates, biomass stoichiometry was strongly homeostatic in both strains (C:N:P of 70:13:1 and 73:14:1) and elemental quotas of C, N, and P were tightly coupled (but not constant). Respiration and cell size increased with both growth rate and P limitation, and P limitation induced C accumulation and excess respiration. These results show that bacterial biomass stoichiometry is relatively constrained when all resources are abundant and growth rates are high, but at low growth rates resource imbalance is relatively more important than growth rate in controlling bacterial biomass composition. © 2016 by the Ecological Society of America.

  5. Optimized ventricular restraint therapy: adjustable restraint is superior to standard restraint in an ovine model of ischemic cardiomyopathy.

    Science.gov (United States)

    Lee, Lawrence S; Ghanta, Ravi K; Mokashi, Suyog A; Coelho-Filho, Otavio; Kwong, Raymond Y; Kwon, Michael; Guan, Jian; Liao, Ronglih; Chen, Frederick Y

    2013-03-01

    The effects of ventricular restraint level on left ventricular reverse remodeling are not known. We hypothesized that restraint level affects the degree of reverse remodeling and that restraint applied in an adjustable manner is superior to standard, nonadjustable restraint. This study was performed in 2 parts using a model of chronic heart failure in the sheep. In part I, restraint was applied at control (0 mm Hg, n = 3), low (1.5 mm Hg, n = 3), and high (3.0 mm Hg, n = 3) levels with an adjustable and measurable ventricular restraint (AMVR) device. Restraint level was not altered throughout the 2-month treatment period. Serial restraint level measurements and transthoracic echocardiography were performed. In part II, restraint was applied with the AMVR device set at 3.0 mm Hg (n = 6) and adjusted periodically to maintain that level. This was compared with restraint applied in a standard, nonadjustable manner using a mesh wrap (n = 6). All subjects were followed up for 2 months with serial magnetic resonance imaging. In part I, there was greater and earlier reverse remodeling in the high restraint group. In both groups, the rate of reverse remodeling peaked and then declined as the measured restraint level decreased with progression of reverse remodeling. In part II, adjustable restraint resulted in greater reverse remodeling than standard restraint. Left ventricular end diastolic volume decreased by 12.7% (P = .005) with adjustable restraint and by 5.7% (P = .032) with standard restraint. Left ventricular ejection fraction increased by 18.9% (P = .014) and 14.4% (P standard restraint, respectively. Restraint level affects the rate and degree of reverse remodeling and is an important determinant of therapy efficacy. Adjustable restraint is more effective than nonadjustable restraint in promoting reverse remodeling. Copyright © 2013 The American Association for Thoracic Surgery. Published by Mosby, Inc. All rights reserved.

  6. Optimized ventricular restraint therapy: Adjustable restraint is superior to standard restraint in an ovine model of ischemic cardiomyopathy

    Science.gov (United States)

    Lee, Lawrence S.; Ghanta, Ravi K.; Mokashi, Suyog A.; Coelho-Filho, Otavio; Kwong, Raymond Y.; Kwon, Michael; Guan, Jian; Liao, Ronglih; Chen, Frederick Y.

    2014-01-01

    Objective The effects of ventricular restraint level on left ventricular reverse remodeling are not known. We hypothesized that restraint level affects the degree of reverse remodeling and that restraint applied in an adjustable manner is superior to standard, nonadjustable restraint. Methods This study was performed in 2 parts using a model of chronic heart failure in the sheep. In part I, restraint was applied at control (0 mm Hg, n = 3), low (1.5 mm Hg, n = 3), and high (3.0 mm Hg, n = 3) levels with an adjustable and measurable ventricular restraint (AMVR) device. Restraint level was not altered throughout the 2-month treatment period. Serial restraint level measurements and transthoracic echocardiography were performed. In part II, restraint was applied with the AMVR device set at 3.0 mm Hg (n = 6) and adjusted periodically to maintain that level. This was compared with restraint applied in a standard, nonadjustable manner using a mesh wrap (n = 6). All subjects were followed up for 2 months with serial magnetic resonance imaging. Results In part I, there was greater and earlier reverse remodeling in the high restraint group. In both groups, the rate of reverse remodeling peaked and then declined as the measured restraint level decreased with progression of reverse remodeling. In part II, adjustable restraint resulted in greater reverse remodeling than standard restraint. Left ventricular end diastolic volume decreased by 12.7% (P = .005) with adjustable restraint and by 5.7% (P = .032) with standard restraint. Left ventricular ejection fraction increased by 18.9% (P = .014) and 14.4% (Prestraint, respectively. Conclusions Restraint level affects the rate and degree of reverse remodeling and is an important determinant of therapy efficacy. Adjustable restraint is more effective than nonadjustable restraint in promoting reverse remodeling. PMID:22698557

  7. Effects of Yoga on Heart Rate Variability and Mood in Women: A Randomized Controlled Trial.

    Science.gov (United States)

    Chu, I-Hua; Lin, Yuh-Jen; Wu, Wen-Lan; Chang, Yu-Kai; Lin, I-Mei

    2015-12-01

    To examine the effects of an 8-week yoga program on heart rate variability and mood in generally healthy women. Randomized controlled trial. Fifty-two healthy women were randomly assigned to a yoga group or a control group. Participants in the yoga group completed an 8-week yoga program, which comprised a 60-minute session twice a week. Each session consisted of breathing exercises, yoga pose practice, and supine meditation/relaxation. The control group was instructed not to engage in any yoga practice and to maintain their usual level of physical activity during the study. Participants' heart rate variability, perceived stress, depressive symptoms, and state and trait anxiety were assessed at baseline (week 0) and after the intervention (week 9). No measures of heart rate variability changed significantly in either the yoga or control group after intervention. State anxiety was reduced significantly in the yoga group but not in the control group. No significant changes were noted in perceived stress, depression, or trait anxiety in either group. An 8-week yoga program was not sufficient to improve heart rate variability. However, such a program appears to be effective in reducing state anxiety in generally healthy women. Future research should involve longer periods of yoga training, include heart rate variability measures both at rest and during yoga practice, and enroll women with higher levels of stress and trait anxiety.

  8. Stroke prophylaxis in high-risk patients with atrial fibrillation: rhythm vs. rate control strategy.

    Science.gov (United States)

    Filippi, Alessandro; Zoni-Berisso, Massimo; Ermini, Giuliano; Landolina, Maurizio; Brignoli, Ovidio; D'Ambrosio, Gaetano; Zingarini, Gianluca; Pedrinazzi, Claudio

    2013-06-01

    "Rhythm" and "Rate" control strategies require partially different organization, and a different involvement of Specialists and General Practitioners; we verified whether the strategy assignment modified the approach to stroke prophylaxis. Survey in general practice: 233 GPs identified all patients with codified atrial fibrillation (AF) diagnosis, checked the diagnosis (ECG/hospital discharge document), and filled a structured questionnaire on stroke risk-factors, prophylactic therapy, and reasons for warfarin non prescription in CHADS ≥2 patients. Data were collected as an "aggregate." Population observed: 295,906 patients aged >14; 6,036 with confirmed AF; 5,888 with complete data about anti-thrombotic prophylaxis are analyzed here. In the "rhythm strategy" group 45.6% of the CHADS score ≥2 patients (594) were on warfarin, vs. 73.2% (1,741) in the "rate strategy" group (pcontrol vs. 30.9% in rate control group. Anti-thrombotic prophylaxis in CHADS ≥2 patients is different in subjects assigned to the Rhythm vs. the Rate control strategy, as well as reported reasons for warfarin non use. GPs do not know why warfarin is not used in a large percentage of cases, mainly in the rhythm control strategy group. Improving efforts should probably be differently tailored for patients assigned to the "rhythm" or the "rate" control strategy. Copyright © 2013 European Federation of Internal Medicine. Published by Elsevier B.V. All rights reserved.

  9. The use of quality control performance charts to analyze cesarean delivery rates nationally.

    LENUS (Irish Health Repository)

    Turner, Michael J

    2012-02-01

    OBJECTIVE: To examine the use of quality control performance charts to analyze cesarean rates nationally. METHODS: Information on cesarean rates was obtained for all 19 Irish maternity hospitals receiving state funding in 2009. All women who underwent cesarean delivery of a live or stillborn infant weighing 500 g or more between January 1 and December 31 were included. Deliveries were classified as elective or emergency. Individual hospitals were not identified in the analysis. RESULTS: The mean rates per hospital of elective and emergency cesarean were 12.9+\\/-2.6% (n=9337) and 13.8+\\/-3.0% (n=9989), respectively-giving an overall mean rate of 26.7+\\/-4.2% (n=19326) per hospital. Cesarean rates were normally distributed. Using a quality control performance chart with a cutoff 2 standard deviations from the mean, 1 hospital was above the normal range for both total and elective cesareans, indicating that its pre-labor obstetric practices warrant clinical review. Another hospital had a mean emergency cesarean rate above the normal range, indicating that its labor ward practices warrant review. CONCLUSION: Quality control performance charts can be used to analyze cesarean rates nationally and, thus, to identify hospitals at which obstetric practices should be reviewed.

  10. Congestion-Aware Routing and Fuzzy-based Rate Controller for Wireless Sensor Networks

    Directory of Open Access Journals (Sweden)

    M. Hatamian

    2016-04-01

    Full Text Available In this paper, congestion-aware routing and fuzzy-based rate controller for wireless sensor networks (WSNs is proposed. The proposed method tries to make a distinction between locally generated data and transit data by using a priority-based mechanism which provides a novel queueing model. Furthermore, a novel congestion-aware routing using greedy approach is proposed. The proposed congestion-aware routing tries to find more affordable routes. Moreover, a fuzzy rate controller is utilized for rate controlling which uses two criteria as its inputs, including congestion score and buffer occupancy. These two parameters are based on total packet input rate, packet forwarding rate at MAC layer, number of packets in the queue buffer, and total buffer size at each node. As soon as the congestion is detected, the notification signal is sent to offspring nodes. As a result, they are able to adjust their data transmission rate. Simulation results clearly show that the implementation of the proposed method using a greedy approach and fuzzy logic has done significant reduction in terms of packet loss rate, end-to-end delay and average energy consumption.

  11. How to determine control of growth rate in a chemostat. Using metabolic control analysis to resolve the paradox

    DEFF Research Database (Denmark)

    Snoep, Jacky L.; Jensen, Peter Ruhdal; Groeneveld, Philip

    1994-01-01

    The chemostat makes it possible to study microbial physiology at steady state. However, because growth rate in a chemostat is set by the experimenter, it seems impossible to employ the chemostat to study the control of microbial growth by processes within the microorganism. In this paper we show ...

  12. Ivabradine for patients with stable coronary artery disease and left-ventricular systolic dysfunction (BEAUTIFUL): a randomised, double-blind, placebo-controlled trial

    NARCIS (Netherlands)

    Fox, Kim; Ford, Ian; Steg, P. Gabriel; Tendera, Michal; Ferrari, Roberto; Grancelli, H.; Freedman, B.; Eber, B.; Vanoverschelde, J. L.; Finkov, B.; Yotov, Y.; Tardif, J. C.; Hu, D.; Lau, C.; Hradec, J.; Hildebrandt, P.; Eha, J.; Peuhkurinen, K.; Danchin, N.; Steg, P. G.; Meinertz, T.; Vardas, P.; Borbola, J.; Mulcahy, D.; Maggioni, A.; Erglis, A.; Jirgensons, J.; Kalnins, U.; Laucevicius, A.; Dickstein, K.; Ruzyllo, W.; Tendera, M.; Seabra-Gomes, R.; Capalneanu, R.; Belenkov, Y.; Mareev, Y.; Murin, J.; Rakovec, P.; Macaya, C.; Dellborg, M.; Lüscher, T. U.; van Gilst, W.; Oto, A.; Ford, I.; Fox, K.; Hall, A.; Parkhomenko, A.; Robertson, M.; Weir, C.; Aziz, J.; Kean, S.; Wilson, R.; Thygesen, K.; Frenneaux, M.; Jondeau, G.; Camm, A. J.; Dargie, H.; Kjekshus, J.; Murray, G.; Ahuad Guerrero, R. A.; Allall, O. A.; Amuchastegui, M.; Buscema, J. J.; Bustos, B.; Cartasegna, L. R.; Cohen Arazi, H.; Fernandez, A. A.; Fuselli, J. J.; Guzmén, L. A.; Hasbani, E.; Ibañez, J. O.; Iglesias, R. M.; Lembo, L. A.; Luciardi, H. L.; Luquez, H. A.; Montaña, O. R.; Nul, D. R.; Orlandini, A. D.; Perna, E. R.; Sanchez, A.; Sanjurjo, M. S.; Schygiel, P. O.; Sinisi, V. A.; Sokn, F. J.; Thierer, J.; del Valle Lobo Marquez, L. L.; Varini, S.; Vogel, D.; Alford, K.; Amerena, J.; Arnolda, L.; Atherton, J.; Bradley, J.; Cameron, J.; Colquhoun, D.; Counsell, J.; Fitzpatrick, A.; Horowitz, J.; Ireland, M.; Karrasch, J.; Kaye, D.; Lattimore, J. D.; Marwick, T.; O'Shea, J.; Owensby, D.; de Pasquale, C.; Prior, D.; Rogers, J.; Sindone, A.; Singh, B. B.; Stickland, J.; Szto, G.; Tofler, G.; Vogl, E.; Waites, J.; Walsh, W.; Eber, E.; Huber, K.; Lang, I.; Pichler, M.; Chenu, P.; Dendale, P. A. C.; François, P. A. A.; Friart, A.; Goethals, M.; Materne, P.; van Mieghem, W.; Missault, L.; Vachiery, J. L.; Vanderheyden, M.; Chompalova, B.; Denchev, S.; Donova, T.; Dzhurzdhev, A.; Georgiev, B.; Gotchev, D.; Goudev, A.; Grigorov, M.; Guenova, D.; Hergeldjieva, V.; Kamenova, Z.; Nachev, C.; Penkov, N.; Perchev, I.; Raev, D.; Sirakova, V.; Taseva, T.; Torbova, S.; Tzekova, M.; Baird, M.; Bernstein, V.; Chehayeb, R.; Constance, C.; Coutu, B.; Desrochers, D.; Fortin, C.; Glanz, A.; Haddad, H.; Heath, J.; Hill, L. L.; Klinke, W. P.; Kouz, S.; Lalani, A.; Lauzon, C.; Lepage, S.; Lonn, E.; Ma, P.; Matangi, M.; Nawaz, S.; Pandey, S.; Parker, J. D.; Parker, J. O.; Poirier, P.; Raco, D.; Rajda, M.; Rebane, T.; Rupka, D.; Savard, D.; Syan, G. S.; Talbot, P.; To, T. B.; Vakani, M. T.; Vertes, G. E.; Yao, L.; Dong, Y.; Gai, L.; Ge, J. B.; Lv, S.; Sun, Y.; Wang, W.; Wang, X.; Yan, X.; Yuan, Z.; Zhang, F.; Ballek, L.; Drazka, J.; Fébik, L.; Florian, J.; Kaislerová, M.; Karetová, D.; Jerábek, O.; Kotík, L.; Krejcova, H.; Kryza, R.; Kuchar, J.; Lavicka, V.; Maratka, T.; Marcinek, G.; Penicka, M.; Povolný, J.; Sochor, K.; Soucek, M.; Spacek, R.; Spinar, J.; Stípal, R.; Sulda, M.; Vencour, D.; Vitovec, J.; Vojacek, J.; Vojtísek, P.; Agner, E.; Asklund, M.; Brønnum Schou, J.; Dahlstrøm, C. G.; Dodt, K. K.; Egstrup, K.; Gøtzsche, L.; Gøtzsche, O.; Haghfelt, T.; Jakobsen, T.; Jensen, G.; Klarlund, K.; Køber, L.; Larsen, C. T.; Larsen, J.; Lind Rasmussen, S.; Lysko Svendsen, T.; Markenvard, J.; McNair, A.; Nielson, H.; Pedersen, L.; Petersen, J.; Ralfkiaer, N.; Rickers, H.; Rokkedal, J.; Romer, F.; Roseva Nielsen, N.; Scheibel, M.; Sejersen, H.; Skagen, K.; Stentebjerg, S. E.; Torp-Pedersen, C.; Tuxen, C.; Vigholt, E.; Averina, O.; Kolbassova, O.; Sildmäe, S.; Vahula, V.; Viigimaa, M.; Harjola, V. P.; Luoma, J.; Melin, J.; Aliot, E.; Barthelemy, J. C.; Bauer, F.; Beaune, J.; Belin, A.; Bodur, G.; Boudahne, A.; Bourdon, A.; Bouvier, J. M.; Carlioz, R.; Chati, Z.; Cherbi, C.; Chevalier, J. M.; Chevrier, J.; Claudon, O.; Colin, P.; Dambrine, P.; Decoulx, E.; Demarcq, J. M.; Doucet, B.; Drawin, T.; Dubois-Rande, J. L.; El Mansour, N.; Escande, M.; Fournier, P. Y.; Funck, F.; Gabrovescu, M.; Galinier, M.; Galley, D.; Gay, A.; Genest, M.; Godenir, J. P.; Guillot, J. P.; Gully, C.; Habib, G.; Huyghe de Mahenge, A.; Jaboureck, O.; Kahn, J. C.; Khalife, K.; Khanoyan, P.; Koenig, A.; Leborgne, L.; Lemoine, C.; Magnin, D.; Mann, H.; Mansourati, J.; Martelet, M.; Matina, D.; Meurice, T.; Olive, T. G.; Ovize, M.; Perret, T.; Pierre-Justin, E.; Riou, A.; Roudaut, R.; Roul, G.; Roynard, J. L.; Sellier, P.; Slama, M.; Soto, F. X.; Thisse, J. Y.; Wolf, J. E.; Ammer, K.; Appel, K. F.; Baar, M.; Bauknecht, C.; Baumann, G.; Bergmann, K.; Böhm, M.; Bosch, R.; Bott, J.; Cieslinski, G.; Deissner, M.; Drescher, T.; Droese, K.; Figulla, H. R.; Frick, H. M.; Fries, P.; Gärtner, J.; Gola, G.; Gonska, B. D.; Grooterhorst, P.; Hasenfuss, G.; Haverkamp, W.; Heckel, D.; Hengstenberg, C.; Hering, R.; Heuer, H.; Hoppe, U.; Jahnke, N.; Jeserich, M.; Katus, H.; Kleinertz, K.; Kombächer, H. D.; Lange, R.; Lehmann, G.; Müller, O.; Münzel, T.; Natour, M.; Nienaber, C.; Oeff, M.; Pötsch, T.; Proskynitopoulos, N.; Rüdell, U.; Rummel, R.; Rupprecht, H. J.; von Schacky, C.; Schenkenberger, I.; Schmidt, J.; Schreckenberg, A.; Schuler, G.; Schultheiss, H. P.; Seidl, K.; Spanier, C.; Spengler, U.; Steindorf, J.; Strasser, R.; Taggeselle, J.; Tammen, A.; Werdan, K.; Windstetter, U.; Winkelmann, B. R.; Wolde, C. H.; Zahorsky, R.; Al-Zoebi, A.; Alexopoulos, D.; Anastasiou-Nana, M.; Apostolou, T.; Fotiadis, I.; Hatzinikolaou-Kotsakou, E.; Kallikazaros, I.; Kapordelis, C.; Karvounis, H.; Kolettis, T.; Koliopoulos, N.; Kremastinos, D.; Kyriakides, Z.; Manolis, A.; Papadopoulos, C.; Pras, A.; Pyrgakis, V. N.; Siogas, K.; Theodorakis, G.; Tryposkiadis, F.; Tziakas, D.; Lee, K.; Barsi, B.; Cziráki, A.; Dézsi, C. A.; Edes, I.; Farsang, C.; Harmati, L.; Juhász, A.; Kovács, A.; Lakatos, F.; Lippai, J.; Lupkovics, G.; Matoltsy, A.; Mohácsi, A.; Mohay, A.; Nagy, A.; Nagy, K.; Nagy, L.; Nyárádi, A.; Pálinkás, A.; Piros, G.; Polgár, P.; Préda, I.; Regos, L.; Rumi, G.; Sármán, P.; Sereg, M.; Sidó, Z.; Tahy, A.; Takács, J.; Tomcsányi, J.; Tóth, K.; Váradi, A.; Vegh, G.; Veress, G.; Zámolyi, K.; Barton, J.; Crean, P.; Daly, K.; Foley, D.; Alberti, E.; Ambrosio, G.; Barbuzzi, S.; Bellone, E.; Buia, E.; Capucci, A.; Carbonieri, E.; Cardona, N.; Della Casa, S.; Cocchieri, M.; Colombo, A.; Cosmi, F.; de Cristofaro, M.; Ferrari, R.; Fuscaldo, G.; Gavazzi, A.; Giannuzzi, P.; Giustiniani, S.; Ingrilli, F.; Leghissa, R.; de Luca, I.; Maresta, A.; de Matteis, C.; Minneci, C.; Mos, L.; Paparoni, S.; Perna, B.; Pettinati, G.; Pinelli, G.; Pizzimenti, G.; Porcu, M.; Proietti, G.; Proto, C.; Pulitano, G.; Reggianini, L.; Santini, M.; Uguccioni, M.; Urbinati, S.; Zanetta, M.; Zanini, R.; Gailiss, E.; Gersamija, A.; Keisa, M.; Libins, A.; Ozolina, M. A.; Stoma, M.; Volans, E.; Berukstis, E.; Grabauskiene, V.; Kibarskis, A.; Kirkutis, A.; Marcinkeviciene, J.; Naudziunas, A.; Petrulioniene, Z.; Varoneckas, G.; Zaliunas, R.; Bartels, G. L.; van Beek, G. J.; van den Berg, B. J.; Bruning, T. A.; Cornel, J. H.; Daniels, M. C. G.; Dijkgraaf, R.; Fast, J.; Freericks, M. P.; Galema, T. W.; Göbel, E. J. A.; Hamer, L. H. J.; van der Heijden, R.; Herrman, J. P. R.; Hoedemaker, G.; Holwerda, N. J.; Hoogslag, P. A. M.; Jaarsma, W.; Jap Tjoen San, W. T. J.; van Kempen, L. H. J.; Kirkels, J. H.; Kragten, J. A.; Leenders, C. M.; Linssen, G. C. M.; Lionarons, R. J.; Maas, A. H. E. M.; Michels, H. M.; de Milliano, P. A. R.; Nagelsmit, M. J.; Nierop, P. R.; Pinto, Y. M.; Robles de Medina, R.; van Rossum, P.; van Rugge, F. P.; Somer, S. T.; Swart, H.; Thijssen, H.; van der Veen, M.; Verheul, J. A.; van Vlies, B.; Voors, A. A.; Wesdorp, J. C. L.; van Wijk, L. M.; Willems, A. R.; Winter, J. B.; Withagen, A. J. A. M.; van der Zwaan, C.; Zwart, P. A. G.; Atar, D.; Myhre, E. P.; Achremczyk, P.; Andrzejak, R.; Baska, J.; Bloch, C.; Dluzniewski, M.; Drozdowski, P.; Goch, J. H.; Janik, K.; Janion, M.; Jaworska, K.; Kalarus, Z.; Kawecka-Jaszcz, K.; Kozlowski, A.; Krupa, E.; Krynicki, R.; Krzciuk, M.; Krzeminska-Pakula, M.; Kubica, J.; Kurowski, M.; Kuzniar, J.; Loboz-Grudzien, K.; Mazurek, W.; Miekus, P.; Musial, W.; Opolski, G.; Piepiorka, M.; Piotrowski, W.; Piwowarska, W.; Pluta, W.; Ponikowski, P.; Pulkowski, G.; Pusz, T.; Ruszkowski, P.; Rynkiewicz, A.; Sinkiewicz, W.; Skura, M.; Slowinski, S.; Szolkiewicz, M.; Szpajer, M.; Targonski, R.; Tracz, W.; Trojnar, R.; Trusz-Gluza, M.; Wodniecki, J.; Wrabec, K.; Zadrozna, Z.; Zinka, E.; Aguiar, J.; Carvalho, N.; Ferreira Da Silva, G.; Freitas, J.; Lousada, N.; Oliveira Soares, A.; Paisana Lopes, J. P.; Providencia, L. A.; Salgado, A.; Teixeira, M.; Apetrei, E.; Arsenescu, C.; Avram, R.; Babes, K.; Bruckner, I.; Carasca, E.; Cinteza, M.; Craiu, E.; Dan, G. A.; Datcu, M. D.; Dimulescu, D. R.; Dorobantu, M.; Dragomor, D.; Dragulescu, I. S.; Dumitrascu, D. L.; Georgescu, I. M.; Ionescu, D. D.; Ionascu-Fometescu, C. R.; Kiss, L.; Macarie, C.; Manitiu, I.; Minescu, B.; Nanea, T.; Olariu, C.; Olinic, N. C.; Opris, M.; Pop, C.; Radoi, M.; Radu, I.; Sinescu, C. J.; Tanaseanu, C. M.; Tase, A.; Tintoiu, I.; Tomescu, M.; Topolnitchi, L.; Vintila, M.; Vladoianu, M.; Arkhipov, M. V.; Aroutiounov, G. P.; Azarin, O. G.; Barbarash, O. L.; Bart, B. Y.; Beloussov, Y. B.; Bychkova, L.; Chumakova, G. A.; Glezer, M. G.; Golukhova, E.; Gorbachenkov, A. A.; Gordeev, I. G.; Ivleva, A. Ya; Karpov, Y. A.; Karpov, Y. B.; Kastanaian, A. A.; Kisliak, O. A.; Kobalava, J. D.; Konyakhin, A. Yu; Khrustalev, O. A.; Kuimov, A. D.; Kukes, A. G.; Lopatin, Y. M.; Mareev, V. Yu; Moiseeva, O. M.; Mkrtchyan, V. R.; Nedogoda, S. V.; Orlov, V. A.; Perepech, N. B.; Pimenov, L. T.; Pozdnyakov, Y. M.; Rodoman, G. V.; Rudnev, D. V.; Sayganov, S. A.; Shlyakhto, E. V.; Shostak, N. A.; Shpektor, A. V.; Sidorenko, B. A.; Sorokin, L. A.; Stryuk, R. I.; Svistov, A. S.; Tankhilevich, B. M.; Tereschenko, S. N.; Tsyba, L. P.; Vasyuk, Y. A.; Vertkine, A. L.; Yakhontova, P. K.; Yakusevich, V. V.; Yakushin, S. S.; Zadionchenko, V. S.; Zateyshchikov, D. A.; Zhilyaev, E. V.; Bada, V.; Bugán, V.; Gonsorcík, J.; Kamenský, G.; Kmec, J.; Micko, K.; Murín, J.; Pella, D.; Sojka, G.; Vahala, P.; Bombek, M.; Kanic, V.; Markez, J.; Melihen-Bartolic, C.; Rakove, P.; Skrabl-Mocnik, F.; Slemenik-Pusnik, C.; Balaguer Recena, J.; Bertomeu Martinez, V.; Bruguera Cortada, J.; Calvo Gomez, C.; Calvo Iglesias, F.; Caparros Valderrama, J.; Casares Garcia, G.; Fernandez Alvarez, R.; Galve, E.; Garcia de Burgos, F.; Grande, A.; Gusi Tragant, G.; Iglesias Alonso, L. F.; Iglesias Cubero, G.; Illa Gay, J.; Jimenez Navarro, M.; López Bescós, L.; López García-Aranda, V.; Macaya de Miguel, C.; Noriega Peiro, F.; Paz Bermejo, M. A.; Perez Villa, F.; Romero Hinojosa, J. A.; San Román Calvar, A.; Sevilla Toral, B.; Sola Casado, R.; Bandh, A.; Blomgren, J.; Herlitz, J.; Ohlin, H.; Ullman, B.; Delabays, A.; Dubach, P.; Eeckhout, E.; Gallino, A.; Hess, O.; Moccetti, T.; Vontobel, H.; Acarturk, E.; Ergene, O.; Erol, K.; Kozan, O.; Mutlu, B.; Ural, D.; Yilmaz, H.; Amosova, K.; Barna, O.; Batushkin, V.; Bazylevych, A.; Bereznyakov, I.; Dyadyk, A.; Dzyak, G.; Girina, O.; Glushko, L.; Goloborodko, B.; Karpenko, O.; Khomazyuk, T.; Kolchin, Y.; Kolomiets, S.; Korkushko, O.; Korzh, O.; Kovalenko, V.; Kovalsky, I.; Krayz, I.; Kubyshkin, V.; Lutay, M.; Mostovoy, Y.; Netyazhenko, V.; Perepelytsya, M.; Pertseva, T.; Polyvoda, S.; Putintsev, V.; Rishko, L. M.; Rudyk, Y.; Sakharchuk, I.; Semidotska, Z.; Seredyuk, N.; Serkova, V.; Sharuk, O.; Slyvka, Y.; Soldatchenko, S.; Stadnyuk, L.; Storozhuk, B.; Tashchuk, V.; Tseluyko, V.; Vatutin, M.; Vizir, V.; Vlasenko, M.; Voronkov, L.; Yurlov, V.; Zharinov, O.; Baig, M. W.; Brady, A.; Brooks, N.; Brooksby, P.; Crook, J. R.; Dutka, D.; Francis, C. M.; Greaves, K.; Groves, P.; Kadr, H.; Lindsay, S.; Moriarty, A.; Purvis, J.; Rozkovec, A.; Saltissi, S.; Stewart, M.; Timmis, A.; Williams, S.

