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Sample records for atrial flutter

  1. Atrial fibrillation or flutter

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/000184.htm Atrial fibrillation or flutter To use the sharing features on this page, please enable JavaScript. Atrial fibrillation or flutter is a common type of abnormal ...

  2. Electrophysiological Mechanisms of Atrial Flutter

    OpenAIRE

    2006-01-01

    Atrial flutter (AFL) is a common arrhythmia in clinical practice. Several experimental models such as tricuspid regurgitation model, tricuspid ring model, sterile pericarditis model and atrial crush injury model have provided important information about reentrant circuit and can test the effect of antiarrhythmic drugs. Human atrial flutter has typical and atypical forms. Typical atrial flutter rotates around tricuspid annulus and uses the crista terminalis and sometimes sinus venosa as the ...

  3. Determinants of recurrent atrial flutter after cardioversion.

    OpenAIRE

    Pozen, R G; Pastoriza, J; Rozanski, J J; Kessler, K M; Myerburg, R J

    1983-01-01

    Eighteen male patients (mean age 59 years) who were electrically cardioverted for pure atrial flutter were retrospectively studied to determine those factors influencing the maintenance of regular sinus rhythm or reversion to atrial flutter. Six months after successful cardioversion, 10 patients (55%) had recurrent atrial flutter and eight patients (45%) were still in sinus rhythm. The two groups were not significantly different with respect to age, symptomatology, abnormalities on the 12 lea...

  4. A not so benign atrial flutter: spontaneous 1:1 conduction of atrial flutter

    OpenAIRE

    Murthy, Avinash M A; Jain, Ankit; Tan, Henry

    2013-01-01

    A 1:1 conduction of atrial tachyarrhythmias, although not uncommon, usually is associated with the use of antiarrhythmic drugs; hyperthyroidism etc. Spontaneous 1:1 conduction of atrial flutter is indeed rare. We present a case of a spontaneous 1:1 conduction of a cavotricuspid isthmus-dependent atrial flutter.

  5. Radiofrequency catheter oblation in atrial flutter

    International Nuclear Information System (INIS)

    Objective: To evaluate the radiofrequency catheter ablation for type I atrial flutter through application of Holo catheter labelling with anatomic imaging localization to ablate the isthmus of IVCTA during complete double-way block. Methods: Eleven cases with type I atrial flutter undergone Holo catheter labelling technique and consecution with conduction time change of coronary venous sinus orifice with-right atrial lower lateral wall pace excitation, were performed with radiofrequency catheter ablation for the isthmus outcoming with complete double-way conduction block. Results: All together 11 cases with 4 of atrial flutter and 7 of sinus rhythm were undergone radiofrequency catheter ablation resulting with double-way conduction block of the isthmus accompanied by prolongation of right atrial conduction time 56.0 ± 2.3 ms and 53.0 ± 4.6 ms respectively. The right atrial excitation appeared to be in clockwise and counter-clockwise of single direction. No recurrence occurred during 3-34 months follow up with only one showing atrial fibrillation. Conclusions: The application of Holo catheter labelling technique with anatomic imaging localization to achieve the double-way conduction block by radiofrequency catheter ablation of TVC-TA isthmus, is a reliable method for treating atrial flutter

  6. Response of atrial flutter to overdrive atrial pacing and intravenous disopyramide phosphate, singly and in combination.

    OpenAIRE

    Camm, J; Ward, D.; Spurrell, R

    1980-01-01

    Ten patients who suffered spontaneous paroxysms of atrial flutter were investigated by electrophysiological techniques. Two had overt Wolff-Parkinson-White syndrome; three Lown-Ganong-Levine syndrome; and one a concealed accessory atrioventricular connection. Atrial flutter was initiated, at study, by right atrial pacing and electrograms from the right atrium and coronary sinus were observed for at least five minutes to ensure stable flutter in both atria. Atrial flutter was terminated by 2.5...

  7. Effect of exercise on cycle length in atrial flutter.

    OpenAIRE

    van den Berg, M.P.; Crijns, H J; Szabó, B. M.; Brouwer, J.; Lie, K.I.