    2008-01-01

    BACKGROUND: Ivabradine specifically inhibits the I(f) current in the sinoatrial node to lower heart rate, without affecting other aspects of cardiac function. We aimed to test whether lowering the heart rate with ivabradine reduces cardiovascular death and morbidity in patients with coronary artery

  13. Coordinated Secondary Control for Balanced Discharge Rate of Energy Storage System in Islanded Microgrids

    DEFF Research Database (Denmark)

    Guan, Yajuan; Guerrero, Josep M.; Quintero, Juan Carlos Vasquez

    2015-01-01

    current and unintentional outage of DGs. Thus, the stability and reliability of islanded MG can be improved. The eigenvalues and root locus with the proposed controller are presented to design the parameters as well as analyzing the system stability. Simulation results based on Matlab......A coordinated secondary control based on a novel autonomous currents sharing control strategy for balanced discharge rate of energy storage systems in islanded microgrid (MG) is proposed in this paper. The coordinated secondary controller is able to regulate the output power of distributed...... generating (DG) systems according to their state-of-charge by adjusting the virtual resistances of their voltage controlled inverters. This controller can not only provide the faster response and accurate output current sharing control, but also avoid the potential operation failure resulting from the over...

  14. Restrained eating predicts effortful self-control as indicated by heart rate variability during food exposure.

    Science.gov (United States)

    Geisler, Fay C M; Kleinfeldt, Anne; Kubiak, Thomas

    2016-01-01

    When confronted with food, restrained eaters have to inhibit the pursuit of the short-term goal of enjoying their food for the sake of the long-term goal of controlling their weight. Thus, restrained eating creates a self-control situation. In the present study we investigated the initiation of effortful self-control by food cues in accordance with the level of restrained eating. We expected that a preceding act of self-control would moderate the association between restrained eating and effortful self-control initiated by food cues. Participants (N=111) were randomly assigned to a task requiring self-control or a task not requiring self-control. Subsequently, participants were exposed to palatable food, and effortful self-control was measured via heart rate variability (HRV). Restrained eating was associated with enhanced HRV during food exposure after exercising self-control but not after not exercising self-control. The results indicate that maintaining dieting goals results in food cues initiating effortful self-control after a preceding act of self-control. We suggest considering the effect of acts of self-control when modeling the initial steps on the path from food cues to unsuccessful restrained eating. Copyright © 2015 Elsevier Ltd. All rights reserved.

  15. Right ventricular function during acute exacerbation of severe equine asthma.

    Science.gov (United States)

    Decloedt, A; Borowicz, H; Slowikowska, M; Chiers, K; van Loon, G; Niedzwiedz, A

    2017-09-01

    Pulmonary hypertension has been described in horses with severe equine asthma, but its effect on the right ventricle has not been fully elucidated. To evaluate right ventricular structure and function after a 1-week period of pulmonary hypertension secondary to acute exacerbation of severe equine asthma. Prospective study. A clinical episode of severe equine asthma was induced experimentally in six susceptible horses. Examinations in remission and on day 7 of the clinical episode included a physical examination with clinical scoring, echocardiography, arterial blood gas measurements, venous blood sampling for cardiac biomarkers, intracardiac pressure measurements, right ventricular and right atrial myocardial biopsies, airway endoscopy and bronchoalveolar lavage. After 1 month of recovery, physical examination, echocardiography and cardiac biomarker analysis were repeated. Echocardiographic and pressure measurements were compared with those in 10 healthy control horses. All horses developed clinical signs of acute pulmonary obstruction. Right heart pressures increased significantly. Altered right ventricular function could be detected by tissue Doppler and speckle tracking echocardiography. Cardiac troponin concentrations did not increase significantly, but were highly elevated in one horse which exercised in the paddock prior to sampling. Focal neutrophil infiltration was present in two myocardial samples. Even in remission, asthmatic horses showed a thicker right ventricular wall, an increased left ventricular end-systolic eccentricity index at chordal level and decreased right ventricular longitudinal strain compared with controls. The induced clinical episode was rather mild and the number of horses was limited because of the invasive nature of the study. Pulmonary obstruction in asthmatic horses induces pulmonary hypertension with right ventricular structural and functional changes. © 2017 EVJ Ltd.

  16. Accumulation of slowly activating delayed rectifier potassium current (IKs) in canine ventricular myocytes

    DEFF Research Database (Denmark)

    Stengl, Milan; Volders, Paul G A; Thomsen, Morten Bækgaard

    2003-01-01

    the deactivation is much faster, is still unclear. In this study the conditions under which accumulation occurs in canine ventricular myocytes were studied with regard to its physiological relevance in controlling action potential duration (APD). At baseline, square pulse voltage clamp experiments revealed...... that the accumulation of canine IKs could occur, but only at rather short interpulse intervals (... in the presence of isoproterenol. Block of IKs, however, led to a reverse rate-dependent prolongation of APD indicating that IKs does not have a dominant role at short cycle lengths....

  17. Source and Channel Adaptive Rate Control for Multicast Layered Video Transmission Based on a Clustering Algorithm

    Directory of Open Access Journals (Sweden)

    Jérôme Viéron

    2004-03-01

    Full Text Available This paper introduces source-channel adaptive rate control (SARC, a new congestion control algorithm for layered video transmission in large multicast groups. In order to solve the well-known feedback implosion problem in large multicast groups, we first present a mechanism for filtering RTCP receiver reports sent from receivers to the whole session. The proposed filtering mechanism provides a classification of receivers according to a predefined similarity measure. An end-to-end source and FEC rate control based on this distributed feedback aggregation mechanism coupled with a video layered coding system is then described. The number of layers, their rate, and their levels of protection are adapted dynamically to aggregated feedbacks. The algorithms have been validated with the NS2 network simulator.

  18. Measuring device for purging water flow rate in control rod drive

    Energy Technology Data Exchange (ETDEWEB)

    Inoue, Hiroshi.

    1993-11-12

    The device of the present invention enables highly accurate measurement for an amount of purging water supplied to control rod drives of a BWR type reactor. That is, purging water is supplied from an inlet of a scram line of the control rod drives. A temperature measuring portion is disposed, for measuring temperature fluctuation of purging water, to a hydropressure control unit for providing pressure and flow rate of water required for supplying the purging water and scram operation. An instrumentation section is disposed for calculating the flow rate of purging water based on the measured data obtained in the section. An output device is disposed for outputting a flow rate value of the purging water based on the result of the calculation obtained therein. With such a constitution, flow rate of the purging water can be measured quantitatively at the hydropressure control unit. Accordingly, influences, such as fluctuation of reactor core temperature are reduced, and accuracy for the measurement of the purging water flow rate is improved. As a result, reactor safety and maintainability can be improved. (I.S.).

  19. Multi-rate control over AWGN channels via analog joint source-channel coding

    KAUST Repository

    Khina, Anatoly

    2017-01-05

    We consider the problem of controlling an unstable plant over an additive white Gaussian noise (AWGN) channel with a transmit power constraint, where the signaling rate of communication is larger than the sampling rate (for generating observations and applying control inputs) of the underlying plant. Such a situation is quite common since sampling is done at a rate that captures the dynamics of the plant and which is often much lower than the rate that can be communicated. This setting offers the opportunity of improving the system performance by employing multiple channel uses to convey a single message (output plant observation or control input). Common ways of doing so are through either repeating the message, or by quantizing it to a number of bits and then transmitting a channel coded version of the bits whose length is commensurate with the number of channel uses per sampled message. We argue that such “separated source and channel coding” can be suboptimal and propose to perform joint source-channel coding. Since the block length is short we obviate the need to go to the digital domain altogether and instead consider analog joint source-channel coding. For the case where the communication signaling rate is twice the sampling rate, we employ the Archimedean bi-spiral-based Shannon-Kotel\\'nikov analog maps to show significant improvement in stability margins and linear-quadratic Gaussian (LQG) costs over simple schemes that employ repetition.

  20. Cardiac remodeling with rhythm versus rate control strategies for atrial fibrillation in patients with heart failure: insights from the AF-CHF echocardiographic sub-study.

    Science.gov (United States)

    Henrard, Valérie; Ducharme, Anique; Khairy, Paul; Gisbert, Alejandro; Roy, Denis; Levesque, Sylvie; Talajic, Mario; Thibault, Bernard; Racine, Normand; White, Michel; Guerra, Peter G; Tardif, Jean-Claude

    2013-05-25

    In patients with heart failure and atrial fibrillation, the AF-CHF (Atrial Fibrillation and Congestive Heart Failure) trial did not demonstrate the superiority of rhythm control (RhyC) over a rate control (RaC) strategy on cardiovascular mortality. Nevertheless, deleterious hemodynamic effects of atrial fibrillation can lead to further decrease in left ventricular (LV) function and progression of symptoms. This echocardiographic sub-study was designed to compare the effects of the two treatment strategies on LV ejection fraction (LVEF), chamber volumes and dimensions, valvular regurgitation and functional status. A total of 59 patients (29 RhyC, 30 RaC) aged 67±8 years (14% women), enrolled in the AF-CHF trial at the Montreal Heart Institute underwent standardized echocardiograms at baseline and at 12 months. Mean LVEF at baseline was severely depressed (RhyC: 27.0±4.9% and RaC: 27.6±7.4%, p=0.73), and improved to a similar degree in both groups (RhyC: +8.0±10.4% and RaC: +4.5±10.6, both p<0.05; p=0.19 for RhyC versus RaC). Other echocardiographic parameters, such as LV end-systolic volume index and degree of mitral and tricuspid regurgitation, remained unchanged. New York Heart Association functional class and distance walked in 6 min improved significantly in both groups (RhyC: +48.9±78.7 m and RaC: +47.2±96.7 m, both p≤0.01), with no difference between RhyC and RaC strategies. Improvements in LVEF and functional status are observed after 12 months in patients with heart failure and atrial fibrillation, regardless of whether rate or rhythm control strategies are used. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

  1. Ventricular arrhythmias and left ventricular hypertrophy in hypertrophic cardiomyopathy.

    Science.gov (United States)

    Piva e Mattos, Beatriz; Torres, Marco Antonio Rodrigues; Freitas, Valéria Centeno de; Scolari, Fernando Luís; Loreto, Melina Silva de

    2013-05-01

    In hypertrophic cardiomyopathy (HCM), the degree of left ventricular hypertrophy (LVH) could influence the development of ventricular arrhythmias. In HCM, analyze the association between the occurrence of ventricular arrhythmias determined by Holter electrocardiogram (ECG-Holter) and the degree of LVH determined by maximum wall thickness (MWT) in echocardiography and body mass index (BMI). Fifty-four consecutive patients with HCM underwent 24-hour ECG-Holter and echocardiography for assessment of level of LVH through MWT and BMI. Two levels were established for the occurrence of Ventricular Arrhythmias: I - alone or paired extrasystoles and II - Non- Sustained Ventricular Tachycardia (NSVT). In 13 patients (24%) with NSVT (level II), there was a higher frequency of MWT of the left ventricle (LV) > 21 mm (n = 10, 77%, 25 ± 4 mm) and LLLV = 144 g/m² (n = 10, 77%, 200 ± 30 g/m²), in comparison with those presenting with extrasystole arrhythmias (level I) (n = 41, 76%), in which these measures were identified in, respectively, 37 % (n= 15, 23 ± 1 mm), p = 0.023, and 39% (n = 16, 192 ± 53 g / m²) of the cases (p = 0.026). The cut-off values mentioned were determined by the ROC curve with a confidence interval of 95%. NSVT was more common in patients with MWTLV > 21 mm and LLLV > 144 g/m² (8 of 13, 62%) than in those with (4 of 13, 31%) or without (1 of 13; 8%) echocardiographic variables above cut-off values (p = 0.04). In HCM, occurrence of ventricular arrhythmias by Holter was associated with the degree of LVH assessed by echocardiography through MWT and BMI.

  2. Hemodynamic effects of Purkinje potential pacing in the left ventricular endocardium in patients with advanced heart failure.

    Science.gov (United States)

    Hamaoka, Mamoru; Mine, Takanao; Kodani, Takeshi; Kishima, Hideyuki; Mitsuno, Masataka; Masuyama, Tohru

    2015-12-01

    Various difficulties can occur in patients who undergo cardiac resynchronization therapy for drug-refractory heart failure with respect to placement of the left ventricular (LV) lead, because of anatomical features, pacing thresholds, twitching, or pacing lead anchoring, possibly requiring other pacing sites. The goal of this study was to determine whether Purkinje potential (PP) pacing could provide better hemodynamics in patients with left bundle branch block and heart failure than biventricular (BiV) pacing. Eleven patients with New York Heart Association functional class II or III heart failure despite optimal medical therapy were selected for this study. All patients underwent left- and right-sided cardiac catheterization for measurement of LV functional parameters in the control state during BiV and PP pacing. Maximum dP/dt increased during BiV and PP pacing when compared with control measurements. This study compared parameters measured during BiV pacing with PP pacing and non-paced beats as the control state in each patient (717±171 mmHg/s vs. 917±191 mmHg/s, pheart rate, electrocardiographic wave complex duration, minimum dP/dt, left ventricular end-diastolic pressure, left ventricular end-systolic pressure, pulmonary capillary wedge pressure, or cardiac index when comparing BiV pacing and PP pacing to control measurements. The hemodynamic outcome of PP pacing was comparable to that of BiV pacing in patients with advanced heart failure.

  3. A two-round Delphi study examining consensus of recommended clinical practices for patients with ventricular assist devices as destination therapy.

    Science.gov (United States)

    Chichetti, JoAnne V

    2011-03-01

    To identify the current clinical practices of Medicare-certified facilities offering ventricular assist devices as destination therapy and to attain a consensus of recommended clinical practices across the United States for the management of adults with ventricular assist devices as destination therapy. Sixty ventricular assist device coordinators from Medicare-certified centers were invited to participate in an online, 2-round Delphi survey. The surveys asked whether recommended practices are current practices and whether respondents always/agreed or never/disagreed with performing the recommended practice guidelines. Consensus was defined as 75% agreement. The clinical areas of focus were patient selection, preoperative preparation, postoperative care, infection control, nutrition, and patient discharge preparation. Practices were extracted from the advanced practice guidelines for HeartMate destination therapy and the International Society for Heart and Lung Transplantation's 2006 guidelines for the care of heart transplant candidates. Representing 21 states across the country, the first-round survey had a response rate of 57% (n = 34). The second-round survey had a response rate of 74% (n = 17), representing 28% of the 60 centers. Consensus was obtained for 122 practices. The dimension of patient selection-diagnostic tests and screening had the highest level of consensus (16%, n = 20), and the dimension of postoperative care-intermediate/intensive care unit dimension had the lowest level of consensus (3.3%, n = 4). Survey results identify a consensus of practices for the specific group of ventricular assist device coordinators who responded, but that consensus cannot be generalized to all ventricular assist device facilities. These results can, however, provide a foundation for further research leading to the development of standard-of-care practices for patients with ventricular assist devices as destination therapy.

  4. Interactions among temperature, moisture, and oxygen concentrations in controlling decomposition rates in a boreal forest soil

    Science.gov (United States)

    Sierra, Carlos A.; Malghani, Saadatullah; Loescher, Henry W.

    2017-02-01

    Determining environmental controls on soil organic matter decomposition is of importance for developing models that predict the effects of environmental change on global soil carbon stocks. There is uncertainty about the environmental controls on decomposition rates at temperature and moisture extremes, particularly at high water content levels and high temperatures. It is uncertain whether observed declines in decomposition rates at high temperatures are due to declines in the heat capacity of extracellular enzymes as predicted by thermodynamic theory, or due to simultaneous declines in soil moisture. It is also uncertain whether oxygen limits decomposition rates at high water contents. Here we present the results of a full factorial experiment using organic soils from a boreal forest incubated at high temperatures (25 and 35 °C), a wide range of water-filled pore space (WFPS; 15, 30, 60, 90 %), and contrasting oxygen concentrations (1 and 20 %). We found support for the hypothesis that decomposition rates are high at high temperatures, provided that enough moisture and oxygen are available for decomposition. Furthermore, we found that decomposition rates are mostly limited by oxygen concentrations at high moisture levels; even at 90 % WFPS, decomposition proceeded at high rates in the presence of oxygen. Our results suggest an important degree of interaction among temperature, moisture, and oxygen in determining decomposition rates at the soil core scale.

  5. Coordinated Secondary Control for Balanced Discharge Rate of Energy Storage System in Islanded AC Microgrids

    DEFF Research Database (Denmark)

    Guan, Yajuan; Quintero, Juan Carlos Vasquez; Guerrero, Josep M.

    2016-01-01

    A coordinated secondary control approach based on an autonomous current-sharing control strategy for balancing the discharge rates of energy storage systems (ESSs) in islanded AC microgrids is proposed in this paper. The coordinated secondary controller can regulate the power outputs of distributed...... generation (DG) units according to their states-of-charge (SoCs) and ESS capacities by adjusting the virtual resistances of the paralleled voltage-controlled inverters. Compared with existing controllers, the proposed control strategy not only effectively prevents operation failure caused by overcurrent...... incidents and unintentional outages in DG units, but also aims to provide a fast transient response and an accurate output-current-sharing performance. A complete root locus analysis is given in order to achieve system stability and parameter sensitivity. Experimental results are presented to show...

  6. Does surgically induced right bundle branch block really effect ventricular function in children after ventricular septal defect closure?

    Science.gov (United States)

    Karadeniz, Cem; Atalay, Semra; Demir, Fikri; Tutar, Ercan; Ciftci, Omer; Ucar, Tayfun; Uysalel, Adnan; Eyileten, Zeynep

    2015-03-01

    In this prospective study, we aimed to assess left and right ventricular function in terms of the presence of right bundle branch block (RBBB) in the cases with repaired ventricular septal defect (VSD). Fifty-three patients who had VSD surgery at least 1-year preceding admission and 52 healthy controls were enrolled into the study. All the participants underwent electrocardiographic and echocardiographic examination. The cases with RBBB were determined. The conventional and tissue Doppler echocardiographic measurements of the patients with and without RBBB were compared with each other and healthy controls. Twenty-eight of VSD repair groups were male and 25 were female. Control group consisted of 30 males and 22 females. The mean age of the study and control groups was 7.5 ± 5.0 and 6.9 ± 4.3 years, respectively. RBBB was detected in 20 of 53 (37.7 %) operated patients. The only significant difference between the cases with and without RBBB was decreased right ventricular fractional area change (%) in the former group (33 ± 7 vs. 39 ± 5 p < 0.05). When compared to controls, operated group had statistically lower [corrected] tricuspid annular plane systolic excursion (p < 0.05), lower systolic, early diastolic, and late diastolic myocardial velocities, higher left and right ventricular myocardial performance indices, irrespective of the presence of RBBB. The ratios of mitral or tricuspid inflow to left or right ventricular myocardial in early diastolic velocities measured from lateral annular levels were increased in operated group (all p values <0.05). In conclusion, RBBB in the cases with surgical VSD repair might be associated with right ventricular dysfunction. Biventricular systolic and diastolic dysfunction may develop following VSD repair irrespective of the presence of RBBB. Tissue Doppler-derived myocardial performance indices are useful in detection of those subclinical dysfunctions.

  7. Spatiotemporal movement variability in ALS: Speaking rate effects on tongue, lower lip, and jaw motor control.

    Science.gov (United States)

    Kuruvilla-Dugdale, Mili; Mefferd, Antje

    2017-05-01

    Although it is frequently presumed that bulbar muscle degeneration in Amyotrophic Lateral Sclerosis (ALS) is associated with progressive loss of speech motor control, empirical evidence is limited. Furthermore, because speaking rate slows with disease progression and rate manipulations are used to improve intelligibility in ALS, this study sought to (i) determine between and within-group differences in articulatory motor control as a result of speaking rate changes and (ii) identify the strength of association between articulatory motor control and speech impairment severity. Ten talkers with ALS and 11 healthy controls repeated the target sentence at habitual, fast, and slow rates. The spatiotemporal variability index (STI) was calculated to determine tongue, lower lip, and jaw movement variability. During habitual speech, talkers with mild-moderate dysarthria displayed significantly lower tongue and lip movement variability whereas those with severe dysarthria showed greater variability compared to controls. Within-group rate effects were significant only for talkers with ALS. Specifically, lip and tongue movement variability significantly increased during slow speech relative to habitual and fast speech. Finally, preliminary associations between speech impairment severity and movement variability were moderate to strong in talkers with ALS. Between-group differences for habitual speech and within-group effects for slow speech replicated previous findings for lower lip and jaw movements. Preliminary findings of moderate to strong associations between speech impairment severity and STI suggest that articulatory variability may vary from pathologically low (possibly indicating articulatory compensation) to pathologically high variability (possibly indicating loss of control) with dysarthria progression in ALS. Copyright © 2017 Elsevier Inc. All rights reserved.

  8. Prevalence, Treatment, and Control Rates of Conventional and Ambulatory Hypertension Across 10 Populations in 3 Continents.

    Science.gov (United States)

    Melgarejo, Jesus D; Maestre, Gladys E; Thijs, Lutgarde; Asayama, Kei; Boggia, José; Casiglia, Edoardo; Hansen, Tine W; Imai, Yutaka; Jacobs, Lotte; Jeppesen, Jørgen; Kawecka-Jaszcz, Kalina; Kuznetsova, Tatiana; Li, Yan; Malyutina, Sofia; Nikitin, Yuri; Ohkubo, Takayoshi; Stolarz-Skrzypek, Katarzyna; Wang, Ji-Guang; Staessen, Jan A

    2017-07-01

    Hypertension is a major global health problem, but prevalence rates vary widely among regions. To determine prevalence, treatment, and control rates of hypertension, we measured conventional blood pressure (BP) and 24-hour ambulatory BP in 6546 subjects, aged 40 to 79 years, recruited from 10 community-dwelling cohorts on 3 continents. We determined how between-cohort differences in risk factors and socioeconomic factors influence hypertension rates. The overall prevalence was 49.3% (range between cohorts, 40.0%-86.8%) for conventional hypertension (conventional BP ≥140/90 mm Hg) and 48.7% (35.2%-66.5%) for ambulatory hypertension (ambulatory BP ≥130/80 mm Hg). Treatment and control rates for conventional hypertension were 48.0% (33.5%-74.1%) and 38.6% (10.1%-55.3%) respectively. The corresponding rates for ambulatory hypertension were 48.6% (30.5%-71.9%) and 45.6% (18.6%-64.2%). Among 1677 untreated subjects with conventional hypertension, 35.7% had white coat hypertension (23.5%-56.2%). Masked hypertension (conventional BP hypertension rates. Higher social and economic development, measured by the Human Development Index, was associated with lower rates of conventional and ambulatory hypertension. In conclusion, high rates of hypertension in all cohorts examined demonstrate the need for improvements in prevention, treatment, and control. Strategies for the management of hypertension should continue to not only focus on preventable and modifiable risk factors but also consider societal issues. © 2017 American Heart Association, Inc.

  9. Nap environment control considering respiration rate and music tempo by using sensor agent robot

    Science.gov (United States)

    Nakaso, Sayaka; Mita, Akira

    2015-03-01

    We propose a system that controls a nap environment considering respiration rates and music tempo by using a sensor agent robot. The proposed system consists of two sub-systems. The first sub-system measures respiration rates using optical flow. We conducted preparatory experiments to verify the accuracy of this sub-system. The experimental results showed that this sub-system can measure the respiration rates accurately despite several positional relationships. It was also shown that the accuracy could be affected by clothes, movements and light. The second sub-system we constructed was the music play sub-system that chooses music with the certain tempo corresponding to the respiration rates measured by the first sub-system. We conducted verification experiments to verify the effectiveness of this music play sub-system. The experimental results showed the effectiveness of varying music tempo based on the respiration rates in taking a nap. We also demonstrated this system in a real environment; a subject entered into the room being followed by ebioNα. When the subject was considered sleeping, ebioNα started measuring respiration rates, controlling music based on the respiration rates. As a result, we showed that this system could be realized. As a next step, we would like to improve this system to a nap environment control system to be used in offices. To realize this, we need to update the first sub-system measuring respiration rates by removing disturbances. We also need to upgrade music play sub-system considering the numbers of tunes, the kinds of music and time to change music.

  10. Galen and the ventricular system.

    Science.gov (United States)

    Rocca, J

    1997-12-01

    This paper examines the anatomy and physiology, together with the pathophysiology, of the ventricular system of the brain, as it was understood by arguably its greatest exponent in Western Antiquity, Galen. According to him, the purpose of the ventricles was to elaborate, store and distribute psychic pneuma, the motive force of Galenic neurology, throughout the nervous system. However, impressive as the delineation of the ventricular system is, the details of this distribution are not forthcoming from Galen. Finally, I discuss the ventricles as the site of intellect, a notion only tentatively advanced by Galen, but cast into dogma by his successors. For all the mistakes Galen made in anatomy and physiology, the study of the ventricular system reveals a mind not dissimilar to our own.

  11. Electronic circuit detects left ventricular ejection events in cardiovascular system

    Science.gov (United States)

    Gebben, V. D.; Webb, J. A., Jr.

    1972-01-01

    Electronic circuit processes arterial blood pressure waveform to produce discrete signals that coincide with beginning and end of left ventricular ejection. Output signals provide timing signals for computers that monitor cardiovascular systems. Circuit operates reliably for heart rates between 50 and 200 beats per minute.

  12. Assessment of left ventricular diastolic function in bronchial asthma ...

    African Journals Online (AJOL)

    Ehab

    a relevance of oral β2-AG to acute cardiac death8,9,10 and heart failure11,12. Children with acute severe asthma may ... also by age, heart rate, valvular disease, loading conditions, and contractility of both ventricular and ... up at the Chest clinic, the Children's Hospital, Ain. Shams University hospitals, and presenting in an.

  13. Right ventricular function assessment in single LAD lesion patients ...

    African Journals Online (AJOL)

    Rania Gaber

    2015-10-09

    Oct 9, 2015 ... Abstract Background: Strain and strain rate imaging is currently the most popular echocardio- graphic technique that reveals subclinical myocardial damage, and data are not available on this imaging method with regard to assessing right ventricular involvement in single LAD lesion. Aim: To evaluate right ...

  14. Early ventricular restraint after myocardial infarction: extent of the wrap determines the outcome of remodeling.

    Science.gov (United States)

    Enomoto, Yoshiharu; Gorman, Joseph H; Moainie, Sina L; Jackson, Benjamin M; Parish, Landi M; Plappert, Theodore; Zeeshan, Ahmad; St John-Sutton, Martin G; Gorman, Robert C

    2005-03-01

    Early infarct expansion initiates adverse remodeling, leads to left ventricular dilatation and portends a poor long-term outcome. Early mechanical prevention of infarct expansion has been proposed as a method to improve remodeling, but the extent of ventricular restraint necessary to optimize the salutary effect is not known. We tested the hypothesis that left ventricular restraint (wrap) is superior to infarct stiffening (patch). Infarction of 20% to 25% of the left ventricle was induced by coronary ligation in 69 sheep. Infarcts were either anteroapical (n = 33) or posterobasal (n = 36). Animals with each infarct received either no treatment (anteroapical, n = 26; posterobasal, n = 17), infarct stiffening with a localized Marlex mesh patch (posterobasal, n = 9) or left ventricular wrapping with Merseline mesh (anteroapical, n = 7; posterobasal, n = 10). End-systolic volume, end-diastolic volume, end-systolic muscle to cavity area ratio, left ventricular sphericity, ejection fraction, and degree of mitral regurgitation as determined by quantitative echocardiography were assessed before infarction and at 2, 5, and 8 weeks after infarction to evaluate the extent of left ventricular remodeling. Control animals in both groups experienced adverse remodeling. Anteroapical infarct animals developed large left ventricular aneurysms and the posterobasal infarct animals developed severe mitral regurgitation. Early infarct stiffening did not significantly improve any aspect of remodeling due to the posterobasal infarct. Early left ventricular wrapping significantly improved remodeling after both types of infarctions. Early left ventricular wrapping attenuates infarct expansion and has a salutary effect on remodeling. Simple infarct stiffening alone is not effective.

  15. A CMI (cell metabolic indicator)-based controller for achieving high growth rate Escherichia coli cultures.

    Science.gov (United States)

    Pepper, Matthew E; Wang, Li; Padmakumar, Ajay; Burg, Timothy C; Harcum, Sarah W; Groff, Richard E

    2014-01-01

    A large fraction of biopharmaceuticals are produced in Escherichia coli, where each new product and strain currently requires a high degree of growth characterization in benchtop and industrial bioreactors to achieve economical production protocols. The capability to use a standard set of sensors to characterize a system quickly without the need to conduct numerous experiments to determine stable growth rate for the strain would significantly decrease development time. This paper presents a cell metabolic indicator (CMI) which provides better insight into the E. coli metabolism than a growth rate value. The CMI is the ratio of the oxygen uptake rate (OUR) of the culture and the base addition rate (BAR) required to keep pH at a desired setpoint. The OUR and BAR are measured using a off-gas sensor and pH probe, respectively, and thus the CMI can be computed online. Experimental results demonstrate the relationship between CMI and the different cell metabolic states. A previously published model is augmented with acid production dynamics, allowing for comparison of the CMI-based controller with an open-loop controller in simulation. The CMI-based controller required little a priori knowledge about the E. coli strain in order to achieve a high growth rate. Since many different types of cells exhibit similar behaviors, the CMI concept can be extended to mammalian and stem cells.

  16. Metabolic rate control during extravehicular activity simulations and measurement techniques during actual EVAS

    Science.gov (United States)

    Horrigan, D. J.

    1975-01-01

    A description of the methods used to control and measure metabolic rate during ground simulations is given. Work levels attained at the Space Environment Simulation Laboratory are presented. The techniques and data acquired during ground simulations are described and compared with inflight procedures. Data from both the Skylab and Apollo Program were utilized and emphasis is given to the methodology, both in simulation and during flight. The basic techniques of work rate assessment are described. They include oxygen consumption, which was useful for averages over long time periods, heart rate correlations based on laboratory calibrations, and liquid cooling garment temperature changes. The relative accuracy of these methods as well as the methods of real-time monitoring at the Mission Control Center are discussed. The advantages and disadvantages of each of the metabolic measurement techniques are discussed. Particular emphasis is given to the problem of utilizing oxygen decrement for short time periods and heart rate at low work levels. A summary is given of the effectiveness of work rate control and measurements; and current plans for future EVA monitoring are discussed.

  17. Dual substrate feedback control of specific growth-rate in vaccine production

    NARCIS (Netherlands)

    Neeleman, R.; Beuvery, E.C.; Vries, D.; Straten, van G.; Boxtel, van A.J.B.

    2004-01-01

    Abstract: Unexpectedly, primary concern of bio-pharmaceutical industry is not optimisation of product yield or cost reduction, but consistency in production and product quality. This paper describes the methodology and experimental results of specific growth-rate control for vaccine production. The

  18. Physical activity, mindfulness meditation, or heart rate variability biofeedback for stress reduction: a randomized controlled trial

    NARCIS (Netherlands)

    van der Zwan, J.E.; de Vente, W.; Huizink, A.C.; Bögels, S.M.; de Bruin, E.I.

    2015-01-01

    In contemporary western societies stress is highly prevalent, therefore the need for stress-reducing methods is great. This randomized controlled trial compared the efficacy of self-help physical activity (PA), mindfulness meditation (MM), and heart rate variability biofeedback (HRV-BF) in reducing

  19. A Framework for Control System Design Subject to Average Data-Rate Constraints

    DEFF Research Database (Denmark)

    Silva, Eduardo; Derpich, Milan; Østergaard, Jan

    2011-01-01

    This paper studies discrete-time control systems subject to average data-rate limits. We focus on a situation where a noisy linear system has been designed assuming transparent feedback and, due to implementation constraints, a source-coding scheme (with unity signal transfer function) has to be ...

  20. A Position and Rate Control System: An Ingredient for Budget Planning.

    Science.gov (United States)

    Gilbert, Linda L.

    A position and rate control system was undertaken at Florida State University in 1974 to alleviate the problems of the manual budgeting system. The budget master file was created biweekly by combining a subset of the current payroll/personnel data base with the updated budget information from the previous budget master file, keying on positional…

  1. SLIP RATE ESTIMATION FOR VEHICLE STABILITY ENHANCEMENT USING FUZZY BASED ELECTRONIC DIFFERENTIAL CONTROLLER

    National Research Council Canada - National Science Library

    A. RAVI; S. PALANI

    2015-01-01

    .... To enhances the vehicle stability, the performances in terms of optimum value of slip rate and also current, torque, back EMF are obtained by the proposed method. By this investigation, a suitable control strategy has been identified and also experimentally validated.

  2. Tracking Controller for Intrinsic Output Saturated Systems in Presence of Amplitude and Rate Input Saturations

    DEFF Research Database (Denmark)

    Chater, E.; Giri, F.; Guerrero, Josep M.

    2014-01-01

    We consider the problem of controlling plants that are subject to multiple saturation constraints. Especially, we are interested in linear systems whose input is subject to amplitude and rate constraints of saturation type. Furthermore, the considered systems output is also subject to an intrinsi...

  3. Potassium supplementation and heart rate : A meta-analysis of randomized controlled trials

    NARCIS (Netherlands)

    Gijsbers, L.; Moelenberg, F. J. M.; Bakker, S. J. L.; Geleijnse, J. M.

    Background and aims: Increasing the intake of potassium has been shown to lower blood pressure, but whether it also affects heart rate (HR) is largely unknown. We therefore assessed the effect of potassium supplementation on HR in a meta-analysis of randomized controlled trials. Methods and results:

  4. A high-rate shape memory alloy actuator for aerodynamic load control on wind turbines

    NARCIS (Netherlands)

    Lara-Quintanilla, A.; Hulskamp, A.W.; Bersee, H.E.N.

    2013-01-01

    This paper discusses the development of a high rate shape memory alloy (SMA) driven actuator. The concept of the actuator was developed to act as aerodynamic load control surface on wind turbines. It was designed as a plate or beam-like structure with prestrained SMA wires embedded off its neutral

  5. Max-Min Optimality of Service Rate Control in Closed Queueing Networks

    KAUST Repository

    Xia, Li

    2013-04-01

    In this technical note, we discuss the optimality properties of service rate control in closed Jackson networks. We prove that when the cost function is linear to a particular service rate, the system performance is monotonic w.r.t. (with respect to) that service rate and the optimal value of that service rate can be either maximum or minimum (we call it Max-Min optimality); When the second-order derivative of the cost function w.r.t. a particular service rate is always positive (negative), which makes the cost function strictly convex (concave), the optimal value of such service rate for the performance maximization (minimization) problem can be either maximum or minimum. To the best of our knowledge, this is the most general result for the optimality of service rates in closed Jackson networks and all the previous works only involve the first conclusion. Moreover, our result is also valid for both the state-dependent and load-dependent service rates, under both the time-average and customer-average performance criteria.

  6. A review of control strategies for manipulating the feed rate in fed-batch fermentation processes

    DEFF Research Database (Denmark)

    Mears, Lisa; Stocks, Stuart M.; Sin, Gürkan

    2017-01-01

    A majority of industrial fermentation processes are operated in fed-batch mode. In this case, the rate of feed addition to the system is a focus for optimising the process operation, as it directly impacts metabolic activity, as well as directly affecting the volume dynamics in the system....... This review covers a range of strategies which have been employed to use the feed rate as a manipulated variable in a control strategy. The feed rate is chosen as the focus for this review, as it is seen that this variable may be used towards many different objectives depending on the process of interest......, the characteristics of the strain, or the product being produced, which leads to different drivers for process optimisation. This review summarises the methods, as well as focusing on the different objectives for the controllers, and the choice of measured variables involved in the strategy. The discussion includes...

  7. CRRT: Congestion-Aware and Rate-Controlled Reliable Transport in Wireless Sensor Networks

    Science.gov (United States)

    Alam, Muhammad Mahbub; Hong, Choong Seon

    For successful data collection in wireless sensor networks, it is important to ensure that the required delivery ratio is maintained while keeping a fair rate for every sensor. Furthermore, emerging high-rate applications might require complete reliability and the transfer of large volume of data, where persistent congestion might occur. These requirements demand a complete but efficient solution for data transport in sensor networks which reliably transports data from many sources to one or more sinks, avoids congestion and maintains fairness. In this paper, we propose congestion-aware and rate-controlled reliable transport (CRRT), an efficient and low-overhead data transport mechanism for sensor networks. CRRT uses efficient MAC retransmission to increase one-hop reliability and end-to-end retransmission for loss recovery. It also controls the total rate of the sources centrally, avoids the congestion in the bottleneck based on congestion notifications from intermediate nodes and centrally assigns the rate to the sources based on rate assignment policy of the applications. Performance of CRRT is evaluated in NS-2 and simulation results demonstrate the effectiveness of CRRT.

  8. Controllable deterioration rate for time-dependent demand and time-varying holding cost

    Directory of Open Access Journals (Sweden)

    Mishra Vinod Kumar

    2014-01-01

    Full Text Available In this paper, we develop an inventory model for non-instantaneous deteriorating items under the consideration of the facts: deterioration rate can be controlled by using the preservation technology (PT during deteriorating period, and holding cost and demand rate both are linear function of time, which was treated as constant in most of the deteriorating inventory models. So in this paper, we developed a deterministic inventory model for non-instantaneous deteriorating items in which both demand rate and holding cost are a linear function of time, deterioration rate is constant, backlogging rate is variable and depend on the length of the next replenishment, shortages are allowed and partially backlogged. The model is solved analytically by minimizing the total cost of the inventory system. The model can be applied to optimizing the total inventory cost of non-instantaneous deteriorating items inventory for the business enterprises, where the preservation technology is used to control the deterioration rate, and demand & holding cost both are a linear function of time.

  9. The evaluation of right ventricular performance using krypton-81m.

    Science.gov (United States)

    Ham, H R; Piepsz, A; Vandevivere, J; Guillaume, M; Goethals, P; Lenaers, A

    1983-06-01

    The availability of krypton-81m suitable for intravenous injection provides an easy means for assessing right ventricular function. The superimposition of the other heart chambers does not constitute a problem. The activity in the left heart is negligible and the study can be performed in the right anterior oblique position to obtain optimal separation between the right atrium and the right ventricle. Lung activity is quite high and should be corrected before computing the right ventricular ejection fraction. This correction can be accomplished by performing Tc-99m MAA perfusion scintigraphy. The measurement of the right ventricular ejection fraction appears to be reproducible with very small inter-and intraobserver variability. Good quality phase and amplitude images can be obtained with such high count rates.

  10. The evaluation of right ventricular performance using krypton-81m

    Energy Technology Data Exchange (ETDEWEB)

    Ham, H.R.; Piepsz, A.; Vandevivere, J.; Guillaume, M.; Goethals, P.; Lenaers, A.

    1983-06-01

    The availability of krypton-81m suitable for intravenous injection provides an easy means for assessing right ventricular function. The superimposition of the other heart chambers does not constitute a problem. The activity in the left heart is negligible and the study can be performed in the right anterior oblique position to obtain optimal separation between the right atrium and the right ventricle. Lung activity is quite high and should be corrected before computing the right ventricular ejection fraction. This correction can be accomplished by performing Tc-99m MAA perfusion scintigraphy. The measurement of the right ventricular ejection fraction appears to be reproducible with very small inter-and intraobserver variability. Good quality phase and amplitude images can be obtained with such high count rates.

  11. The role of inhibitory heterotrimeric G proteins in the control of in vivo heart rate dynamics

    Science.gov (United States)

    Zuberi, Zia; Birnbaumer, Lutz; Tinker, Andrew

    2008-01-01

    Multiple isoforms of inhibitory Gα-subunits (Gαi1,2,3, as well as Gαo) are present within the heart, and their role in modulating pacemaker function remains unresolved. Do inhibitory Gα-subunits selectively modulate parasympathetic heart rate responses? Published findings using a variety of experimental approaches have implicated roles for Gαi2, Gαi3, and Gαo in parasympathetic signal transduction. We have compared in vivo different groups of mice with global genetic deletion of Giα1/Gαi3, Gαi2, and Gαo against littermate controls using implanted ECG telemetry. Significant resting tachycardia was observed in Gαi2−/− and Gαo−/− mice compared with control and Gαi1−/−/Gαi3−/− mice (P heart rate variation was seen exclusively in Gαo−/− mice. Using heart rate variability (HRV) analysis, compared with littermate controls (4.02 ms2 ± 1.17; n = 6, Gαi2−/−) mice have a selective attenuation of high-frequency (HF) power (0.73 ms2 ± 0.31; n = 5, P heart rate was attenuated in Gαi2−/− mice (0.08 ± 0.04; n = 6) compared to control (0.27 ± 0.04; n = 7 P heart rate modulation in mice with Gαi2 deletion. Mice with Gαo deletion also have a defect in short-term heart rate dynamics, but this is qualitatively different to the effects of atropine, tertiapinQ, and Gαi2 deletion. In contrast, Gαi1 and Gαi3 do not appear to be essential for parasympathetic responses in vivo. PMID:18832081

  12. Genetics Home Reference: arrhythmogenic right ventricular cardiomyopathy

    Science.gov (United States)

    ... Twitter Home Health Conditions ARVC Arrhythmogenic right ventricular cardiomyopathy Printable PDF Open All Close All Enable Javascript ... the expand/collapse boxes. Description Arrhythmogenic right ventricular cardiomyopathy ( ARVC ) is a form of heart disease that ...