    1995-01-01

    OBJECTIVE--To examine the effect of exercise on cycle length in atrial flutter. PATIENTS--15 patients with chronic atrial flutter. Seven patients were taking digoxin and six verapamil; two were not taking medication. METHODS--All patients underwent bicycle ergometry. Flutter cycle length was measured at rest and at peak exercise. RESULTS--Mean flutter cycle length increased from 245 ms to 256 ms (P = 0.002). Six patients developed 1:1 atrioventricular conduction. Significant increases in flut...

  8. A difficult case of left atrial flutter

    Directory of Open Access Journals (Sweden)

    Reinder Evertz MD; Juan Acosta MD; David Andreu M.Sc; Josep Brugada MD, PhD; Lluis Mont MD, PhD

    2014-08-01

    Full Text Available A 55-year-old male was referred for a third ablation procedure because of recurrent atrial fibrillation. During re-isolation of the inferior right pulmonary vein the patient developed an atypical flutter with an clockwise activation pattern around the mitral annulus. Linear ablation at the left mitral isthmus transformed but did not terminate the tachycardia. The cavotricuspid isthmus proved to be a second critical isthmus and linear ablation at this site terminated the tachycardia.

  9. Atrial fibrillation and its determinants after radiofrequency ablation of chronic common atrial flutter

    OpenAIRE

    2005-01-01

    Aim. Atrial fibrillation (AFib) is a major clinical issue and its occurrence is the main problem after catheter ablation of atrial flutter. The long-term occurrence of AFib after common atrial flutter ablation is still matter of debate as it may influence the therapeutic approach. So, the aim of our study was to analyze the determinants and the time course of AFib after radiofrequency catheter ablation of chronic common atrial flutter. Methods and Results. 89 consecutive patients (67.5 ± ...

  10. Isthmus Dependent Atrial Flutter Cycle Length Correlates with Right Atrial Cross-Sectional Area

    OpenAIRE

    2009-01-01

    Background Right atrial flutter cycle length can prolong in the presence of antiarrhythmic drug therapy. We hypothesized that the cycle length of right atrial isthmus dependent flutter would correlate with right atrial cross-sectional area measurements. Methods 60 patients who underwent ablation for electrophysiologically proven isthmus dependent right atrial flutter, who were not on Class I or Class III antiarrhythmic drugs and had recent 2-dimensional echocardiographic data comprised the st...

  11. Extreme tachycardia complicating the use of disopyramide in atrial flutter.

    OpenAIRE

    Robertson, C E; Miller, H C

    1980-01-01

    A 59-year-old man presented with atrial flutter and a 2:1 atrioventricular response, which, after intravenous disopyramide, became 1:1. A mechanism of slowed atrial flutter rate and improved atrioventricular nodal conduction, similar to that recognised with quinidine, is suggested.

  12. A Large Right Atrial Myxoma Associated with Atrial Flutter Rhythm

    Directory of Open Access Journals (Sweden)

    Onursal Buğra

    2010-04-01

    Full Text Available A 22 year-old man presented to the emergency unit with the complaint of difficulty in breathing. In the physical exam, dyspnea and orthopnea were found. In the electocardiographic exam (ECG atrial flutter rhythm was seen. The transthoracic echocardiographic exam revealed a large atrial mass that was originating from interatrial septum. During surgery, complete surgical removal of the right atrial mass was successfully performed under moderate hypothermia. Histological investigations revealed a mass of 15 x 3 cm in diameter and the pathological examination showed that the lesion is a myxoma. Twelve months after surgical excision, clinical and chocardiographicalfollow-up showed a satisfactory exercise tolerance, sinus rhythm in ECG exam, and cardiac functions within normal limits.

  13. Atrial flutter: from ECG to electroanatomical 3D mapping

    OpenAIRE

    2006-01-01

    Atrial flutter is a common arrhythmia that may cause significant symptoms, including palpitations, dyspnea, chest pain and even syncope. Frequently it’s possible to diagnose atrial flutter with a 12-lead surface ECG, looking for distinctive waves in leads II, III, aVF, aVL, V1,V2. Puech and Waldo developed the first classification of atrial flutter in the 1970s. These authors divided the arrhythmia into type I and type II. Therefore, in 2001 the European Society of Cardiology and the North Am...

  14. Successful treatment of fetal atrial flutter and congestive heart failure.

    OpenAIRE

    Hirata, K.; Kato, H.; Yoshioka, F; Matsunaga, T

    1985-01-01

    Fetal supraventricular tachycardia may cause congestive heart failure, hydrops fetalis, and intrauterine death. Tachycardia in a fetus of 34 weeks' gestation was diagnosed as atrial flutter by echocardiography, and was successfully treated by giving the mother digoxin.

  15. Atrial flutter in the newborn resulting from maternal lithium ingestion.

    OpenAIRE

    Wilson, N.; Forfar, J D; Godman, M J

    1983-01-01

    We report a case of isolated atrial flutter in a neonate, attributable to maternal lithium treatment, and suggest that the assessment of all infants born to mothers on lithium treatment during pregnancy should include an electrocardiogram.

  16. Atrial flutter: from ECG to electroanatomical 3D mapping

    Directory of Open Access Journals (Sweden)

    Livio Dei Cas

    2009-08-01

    Full Text Available Atrial flutter is a common arrhythmia that may cause significant symptoms, including palpitations, dyspnea, chest pain and even syncope. Frequently it’s possible to diagnose atrial flutter with a 12-lead surface ECG, looking for distinctive waves in leads II, III, aVF, aVL, V1,V2. Puech and Waldo developed the first classification of atrial flutter in the 1970s. These authors divided the arrhythmia into type I and type II. Therefore, in 2001 the European Society of Cardiology and the North American Society of Pacing and Electrophysiology developed a new classification of atrial flutter, based not only on the ECG, but also on the electrophysiological mechanism. New developments in endocardial mapping, including the electroanatomical 3D mapping system, have greatly expanded our understanding of the mechanism of arrhythmias. More recently, Scheinman et al, provided an updated classification and nomenclature. The terms like common, uncommon, typical, reverse typical or atypical flutter are abandoned because they may generate confusion. The authors worked out a new terminology, which differentiates atrial flutter only on the basis of electrophysiological mechanism. (Heart International 2006; 3-4: 161-70

  17. Incidence and predictive factors of atrial fibrillation after ablation of typical atrial flutter.

    Science.gov (United States)

    Laurent, Valérie; Fauchier, Laurent; Pierre, Bertrand; Grimard, Caroline; Babuty, Dominique

    2009-03-01

    Although cavotricuspid isthmus radiofrequency catheter ablation is considered curative therapy for typical atrial flutter, many patients develop an atrial fibrillation after ablation. The purpose of our study was to determine the incidence and the predictive factors of post-ablation atrial fibrillation. One hundred and forty eight consecutive patients underwent cavotricuspid isthmus ablation for the treatment of typical atrial flutter between January 2004 and December 2005 in our electrophysiological department. Complete cavotricuspid isthmus block was successfully obtained in 96.6% of the patients. At the end of the electrophysiological study a sustained atrial fibrillation was inducible in 20 patients (13.5%). During an average follow-up of 21.3 +/- 8.2 months, atrial fibrillation occurred in 27% of the patients. Univariate analysis identified four parameters correlated with post-ablation atrial fibrillation among the 21 parameters tested: the young age of the patients, a prior history of atrial fibrillation, an inducible atrial fibrillation, and a paroxysmal atrial flutter. Only inducible atrial fibrillation and paroxysmal atrial flutter were independent factors linked to atrial fibrillation after ablation. In our study the incidence of atrial fibrillation after cavotricuspid isthmus radiofrequency catheter ablation is 152 per 1,000 patient-years, i.e. 25 times higher than the incidence of atrial fibrillation in the general population of the same age. Twenty five percent of the patients who had neither prior history of atrial fibrillation nor structural heart disease suffered from atrial fibrillation during a mean follow-up of 21.3 +/- 8.2 months. All these results suggest that atrial flutter and fibrillation could be manifestations of a more general electrophysiologic disease. They emphasize the need for all these patients to benefit from regular, long-term cardiological follow-up after cavotricuspid isthmus ablation because of the high incidence of atrial