  13. Relationship of internal-external control and United States suicide rates, 1966-1973.

    Science.gov (United States)

    Boor, M

    1976-10-01

    The annual variations in scores obtained on the Rotter Internal-External (I-E) control scale by United States college students between the years 1966 and 1973 were related to the concomitant annual variations in suicide rates for the total United States population and for eight separate age groups. The I-E scores increased substantially during this time period and were correlated positively with the concomitantly increasing suicide rates among relatively young persons (in and below the 35-44 year age group). However, the suicide rates among older persons generally decreased during this time period and thus were correlated negatively with the I-E scores. These results suggest that perception of internal-external control did not change among older persons as they did among younger persons, perhaps because older persons might be less susceptible to the cultural influences that affect the perceived control of younger persons. Results of this and earlier research suggest that cultural characteristics that foster high perceptions of external control also foster suicidal behavior and suggest the value of attempts to convey perceptions of internal control to psychotherapy clients.

  14. Macrosomia Rates in Women with Diet-Controlled Gestational Diabetes: A Retrospective Study

    Directory of Open Access Journals (Sweden)

    Fatima Vally

    2017-01-01

    Full Text Available Background. Current data on the rates of macrosomia in women with gestational diabetes mellitus (GDM are heterogenous. No study has specifically examined macrosomia rates in women with diet-controlled gestational diabetes. Aims. To compare the rates of macrosomia between mothers with diet-controlled GDM to mothers without diabetes mellitus. Methods. A retrospective study in which all patients with diet-controlled GDM and singleton pregnancies in 2014 were considered for inclusion in the study. These cases were individually matched to mothers without GDM and without type 1 or 2 diabetes. Cases were matched to parity, age, and BMI. Controls were selected from the same year and as close as possible to the date of delivery of the case. Primary outcomes were macrosomia, defined by estimated fetal weight >90th centile and >95th centile (separately. Results. The estimated adjusted odds ratio for the presence of maternal GDM in the presence of EFW > 90th percentile (adjusted for maternal age, BMI, gravidity, parity, baby gender, and EGA was 0.63 (95% CI 0.30–1.3; P=0.21. The estimated adjusted odds ratio for the association of maternal GDM and EFW > 95th percentile was 0.66 (95% CI 0.26–1.7; P=0.38. Conclusions. Our findings suggest that macrosomia is not increased in women with diet-controlled GDM. The study registration number is AQA 16/01.

  15. Macrosomia Rates in Women with Diet-Controlled Gestational Diabetes: A Retrospective Study.

    Science.gov (United States)

    Vally, Fatima; Presneill, Jeffrey; Cade, Thomas

    2017-01-01

    Current data on the rates of macrosomia in women with gestational diabetes mellitus (GDM) are heterogenous. No study has specifically examined macrosomia rates in women with diet-controlled gestational diabetes. To compare the rates of macrosomia between mothers with diet-controlled GDM to mothers without diabetes mellitus. A retrospective study in which all patients with diet-controlled GDM and singleton pregnancies in 2014 were considered for inclusion in the study. These cases were individually matched to mothers without GDM and without type 1 or 2 diabetes. Cases were matched to parity, age, and BMI. Controls were selected from the same year and as close as possible to the date of delivery of the case. Primary outcomes were macrosomia, defined by estimated fetal weight >90th centile and >95th centile (separately). The estimated adjusted odds ratio for the presence of maternal GDM in the presence of EFW > 90th percentile (adjusted for maternal age, BMI, gravidity, parity, baby gender, and EGA) was 0.63 (95% CI 0.30-1.3; P = 0.21). The estimated adjusted odds ratio for the association of maternal GDM and EFW > 95th percentile was 0.66 (95% CI 0.26-1.7; P = 0.38). Our findings suggest that macrosomia is not increased in women with diet-controlled GDM. The study registration number is AQA 16/01.

  16. Microchannel system for rate-controlled, sequential, and pH-responsive drug delivery.

    Science.gov (United States)

    Yang, Dasom; Lee, Jung Seung; Choi, Chang-Kuk; Lee, Hong-Pyo; Cho, Seung-Woo; Ryu, WonHyoung

    2017-12-18

    Controlled delivery of drug at a constant rate, in a sequential order, or responsive to environment conditions has been pursued for a long time to enhance the efficacy of therapeutic molecules and to minimize side effects of highly potent drugs. However, achieving such delicately-controlled delivery of a drug molecule is non-trivial and still remains a challenge. We propose the use of microchannels to control the rate, sequence, and pH-responsiveness of drug delivery for high precision and predictability. In this study, we introduce elementary drug delivery units consisting of micro-reservoirs and microchannels that have variations in their lengths, widths, numbers, and straightness. The release study demonstrates that the release rates of model drugs can be modulated by the design of microchannels. Finite element modeling of drug release predicts the performance of the drug delivery units with high accuracy. The possibility of sequential drug delivery is also demonstrated using biodegradable polymer plug in microchannels. Finally, pH-responsive delivery of drugs in microfluidic units is also discussed and demonstrated via cell viability tests. In this work, we developed microchannel-based drug delivery devices whose release rate could be accurately calculated and controlled by design of microchannel geometry. Although there have been many advances in microfabricated drug delivery systems, in particular, reservoir-based systems, no systematic investigation has been made to utilize the release channels. In our work, an equivalent electrical circuit concept was applied to the microfluidic systems for more detailed design and analysis. A microfluidic channel was regarded as an electrical resistor; their diffusion/electrical flux could be tuned with geometric factors such as length, width, a number of channel/resistor and their connections. Furthermore, from delivery rate control using channel geometry, multifunctional channel-based release systems for sequential and p

  17. Effect of prolonged inotropic stimulation on ventricular remodeling during healing after myocardial infarction in the dog: mechanistic insights.

    Science.gov (United States)

    Jugdutt, B I; Khan, M I; Jugdutt, S J; Blinston, G E

    1996-06-01

    We hypothesized that positive inotropic stimulation during healing after myocardial infarction might increase contractile pull on the infarct segment, increase expansion and promote ventricular dilation. The effect of prolonged inotropic stimulation on left ventricular remodeling during healing after myocardial infarction has not been studied. The effects of 6 weeks of inotropic stimulation on in vivo changes in left ventricular topography, function and mass (serial two-dimensional echocardiograms), hemodynamic variables, postmortem topography (planimetry) and collagen (hydroxyproline content) were studied in 36 chronically instrumented dogs randomized, 2 days after small anterior infarction, to digoxin (0.125 mg daily) and no digoxin (control group). Heart rate and arterial and left atrial pressures were similar in the two groups, but the first derivative of left ventricular pressure (peak dP/dt), systolic thickening of the noninfarct wall and systolic thinning of the infarct wall were higher in the digoxin group during the 6 weeks. At 6 weeks, infarct scar size and collagen content were similar in both groups, but the digoxin group had more infarct expansion and thinning. Between 2 days and 6 weeks, the digoxin group showed more in vivo diastolic infarct expansion, thinning and bulging; more aneurysm but less global dilation and increase in mass; and no change in ejection fraction. The effects of inotropic stimulation on remodeling were more marked in infarcts with 100% than 85% transmurality. Prolonged inotropic stimulation with digoxin during healing after small anterior infarction increases infarct bulging without decreasing infarct collagen content and preserves global ventricular size, mass and systolic function.

  18. Controlling the Actuation Rate of Low-Density Shape-Memory Polymer Foams in Water

    Science.gov (United States)

    Singhal, Pooja; Boyle, Anthony; Brooks, Marilyn L.; Infanger, Stephen; Letts, Steve; Small, Ward; Maitland, Duncan J.; Wilson, Thomas S.

    2014-01-01

    SMPs have been shown to actuate below their dry glass transition temperatures in the presence of moisture due to plasticization. This behavior has been proposed as a self-actuating mechanism of SMPs in water/physiological media. However, control over the SMP actuation rate, a critical factor for in vivo transcatheter device delivery applications, has not been previously reported. Here, a series of polyurethane SMPs with systematically varied hydrophobicity is described that permits control of the time for their complete shape recovery in water from under 2 min to more than 24 h. This control over the SMP actuation rate can potentially provide significant improvement in their delivery under conditions, which may expose them to high-moisture environments prior to actuation. PMID:25530688

  19. Thermodynamic Characteristic Study of a High-temperature Flow-rate Control Valve for Fuel Supply of Scramjet Engines

    National Research Council Canada - National Science Library

    ZENG Wen TONG Zhizhong LI Songjing LI Hongzhou ZHANG Liang

    2012-01-01

    ... and increasing of leakage,to the valve.In this paper,a high-temperature flow-rate control valve,pilot-controlled by a pneumatic servo system is developed to control the fuel supply for scramjet...

  20. Growth rate controls mRNA turnover in steady and non-steady states.

    Science.gov (United States)

    García-Martínez, José; Troulé, Kevin; Chávez, Sebastián; Pérez-Ortín, José E

    2016-12-01

    Gene expression has been investigated in relation with growth rate in the yeast Saccharomyces cerevisiae, following different experimental strategies. The expression of some specific gene functional categories increases or decreases with growth rate. Our recently published results have unveiled that these changes in mRNA concentration with growth depend on the relative alteration of mRNA synthesis and decay, and that, in addition to this gene-specific transcriptomic signature of growth, global mRNA turnover increases with growth rate. We discuss here these results in relation with other previous and concurrent publications, and we add new evidence which indicates that growth rate controls mRNA turnover even under non-steady-state conditions.

  1. Hydrodynamic size distribution of gold nanoparticles controlled by repetition rate during pulsed laser ablation in water

    Science.gov (United States)

    Menéndez-Manjón, Ana; Barcikowski, Stephan

    2011-02-01

    Most investigations on the laser generation and fragmentation of nanoparticles focus on Feret particle size, although the hydrodynamic size of nanoparticles is of great importance, for example in biotechnology for diffusion in living cells, or in engineering, for a tuned rheology of suspensions. In this sense, the formation and fragmentation of gold colloidal nanoparticles using femtosecond laser ablation at variable pulse repetition rates (100-5000 Hz) in deionized water were investigated through their plasmon resonance and hydrodynamic diameter, measured by Dynamic Light Scattering. The increment of the repetition rate does not influence the ablation efficiency, but produces a decrease of the hydrodynamic diameter and blue-shift of the plasmon resonance of the generated gold nanoparticles. Fragmentation, induced by inter-pulse irradiation of the colloids was measured online, showing to be more effective low repetition rates. The pulse repetition rate is shown to be an appropriate laser parameter for hydrodynamic size control of nanoparticles without further influence on the production efficiency.

  2. Topographic control and accumulation rate of some Holocene coral reefs: south Florida and Dry Tortugas

    Science.gov (United States)

    Shinn, E.A.; Hudson, J.H.; Halley, R.B.; Lidz, B.H.; Taylor, D.L.

    1977-01-01

    Core drilling and examination of underwater excavation on 6 reef sites in south Florida and Dry Tortugas revealed that underlying topography is the major factor controlling reef morphology. Carbon-14 dating on coral recovered from cores enables calculation of accumulation rates. Accumulation rates were found to range from 0.38 m/1000 years in thin Holocene reefs to as much as 4.85 m/1000 years in thicker buildups. Cementation and alteration of corals were found to be more pronounced in areas of low buildup rates than in areas of rapid accumulation rates. Acropora palmata, generally considered the major reef builder in Florida, was found to be absent in most reefs drilled. At Dry Tortugas, the more than 13-meter thick Holocene reef did not contain A. palmata. The principal reef builders in this outer reef are the same as those which built the Pleistocene Key Largo formation, long considered to be fossilized patch reef complex.

  3. Use of azithromycin and risk of ventricular arrhythmia.

    Science.gov (United States)

    Trifirò, Gianluca; de Ridder, Maria; Sultana, Janet; Oteri, Alessandro; Rijnbeek, Peter; Pecchioli, Serena; Mazzaglia, Giampiero; Bezemer, Irene; Garbe, Edeltraut; Schink, Tania; Poluzzi, Elisabetta; Frøslev, Trine; Molokhia, Mariam; Diemberger, Igor; Sturkenboom, Miriam C J M

    2017-04-18

    There are conflicting findings from observational studies of the arrhythrogenic potential of azithromycin. Our aim was to quantify the association between azithromycin use and the risk of ventricular arrhythmia. We conducted a nested case-control study within a cohort of new antibiotic users identified from a network of 7 population-based health care databases in Denmark, Germany, Italy, the Netherlands and the United Kingdom for the period 1997-2010. Up to 100 controls per case were selected and matched by age, sex and database. Recency of antibiotic use and type of drug (azithromycin was the exposure of interest) at the index date (occurrence of ventricular arrhythmia) were identified. We estimated the odds of ventricular arrhythmia associated with current azithromycin use relative to current amoxicillin use or nonuse of antibiotics (≥ 365 d without antibiotic exposure) using conditional logistic regression, adjusting for confounders. We identified 14 040 688 new antibiotic users who met the inclusion criteria. Ventricular arrhythmia developed in 12 874, of whom 30 were current azithromycin users. The mean age of the cases and controls was 63 years, and two-thirds were male. In the pooled data analyses across databases, azithromycin use was associated with an increased risk of ventricular arrhythmia relative to nonuse of antibiotics (adjusted odds ratio [OR] 1.97, 95% confidence interval [CI] 1.35-2.86). This increased risk disappeared when current amoxicillin use was the comparator (adjusted OR 0.90, 95% CI 0.48-1.71). Database-specific estimates and meta-analysis confirmed results from the pooled data analysis. Current azithromycin use was associated with an increased risk of ventricular arrhythmia when compared with nonuse of antibiotics, but not when compared with current amoxicillin use. The decreased risk with an active comparator suggests significant confounding by indication. © 2017 Canadian Medical Association or its licensors.

  4. Left ventricular remodeling and torsion dynamics in hypertensive patients.

    Science.gov (United States)

    Cameli, Matteo; Lisi, Matteo; Righini, Francesca Maria; Massoni, Alberto; Mondillo, Sergio

    2013-01-01

    Left ventricular (LV) torsion is a fundamental component of wall motion and plays an important role to optimize ventricular ejection fraction. The aim of our study was to calculate by speckle tracking echocardiography LV twist angle in patients with hypertension and LV remodeling, analyzing torsional indices in all patterns of hypertrophy, in comparison to torsional dynamics of age-matched healthy subjects. Hypertensive patients (n = 202) were divided in three groups, patients with concentric remodeling (n = 70), concentric hypertrophy (n = 68) and eccentric hypertrophy (n = 64), in relation to the echocardiographic measurements of relative wall thickness and LV mass, analyzing their torsional patterns by speckle tracking in comparison to age-matched control group. Compared to healthy controls, LV twist angle was increased in patients with hypertension and concentric remodeling (15.2° ± 1.9° vs. 11.0° ± 1.6°; p < 0.001), reaching the highest value in patients with concentric hypertrophy (19.4° ± 2.6°); instead LV twist angle presented depressed in the group of patients that presented eccentric hypertrophy (5.0° ± 1.1°). Regarding LV untwisting rate, it was higher in the concentric remodeling and concentric hypertrophy groups (-123.1°/s ± 12.1°/s and -145.1°/s ± 15.5°/s, respectively) in comparison with the controls (-90.0°/s ± 10.1°/s; p < 0.0001 for both). Instead, lower values of LV untwisting rate were observed in the eccentric remodeling group (-81.6°/s ± 8.1°/s), not significantly different to controls' values (p = 0.09). Enhanced LV twist angle appears to be a compensatory mechanism in hypertensive patients during the earlier stages of concentric remodeling and concentric hypertrophy; this hyper-torsion is inevitably loss in the more advanced stage of eccentric hypertrophy.

  5. Normal ranges of left ventricular strain: a meta-analysis.

    Science.gov (United States)

    Yingchoncharoen, Teerapat; Agarwal, Shikhar; Popović, Zoran B; Marwick, Thomas H

    2013-02-01

    The definition of normal values of left ventricular global longitudinal strain (GLS), global circumferential strain, and global radial strain is of critical importance to the clinical application of this modality. The investigators performed a meta-analysis of normal ranges and sought to identify factors that contribute to reported variations. MEDLINE, Embase, and the Cochrane Library database were searched through August 2011 using the key terms "strain," "speckle tracking," "left ventricle," and "echocardiography" and related phrases. Studies were included if the articles reported left ventricular strain using two-dimensional speckle-tracking echocardiography in healthy normal subjects, either in the control group or as a primary objective of the study. Data were combined using a random-effects model, and effects of demographic, hemodynamic, and equipment variables were sought in a meta-regression. The search identified 2,597 subjects from 24 studies. Reported normal values of GLS varied from -15.9% to -22.1% (mean, -19.7%; 95% CI, -20.4% to -18.9%). Normal global circumferential strain varied from -20.9% to -27.8% (mean, -23.3%; 95% CI, -24.6% to -22.1%). Global radial strain ranged from 35.1% to 59.0% (mean, 47.3%; 95% CI, 43.6% to 51.0%). There was significant between-study heterogeneity and inconsistency. The source of variation was sought between studies using meta-regression. Blood pressure, but not age, gender, frame rate, or equipment, was associated with variation in normal GLS values. The narrowest confidence intervals from this meta-analysis were for GLS and global circumferential strain, but individual studies have shown a broad range of strain in apparently normal subjects. Variations between different normal ranges seem to be associated with differences in systolic blood pressure, emphasizing that this should be considered in the interpretation of strain. Copyright © 2013 American Society of Echocardiography. Published by Mosby, Inc. All rights

  6. Improving participation rates by providing choice of participation mode: two randomized controlled trials.

    Science.gov (United States)

    Heijmans, Naomi; van Lieshout, Jan; Wensing, Michel

    2015-04-02

    Low participation rates reduce effective sample size, statistical power and can increase risk for selection bias. Previous research suggests that offering choice of participation mode can improve participation rates. However, few head-to-head trials compared choice of participation mode using telephone interviews and postal questionnaires as modes of interest. Aiming to explore effects of choice of participation, two randomized controlled trials were performed comparing participation rates of patients provided with and without choice of participation mode, using interviews and questionnaires as participation modes. Two trials were embedded in a larger study on cardiovascular risk management in primary care. Patients with a chronic cardiovascular condition recruited for the larger study were invited to participate in an additional survey on social networks, using invitations with and without choice of participation mode. Primary outcome was participation rate. Other outcomes of interest were participation rate conditional on willingness to participate, and initial willingness to participate. In trial 1 we compared outcomes after choice of participation mode (interview or questionnaire) with invitations for participation in a telephone interview. In Trial 2 results for choice of participation mode were compared with postal questionnaires. In Trial 1 no differences were found in participation rates (65% vs 66%, p = 0.853) although conditional participation rate was highest for interviews (90% vs 72%, p choice of participation mode was provided (90% versus 73%, p choice of participation mode was provided (59% vs 46%, p choice of participation mode had benefit on participation rates compared to invitations to participate in questionnaires, but not when compared to invitations to participate in telephone interviews. Current Controlled Trials ISRCTN89237105 .

  7. Model for end-stage liver disease predicts right ventricular failure in patients with left ventricular assist devices.

    Science.gov (United States)

    Yost, Gardner L; Coyle, Laura; Bhat, Geetha; Tatooles, Antone J

    2016-03-01

    High rates of right ventricular failure continue to affect postoperative outcomes in patients implanted with left ventricular assist devices (LVADs). Development of right ventricular failure and implantation with right ventricular assist devices is known to be associated with significantly increased mortality. The model for end-stage liver disease (MELD) score is an effective means of evaluating liver dysfunction. We investigated the prognostic utility of postoperative MELD on post-LVAD implantation outcomes. MELD scores, demographic data, and outcomes including length of stay, survival, and postoperative right ventricular failure were collected for 256 patients implanted with continuous flow LVADs. Regression and Kaplan-Meier analyses were used to investigate the relationship between MELD and all outcomes. Increased MELD score was found to be an independent predictor of both right heart failure and necessity for RVAD implantation (OR 1.097, CI 1.040-1.158, p = 0.001; OR 1.121, CI 1.015, p = 0.024, respectively). Patients with RV failure and who underwent RVAD implantation had reduced postoperative survival compared to patients with RV dysfunction (no RV failure = 651.4 ± 609.8 days, RV failure = 392.6 ± 444.8 days, RVAD = 89.3 ± 72.8 days; p < 0.001). In conclusion, MELD can be used to reliably predict postoperative right heart failure and the necessity for RVAD implantation. Those patients with RV failure and RVADs experience significantly increased postoperative mortality compared to those without RV dysfunction.

  8. Attenuated ventricular β-adrenergic response and reduced repolarization reserve in a rabbit model of chronic heart failure

    DEFF Research Database (Denmark)

    Nissen, Jakob Dahl; Thomsen, Morten Bækgaard; Bentzen, Bo Hjorth

    2012-01-01

    Animal models of pacing-induced heart failure (HF) are often associated with high acute mortality secondary to high pacing frequencies. The present study therefore exploits lower-frequency left ventricular pacing (300 beats per minute) in rabbits for 11 weeks to produce chronic HF with low acute...... in paced animals. Ventricular arrhythmias or sudden death was not observed. Isoproterenol increased heart rate similarly in both groups but showed a blunted QT-shortening effect in tachypaced rabbits compared with controls. Langendorff experiments revealed significant monophasic action potential duration...... prolonged monophasic action potential duration and increased short-term variability of repolarization in tachypaced hearts. A blunted monophasic action potential duration response was observed ex vivo in tachypaced hearts after isoproterenol. The HF rabbits showed structural, functional, and electrical...

  9. The long-term corrosion behavior of titanate ceramics for Pu disposition : rate-controlling processes.

    Energy Technology Data Exchange (ETDEWEB)

    Bakel, A. J.; Mertz, C. J.; Hash, M. C.; Chamberlain, D. C.

    1999-12-02

    The corrosion behavior of a titanate ceramic was investigated with the aim of describing the rate-controlling process or processes. These titanate ceramics are similar to SYNROC and are proposed as immobilization materials for surplus Pu. The corrosion behavior was described with results from MCC-I and PCT-B static dissolution tests. Three important observations were made: (a) Ca is released at a constant rate [6x10{sup -5}g/(m{sup 2} day)] in PCT-B tests for up to two years, (b) all of the test leachates are oversaturated with respect to rutile and anatase, and (c) the release rates for Pu and Gd increase with time (up to two years) in PCT-B tests. The first observation suggests that the ceramics continue to corrode at a low rate for at least 2 years in PCT-B tests. The second observation shows that the rate of the corrosion reaction is not affected by the concentration of Ti in solution, suggesting that the approach to saturation with respect to either rutile or anatase is not a rate-limiting process. The third observation shows that the rate of Pu and Gd release increases with time in these tests. While this observation cannot be fully explained at this point, two possible explanations, alteration phase formation and grain boundary corrosion, are forwarded.