  18. Foetal atrial flutter management—the role of electrical cardioversion

    OpenAIRE

    Al-Naami, Ghassan

    2012-01-01

    We report a successful electrical cardioversion of a foetal atrial flutter (AFL) immediately post delivery. We describe the diagnostic tools, assessment and the management antenatally. Then, we review the literature and discuss the debate about management. We stress the point that if the flutter wave is not progressing, the foetal heart will tolerate till term and we can try electrical cardioversion with confidence after delivery.

  19. Outcomes after ablation for typical atrial flutter (from the Loire Valley Atrial Fibrillation Project).

    Science.gov (United States)

    Clementy, Nicolas; Desprets, Laurent; Pierre, Bertrand; Lallemand, Bénédicte; Simeon, Edouard; Brunet-Bernard, Anne; Babuty, Dominique; Fauchier, Laurent

    2014-11-01

    Similar predisposing factors are found in most types of atrial arrhythmias. The incidence of atrial fibrillation (AF) among patients with atrial flutter is high, suggesting similar outcomes in patients with those arrhythmias. We sought to investigate the long-term outcomes and prognostic factors of patients with AF and/or atrial flutter with contemporary management using radiofrequency ablation. In an academic institution, we retrospectively examined the clinical course of 8,962 consecutive patients admitted to our department with a diagnosis of AF and/or atrial flutter. After a median follow-up of 934 ± 1,134 days, 1,155 deaths and 715 stroke and/thromboembolic (TE) events were recorded. Patients with atrial flutter undergoing cavotricuspid isthmus ablation (n = 875, 37% with a history of AF) had a better survival rate than other patients (hazard ratio [HR] 0.35, 95% confidence interval [CI] 0.25 to 0.49, p <0.0001). Using Cox proportional hazards model and propensity score model, after adjustment for main other confounders, ablation for atrial flutter was significantly associated with a lower risk of all-cause mortality (HR 0.55, 95% CI 0.36 to 0.84, p = 0.006) and stroke and/or TE events (HR 0.53, 95% CI 0.30 to 0.92, p = 0.02). After ablation, there was no significant difference in the risk of TE between patients with a history of AF and those with atrial flutter alone (HR 0.83, 95% CI 0.41 to 1.67, p = 0.59). In conclusion, in patients with atrial tachyarrhythmias, those with atrial flutter with contemporary management who undergo cavotricuspid isthmus radiofrequency ablation independently have a lower risk of stroke and/or TE events and death of any cause, whether a history of AF is present or not. PMID:25200340

  20. Prevention of atrial flutter with cryoablation may be proarrhythmogenic

    DEFF Research Database (Denmark)

    Lukac, Peter; Hjortdal, Vibeke E; Pedersen, Anders K;

    2007-01-01

    congenital heart disease. Coronary angiography and electrophysiology study using an electroanatomic mapping system to assess the conduction across the line and to try to induce atrial flutter were performed three months after the operation in 15 patients. RESULTS: Eleven patients had bidirectional block in...... patient with bidirectional block and all patients without bidirectional block had inducible or spontaneous atrial flutter (p = 0.0007). No lesion of the right coronary artery was detected at coronary angiography. CONCLUSIONS: The success rate was suboptimal and the intervention is potentially...

  1. Impact of dronedarone in atrial fibrillation and flutter on stroke reduction

    DEFF Research Database (Denmark)

    Christiansen, Christine Benn; Torp-Pedersen, Christian; Køber, Lars

    2010-01-01

    Dronedarone has been developed for treatment of atrial fibrillation (AF) or atrial flutter (AFL). It is an amiodarone analogue but noniodinized and without the same adverse effects as amiodarone.......Dronedarone has been developed for treatment of atrial fibrillation (AF) or atrial flutter (AFL). It is an amiodarone analogue but noniodinized and without the same adverse effects as amiodarone....

  2. How anatomy can guide ablation in isthmic atrial flutter

    OpenAIRE

    Cabrera Rodríguez, José Ángel; Ho, Siew Yen; Sánchez-Quintana, Damián

    2009-01-01

    Although most ablative procedures undertaken for common atrial flutter target the inferior right atrial isthmus, comparative studies of the morphology of this area are lacking. Our study examines its angiographic anatomy, making correlations with postmortem specimens, to provide a better understanding of the anatomic substrate of this arrhythmia. The gross morphological features and dimensions of the area between the orifice of the inferior caval vein and the attachment of the septal leafl...

  3. ATRIAL FLUTTER: CONTEMPORARY POSSIBILITIES OF DIAGNOSIS AND TREATMENT

    Directory of Open Access Journals (Sweden)

    Yu. A. Bunin

    2016-01-01

    Full Text Available Diagnosis and treatment of atrial flutter (AF is an important clinical task. Epidemiological data, electrophysiological mechanisms and updated classification of AF are presented as well as treatment algorithm that is suggested by leading experts. Two strategies of AF therapy are shown: "rhythm control" and "rate control". Author paid attention that ventricular rate reduction in AF is more difficult task than this in atrial fibrillation. Indications for different AF treatments are discussed: pharmacotherapy, pacing and cardioversion as well as surgical methods.

  4. Atrial flutter in the fetus and young infant: an association with accessory connections.

    OpenAIRE

    Till, J; WREN, C.

    1992-01-01

    OBJECTIVE--To highlight the association between atrial flutter and accessory connections in the fetus and young infant. DESIGN--A retrospective review from January 1985 to January 1990. PATIENTS--Fetuses, neonates, and young infants with atrial flutter. RESULTS--Four fetuses and five infants presented with atrial flutter. In two fetuses and one infant sinus rhythm returned spontaneously. The other six required cardioversion. Three of them developed orthodromic atrioventricular re-entry tachyc...

  5. Symptomatic improvement after radiofrequency catheter ablation for typical atrial flutter

    OpenAIRE

    O'Callaghan, P.; Meara, M; Kongsgaard, E; Poloniecki, J.; Luddington, L; Foran, J; Camm, A; Rowland, E; Ward, D.

    2001-01-01

    OBJECTIVE—To assess the changes in quality of life, arrhythmia symptoms, and hospital resource utilisation following catheter ablation of typical atrial flutter.
DESIGN—Patient questionnaire to compare the time interval following ablation with a similar time interval before ablation.
SETTING—Tertiary referral centre.
PATIENTS—63 consecutive patients were studied. Four patients subsequently underwent an ablate and pace procedure, two died of co-morbid illnesses, and two were lost to follow up....

  6. Atrial flutter complicating severe leptospirosis: a case report

    Directory of Open Access Journals (Sweden)

    Francisco Theogenes Macêdo Silva

    2013-04-01

    Full Text Available Cardiac disturbances are relatively common and electrocardiographic abnormalities may be found in more than 70% of patients with leptospirosis. We report the case of a 68 year-old male with severe leptospirosis who developed atrial flutter. Effective treatment was done with amiodarone. The patient became clinical stable, with complete recovery. Rigorous clinical observation and continuous electrocardiogram (ECG monitoring may facilitate the identification of rhythm disorders, and thus prevent a probable fatal outcome, in severe cases of leptospirosis.

  7. Dronedarone for the treatment of atrial fibrillation and atrial flutter: approval and efficacy

    OpenAIRE

    Deborah Wolbrette, Deborah

    2010-01-01

    Deborah Wolbrette, Mario Gonzalez, Soraya Samii, Javier Banchs, Erica Penny-Peterson, Gerald NaccarelliPenn State Heart and Vascular Institute, Penn State Milton S Hershey Medical Center, Hershey, Pennsylvania, USAAbstract: Dronedarone, a new Class III antiarrhythmic agent, has now been approved by the US Food and Drug Administration for use in patients with atrial fibrillation or atrial flutter. Approval came in March 2009 due to the positive results of the ATHENA trial showing significant r...