  10. Robust and Optimal Control of Magnetic Microparticles inside Fluidic Channels with Time-Varying Flow Rates

    Directory of Open Access Journals (Sweden)

    Islam S.M. Khalil

    2016-06-01

    Full Text Available Targeted therapy using magnetic microparticles and nanoparticles has the potential to mitigate the negative side-effects associated with conventional medical treatment. Major technological challenges still need to be addressed in order to translate these particles into in vivo applications. For example, magnetic particles need to be navigated controllably in vessels against flowing streams of body fluid. This paper describes the motion control of paramagnetic microparticles in the flowing streams of fluidic channels with time-varying flow rates (maximum flow is 35 ml.hr−1. This control is designed using a magnetic-based proportional-derivative (PD control system to compensate for the time-varying flow inside the channels (with width and depth of 2 mm and 1.5 mm, respectively. First, we achieve point-to-point motion control against and along flow rates of 4 ml.hr−1, 6 ml.hr−1, 17 ml.hr−1, and 35 ml.hr−1. The average speeds of single microparticle (with average diameter of 100 μm against flow rates of 6 ml.hr−1 and 30 ml.hr−1 are calculated to be 45 μm.s−1 and 15 μm.s−1, respectively. Second, we implement PD control with disturbance estimation and compensation. This control decreases the steady-state error by 50%, 70%, 73%, and 78% at flow rates of 4 ml.hr−1, 6 ml.hr−1, 17 ml.hr−1, and 35 ml.hr−1, respectively. Finally, we consider the problem of finding the optimal path (minimal kinetic energy between two points using calculus of variation, against the mentioned flow rates. Not only do we find that an optimal path between two collinear points with the direction of maximum flow (middle of the fluidic channel decreases the rise time of the microparticles, but we also decrease the input current that is supplied to the electromagnetic coils by minimizing the kinetic energy of the microparticles, compared to a PD control with disturbance compensation.

  11. Risk Management of Interest Rate Derivative Portfolios: A Stochastic Control Approach

    Directory of Open Access Journals (Sweden)

    Konstantinos Kiriakopoulos

    2014-10-01

    Full Text Available In this paper we formulate the Risk Management Control problem in the interest rate area as a constrained stochastic portfolio optimization problem. The utility that we use can be any continuous function and based on the viscosity theory, the unique solution of the problem is guaranteed. The numerical approximation scheme is presented and applied using a single factor interest rate model. It is shown how the whole methodology works in practice, with the implementation of the algorithm for a specific interest rate portfolio. The recent financial crisis showed that risk management of derivatives portfolios especially in the interest rate market is crucial for the stability of the financial system. Modern Value at Risk (VAR and Conditional Value at Risk (CVAR techniques, although very useful and easy to understand, fail to grasp the need for on-line controlling and monitoring of derivatives portfolio. The portfolios should be designed in a way that risk and return be quantified and controlled in every possible state of the world. We hope that this methodology contributes towards this direction.

  12. [Heart-minute volume during persistent ventricular tachycardia: anti-arrhythmia intervention using ajmaline].

    Science.gov (United States)

    Mletzko, R; Jung, W; Manz, M; Lüderitz, B

    1991-07-01

    The hemodynamic effect of the intravenous application of ajmaline (50 mg) was studied during persistent ventricular tachycardia. With the onset of ventricular tachycardia an increase of heart rate up to 177 +/- 40 bpm and a simultaneous decrease of cardiac output from 7.1 +/- 2.7 l/min to 3.4 +/- 1.1 l/min (p less than 0.001) could be demonstrated. Ajmaline prolonged the QRS interval and slowed the ventricular tachycardia rate to 133 +/- 28 bpm. Simultaneously, an increase of cardiac output to 5.9 +/- 2.3 l/min (p less than 0.001) could be documented. A significant correlation between the increase of cardiac output and the change of ventricular tachycardia rate was found. A drug-induced termination of ventricular tachycardia by ajmaline was possible in 60% of patients. Intravenous application of ajmaline during persistent ventricular tachycardia leads to a hemodynamic improvement caused by the reduction of the tachycardia rate. This temporary stabilization of the hemodynamic status is important for emergency treatment of ventricular tachycardia.

  13. Heart monitoring using left ventricle impedance and ventricular electrocardiography in left ventricular assist device patients.

    Science.gov (United States)

    Her, Keun; Ahn, Chi Bum; Park, Sung Min; Choi, Seong Wook

    2015-03-21

    Patients who develop critical arrhythmia during left ventricular assist device (LVAD) perfusion have a low survival rate. For diagnosis of unexpected heart abnormalities, new heart-monitoring methods are required for patients supported by LVAD perfusion. Ventricular electrocardiography using electrodes implanted in the ventricle to detect heart contractions is unsuitable if the heart is abnormal. Left ventricular impedance (LVI) is useful for monitoring heart movement but does not show abnormal action potential in the heart muscle. To detect detailed abnormal heart conditions, we obtained ventricular electrocardiograms (v-ECGs) and LVI simultaneously in porcine models connected to LVADs. In the porcine models, electrodes were set on the heart apex and ascending aorta for real-time measurements of v-ECGs and LVI. As the carrier current frequency of the LVI was adjusted to 30 kHz, it was easily derived from the original v-ECG signal by using a high-pass filter (cutoff: 10 kHz). In addition, v-ECGs with a frequency band of 0.1 - 120 Hz were easily derived using a low-pass filter. Simultaneous v-ECG and LVI data were compared to detect heart volume changes during the Q-T period when the heart contracted. A new real-time algorithm for comparison of v-ECGs and LVI determined whether the porcine heartbeats were normal or abnormal. Several abnormal heartbeats were detected using the LVADs operating in asynchronous mode, most of which were premature ventricle contractions (PVCs). To evaluate the accuracy of the new method, the results obtained were compared to normal ECG data and cardiac output measured simultaneously using commercial devices. The new method provided more accurate detection of abnormal heart movements. This method can be used for various heart diseases, even those in which the cardiac output is heavily affected by LVAD operation.

  14. Suboccipital decompression enhances heart rate variability indices of cardiac control in healthy subjects.

    Science.gov (United States)

    Giles, Paul D; Hensel, Kendi L; Pacchia, Christina F; Smith, Michael L

    2013-02-01

    Osteopathic manipulative treatment (OMT) focused on the upper cervical spine is theorized to affect the function of the vagus nerve and thereby influence the parasympathetic branch of the autonomic nervous system. This study was designed to determine the acute effect of upper cervical spine manipulation on cardiac autonomic control as measured by heart rate variability. Nineteen healthy, young adult subjects underwent three different experimental interventions administered in random order: cervical OMT, sham manipulation, and time control. Six minutes of electrocardiographic data were collected before and after each intervention, and heart rate variability was assessed by both time-domain and frequency-domain measures. No differences in resting heart rate or any measure of heart rate variability were observed between the baseline periods prior to each intervention. The OMT protocol resulted in an increase in the standard deviation of the normal-to-normal intervals (0.12±0.082 seconds, p0.11 for all variables). These data support the hypothesis that upper cervical spine manipulation can acutely affect measures of heart rate variability in healthy individuals.

  15. Modeling of Amiodarone Effect on Heart Rate Control in Critically Ill Patients with Atrial Tachyarrhythmias.

    Science.gov (United States)

    Salem, Joe-Elie; El-Aissaoui, Maria; Alazard, Margaux; Hulot, Jean-Sébastien; Aissaoui, Nadia; Le-Heuzey, Jean-Yves; Funck-Brentano, Christian; Faisy, Christophe; Urien, Saik

    2016-08-01

    Amiodarone is the gold-standard medication to control heart rate in critically ill patients with atrial tachyarrhythmias (ATs); however, effective doses and covariates influencing its efficacy remain unknown. We therefore performed pharmacodynamic modeling of heart rate reduction induced by amiodarone in these patients. This observational study included 80 consecutive severely ill patients receiving amiodarone to treat ATs. A total of 1348 time-heart rate observations with 361 amiodarone dose administrations were analyzed during a period of up to 6 days after hospital treatment initiation using a nonlinear mixed-effect model. Pretreatment with amiodarone before intensive care administration, paroxysmal versus persistent AT, catecholamine infusion, and fluid and magnesium loading were among the covariates assessed in the model. In case of paroxysmal AT in a patient not pretreated with amiodarone, a 300 mg intravenous loading dose combined with an 800 mg oral dose on the first day, followed by 800 mg/day orally for 4 days was effective in achieving a heart rate between 80 and 115 bpm within the first day, and to maintain it during the next 4 days. Corresponding doses were twice as high in patients with persistent AT. Use of intravenous magnesium (p amiodarone required to control heart rate is influenced by the type of AT and by other easily measurable conditions which may allow better individualization of amiodarone dosing.

  16. Leak Rate Quantification Method for Gas Pressure Seals with Controlled Pressure Differential

    Science.gov (United States)

    Daniels, Christopher C.; Braun, Minel J.; Oravec, Heather A.; Mather, Janice L.; Taylor, Shawn C.

    2015-01-01

    An enhancement to the pressure decay leak rate method with mass point analysis solved deficiencies in the standard method. By adding a control system, a constant gas pressure differential across the test article was maintained. As a result, the desired pressure condition was met at the onset of the test, and the mass leak rate and measurement uncertainty were computed in real-time. The data acquisition and control system were programmed to automatically stop when specified criteria were met. Typically, the test was stopped when a specified level of measurement uncertainty was attained. Using silicone O-ring test articles, the new method was compared with the standard method that permitted the downstream pressure to be non-constant atmospheric pressure. The two methods recorded comparable leak rates, but the new method recorded leak rates with significantly lower measurement uncertainty, statistical variance, and test duration. Utilizing this new method in leak rate quantification, projects will reduce cost and schedule, improve test results, and ease interpretation between data sets.

  17. Suboccipital Decompression Enhances Heart Rate Variability Indices of Cardiac Control in Healthy Subjects

    Science.gov (United States)

    Giles, Paul D.; Hensel, Kendi L.; Pacchia, Christina F.

    2013-01-01

    Abstract Objectives Osteopathic manipulative treatment (OMT) focused on the upper cervical spine is theorized to affect the function of the vagus nerve and thereby influence the parasympathetic branch of the autonomic nervous system. This study was designed to determine the acute effect of upper cervical spine manipulation on cardiac autonomic control as measured by heart rate variability. Design Nineteen healthy, young adult subjects underwent three different experimental interventions administered in random order: cervical OMT, sham manipulation, and time control. Six minutes of electrocardiographic data were collected before and after each intervention, and heart rate variability was assessed by both time-domain and frequency-domain measures. Results No differences in resting heart rate or any measure of heart rate variability were observed between the baseline periods prior to each intervention. The OMT protocol resulted in an increase in the standard deviation of the normal-to-normal intervals (0.12±0.082 seconds, p0.11 for all variables). Conclusions These data support the hypothesis that upper cervical spine manipulation can acutely affect measures of heart rate variability in healthy individuals. PMID:22994907

  18. Treating critical supraventricular and ventricular arrhythmias

    Directory of Open Access Journals (Sweden)

    Trappe Hans-Joachim

    2010-01-01

    Full Text Available Atrial fibrillation (AF, atrial flutter, AV-nodal reentry tachycardia with rapid ventricular response, atrial ectopic tachycardia and preexcitation syndromes combined with AF or ventricular tachyarrhythmias (VTA are typical arrhythmias in intensive care patients (pts. Most frequently, the diagnosis of the underlying arrhythmia is possible from the physical examination (PE, the response to maneuvers or drugs and the 12-lead surface electrocardiogram. In unstable hemodynamics, immediate DC-cardioversion is indicated. Conversion of AF to sinus rhythm (SR is possible using antiarrhythmic drugs. Amiodarone has a conversion rate in AF of up to 80%. Ibutilide represents a class III antiarrhythmic agent that has been reported to have conversion rates of 50-70%. Acute therapy of atrial flutter (Aflut in intensive care pts depends on the clinical presentation. Atrial flutter can most often be successfully cardioverted to SR with DC-energies < 50 joules. Ibutilide trials showed efficacy rates of 38-76% for conversion of Aflut to SR compared to conversion rates of 5-13% when intravenous flecainide, propafenone or verapamil was administered. In addition, high dose (2 mg of ibutilide was more effective than sotalol (1.5 mg/kg in conversion of Aflut to SR (70 versus 19%. Drugs like procainamide, sotalol, amiodarone or magnesium were recommended for treatment of VTA in intensive care pts. However, only amiodarone is today the drug of choice in VTA pts and also highly effective even in pts with defibrillation-resistant out-of-hospital cardiac arrest (CA. There is a general agreement that bystander first aid, defibrillation and advanced life support is essential for neurologic outcome in pts after cardiac arrest due to VTA. Public access defibrillation in the hands of trained laypersons seems to be an ideal approach in the treatment of ventricular fibrillation (VF. The use of automatic external defibrillators (AEDs by basic life support ambulance providers or

  19. Atrial fibrillation: what have recent trials taught us regarding pharmacologic management of rate and rhythm control?

    Science.gov (United States)

    Reiffel, James A

    2011-02-01

    The management of atrial fibrillation (AF) focuses on control of heart rate, correction of rhythm disturbance, prophylaxis of thromboembolism, treatment of underlying disorders, and pathophysiologic mechanisms, and more recently on costs, hospitalizations, and other AF consequences. The goals of therapy are to reduce morbidity and mortality and improve quality of life (QOL). Several large studies have examined the relative efficacy of rhythm- versus rate-control strategies with respect to these outcomes, and have largely failed to demonstrate a survival advantage with either approach by intention-to-treat analysis--both in patients with and without heart failure (HF). However, the results do not support the hypothesis that rate control is preferable as first-line therapy for AF with respect to survival and do not disprove the hypothesis that maintenance of sinus rhythm is preferable to the continuation of AF, particularly if rate control fails to restore adequate QOL or if selective approaches are employed. Many post hoc analyses and substudies have assessed QOL, functional status, and exercise tolerance, with the majority demonstrating important benefits associated with achievement of rhythm control. Moreover, some subanalyses and additional trials have suggested that sinus rhythm can be associated with longer survival, including in patients with HF. In addition, ATHENA demonstrated that a drug, dronedarone, could improve the composite endpoint of cardiovascular hospitalizations and all-cause mortality in a carefully selected, high-risk, nonpermanent AF population, in addition to its recognized reduction in AF. This review examines the clinical outcomes of several important AF trials, discusses the limitations in applying the major morbidity/mortality findings to everyday clinical practice, and summarizes the lessons learned. ©2010, The Author. Journal compilation ©2010 Wiley Periodicals, Inc.

  20. Depression, anxiety, and heart rate variability: A case-control study in Taiwan

    Directory of Open Access Journals (Sweden)

    Li-Fen Chen

    2014-01-01

    Full Text Available Objective: Decreased heart rate variability (HRV has been reported in persons with major depressive disorder (MDD, but the results obtained are inconsistent. Little is known about the impact of comorbid anxiety disorders on HRV in MDD patients. Both issues necessitate further investigation. Materials and Methods: Forty-nine unmedicated, physically healthy, MDD patients without comorbidity, 21 MDD patients with comorbid generalized anxiety disorder (GAD, 24 MDD patients with comorbid panic disorder (PD, and 81 matched controls were recruited. The Hamilton Depression Rating Scale and the Hamilton Anxiety Rating Scale are employed to assess the severity of depression and anxiety, respectively. The cardiac autonomic function was evaluated by measuring the HRV parameters. The frequency-domain indices of HRV were obtained. Results: MDD patients without comorbidity had lower high-frequency (HF-HRV (which reflected vagal control of HRV than controls. Any comorbid anxiety disorder (GAD or PD was associated with significantly faster heart rates, relative to the controls, and caused greater reductions in HF-HRV among MDD patients. MDD participants with comorbid GAD displayed the greatest reductions in HF-HRV, relative to controls. Correlation analyses revealed that the severity of both depression and anxiety were significantly associated with the mean R wave to R wave (R-R intervals, variance, low-frequency (LF-HRV, and HF-HRV. Conclusion: The present results show decreased HRV in MDD patients, suggesting that reduction in HRV is a psychophysiological marker of MDD. MDD patients with comorbid GAD had the greatest reductions in HRV. Further investigation of the links between MDD and comorbid GAD, HRV, and cardiovascular disease is warranted.

  1. Autonomic control of heart rate by metabolically sensitive skeletal muscle afferents in humans

    DEFF Research Database (Denmark)

    Fisher, James P; Seifert, Thomas; Hartwich, Doreen

    2010-01-01

    Isolated activation of metabolically sensitive skeletal muscle afferents (muscle metaboreflex) using post-exercise ischaemia (PEI) following handgrip partially maintains exercise-induced increases in arterial blood pressure (BP) and muscle sympathetic nerve activity (SNA), while heart rate (HR...... of cardiac parasympathetic reactivation on heart rate....... moderate (PEI-M) and high (PEI-H) intensity isometric handgrip performed at 25% and 40% maximum voluntary contraction, under control (no drug), parasympathetic blockade (glycopyrrolate) and beta-adrenergic blockade (metoprolol or propranalol) conditions, while beat-to-beat HR and BP were continuously...

  2. Right ventricular involvement in feline hypertrophic cardiomyopathy.

    Science.gov (United States)

    Schober, K E; Savino, S I; Yildiz, V

    2016-12-01

    To evaluate right ventricular (RV) wall thickness and chamber dimensions in cats with hypertrophic cardiomyopathy (HCM). One hundred fifty-one healthy control cats and 200 cats with HCM. Retrospective, observational, clinical cohort study. Two-dimensional echocardiograms from all cats were analyzed. Right atrial diameter, RV free wall thickness, and RV chamber diameter were quantified using multiple imaging views. Conventional (mean ± 2 standard deviations) and allometrically scaled (Y = a × M b ) reference values were determined in normal cats and compared to values found in cats with HCM. Linear and logistic regression, multivariate regression, and mixed model analysis were performed to identify associations between RV wall thickness and severity of left ventricular (LV) hypertrophy, clinical severity of HCM, and presence of pleural effusion. Mean RV wall thickness was increased in HCM (p0.05) in control cats. Increased RV wall thickness is common in cats with HCM and relates to severity of LV hypertrophy and clinical status. Copyright © 2016 Elsevier B.V. All rights reserved.

  3. Study of Left Ventricular Diastolic Function in Patients with Diabetes ...

    African Journals Online (AJOL)

    Left Ventricular Function: all controls had normal LV function. Studied patients had normal LV systolic function. A total of 29 patients (58%) were found to have LV diastolic dysfunction. Grade I LVDD was most common (40%). LVDD was significantly correlated with duration of DM and age of the patient (P<0.05). There was a ...

  4. Surgical treatment of post-infarction left ventricular pseudoaneurysm: Case series highlighting various surgical strategies

    Directory of Open Access Journals (Sweden)

    Edvin Prifti, MD, PhD

    2017-04-01

    Conclusion: In conclusion, this study revealed that surgical repair of post infarct left ventricular pseudoaneurysm was associated with an acceptable surgical mortality rate, that cardiac rupture did not occur in surgically treated patients.

  5. The Use of β-blockers in Patients with Ventricular Ectopic Heartbeat in the Early and Distant Postinfarction Period

    Directory of Open Access Journals (Sweden)

    N. M. Kulayets

    2017-10-01

    of carvedilol, a slightly less in patients treated with metoprolol and sotalol. Conclusions. Sotalol in patients after ACS has an ability to reduce the ventricular ectopic heartbeat episodes number and prevents life-threatening arrhythmias, provides a permanent and controlled decrease of heart rate, corrects left ventricle (LV contractility and processes of postinfarction remodeling of the heart. When using carvedilol it has been noticed a reduction of LV postinfarction remodeling processes, improvement of contractile function of myocardium, antianginal and antiarrhythmic effects, normalization of heart rate variability, reduction of myocardial ischemia, reduction in sudden cardiac death cases. acute coronary syndrome; ventricular premature complexes; ischemic heart disease; myocardial infarction; sotalol; carvedilol

  6. Improving inferior vena cava filter retrieval rates with the define, measure, analyze, improve, control methodology.

    Science.gov (United States)

    Sutphin, Patrick D; Reis, Stephen P; McKune, Angie; Ravanzo, Maria; Kalva, Sanjeeva P; Pillai, Anil K

    2015-04-01

    To design a sustainable process to improve optional inferior vena cava (IVC) filter retrieval rates based on the Define, Measure, Analyze, Improve, Control (DMAIC) methodology of the Six Sigma process improvement paradigm. DMAIC, an acronym for Define, Measure, Analyze, Improve, and Control, was employed to design and implement a quality improvement project to increase IVC filter retrieval rates at a tertiary academic hospital. Retrievable IVC filters were placed in 139 patients over a 2-year period. The baseline IVC filter retrieval rate (n = 51) was reviewed through a retrospective analysis, and two strategies were devised to improve the filter retrieval rate: (a) mailing of letters to clinicians and patients for patients who had filters placed within 8 months of implementation of the project (n = 43) and (b) a prospective automated scheduling of a clinic visit at 4 weeks after filter placement for all new patients (n = 45). The effectiveness of these strategies was assessed by measuring the filter retrieval rates and estimated increase in revenue to interventional radiology. IVC filter retrieval rates increased from a baseline of 8% to 40% with the mailing of letters and to 52% with the automated scheduling of a clinic visit 4 weeks after IVC filter placement. The estimated revenue per 100 IVC filters placed increased from $2,249 to $10,518 with the mailing of letters and to $17,022 with the automated scheduling of a clinic visit. Using the DMAIC methodology, a simple and sustainable quality improvement intervention was devised that markedly improved IVC filter retrieval rates in eligible patients. Copyright © 2015 SIR. Published by Elsevier Inc. All rights reserved.

  7. Optimization of 2,3-butanediol production by Klebsiella oxytoca through oxygen transfer rate control

    Energy Technology Data Exchange (ETDEWEB)

    Beronio, P.B. Jr. (Amoco Oil Co., Naperville, IL (United States). Amoco Research Center); Tsao, G.T. (Purdue Univ., West Lafayette, IN (United States). Lab. of Renewable Resources Engineering)

    1993-12-01

    Production of 2,3-butanediol by Klebsiella oxytoca is influenced by the degree of oxygen limitation. During batch culture studies, two phases of growth are observed: energy-coupled growth, during which cell growth and oxygen supply are coupled; and, energy-uncoupled growth, which arises when the degree of oxygen limitation reaches a critical value. Optimal 2,3-butanediol productivity occurs during the energy-coupled growth phase. In this article, a control system which maintains the batch culture at a constant level of oxygen limitation in the energy-coupled growth regime has been designed. Control, which involves feedback control on the oxygen transfer coefficient, is achieved by continually increasing the partial pressure of oxygen in the feed gas, which in turn continually increases the oxygen transfer rate. Control has resulted in a balanced state of growth, a repression of ethanol formation, and an increase in 2,3-butanediol productivity of 18%.

  8. Control of a Biped Robot by Total Rate of Angular Momentum Using the Task Function Approach

    Directory of Open Access Journals (Sweden)

    J. A. Rojas-Estrada

    2005-01-01

    Full Text Available In this work we address the control problem of biped robots by using the task function approach. A problem arrives when one of the feet is in contact with the ground, which presents imperfections. There is then the possibility that the biped robot undergoes a fall. It is difficult to track any trajectory due to the presence of unevenness on the ground. What we propose is to use the task function approach combined with the application of the total rate of angular momentum to obtain a control law for the ankle. By this technique, the tracking becomes more smooth and the balance is assured. The control law proposed allows the upper part of the robot to be controlled independently since only the ankle actuators are concerned. We enounce the formal problem and present some simulations with real parameters of a 21 degrees of freedom biped robot.

  9. Effects of a pure alpha/beta-adrenergic receptor blocker on monocrotaline-induced pulmonary arterial hypertension with right ventricular hypertrophy in rats.

    Science.gov (United States)

    Ishikawa, Masaya; Sato, Naoki; Asai, Kuniya; Takano, Teruo; Mizuno, Kyoichi

    2009-12-01

    It is unclear how much the sympathetic nervous system is involved in the development of pulmonary arterial hypertension (PAH). The present study examined whether or not a pure alpha/beta-adrenergic receptor blocker (arotinolol) could prevent the development of PAH and right ventricular hypertrophy (RVH) in a rat model of monocrotaline (MCT)-induced PAH. The heart rate, arterial blood pressure (BP), left ventricular pressure, pulmonary artery pressure (PAP), and right ventricular pressure (RVP) were measured after administration of arotinolol or saline for 2 weeks. Ventricular weight and myocyte size were also measured. Mean PAP was increased less in the arotinolol group (n=6), (53 +/-9 vs 21 +/-2 mmHg in the control (n=6); Parotinolol group (41 +/-3 vs 91 +/-14 mmHg in the control, Parotinolol group. The pure alpha/beta-blocker arotinolol prevented the progression of MCT-induced PAH and RVH in rats, suggesting that sympathetic nervous activation might play a role in the development of PAH.

  10. Maximum Data Collection Rate Routing Protocol Based on Topology Control for Rechargeable Wireless Sensor Networks.

    Science.gov (United States)

    Lin, Haifeng; Bai, Di; Gao, Demin; Liu, Yunfei

    2016-07-30

    In Rechargeable Wireless Sensor Networks (R-WSNs), in order to achieve the maximum data collection rate it is critical that sensors operate in very low duty cycles because of the sporadic availability of energy. A sensor has to stay in a dormant state in most of the time in order to recharge the battery and use the energy prudently. In addition, a sensor cannot always conserve energy if a network is able to harvest excessive energy from the environment due to its limited storage capacity. Therefore, energy exploitation and energy saving have to be traded off depending on distinct application scenarios. Since higher data collection rate or maximum data collection rate is the ultimate objective for sensor deployment, surplus energy of a node can be utilized for strengthening packet delivery efficiency and improving the data generating rate in R-WSNs. In this work, we propose an algorithm based on data aggregation to compute an upper data generation rate by maximizing it as an optimization problem for a network, which is formulated as a linear programming problem. Subsequently, a dual problem by introducing Lagrange multipliers is constructed, and subgradient algorithms are used to solve it in a distributed manner. At the same time, a topology controlling scheme is adopted for improving the network's performance. Through extensive simulation and experiments, we demonstrate that our algorithm is efficient at maximizing the data collection rate in rechargeable wireless sensor networks.

  11. Perinatal sulfur dioxide exposure alters brainstem parasympathetic control of heart rate.

    Science.gov (United States)

    Woerman, Amanda L; Mendelowitz, David

    2013-07-01

    Sulfur dioxide (SO₂) is an air pollutant that impedes neonatal development and induces adverse cardiorespiratory health effects, including tachycardia. Here, an animal model was developed that enabled characterization of (i) in vivo alterations in heart rate and (ii) altered activity in brainstem neurons that control heart rate after perinatal SO₂ exposure. Pregnant Sprague-Dawley dams and their pups were exposed to 5 parts per million SO₂ for 1 h daily throughout gestation and 6 days postnatal. Electrocardiograms were recorded from pups at 5 days postnatal to examine changes in basal and diving reflex-evoked changes in heart rate following perinatal SO₂ exposure. In vitro studies employed whole-cell patch-clamp electrophysiology to examine changes in neurotransmission to cardiac vagal neurons within the nucleus ambiguus upon SO₂ exposure using a preparation that maintains fictive inspiratory activity recorded from the hypoglossal rootlet. Perinatal SO₂ exposure increased heart rate and blunted the parasympathetic-mediated diving reflex-evoked changes in heart rate. Neither spontaneous nor inspiratory-related inhibitory GABAergic or glycinergic neurotransmission to cardiac vagal neurons was altered by SO₂ exposure. However, excitatory glutamatergic neurotransmission was decreased by 51.2% upon SO₂ exposure. This diminished excitatory neurotransmission was tetrodotoxin-sensitive, indicating SO₂ exposure impaired the activity of preceding glutamatergic neurons that synapse upon cardiac vagal neurons. Diminished glutamatergic, but unaltered inhibitory neurotransmission to cardiac vagal neurons provides a mechanism for the observed SO₂-induced elevated heart rate via an impairment of brainstem cardioinhibitory parasympathetic activity to the heart.

  12. Improvement in Device Performance and Reliability of Organic Light-Emitting Diodes through Deposition Rate Control

    Directory of Open Access Journals (Sweden)

    Shun-Wei Liu

    2014-01-01

    Full Text Available We demonstrated a fabrication technique to reduce the driving voltage, increase the current efficiency, and extend the operating lifetime of an organic light-emitting diode (OLED by simply controlling the deposition rate of bis(10-hydroxybenzo[h]qinolinato beryllium (Bebq2 used as the emitting layer and the electron-transport layer. In our optimized device, 55 nm of Bebq2 was first deposited at a faster deposition rate of 1.3 nm/s, followed by the deposition of a thin Bebq2 (5 nm layer at a slower rate of 0.03 nm/s. The Bebq2 layer with the faster deposition rate exhibited higher photoluminescence efficiency and was suitable for use in light emission. The thin Bebq2 layer with the slower deposition rate was used to modify the interface between the Bebq2 and cathode and hence improve the injection efficiency and lower the driving voltage. The operating lifetime of such a two-step deposition OLED was 1.92 and 4.6 times longer than that of devices with a single deposition rate, that is, 1.3 and 0.03 nm/s cases, respectively.

  13. Global Dynamics and Optimal Control of a Viral Infection Model with Generic Nonlinear Infection Rate

    Directory of Open Access Journals (Sweden)

    Chenquan Gan

    2017-01-01

    Full Text Available This paper is devoted to exploring the combined impact of a generic nonlinear infection rate and infected removable storage media on viral spread. For that purpose, a novel dynamical model with an external compartment is proposed, and the explanations of the main model assumptions (especially the generic nonlinear infection rate are also examined. The existence and global stability of the unique equilibrium of the model are fully investigated, from which it can be seen that computer virus would persist. On this basis, a next-best approach to controlling the level of infected computers is suggested, and the theoretical analysis of optimal control of the model is also performed. Additionally, some numerical examples are given to illustrate the main results.

  14. Multi-objective control of nonlinear boiler-turbine dynamics with actuator magnitude and rate constraints.

    Science.gov (United States)

    Chen, Pang-Chia

    2013-01-01

    This paper investigates multi-objective controller design approaches for nonlinear boiler-turbine dynamics subject to actuator magnitude and rate constraints. System nonlinearity is handled by a suitable linear parameter varying system representation with drum pressure as the system varying parameter. Variation of the drum pressure is represented by suitable norm-bounded uncertainty and affine dependence on system matrices. Based on linear matrix inequality algorithms, the magnitude and rate constraints on the actuator and the deviations of fluid density and water level are formulated while the tracking abilities on the drum pressure and power output are optimized. Variation ranges of drum pressure and magnitude tracking commands are used as controller design parameters, determined according to the boiler-turbine's operation range. Copyright © 2012 ISA. Published by Elsevier Ltd. All rights reserved.

  15. Changes in overall ventricular myocardial architecture in the setting of a porcine animal model of right ventricular dilation

    DEFF Research Database (Denmark)

    Agger, Peter; Ilkjær, Christine; Laustsen, Christoffer

    2017-01-01

    , surgical suturing of its leaflets in seven piglets, performing sham operations in seven control animals. Using cardiovascular magnetic resonance imaging after 12 weeks of recovery, we demonstrated significantly increased right ventricular volumes in the test group. After sacrifice, diffusion tensor imaging...

  16. Supplier Outreach and Process Control (SOPC) and Supplier Rating Initiative (SRI)

    Science.gov (United States)

    Crenshaw, Harrel

    2003-01-01

    The viewgraph presentation presents an overview of NASA's Supplier Outreach and Process Control (SOPC) and Supplier Risk Initiatives. The discussion of the SOPC examines its importance, current groups who are involved, provides a mission statement, and describes outreach activities and how suppliers are selected. The discussion of the Supplier Risk Initiative examines the variety of ways that integrity, availability, and assurance factor in to supplier risk and describes a new supplier rating program.

  17. Physical Activity, Mindfulness Meditation, or Heart Rate Variability Biofeedback for Stress Reduction: A Randomized Controlled Trial

    OpenAIRE

    van der Zwan, Judith Esi; de Vente, Wieke; Huizink, Anja C.; B?gels, Susan M.; de Bruin, Esther I.

    2015-01-01

    In contemporary western societies stress is highly prevalent, therefore the need for stress-reducing methods is great. This randomized controlled trial compared the efficacy of self-help physical activity (PA), mindfulness meditation (MM), and heart rate variability biofeedback (HRV-BF) in reducing stress and its related symptoms. We randomly allocated 126 participants to PA, MM, or HRV-BF upon enrollment, of whom 76 agreed to participate. The interventions consisted of psycho-education and a...

  18. Arterial baroreflex control of heart rate during exercise in postural tachycardia syndrome.

    Science.gov (United States)

    Masuki, Shizue; Eisenach, John H; Schrage, William G; Dietz, Niki M; Johnson, Christopher P; Wilkins, Brad W; Dierkhising, Ross A; Sandroni, Paola; Low, Phillip A; Joyner, Michael J

    2007-10-01

    Patients with postural tachycardia syndrome (POTS) have excessive tachycardia without hypotension during orthostasis as well as exercise. We tested the hypothesis that excessive tachycardia during exercise in POTS is not related to abnormal baroreflex control of heart rate (HR). Patients (n = 13) and healthy controls (n = 10) performed graded cycle exercise at 25, 50, and 75 W in both supine and upright positions while arterial pressure (arterial catheter) and HR (ECG) were measured. Baroreflex sensitivity of HR was assessed by bolus intravenous infusion of phenylephrine at each workload. In both positions, HR was higher in the patients than the controls during exercise. Supine baroreflex sensitivity (HR/systolic pressure) in POTS patients was -1.3 +/- 0.1 beats.min(-1).mmHg(-1) at rest and decreased to -0.6 +/- 0.1 beats.min(-1).mmHg(-1) during 75-W exercise, neither significantly different from the controls (P > 0.6). In the upright position, baroreflex sensitivity in POTS patients at rest (-1.4 +/- 0.1 beats.min(-1).mmHg(-1)) was higher than the controls (-1.0 +/- 0.1 beats.min(-1).mmHg(-1)) (P pulse pressure in the patients than in the controls with 56 and 90% higher coefficient of variations, respectively (P tachycardia during exercise in POTS was not due to abnormal baroreflex control of HR.

  19. The Selective Late Sodium Current Inhibitor Eleclazine, Unlike Amiodarone, Does Not Alter Defibrillation Threshold or Dominant Frequency of Ventricular Fibrillation.

    Science.gov (United States)

    Silva, Ana F G; Bonatti, Rodolfo; Batatinha, Julio A P; Nearing, Bruce D; Zeng, Dewan; Belardinelli, Luiz; Verrier, Richard L

    2017-03-01

    We examined the effects of the selective late INa inhibitor eleclazine on the 50% probability of successful defibrillation (DFT50) before and after administration of amiodarone to determine its suitability for use in patients with implantable cardioverter defibrillators (ICDs). In 20 anesthetized pigs, transvenous active-fixation cardiac defibrillation leads were fluoroscopically positioned into right ventricular apex through jugular vein. ICDs were implanted subcutaneously. Dominant frequency of ventricular fibrillation was analyzed by fast Fourier transform. The measurements were made before drug administration (control), and at 40 minutes after vehicle, eleclazine (2 mg/kg, i.v., bolus over 15 minutes), or subsequent/single amiodarone administration (10 mg/kg, i.v., bolus over 10 minutes). Eleclazine did not alter DFT50, dominant frequency, heart rate, or mean arterial pressure (MAP). Subsequent amiodarone increased DFT50 (P = 0.006), decreased dominant frequency (P = 0.022), and reduced heart rate (P = 0.031) with no change in MAP. Amiodarone alone increased DFT50 (P = 0.005; NS compared to following eleclazine) and decreased dominant frequency (P = 0.003; NS compared to following eleclazine). Selective late INa inhibition with eleclazine does not alter DFT50 or dominant frequency of ventricular fibrillation when administered alone or in combination with amiodarone. Accordingly, eleclazine would not be anticipated to affect the margin of defibrillation safety in patients with ICDs.

  20. Control of ventricular ciliary beating by the melanin concentrating hormone-expressing neurons of the lateral hypothalamus: a functional imaging survey.

    Science.gov (United States)

    Conductier, Grégory; Martin, Agnès O; Risold, Pierre-Yves; Jego, Sonia; Lavoie, Raphaël; Lafont, Chrystel; Mollard, Patrice; Adamantidis, Antoine; Nahon, Jean-Louis

    2013-01-01

    The cyclic peptide Melanin Concentrating Hormone (MCH) is known to control a large number of brain functions in mammals such as food intake and metabolism, stress response, anxiety, sleep/wake cycle, memory, and reward. Based on neuro-anatomical and electrophysiological studies these functions were attributed to neuronal circuits expressing MCHR1, the single MCH receptor in rodents. In complement to our recently published work (1) we provided here new data regarding the action of MCH on ependymocytes in the mouse brain. First, we establish that MCHR1 mRNA is expressed in the ependymal cells of the third ventricle epithelium. Second, we demonstrated a tonic control of MCH-expressing neurons on ependymal cilia beat frequency using in vitro optogenics. Finally, we performed in vivo measurements of CSF flow using fluorescent micro-beads in wild-type and MCHR1-knockout mice. Collectively, our results demonstrated that MCH-expressing neurons modulate ciliary beating of ependymal cells at the third ventricle and could contribute to maintain cerebro-spinal fluid homeostasis.

  1. Control of ventricular ciliary beating by the Melanin Concentrating Hormone-expressing neurons of the lateral hypothalamus : a functional imaging survey.

    Directory of Open Access Journals (Sweden)

    Gregory eConductier

    2013-11-01

    Full Text Available The cyclic peptide Melanin-Concentrating Hormone (MCH is known to control a large number of brain functions in mammals such as food intake and metabolism, stress response, anxiety, sleep/wake cycle, memory and reward. Based on neuroanatomical and electrophysiological studies these functions were attributed to neuronal circuits expressing MCHR1, the single MCH receptor in rodents. In complement to our recently published work (Conductier et al. 2013 we provided here new data regarding the action of MCH on ependymocytes in the mouse brain. First, we establish that MCHR1 mRNA is expressed in the ependymal cells of the third ventricle epithelium. Second, we demonstated a tonic control of MCH-expressing neurons on ependymal cilia beat frequency using in vitro optogenics. Finally, we performed in vivo measurements of CSF flow using fluorescent micro-beads in wild-type and MCHR1 knockout mice. Collectively, our results demonstrated that MCH-expressing neurons modulate ciliary beating of ependymal cells at the third ventricle and could contribute to maintain cerebro-spinal fluid homeostasis.

  2. Left ventricular mass in male adolescent athletes and non-athletes

    Directory of Open Access Journals (Sweden)

    Erling David Kaunang

    2014-10-01

    Full Text Available Background Systematic exercise leads to increased left ventricular mass, which may be misleading in a differential diagnosis of heart disease in athletes (physiologic hypertrophy versus pathologic hypertrophy. T he cause of left ventricular hypertrophy is an important risk factor in the morbidity and mortality of cardiovascular diseases. Objective To compare left ventricular mass and left ventricular hypertrophy in male adolescent athletes and non-athletes. Methods We conducted a cross-sectional, analytic study, from September to December 2012 in male adolescents aged 15-18 years. The case group included athletes from the Bina Taruna Football Club Manado, while the control group included non-athlete adolescents. All subjects underwent history-taking, physical examinations and further supporting examinations. Left ventricular mass was measured by cardiovascular echocardiography (Esaote Mylab 4.0 and calculated based on a formula. Left ventricular hypertrophy was defined as left ventricular mass of > 134 g/m2 body surface area. Results Subjects' mean left ventricular masses were 359.69 (SD 188.4; 95%CI 283.58 to 435.81 grams in the athlete group and 173.04 (SD 50.69; 95%CI 152.56 to 103.51 grams in the non· athlete group, a statistically significant difference (P=0.0001. Ventricular hypertrophy was found 76.9% compared to 11.5% in  the non-athlete group (P= 0.0001. Conclusion Left ventricular mass in athletes is bigger than in non-athletes. In addition, left ventricular hypertrophy is more cornmon in male adolescent athletes than in non-athletes.

  3. Single-Beat Noninvasive Imaging of Ventricular Endocardial and Epicardial Activation in Patients Undergoing CRT

    Science.gov (United States)

    Berger, Thomas; Pfeifer, Bernhard; Hanser, Friedrich F.; Hintringer, Florian; Fischer, Gerald; Netzer, Michael; Trieb, Thomas; Stuehlinger, Markus; Dichtl, Wolfgang; Baumgartner, Christian; Pachinger, Otmar; Seger, Michael

    2011-01-01

    Background Little is known about the effect of cardiac resynchronization therapy (CRT) on endo- and epicardial ventricular activation. Noninvasive imaging of cardiac electrophysiology (NICE) is a novel imaging tool for visualization of both epi- and endocardial ventricular electrical activation. Methodology/Principal Findings NICE was performed in ten patients with congestive heart failure (CHF) undergoing CRT and in ten patients without structural heart disease (control group). NICE is a fusion of data from high-resolution ECG mapping with a model of the patient's individual cardiothoracic anatomy created from magnetic resonance imaging. Beat-to-beat endocardial and epicardial ventricular activation sequences were computed during native rhythm as well as during ventricular pacing using a bidomain theory-based heart model to solve the related inverse problem. During right ventricular (RV) pacing control patients showed a deterioration of the ventricular activation sequence similar to the intrinsic activation pattern of CHF patients. Left ventricular propagation velocities were significantly decreased in CHF patients as compared to the control group (1.6±0.4 versus 2.1±0.5 m/sec; pCHF patients showed right-to-left septal activation with the latest activation epicardially in the lateral wall of the left ventricle. Biventricular pacing resulted in a resynchronization of the ventricular activation sequence and in a marked decrease of total LV activation duration as compared to intrinsic conduction and RV pacing (129±16 versus 157±28 and 173±25 ms; both p<0.05). Conclusions/Significance Endocardial and epicardial ventricular activation can be visualized noninvasively by NICE. Identification of individual ventricular activation properties may help identify responders to CRT and to further improve response to CRT by facilitating a patient-specific lead placement and device programming. PMID:21298045

  4. Single-beat noninvasive imaging of ventricular endocardial and epicardial activation in patients undergoing CRT.

    Directory of Open Access Journals (Sweden)

    Thomas Berger

    Full Text Available BACKGROUND: Little is known about the effect of cardiac resynchronization therapy (CRT on endo- and epicardial ventricular activation. Noninvasive imaging of cardiac electrophysiology (NICE is a novel imaging tool for visualization of both epi- and endocardial ventricular electrical activation. METHODOLOGY/PRINCIPAL FINDINGS: NICE was performed in ten patients with congestive heart failure (CHF undergoing CRT and in ten patients without structural heart disease (control group. NICE is a fusion of data from high-resolution ECG mapping with a model of the patient's individual cardiothoracic anatomy created from magnetic resonance imaging. Beat-to-beat endocardial and epicardial ventricular activation sequences were computed during native rhythm as well as during ventricular pacing using a bidomain theory-based heart model to solve the related inverse problem. During right ventricular (RV pacing control patients showed a deterioration of the ventricular activation sequence similar to the intrinsic activation pattern of CHF patients. Left ventricular propagation velocities were significantly decreased in CHF patients as compared to the control group (1.6±0.4 versus 2.1±0.5 m/sec; p<0.05. CHF patients showed right-to-left septal activation with the latest activation epicardially in the lateral wall of the left ventricle. Biventricular pacing resulted in a resynchronization of the ventricular activation sequence and in a marked decrease of total LV activation duration as compared to intrinsic conduction and RV pacing (129±16 versus 157±28 and 173±25 ms; both p<0.05. CONCLUSIONS/SIGNIFICANCE: Endocardial and epicardial ventricular activation can be visualized noninvasively by NICE. Identification of individual ventricular activation properties may help identify responders to CRT and to further improve response to CRT by facilitating a patient-specific lead placement and device programming.

  5. Endogenous vasopressin and the central control of heart rate during dynamic exercise

    Directory of Open Access Journals (Sweden)

    L.C. Michelini

    1998-09-01

    Full Text Available The present article contains a brief review on the role of vasopressinergic projections to the nucleus tractus solitarii in the genesis of reflex bradycardia and in the modulation of heart rate control during exercise. The effects of vasopressin on exercise tachycardia are discussed on the basis of both the endogenous peptide content changes and the heart rate response changes observed during running in sedentary and trained rats. Dynamic exercise caused a specific vasopressin content increase in dorsal and ventral brainstem areas. In accordance, rats pretreated with the peptide or the V1 blocker into the nucleus tractus solitarii showed a significant potentiation or a marked blunting of the exercise tachycardia, respectively, without any change in the pressure response to exercise. It is proposed that the long-descending vasopressinergic pathway to the nucleus tractus solitarii serves as one link between the two main neural controllers of circulation, i.e., the central command and feedback control mechanisms driven by the peripheral receptors. Therefore, vasopressinergic input could contribute to the adjustment of heart rate response (and cardiac output to the circulatory demand during exercise.

  6. Controlled precipitation for enhanced dissolution rate of flurbiprofen: development of rapidly disintegrating tablets.

    Science.gov (United States)

    Essa, Ebtessam A; Elmarakby, Amira O; Donia, Ahmed M A; El Maghraby, Gamal M

    2017-09-01

    The aim of this work was to investigate the potential of controlled precipitation of flurbiprofen on solid surface, in the presence or absence of hydrophilic polymers, as a tool for enhanced dissolution rate of the drug. The work was extended to develop rapidly disintegrated tablets. This strategy provides simple technique for dissolution enhancement of slowly dissolving drugs with high scaling up potential. Aerosil was dispersed in ethanolic solution of flurbiprofen in the presence and absence of hydrophilic polymers. Acidified water was added as antisolvent to produce controlled precipitation. The resultant particles were centrifuged and dried at ambient temperature before monitoring the dissolution pattern. The particles were also subjected to FTIR spectroscopic, X-ray diffraction and thermal analyses. The FTIR spectroscopy excluded any interaction between flurbiprofen and excipients. The thermal analysis reflected possible change in the crystalline structure and or crystal size of the drug after controlled precipitation in the presence of hydrophilic polymers. This was further confirmed by X-ray diffraction. The modulation in the crystalline structure and size was associated with a significant enhancement in the dissolution rate of flurbiprofen. Optimum formulations were successfully formulated as rapidly disintegrating tablet with subsequent fast dissolution. Precipitation on a large solid surface area is a promising strategy for enhanced dissolution rate with the presence of hydrophilic polymers during precipitation process improving the efficiency.

  7. Increased coronary intervention rate among diabetic patients with poor glycaemic control: a cross-sectional study.

    Science.gov (United States)

    Çetin, Süha; Öztürk, Mehmet Akif; Barındık, Nadir; İmren, Ersin; Peker, Yüksel

    2014-02-01

    The relationship between glycaemic control and coronary artery disease (CAD) in type 2 diabetes mellitus (T2DM) is controversial. In the current cross-sectional study, we addressed the relationship between Hemoglobin A1c (HbA1c) values and the need for revascularization among diabetic patients undergoing coronary angiography. A total of 301 consecutive patients with known T2DM (age 61.8±10.1 years, 46.2 % women) requiring coronary angiography due to CAD symptoms were included. T2DM patients were categorized into two groups based on their HbA1c values: 93 (30.9%) diabetics with good glycaemic control (HbA1c≤7 %), and 208 (69.1%) diabetics with poor glycaemic control (HbA1c>7 %). A total of 123 patients (40.9%) required revascularization. The revascularization rate was 28.0% among T2DM patients with good glycaemic control and 46.6% among T2DM patients with poor glycaemic control, respectively (p=0.002). In a logistic regression analysis, the need for revascularization was predicted by poor glycaemic control (Odds Ratio [OR] 2.26, 95% Confidence Interval [CI] 1.32-3.82; p=0.003) adjusted for age, gender, Body-Mass-Index and diabetes duration. Moreover, there was a linear relationship between HbA1c values and number of affected coronary arteries (r= 0.169; p=0.003). Our data suggest that there is a close association between poor glycaemic control and increased revascularization rate in T2DM, which should be considered in primary and secondary prevention models.