  8. CLINICAL CASE OF PERSISTENT ATRIAL FLUTTER IN PATIENT WITH COMORBID PATHOLOGY

    OpenAIRE

    Gavrilyuk, O.; Boeva, Y.; Anyasi, I.; Maltseva, M.; Volkov, D.

    2013-01-01

    Clinical case of persistent atrial flutter in combination with comorbid pathology is presented. Clinical diagnosis, choice of optimal interventional and drug therapy are discussed. Catheter ablation was considered as the optimal method for radical treatment of the atrial flutter. A modification of drug therapy is required according to the condition of the patient after the catheter ablation.

  9. Healthcare Utilization and Clinical Outcomes after Catheter Ablation of Atrial Flutter

    OpenAIRE

    Dewland, Thomas A.; Glidden, David V.; Marcus, Gregory M

    2014-01-01

    Atrial flutter ablation is associated with a high rate of acute procedural success and symptom improvement. The relationship between ablation and other clinical outcomes has been limited to small studies primarily conducted at academic centers. We sought to determine if catheter ablation of atrial flutter is associated with reductions in healthcare utilization, atrial fibrillation, or stroke in a large, real world population. California Healthcare Cost and Utilization Project databases were u...

  10. Electrophysiological determinant for induction of isthmus dependent counterclockwise and clockwise atrial flutter in humans

    OpenAIRE

    J. Lin; Lai, L; Lin, L.; Tseng, Y; Lien, W; Huang, S.

    1999-01-01

    Objective—To investigate the electrophysiological determinant underlying the electrical induction of counterclockwise and clockwise isthmus dependent atrial flutter.
Patients and methods—The isthmus bordered by the inferior vena caval orifice-tricuspid annulus-coronary sinus ostium (IVCO-TA-CSO) has been assumed to be the site of both slow conduction and unidirectional block critical to the initiation of atrial flutter. Trans-isthmus and the global atrial conduction were studied in 25 patient...

  11. Typical flutter ablation as an adjunct to catheter ablation of atrial fibrillation

    OpenAIRE

    Dipen Shah

    2008-01-01

    Typical atrial flutter and atrial fibrillation are frequently observed to coexist(1) .  In the current context of interventional electrophysiology, curative or at least definitive ablation is available for both arrhythmias. Despite their coexistence, it is not clear whether typical flutter ablation is necessary in all patients undergoing catheter ablation of atrial fibrillation. The following review explores the pathophysiology of both arrhythmias, their interrelationships and the availa...

  12. Clinical Differences between Subtypes of Atrial Fibrillation and Flutter: Cross-Sectional Registry of 407 Patients

    OpenAIRE

    Eduardo Dytz Almeida; Raphael Boesche Guimarães; Laura Siga Stephan; Alexandre Kreling Medeiros; Katia Foltz; Roberto Tofani Santanna; Leonardo Martins Pires; Marcelo Lapa Kruse; Gustavo Glotz de Lima; Tiago Luiz Luz Leiria

    2015-01-01

    Introduction: Atrial fibrillation and atrial flutter account for one third of hospitalizations due to arrhythmias, determining great social and economic impacts. In Brazil, data on hospital care of these patients is scarce. Objective: To investigate the arrhythmia subtype of atrial fibrillation and flutter patients in the emergency setting and compare the clinical profile, thromboembolic risk and anticoagulants use. Methods: Cross-sectional retrospective study, with data collection from medic...

  13. Typical flutter ablation as an adjunct to catheter ablation of atrial fibrillation

    Directory of Open Access Journals (Sweden)

    Dipen Shah

    2008-12-01

    Full Text Available Typical atrial flutter and atrial fibrillation are frequently observed to coexist(1 .  In the current context of interventional electrophysiology, curative or at least definitive ablation is available for both arrhythmias. Despite their coexistence, it is not clear whether typical flutter ablation is necessary in all patients undergoing catheter ablation of atrial fibrillation. The following review explores the pathophysiology of both arrhythmias, their interrelationships and the available data pertaining to this theme.

  14. New electrocardiographic criteria for the differentiation between counterclockwise and clockwise atrial flutter: correlation with electrophysiological study and radiofrequency catheter ablation

    OpenAIRE

    Lai, L; J. Lin; Lin, L.; Chen, W.; Ho, Y.; Tseng, Y; Chen, C.; Y. Lee; Lien, W; Huang, S.

    1998-01-01

    Objective—To develop new electrocardiographic (ECG) criteria for the differentiation between counterclockwise and clockwise atrial flutters.
Background—Traditionally, the ECG differentiation between counterclockwise and clockwise atrial flutters is based on the flutter wave polarity in the inferior leads. However, determination of flutter wave polarity is subjective and sometimes difficult, especially in flutter waves of undulating pattern. 
Patients—The study comprised 37 consecutive patient...

  15. Clinical Differences between Subtypes of Atrial Fibrillation and Flutter: Cross-Sectional Registry of 407 Patients

    Directory of Open Access Journals (Sweden)

    Eduardo Dytz Almeida

    2015-01-01

    Full Text Available Introduction: Atrial fibrillation and atrial flutter account for one third of hospitalizations due to arrhythmias, determining great social and economic impacts. In Brazil, data on hospital care of these patients is scarce. Objective: To investigate the arrhythmia subtype of atrial fibrillation and flutter patients in the emergency setting and compare the clinical profile, thromboembolic risk and anticoagulants use. Methods: Cross-sectional retrospective study, with data collection from medical records of every patient treated for atrial fibrillation and flutter in the emergency department of Instituto de Cardiologia do Rio Grande do Sul during the first trimester of 2012. Results: We included 407 patients (356 had atrial fibrillation and 51 had flutter. Patients with paroxysmal atrial fibrillation were in average 5 years younger than those with persistent atrial fibrillation. Compared to paroxysmal atrial fibrillation patients, those with persistent atrial fibrillation and flutter had larger atrial diameter (48.6 ± 7.2 vs. 47.2 ± 6.2 vs. 42.3 ± 6.4; p < 0.01 and lower left ventricular ejection fraction (66.8 ± 11 vs. 53.9 ± 17 vs. 57.4 ± 16; p < 0.01. The prevalence of stroke and heart failure was higher in persistent atrial fibrillation and flutter patients. Those with paroxysmal atrial fibrillation and flutter had higher prevalence of CHADS2 score of zero when compared to those with persistent atrial fibrillation (27.8% vs. 18% vs. 4.9%; p < 0.01. The prevalence of anticoagulation in patients with CHA2DS2-Vasc ≤ 2 was 40%. Conclusions: The population in our registry was similar in its comorbidities and demographic profile to those of North American and European registries. Despite the high thromboembolic risk, the use of anticoagulants was low, revealing difficulties for incorporating guideline recommendations. Public health strategies should be adopted in order to improve these rates.

  16. Results of Atrial Fibrillation Ablation in Patients With or Without a History of Atrial Flutter

    Institute of Scientific and Technical Information of China (English)