  8. Right ventricular function in children with bronchial asthma: a tissue Doppler echocardiographic study.

    Science.gov (United States)

    Shedeed, Soad A

    2010-10-01

    Asthma is the most common cause of respiratory disability among children. Patients with severe bronchial asthma can experience cor pulmonale later in life, but little is known about the function of the right ventricle early in the disease. This study aimed to investigate the right ventricular function in children with bronchial asthma as detected by tissue Doppler echocardiography. This case-control study compared 60 asthmatic children ages 5 to 15 years between attacks (study group) with 60 apparently healthy children (control group). All the children were subjected to full history-taking, complete physical examination, measurement of peak expiratory flow rate (PEFR), chest x-ray, electrocardiography (ECG), echocardiographic examination, and both conventional and tissue Doppler study. The results of the tissue Doppler study examining the right ventricular diastolic function showed that peak E' velocity (10.08 ± 2.8 cm/s), peak A' velocity (5.7 ± 2.5 cm/s), E'/A' ratio (1.77 ± 0.58 m/s), and isovolumetric relaxation time (IVRT) of the lateral tricuspid annulus (138.9 ± 30.7 m/s) among the asthmatic patients differed significantly from those among the control subjects (12.4 ± 2.3, 7.8 ± 2.1 cm/s; 1.58 ± 0.32, and 91.1 ± 32.6 m/s, respectively). In addition, the E' velocity and IVRT of the lateral tricuspid annulus were significantly different among the mild, moderate, and severe cases (P children were apparently normal, the tissue Doppler echocardiographic study showed right ventricular dysfunction that is positively correlated with the severity of asthma. These findings signify the diagnostic value of tissue Doppler echocardiography for the early detection and monitoring of such deleterious effects among asthmatic patients.

  9. Multicenter Evaluation of Octreotide as Secondary Prophylaxis in Patients With Left Ventricular Assist Devices and Gastrointestinal Bleeding.

    Science.gov (United States)

    Shah, Keyur B; Gunda, Sampath; Emani, Sitaramesh; Kanwar, Manreet K; Uriel, Nir; Colombo, Paolo C; Uber, Patricia A; Sears, Melissa L; Chuang, Joyce; Farrar, David J; Brophy, Donald F; Smallfield, George B

    2017-11-01

    Gastrointestinal (GI) bleeding is one of the most common complications after continuous-flow left ventricular assist device implantation. More than one third of patients with incident bleed go on to develop recurrent GI bleeding. Octreotide, a somatostatin analog, is proposed to reduce the risk of recurrent GI bleeding in this population. This multicenter, retrospective analysis evaluated 51 continuous-flow left ventricular assist device patients who received secondary prophylaxis with octreotide after their index GI bleed from 2009 to 2015. All patients had a hospitalization for GI bleed and received octreotide after discharge. Patient demographics, medical and medication history, and clinical characteristics of patients who rebled after receiving octreotide were compared with non-rebleeders. These data were also compared with matched historical control patients previously enrolled in the HMII (HeartMate II) clinical trials, none of whom received octreotide, to provide a context for the bleeding rates. Twelve patients (24%) who received secondary octreotide prophylaxis developed another GI bleed, whereas 39 (76%) did not. There were similar intergroup demographics; however, significantly more bleeders had a previous GI bleeding history before left ventricular assist device placement (33% versus 5%; P=0.02) and greater frequency of angiodysplasia confirmed during endoscopy (58% versus 23%; P=0.03). Fewer patients in this study experienced a recurrent GI bleed compared with a matched historical control group that did not receive octreotide (24% versus 43%; P=0.04). Patients with continuous-flow left ventricular assist device receiving secondary prophylaxis with octreotide had a significantly lower GI bleed recurrence compared with historical controls not treated with octreotide. Additional prospective studies are needed to confirm these data. © 2017 American Heart Association, Inc.

  10. Procollagen type III amino terminal peptide and myocardial fibrosis: A study in hypertensive patients with and without left ventricular hypertrophy.

    Science.gov (United States)

    dos Santos Moreira, Carlos; Serejo, Fátima; Alcântara, Paula; Ramalhinho, Vítor; Braz Nogueira, J

    2015-05-01

    An exaggerated accumulation of type I and type III fibrillar collagens occurs throughout the free wall and interventricular septum of patients with primary hypertension and left ventricular hypertrophy (LVH). In the present study the serum concentration of procollagen type III amino terminal peptide (PIIIP) was measured to determine the value of this peptide as a potential marker of ventricular fibrosis in hypertensive patients, particularly those with LVH. The study population consisted of patients with never-treated mild to moderate essential hypertension and 30 normotensive control subjects. Clinical, echocardiographic, electrocardiographic and biochemical parameters were assessed in all patients. Heart rate, body mass index and levels of blood pressure were increased in hypertensives, particularly those with LVH, compared to normotensive controls. Posterior wall thickness, left ventricular (LV) mass and LV mass index, and serum PIIIP concentration were also increased in hypertensives, with significant differences between the two hypertensive groups. The ratio between maximal early and late transmitral flow velocity measured during diastole was lower in hypertensives, particularly those with LVH, than in normotensive controls. The increase in PIIIP indicates that type III collagen synthesis increases in hypertensives, particularly those with LVH, implying that alterations in the heart in hypertension are the result not solely of hypertrophied LV muscle, but also of increased collagen deposition within the ventricular wall and around the coronary vessels. Thus, measurement of serum PIIIP could be a practical and useful tool in the non-invasive assessment of myocardial remodeling in hypertension. Copyright © 2014 Sociedade Portuguesa de Cardiologia. Published by Elsevier España. All rights reserved.

  11. Echocardiographic evaluation of ventricular septal defect haemodynamics

    Directory of Open Access Journals (Sweden)

    Miranović Vesna

    2007-01-01

    Full Text Available Introduction Ventricular septal defect (VSD is an opening in the interventricular septum. 30-50% of patients with congenital heart disease have VSD. Objective The aim of the study was to determine the dependence of the left ventricular diastolic dimension (LVD, left ventricular systolic dimension (LVS, shortening fraction (SF, left atrium (LA, pulmonary artery truncus (TPA on the body surface and compare their values among experimental, control and a group of healthy children. Values of maximal systolic gradient pressure (Pvsd of VSD were compared with children from one experimental and control group. Method Children were divided into three groups: experimental (32 children with VSD that were to go to surgery, control (20 children with VSD who did not require surgery and 40 healthy children. Measurements of LVD, LVS, SF, LA, TPA were performed in accordance to recommendations of the American Echocardiographic Association. The value of Pvsd was calculated from the maximal flow velocity (V in VSD using the following formula: Pvsd=4xVІ (mm Hg. Results For children from the experimental group, the relationship between the body surface and the variability of the LVD was explained with 56.85%, LVS with 66.15%, SF with 4.9%, TPA with 58.92%. For children from the control group, the relationship between the body surface and the variability of LVD was explained with 88.8%, LVS with 72.5%, SF with 0.42%, PA with 58.92%. For healthy children, the relationship between the body surface and the variabilitiy of the LVD was explained with 88.8%, LVS with 88.78%, SF with 5.25% and PA with 84.75%. There was a significant statistical difference between average values of Pvsd in the experimental and control group (p<0.02. Conclusion The presence of the large VSD has an influence on the enlargement of LVD, LVS, SF, TPA. The enlargement of the size of the pulmonary artery depends on the presence of VSD and there is a direct variation in the magnitude of the shunt

  12. Capital Controls, Two-tiered Exchange Rate Systems and the Exchange Rate Policy : The South African Experience

    NARCIS (Netherlands)

    Schaling, E.

    2005-01-01

    South Africa's 40 years of experience with capital controls on residents and non-residents (1961-2001) reads like a collection of examples of perverse unanticipated effects of legislation and regulation.We show that the presence of capital controls on residents and non-residents, enabled the South

  13. Congenital left ventricular apical aneurysm presenting as ventricular tachycardia.

    Science.gov (United States)

    Amado, José; Marques, Nuno; Candeias, Rui; Gago, Paula; de Jesus, Ilídio

    2016-10-01

    The authors present the case of a 34-year-old male patient seen in our department due to palpitations. On the electrocardiogram monomorphic ventricular tachycardia (VT) was documented, treated successfully with amiodarone. The subsequent study revealed a normal echocardiogram and an apical aneurysm of the left ventricle on magnetic resonance imaging, confirmed by computed tomography coronary angiography that also excluded coronary disease. He underwent an electrophysiological study to determine the origin of the VT and to perform catheter ablation using electroanatomical mapping. VT was induced and radiofrequency applications were performed in the left ventricular aneurysm area. VT was no longer inducible, with acute success. Despite this it was decided to implant a subcutaneous implantable cardioverter-defibrillator (ICD). Eight months after the ablation the patient was admitted again due to VT, treated by the ICD. Copyright © 2016 Sociedade Portuguesa de Cardiologia. Publicado por Elsevier España, S.L.U. All rights reserved.

  14. Lottery incentives did not improve response rate to a mailed survey: a randomized controlled trial.

    Science.gov (United States)

    Harris, Ian A; Khoo, Oliver K; Young, Jane M; Solomon, Michael J; Rae, Hamish

    2008-06-01

    Our study aimed to examine the effect of an instant lottery ticket incentive on the response rate to a mailed questionnaire in a population of trauma patients. A randomized controlled trial at a major trauma center with 728 patients randomized into 2 groups prior to mailing of a questionnaire. One group of patients (Group A) had a sentence inserted into the cover letter stating that they would receive a $4 instant lottery ticket upon receipt of a completed questionnaire; Group B did not have an incentive. The response rate for both groups was measured after the initial mailing and at the end of the study. The results were analyzed using the X2 test to compare 2 proportions and a P value of .05 was considered significant. The early response rate in Group A was lower than in Group B, and the response rates for both groups were similar at final follow-up. The differences at both time periods were not statistically significant. The use of an instant lottery ticket incentive did not improve the response rate to a mailed questionnaire.

  15. Randomized controlled trial of relaxation music to reduce heart rate in patients undergoing cardiac CT

    Energy Technology Data Exchange (ETDEWEB)

    Ng, Ming Yen [University of Toronto, Department of Medical Imaging, Toronto General Hospital, Toronto, ON (Canada); The University of Hong Kong, Queen Mary Hospital, Department of Diagnostic Radiology, Hong Kong (China); Karimzad, Yasser; Menezes, Ravi J.; Wintersperger, Bernd J.; Li, Qin; Forero, Julian; Paul, Narinder S.; Nguyen, Elsie T. [University of Toronto, Department of Medical Imaging, Toronto General Hospital, Toronto, ON (Canada)

    2016-10-15

    To evaluate the heart rate lowering effect of relaxation music in patients undergoing coronary CT angiography (CCTA), pulmonary vein CT (PVCT) and coronary calcium score CT (CCS). Patients were randomised to a control group (i.e. standard of care protocol) or to a relaxation music group (ie. standard of care protocol with music). The groups were compared for heart rate, radiation dose, image quality and dose of IV metoprolol. Both groups completed State-Trait Anxiety Inventory anxiety questionnaires to assess patient experience. One hundred and ninety-seven patients were recruited (61.9 % males); mean age 56y (19-86 y); 127 CCTA, 17 PVCT, 53 CCS. No significant difference in heart rate, radiation dose, image quality, metoprolol dose and anxiety scores. 86 % of patients enjoyed the music. 90 % of patients in the music group expressed a strong preference to have music for future examinations. The patient cohort demonstrated low anxiety levels prior to CT. Relaxation music in CCTA, PVCT and CCS does not reduce heart rate or IV metoprolol use. Patients showed low levels of anxiety indicating that anxiolytics may not have a significant role in lowering heart rate. Music can be used in cardiac CT to improve patient experience. (orig.)

  16. Road accidents rate in the northern border of Tamaulipas. The approach on the administrative control processes

    Directory of Open Access Journals (Sweden)

    Yolanda Velázquez Narváez

    2017-05-01

    Full Text Available The objective of this study is to identify the failures in the administrative control processes that favor risky behaviors in the operators of motor vehicles. Through the analysis of the context of the northern border of Tamaulipas and the most recent accident rate statistics, complementing it with an exploratory study done with a sample of 535 subjects, identifying issues associated with the deficiencies of said processes, and having as limitation the fact that the variables are inherent to the geographic context, it was found that the main causes of road accidents in the municipality are the risky behaviors of the vehicle operators; moreover, there are failures in the administrative control processes, which favor these behaviors. Information is provided to carry out interventions regarding public health and, to conclude, evidence is provided on the existence of differences in the administrative control processes on road safety that favor the risky behaviors of the drivers.

  17. Engineering strategies aimed at control of acidification rate of lactic acid bacteria

    DEFF Research Database (Denmark)

    Martinussen, Jan; Solem, Christian; Holm, Anders Koefoed

    2013-01-01

    , alternative end products - ethanol, acetic acid and formic acid - are formed by many species. The central role of glycolysis in lactic acid bacteria has provoked numerous studies aiming at identifying potential bottleneck(s) since knowledge about flux control could be important not only for optimizing food......The ability of lactic acid bacteria to produce lactic acid from various sugars plays an important role in food fermentations. Lactic acid is derived from pyruvate, the end product of glycolysis and thus a fast lactic acid production rate requires a high glycolytic flux. In addition to lactic acid...... fermentation processes, but also for novel applications of lactic acid bacteria, such as cell factories for the production of green fuels and chemicals. With respect to the control and regulation of the fermentation mode, some progress has been made, but the question of which component(s) control the main...

  18. [Posterior ventricular septal perforation successfully repaired through right ventricular approach].

    Science.gov (United States)

    Takeuchi, Kazuma; Morishige, N; Iwahashi, H; Hayashida, Y; Teshima, H; Ito, N; Tashiro, T

    2006-12-01

    A 65-year-old man underwent a successful repair of a posterior ventricular septal perforation (VSP) 9 days after suffering an acute inferior myocardial infarction. After hospitalization, his hemodynamic condition gradually worsened, in spite of administering intensive medical therapy. Emergent operation was performed on the 4th day after onset. An equine pericardial patch was sutured around the VSP through the right ventricular side of the septum using the double-patch repair method and the right ventricular wall was closed as using the standard extracorporeal perfusion technique. The dimensions of the VSP measured 5 mm in diameter. Transesophageal echocardiography was performed on the 14th postoperative day. Cardiac catheter examination was done on the 18th postoperative day. No residual shunt was recognized and cardiac function was good. He was discharged on the 20th postoperative day. The occurrence of a posterior VSP is comparatively rare, and repair of VSP is difficult to perform during an acute period. Therefore, the operative results of VSP cases remain poor.

  19. Tourette Syndrome: Complementary Insights from Measures of Cognitive Control, Eyeblink Rate, and Pupil Diameter.

    Science.gov (United States)

    Tharp, Jordan A; Wendelken, Carter; Mathews, Carol A; Marco, Elysa J; Schreier, Herbert; Bunge, Silvia A

    2015-01-01

    Some individuals with Tourette syndrome (TS) have severe motoric and vocal tics that interfere with all aspects of their lives, while others have mild tics that pose few problems. We hypothesize that observed tic severity reflects a combination of factors, including the degree to which dopaminergic (DA) and/or noradrenergic (NE) neurotransmitter systems have been affected by the disorder, and the degree to which the child can exert cognitive control to suppress unwanted tics. To explore these hypotheses, we collected behavioral and eyetracking data from 26 patients with TS and 26 controls between ages 7 and 14, both at rest and while they performed a test of cognitive control. To our knowledge, this is the first study to use eyetracking measures in patients with TS. We measured spontaneous eyeblink rate as well as pupil diameter, which have been linked, respectively, to DA and NE levels in the central nervous system. Here, we report a number of key findings that held when we restricted analyses to unmedicated patients. First, patients' accuracy on our test of cognitive control accounted for fully 50% of the variance in parentally reported tic severity. Second, patients exhibited elevated spontaneous eyeblink rates compared to controls, both during task performance and at rest, consistent with heightened DA transmission. Third, although neither task-evoked pupil dilation nor resting pupil diameter differed between TS patients and controls, pupil diameter was positively related to parentally reported anxiety levels in patients, suggesting heightened NE transmission in patients with comorbid anxiety. Thus, with the behavioral and eyetracking data gathered from a single task, we can gather objective data that are related both to tic severity and anxiety levels in pediatric patients with TS, and that likely reflect patients' underlying neurochemical disturbances.

  20. Oxidative Stress State Is Associated with Left Ventricular Mechanics Changes, Measured by Speckle Tracking in Essential Hypertensive Patients

    OpenAIRE

    Luis Antonio Moreno-Ruíz; David Ibarra-Quevedo; Erika Rodríguez-Martínez; Maldonado, Perla D.; Benito Sarabia-Ortega; José Gustavo Hernández-Martínez; Beda Espinosa-Caleti; Beatriz Mendoza-Pérez; Selva Rivas-Arancibia

    2015-01-01

    The oxidative stress state is characterized by an increase in oxygen reactive species that overwhelms the antioxidant defense; we do not know if these pathological changes are correlated with alterations in left ventricular mechanics. The aim was correlating the oxidative stress state with the left ventricular global longitudinal strain (GLS) and the left ventricular end diastolic pressure (LVEDP). Twenty-five patients with essential hypertension and 25 controls paired by age and gender were ...

  1. Cerebrovascular accidents in patients with a ventricular assist device.

    Science.gov (United States)

    Tsukui, Hiroyuki; Abla, Adib; Teuteberg, Jeffrey J; McNamara, Dennis M; Mathier, Michael A; Cadaret, Linda M; Kormos, Robert L

    2007-07-01

    A cerebrovascular accident is a devastating adverse event in a patient with a ventricular assist device. The goal was to clarify the risk factors for cerebrovascular accident. Prospectively collected data, including medical history, ventricular assist device type, white blood cell count, thrombelastogram, and infection, were reviewed retrospectively in 124 patients. Thirty-one patients (25%) had 48 cerebrovascular accidents. The mean ventricular assist device support period was 228 and 89 days in patients with and without cerebrovascular accidents, respectively (P cerebrovascular accidents occurred within 4 months after implantation. Actuarial freedom from cerebrovascular accident at 6 months was 75%, 64%, 63%, and 33% with the HeartMate device (Thoratec Corp, Pleasanton, Calif), Thoratec biventricular ventricular assist device (Thoratec Corp), Thoratec left ventricular assist device (Thoratec), and Novacor device (WorldHeart, Oakland, Calif), respectively. Twenty cerebrovascular accidents (42%) occurred in patients with infections. The mean white blood cell count at the cerebrovascular accident was greater than the normal range in patients with infection (12,900/mm3) and without infection (9500/mm3). The mean maximum amplitude of the thrombelastogram in the presence of infection (63.6 mm) was higher than that in the absence of infection (60.7 mm) (P = .0309). The risk of cerebrovascular accident increases with a longer ventricular assist device support period. Infection may activate platelet function and predispose the patient to a cerebrovascular accident. An elevation of the white blood cell count may also exacerbate the risk of cerebrovascular accident even in patients without infection. Selection of device type, prevention of infection, and meticulous control of anticoagulation are key to preventing cerebrovascular accident.

  2. Nuclear medicine incident reporting in Australia: control charts and notification rates inform quality improvement.

    Science.gov (United States)

    Larcos, G; Collins, L T; Georgiou, A; Westbrook, J I

    2015-06-01

    Australia has a statutory incident reporting system for radiopharmaceutical maladministrations, but additional research into registry data is required for the purpose of quality improvement in nuclear medicine. We (i) used control charts to identify factors contributing to special cause variation (indicating higher than expected rates) in maladministrations and (ii) evaluated the impact of heterogeneous notification criteria and extent of underreporting among jurisdictions and individual facilities, respectively. Anonymised summaries of Australian Radiation Incident Register reports permitted calculation of national monthly maladministration notification rates for 2007-2012 and preparation of control charts. Multivariate logistic regression assessed the association of population, insurance and regulatory characteristics with maladministration notifications in each Australian State and Territory. Maladministration notification rates from two facilities with familiarity of notification processes and commitment to radiation protection were compared with those elsewhere. Special cause variation occurred in only 3 months, but contributed to 21% of all incidents (42 of 197 patients), mainly because of 'clusters' of maladministrations (n = 24) arising from errors in bulk radiopharmaceutical dispensing. Maladministration notification rates varied significantly between jurisdictions (0 to 12.2 maladministrations per 100 000 procedures (P < 0.05)) and individual facilities (31.7 vs 5.8 per 100 000; χ(2) = 40; 1 degree of freedom, P < 0.001). Unexpected increases in maladministration notifications predominantly relate to incident 'clusters' affecting multiple patients. The bulk preparation of radiopharmaceuticals is a vulnerable process and merits additional safeguards. Maladministration notification rates in Australia are heterogeneous. Adopting uniform maladministration notification criteria among States and Territories and methods to overcome underreporting are

  3. His bundle activates faster than ventricular myocardium during prolonged ventricular fibrillation.

    Science.gov (United States)

    Angel, Nathan; Li, Li; Dosdall, Derek J

    2014-01-01

    The Purkinje fiber system has recently been implicated as an important driver of the rapid activation rate during long duration ventricular fibrillation (VF>2 minutes). The goal of this study is to determine whether this activity propagates to or occurs in the proximal specialized conduction system during VF as well. An 8×8 array with 300 µm spaced electrodes was placed over the His bundles of isolated, perfused rabbit hearts (n = 12). Ventricular myocardial (VM) and His activations were differentiated by calculating Laplacian recordings from unipolar signals. Activation rates of the VM and His bundle were compared and the His bundle conduction velocity was measured during perfused VF followed by 8 minutes of unperfused VF. During perfused VF the average VM activation rate of 11.04 activations/sec was significantly higher than the His bundle activation rate of 6.88 activations/sec (pHis system activation rate (6.16, 5.53, 5.14, 5.22, 6.00, and 4.62 activations/sec significantly faster than the rate of the VM (4.67, 3.63, 2.94, 2.24, 3.45, and 2.31 activations/sec) (pHis system immediately decreased to 94% of the sinus rate during perfused VF then gradually decreased to 67% of sinus rhythm conduction at 8 minutes of unperfused VF. During prolonged VF the activation rate of the His bundle is faster than that of the VM. This suggests that the proximal conduction system, like the distal Purkinje system, may be an important driver during long duration VF and may be a target for interventional therapy.

  4. Levosimendan in Patients with Left Ventricular Dysfunction Undergoing Cardiac Surgery.

    Science.gov (United States)

    Mehta, Rajendra H; Leimberger, Jeffrey D; van Diepen, Sean; Meza, James; Wang, Alice; Jankowich, Rachael; Harrison, Robert W; Hay, Douglas; Fremes, Stephen; Duncan, Andra; Soltesz, Edward G; Luber, John; Park, Soon; Argenziano, Michael; Murphy, Edward; Marcel, Randy; Kalavrouziotis, Dimitri; Nagpal, Dave; Bozinovski, John; Toller, Wolfgang; Heringlake, Matthias; Goodman, Shaun G; Levy, Jerrold H; Harrington, Robert A; Anstrom, Kevin J; Alexander, John H

    2017-05-25

    Levosimendan is an inotropic agent that has been shown in small studies to prevent or treat the low cardiac output syndrome after cardiac surgery. In a multicenter, randomized, placebo-controlled, phase 3 trial, we evaluated the efficacy and safety of levosimendan in patients with a left ventricular ejection fraction of 35% or less who were undergoing cardiac surgery with the use of cardiopulmonary bypass. Patients were randomly assigned to receive either intravenous levosimendan (at a dose of 0.2 μg per kilogram of body weight per minute for 1 hour, followed by a dose of 0.1 μg per kilogram per minute for 23 hours) or placebo, with the infusion started before surgery. The two primary end points were a four-component composite of death through day 30, renal-replacement therapy through day 30, perioperative myocardial infarction through day 5, or use of a mechanical cardiac assist device through day 5; and a two-component composite of death through day 30 or use of a mechanical cardiac assist device through day 5. A total of 882 patients underwent randomization, 849 of whom received levosimendan or placebo and were included in the modified intention-to-treat population. The four-component primary end point occurred in 105 of 428 patients (24.5%) assigned to receive levosimendan and in 103 of 421 (24.5%) assigned to receive placebo (adjusted odds ratio, 1.00; 99% confidence interval [CI], 0.66 to 1.54; P=0.98). The two-component primary end point occurred in 56 patients (13.1%) assigned to receive levosimendan and in 48 (11.4%) assigned to receive placebo (adjusted odds ratio, 1.18; 96% CI, 0.76 to 1.82; P=0.45). The rate of adverse events did not differ significantly between the two groups. Prophylactic levosimendan did not result in a rate of the short-term composite end point of death, renal-replacement therapy, perioperative myocardial infarction, or use of a mechanical cardiac assist device that was lower than the rate with placebo among patients with a

  5. Mitral Annular Kinetics, Left Atrial and Left Ventricular Diastolic Function Post Mitral Valve Repair in Degenerative Mitral Regurgitation

    Directory of Open Access Journals (Sweden)

    Chun eSchiros

    2015-08-01

    Full Text Available Objective: The relationship of mitral annular (MA kinetics to left ventricular (LV and left atrial (LA function before and after mitral valve repair has not been well studied. Here we sought to provide comprehensive analysis that relates to MA motions, LA and LV diastolic function post mitral valve repair. Methods: Three-dimensional analyses of mitral annular motion, LA function and LV volumetric and diastolic strain rates were performed on 35 degenerative mitral regurgitation (MR patients at baseline and 1-year post mitral valve repair, and 51 normal controls, utilizing cardiac magnetic resonance imaging with tissue tagging. Results: All had normal LV ejection fraction (EF at baseline. LV and LA EFs decreased 1-year post-surgery vs. controls. LV early-diastolic myocardial strain rates decreased post-surgery along with decreases in normalized early-diastolic filling rate, E/A ratio and early-diastolic MA relaxation rates. Post-surgical LA late active kick remained higher in MR patients vs. control. LV and LA EFs were significantly associated with peak MA centroid to apex shortening. Furthermore, during LV systolic phase, peak LV ejection and LA filling rates were significantly correlated with peak MA centroid to apex shortening rate, respectively. While during LV diastolic phase, both peak early diastolic MA centroid to apex relaxation rate and LA ejection rate were positively significantly associated with LV peak early diastolic filling rate. Conclusions— MA motion is significantly associated with LA and LV function. Mitral annular motion, left atrial function and left ventricular diastolic strain rates are still impaired one year post mitral valve repair. Long term effects of these impairments should be prospectively evaluated.

  6. Magnetic resonance tissue phase mapping demonstrates altered left ventricular diastolic function in children with chronic kidney disease

    Energy Technology Data Exchange (ETDEWEB)

    Gimpel, Charlotte; Pohl, Martin [Medical Center - University of Freiburg, Department of General Pediatrics, Adolescent Medicine and Neonatology, Center for Pediatrics, Freiburg (Germany); Jung, Bernd A. [Inselspital Bern, Institute of Diagnostic, Interventional and Pediatric Radiology, Bern (Switzerland); Jung, Sabine [Medical Center - University of Freiburg, Department of Nuclear Medicine, Freiburg (Germany); Brado, Johannes; Odening, Katja E. [University Heart Center Freiburg, Department of Cardiology and Angiology I, Freiburg (Germany); Schwendinger, Daniel [University Children' s Hospital Zurich, Zurich (Switzerland); Burkhardt, Barbara [University Children' s Hospital Zurich, Pediatric Heart Center, Zurich (Switzerland); Geiger, Julia [University Children' s Hospital Zurich, Department of Radiology, Zurich (Switzerland); Northwestern University, Department of Radiology, Chicago, IL (United States); Arnold, Raoul [University Hospital Heidelberg, Department of Pediatric and Congenital Cardiology, Heidelberg (Germany)

    2017-02-15

    Echocardiographic examinations have revealed functional cardiac abnormalities in children with chronic kidney disease. To assess the feasibility of MRI tissue phase mapping in children and to assess regional left ventricular wall movements in children with chronic kidney disease. Twenty pediatric patients with chronic kidney disease (before or after renal transplantation) and 12 healthy controls underwent tissue phase mapping (TPM) to quantify regional left ventricular function through myocardial long (Vz) and short-axis (Vr) velocities at all 3 levels of the left ventricle. Patients and controls (age: 8 years - 20 years) were matched for age, height, weight, gender and heart rate. Patients had higher systolic blood pressure. No patient had left ventricular hypertrophy on MRI or diastolic dysfunction on echocardiography. Fifteen patients underwent tissue Doppler echocardiography, with normal z-scores for mitral early diastolic (V{sub E}), late diastolic (V{sub A}) and peak systolic (V{sub S}) velocities. Throughout all left ventricular levels, peak diastolic Vz and Vr (cm/s) were reduced in patients: Vz{sub base} -10.6 ± 1.9 vs. -13.4 ± 2.0 (P < 0.0003), Vz{sub mid} -7.8 ± 1.6 vs. -11 ± 1.5 (P < 0.0001), Vz{sub apex} -3.8 ± 1.6 vs. -5.3 ± 1.6 (P = 0.01), Vr{sub base} -4.2 ± 0.8 vs. -4.9 ± 0.7 (P = 0.01), Vr{sub mid} -4.7 ± 0.7 vs. -5.4 ± 0.7 (P = 0.01), Vr{sub apex} -4.7 ± 1.4 vs. -5.6 ± 1.1 (P = 0.05). Tissue phase mapping is feasible in children and adolescents. Children with chronic kidney disease show significantly reduced peak diastolic long- and short-axis left ventricular wall velocities, reflecting impaired early diastolic filling. Thus, tissue phase mapping detects chronic kidney disease-related functional myocardial changes before overt left ventricular hypertrophy or echocardiographic diastolic dysfunction occurs. (orig.)

  7. Computed tomography coronary angiography with heart rate control premedication: a best practice implementation project.

    Science.gov (United States)

    Mander, Gordon Thomas Waterland

    2017-07-01

    Computed tomography coronary angiography patient preparation with heart rate control premedication is employed in departments across Australia. However, the methods of administration vary widely between institutions and do not always follow best practice. This aim of the study was to identify and promote best practice in the administration of heart rate premedication in computed tomography coronary angiography at a regional hospital in Australia. The Joanna Briggs Institute have validated audit and feedback tools to assist with best practice implementation projects. This project used these tools, which involve three phases of activity - a pre-implementation audit, reflecting on results and implementing strategies to address non-compliance, and a post-implementation audit to assess the outcomes. A baseline audit identified non-compliance in the majority of measured audit criteria. Following implementation of an institution-specific guideline and associated worksheet, improved compliance was shown across all audit criteria. Following the development and implementation of institution-specific evidence-based resources relating to heart rate control in computed tomography coronary angiography, a high level of compliance consistent with best practice was achieved.

  8. Cycling before and after Exhaustion Differently Affects Cardiac Autonomic Control during Heart Rate Matched Exercise.

    Science.gov (United States)

    Weippert, Matthias; Behrens, Martin; Mau-Moeller, Anett; Bruhn, Sven; Behrens, Kristin

    2017-01-01

    During cycling before (PRE) and after exhaustion (POST) different modes of autonomic cardiac control might occur due to different interoceptive input and altered influences from higher brain centers. We hypothesized that heart rate variability (HRV) is significantly affected by an interaction of the experimental period (PRE vs. POST) and exercise intensity (HIGH vs. LOW; HIGH = HR > HR at the lactate threshold (HR LT ), LOW = HR ≤ HR LT ) despite identical average HR. Methods: Fifty healthy volunteers completed an incremental cycling test until exhaustion. Workload started with 30 W at a constant pedaling rate (60 revolutions · min -1 ) and was gradually increased by 30 W · 5 min -1 . Five adjacent 60 s inter-beat (R-R) interval segments from the immediate recovery period (POST 1-5 at 30 W and 60 rpm) were each matched with their HR-corresponding 60 s-segments during the cycle test (PRE 1-5). An analysis of covariance was carried out with one repeated-measures factor (PRE vs. POST exhaustion), one between-subject factor (HIGH vs. LOW intensity) and respiration rate as covariate to test for significant effects ( p exhaustion at HIGH intensity. On the opposite, at LOW intensity cycling, a stronger coactivational cardiac autonomic modulation pattern occurs during PRE-exhaustion if compared to POST-exhaustion cycling. The different autonomic modes during these phases might be the result of different afferent and/or central inputs to the cardiovascular control centers in the brainstem.

  9. Joint Machine Learning and Game Theory for Rate Control in High Efficiency Video Coding.

    Science.gov (United States)

    Gao, Wei; Kwong, Sam; Jia, Yuheng

    2017-08-25

    In this paper, a joint machine learning and game theory modeling (MLGT) framework is proposed for inter frame coding tree unit (CTU) level bit allocation and rate control (RC) optimization in High Efficiency Video Coding (HEVC). First, a support vector machine (SVM) based multi-classification scheme is proposed to improve the prediction accuracy of CTU-level Rate-Distortion (R-D) model. The legacy "chicken-and-egg" dilemma in video coding is proposed to be overcome by the learning-based R-D model. Second, a mixed R-D model based cooperative bargaining game theory is proposed for bit allocation optimization, where the convexity of the mixed R-D model based utility function is proved, and Nash bargaining solution (NBS) is achieved by the proposed iterative solution search method. The minimum utility is adjusted by the reference coding distortion and frame-level Quantization parameter (QP) change. Lastly, intra frame QP and inter frame adaptive bit ratios are adjusted to make inter frames have more bit resources to maintain smooth quality and bit consumption in the bargaining game optimization. Experimental results demonstrate that the proposed MLGT based RC method can achieve much better R-D performances, quality smoothness, bit rate accuracy, buffer control results and subjective visual quality than the other state-of-the-art one-pass RC methods, and the achieved R-D performances are very close to the performance limits from the FixedQP method.

  10. Enclosure fire hazard analysis using relative energy release criteria. [burning rate and combustion control

    Science.gov (United States)

    Coulbert, C. D.

    1978-01-01

    A method for predicting the probable course of fire development in an enclosure is presented. This fire modeling approach uses a graphic plot of five fire development constraints, the relative energy release criteria (RERC), to bound the heat release rates in an enclosure as a function of time. The five RERC are flame spread rate, fuel surface area, ventilation, enclosure volume, and total fuel load. They may be calculated versus time based on the specified or empirical conditions describing the specific enclosure, the fuel type and load, and the ventilation. The calculation of these five criteria, using the common basis of energy release rates versus time, provides a unifying framework for the utilization of available experimental data from all phases of fire development. The plot of these criteria reveals the probable fire development envelope and indicates which fire constraint will be controlling during a criteria time period. Examples of RERC application to fire characterization and control and to hazard analysis are presented along with recommendations for the further development of the concept.

  11. Prophylactic implantable defibrillator in patients with arrhythmogenic right ventricular cardiomyopathy/dysplasia and no prior ventricular fibrillation or sustained ventricular tachycardia.

    LENUS (Irish Health Repository)

    Corrado, Domenico

    2010-09-21

    The role of implantable cardioverter-defibrillator (ICD) in patients with arrhythmogenic right ventricular cardiomyopathy\\/dysplasia and no prior ventricular fibrillation (VF) or sustained ventricular tachycardia is an unsolved issue.

  12. Left ventricular aneurysm associated with isolated noncompaction of the ventricular myocardium.

    Science.gov (United States)

    Sato, Yuichi; Matsumoto, Naoya; Yoda, Shunichi; Inoue, Fumio; Kunimoto, Satoshi; Fukamizu, Seiji; Tani, Shigemasa; Takayama, Tadateru; Tokai, Kotaro; Kasamaki, Yuji; Saito, Satoshi; Uchiyama, Takahisa; Koyama, Yasushi

    2006-05-01

    A 66-year-old woman was admitted to our hospital because of left ventricular failure and nonsustained ventricular tachycardia. Two-dimensional echocardiography demonstrated prominent trabeculations and deep intertrabecular recesses, findings consistent with noncompaction of the ventricular myocardium. Myocardial perfusion scintigraphy demonstrated a defect in the anterobasal left ventricular segment. Coronary angiogram was normal, but the left ventriculogram showed an aneurysm in the anterior myocardial segments. This is the first reported case with isolated noncompaction of the ventricular myocardium associated with left ventricular aneurysm.

  13. May Fever Trigger Ventricular Fibrillation?

    Directory of Open Access Journals (Sweden)

    Jean Luc Pasquié

    2005-04-01

    Full Text Available The clinical precipitants of ventricular fibrillation (VF remain poorly understood. Clinical factors such as hypoxemia, acidosis or electrolyte imbalance, drug-related toxicity, autonomic nervous system disorders as well as viral myocarditis have been proposed to be associated with sudden cardiac death particularly in patients with structural heart disease. However, In the Brugada syndrome, concurrent febrile illness has been reported to unmask the electrocardiographic features of the Brugada syndrome and be associated with an increased propensity for VF. More recently, a febrile illnesses of infectious etiology was associated to polymorphic ventricular tachycardia or VF in patients with normal hearts and without known repolarization abnormality. In this review we detail this phenomenon and its putative mechanisms.

  14. Randomized controlled trial of relaxation music to reduce heart rate in patients undergoing cardiac CT.

    Science.gov (United States)

    Ng, Ming Yen; Karimzad, Yasser; Menezes, Ravi J; Wintersperger, Bernd J; Li, Qin; Forero, Julian; Paul, Narinder S; Nguyen, Elsie T

    2016-10-01

    To evaluate the heart rate lowering effect of relaxation music in patients undergoing coronary CT angiography (CCTA), pulmonary vein CT (PVCT) and coronary calcium score CT (CCS). Patients were randomised to a control group (i.e. standard of care protocol) or to a relaxation music group (ie. standard of care protocol with music). The groups were compared for heart rate, radiation dose, image quality and dose of IV metoprolol. Both groups completed State-Trait Anxiety Inventory anxiety questionnaires to assess patient experience. One hundred and ninety-seven patients were recruited (61.9 % males); mean age 56y (19-86 y); 127 CCTA, 17 PVCT, 53 CCS. No significant difference in heart rate, radiation dose, image quality, metoprolol dose and anxiety scores. 86 % of patients enjoyed the music. 90 % of patients in the music group expressed a strong preference to have music for future examinations. The patient cohort demonstrated low anxiety levels prior to CT. Relaxation music in CCTA, PVCT and CCS does not reduce heart rate or IV metoprolol use. Patients showed low levels of anxiety indicating that anxiolytics may not have a significant role in lowering heart rate. Music can be used in cardiac CT to improve patient experience. • Relaxation music does not reduce heart rate in cardiac CT • Relaxation music does not reduce beta-blocker use in cardiac CT • Relaxation music has no effect on cardiac CT image quality • Low levels of anxiety are present in patients prior to cardiac CT • Patients enjoyed the relaxation music and this results in improved patient experience.

  15. Blood pressure and heart rate during ovariohysterectomy in pyometra and control dogs: a preliminary investigation.

    Science.gov (United States)

    Höglund, Odd Viking; Lövebrant, Johanna; Olsson, Ulf; Höglund, Katja

    2016-11-17

    Surgery causes a stress response, a physiologic response to trauma. The intraoperative surgical stress response in dogs diagnosed with pyometra has not previously been described. The aim of this study was to investigate the intraoperative surgical stress response, assessed by blood pressure and heart rate measurements, in dogs diagnosed with pyometra and healthy controls. All dogs were premedicated with acepromazine and methadone, anaesthesia was induced with propofol and maintained with isoflurane, where after the dogs were subjected to ovariohysterectomy. Eight dogs diagnosed with pyometra and eight healthy controls were used. Systolic blood pressure and heart rate were measured to assess the surgical stress response. Additionally propofol dosage at induction of anaesthesia and the end-tidal isoflurane concentration were investigated. The surgery was split into four phases. Phase 0 was the period 10 min before the skin incision, phase 1 was skin incision and opening of abdomen, phase 2 was manipulation of uterine horns, lifting of the ovary with stretching of the mesovarium, ligation and transection of mesovarium and phase 3 was ligation and transection of cervix, removal of organs and closing of the abdomen. Dosage of propofol at induction of anaesthesia was 3.6 ± 1 mg/kg in dogs with pyometra and 4.1 ± 1 in healthy controls (P = 0.37). In both groups, systolic blood pressure increased between phase 1 and 2, from 87 ± 15 to 114 ± 19 mmHg in dogs with pyometra, and from 88 ± 18 to 106 ± 20 mmHg in healthy controls, (both P pyometra and healthy controls.

  16. Rate Control Performance under End-User's Perspective: A Test Tool

    Directory of Open Access Journals (Sweden)

    Hermann De Meer

    2010-01-01

    Full Text Available The Internet has been experiencing a large growth of multimedia traffic of applications performing over an RTP stack implemented on top of UDP/IP. Since UDP does not offer a congestion control mechanism (unlike TCP, studies on the rate control schemes have been increasingly done. Usually, new proposals are evaluated, by simulation, in terms of criteria such as fairness towards competing TCP connections and packet losses. However, results related to other performance aspects—quality achieved, overhead introduced by the control, and actual throughput after stream adaptation—are difficult to obtain by simulation. In order to provide actual results about these criteria, we developed a comprehensive live video delivery tool for testing RTP-based controllers. In this version of the tool, the video is encoded on the fly in the MPEG-2 standard, but we intend to use the H.264/AVC standard as soon as common PC's provide enough processing power to encode H.264/AVC live video. The tool allows to easily incorporate new control schemes. In this paper, we describe the tool architecture and some implementation details. We also evaluate the performance of the tool itself, in terms of efficacy, accuracy, and efficiency.

  17. Rate Control Performance under End-User's Perspective: A Test Tool

    Directory of Open Access Journals (Sweden)

    Farines Jean-Marie

    2010-01-01

    Full Text Available Abstract The Internet has been experiencing a large growth of multimedia traffic of applications performing over an RTP stack implemented on top of UDP/IP. Since UDP does not offer a congestion control mechanism (unlike TCP, studies on the rate control schemes have been increasingly done. Usually, new proposals are evaluated, by simulation, in terms of criteria such as fairness towards competing TCP connections and packet losses. However, results related to other performance aspects—quality achieved, overhead introduced by the control, and actual throughput after stream adaptation—are difficult to obtain by simulation. In order to provide actual results about these criteria, we developed a comprehensive live video delivery tool for testing RTP-based controllers. In this version of the tool, the video is encoded on the fly in the MPEG-2 standard, but we intend to use the H.264/AVC standard as soon as common PC's provide enough processing power to encode H.264/AVC live video. The tool allows to easily incorporate new control schemes. In this paper, we describe the tool architecture and some implementation details. We also evaluate the performance of the tool itself, in terms of efficacy, accuracy, and efficiency.

  18. Heart rate control with adrenergic blockade: Clinical outcomes in cardiovascular medicine

    Science.gov (United States)

    Feldman, David; Elton, Terry S; Menachemi, Doron M; Wexler, Randy K

    2010-01-01

    The sympathetic nervous system is involved in regulating various cardiovascular parameters including heart rate (HR) and HR variability. Aberrant sympathetic nervous system expression may result in elevated HR or decreased HR variability, and both are independent risk factors for development of cardiovascular disease, including heart failure, myocardial infarction, and hypertension. Epidemiologic studies have established that impaired HR control is linked to increased cardiovascular morbidity and mortality. One successful way of decreasing HR and cardiovascular mortality has been by utilizing β-blockers, because their ability to alter cell signaling at the receptor level has been shown to mitigate the pathogenic effects of sympathetic nervous system hyperactivation. Numerous clinical studies have demonstrated that β-blocker-mediated HR control improvements are associated with decreased mortality in postinfarct and heart failure patients. Although improved HR control benefits have yet to be established in hypertension, both traditional and vasodilating β-blockers exert positive HR control effects in this patient population. However, differences exist between traditional and vasodilating β-blockers; the latter reduce peripheral vascular resistance and exert neutral or positive effects on important metabolic parameters. Clinical evidence suggests that attainment of HR control is an important treatment objective for patients with cardiovascular conditions, and vasodilating β-blocker efficacy may aid in accomplishing improved outcomes. PMID:20539841

  19. Hemodynamic Performance of a Novel Right Ventricular Assist Device (PERKAT)

    Science.gov (United States)

    Schulze, P. Christian; Ferrari, Markus W.

    2017-01-01

    Acute right ventricular failure (RVF) is an increasing clinical problem and a life-threatening condition. Right ventricular assist devices represent a reasonable treatment option for patients with refractory RVF. We here present a novel percutaneously implantable device for right ventricular support. The PERKAT device is based on a nitinol stent cage, which is covered with valve-carrying foils. A flexible outlet trunk with a pigtail tip is connected to the distal part. The device is driven by an intra-aortic balloon pump (IABP) drive unit, which inflates/deflates a standard IABP-balloon placed within the stent cage. In-vitro evaluation was done in a liquid bath containing water or blood analog. The PERKAT device was tested in different afterload settings using two different IABP-balloons and varying inflation/deflation rates. We detected flow rates ranging from 1.97 to 3.93 L/min depending on the afterload setting, inflation/deflation rate, balloon size, and the medium used. Flow rates between water and blood analog were nearly comparable, and in the higher inflation/deflation rate settings slightly higher with water. Based on this promising in vitro data, the innovative percutaneously implantable PERKAT device has a potential to become a therapeutic option for patients with RVF refractory to medical treatment. PMID:27831998

  20. Disease-Control Rates Following Intensity-Modulated Radiation Therapy for Small Primary Oropharyngeal Carcinoma

    Science.gov (United States)

    Garden, Adam S.; Morrison, William H.; Wong, Pei-Fong; Tung, Sam S.; Rosenthal, David I.; Dong, Lei; Mason, Brian; Perkins, George H.; Ang, K. Kian

    2014-01-01

    Background The purpose of this study was to assess the ability of intensity-modulated radiation therapy (IMRT) to achieve favorable disease-control rates while minimizing parotid gland doses in patients treated for small primary tumors of the oropharynx. Methods We retrospectively identified all patients who received IMRT as treatment for a small (therapy; in 4 patients, the tube remained in place for more than 6 months following completion of IMRT. The median follow-up was 45 months. The 2-year actuarial local-regional control, recurrence-free, and overall survival rates were 94%, 88%, and 94%, respectively. Conclusions These preliminary data suggest that treatment with IMRT results in favorable local-regional control of small primary oropharynx tumors. IMRT did not appear to have a more favorable acute toxicity profile in this group with respect to the use of a feeding tube; however, the mean dose of radiation delivered to the parotid gland by IMRT was decreased, as 95% of patients had a mean dose of < 30 Gy to at least one gland. PMID:17141972