    Lu chunshan; Liu Xingpeng; Dong Jianzeng; Ma Changsheng

    2006-01-01

    Objectives There are two kind of atrial flutter during circumferential ablation for atrial fibrillation (AF): new onset left atrial flutter (LAFL), with a history of atrial flutter (AFL). What is the relationship of AFL and AF? Whether there are some differences in clinical course and mechanism between the new onset LAFL and the with a history of AFL remained unclear. The aim of this study was to assess the impacts of circumferential ablation on the occurrence of arrhythmias in follow-up in 2 groups:( 1 ) patients with a history of AFL and AF, and (2)patients with new onset LAFL. Methods Data from 465 patients who had circumferential pulmonary vein ablation (CPVA) or segmental pulmonary vein ablation (SPVA) were analyzed. Patients with a history of AFL ablation and patients who had concomitant AFL ablation were included from analysis. Forty-one patients constituted the history of AFL group (group 1, aged 57±13 years, 7 females) and twenty-eight patients constituted the new onset LAFL group (group 2, aged 55±12 years, 6 females). bipolar recordings were obtained from the tricuspid annulus, coronary sinus,interatrial septum and left atrium. Target sites were identified by early, fragmented or double potentials and by concealed entrainment. Linear lesions were created between target sites and nearby anatomical barriers (1) typical atrial flutter (cycle length, 242±39 ms). cavotricuspid isthmus ablation was performed.(2) new onset LAFL (cycle length, 282±153 ms). 20 episodes of AAFs were documented in 20/28 (71.4%)patients. Target sites were identified around pulmonary veins (n=10), gap in linear lesion (n=7), left atrial roof lines (1 case). For those cases the ablation line between PV and mitral annulus was performed.Patients in Group 2 had larger left atria, higher incidence of AFL pre-CPVA, and lower ejection fraction. Results There was no significant difference in post-CPVA AF recurrence between Groups 1 and 2, but AFL incidence after CPVA was higher in Group

  17. Sudden flare of rheumatoid arthritis associated with newly diagnosed atrial flutter

    OpenAIRE

    Vaduganathan, Muthiah; Auslander, Joel N.

    2014-01-01

    We present an 89-year-old woman with newly diagnosed atrial flutter associated with a flare of her rheumatoid arthritis (RA). She had a history of diet-controlled type 2 diabetes mellitus, hypertension, and RA and presented with lightheadedness and worsening hand pain. She was found to be in new atrial flutter with rapid ventricular response and to have an active RA flare. In addition to adequate atrial flutter rate control, her RA flare was managed by adding hydroxychloroquine and doubling h...

  18. Class IC antiarrhythmic drug induced atrial flutter: electrocardiographic and electrophysiological findings and their importance for long term outcome after right atrial isthmus ablation

    OpenAIRE

    Nabar, A; Rodriguez, L.; Timmermans, C; van Mechelen, R; Wellens, H

    2001-01-01

    OBJECTIVE—To describe the electrocardiographic and electrophysiological findings of new atrial flutter developing in patients taking class IC antiarrhythmic drugs for recurrent atrial fibrillation, and to report the long term results of right atrial isthmus ablation in relation to the ECG pattern of spontaneous atrial flutter.
DESIGN—Retrospective analysis.
SETTING—Tertiary care academic hospital.
PATIENTS—24 consecutive patients with atrial fibrillation (age 54 (12) years; 5 female, 19 male)...

  19. Catheter ablation by low energy DC shocks for successful management of atrial flutter.

    OpenAIRE

    O'Núnáin, S; Linker, N J; Sneddon, J. F.; Debbas, N M; Camm, A J; Ward, D E

    1992-01-01

    OBJECTIVE--To assess the effects of low energy ablation of the substrate for atrial flutter. DESIGN--Initial retrospective analysis of patients undergoing low energy ablation of the atrioventricular node for refractory atrial flutter (group 1) was followed by a prospective assessment of low energy ablation in the posterio-inferior right atrium for the same condition (group 2). SETTING--Tertiary referral centre for management of cardiac arrhythmias. PATIENTS--Seven men (aged 50-67 years) with ...

  20. Two cases of atrial flutter with fetal hydrops: successful fetal drug therapy.

    OpenAIRE

    Won, H. S.; Lee, I. S.; Yoo, H. K.; Yoo, S. J.; Ko, J K; Lee, P R; A. Kim; Mok, J. E.

    1998-01-01

    We describe two cases of fetal atrial flutter associated with severe fetal hydrops which were unresponsive to digoxin but were successfully treated with flecainide acetate. Two cases of fetal atrial flutter were identified in fetuses with severe fetal hydrops on 3rd trimester ultrasonogram(28 weeks' gestation and 30 weeks' gestation). Following failed digoxin monotherapy, flecainide acetate was added to digoxin. On the 7th day and 13th day after combined therapy, fetal heart rate converted to...

  1. Electrophysiological characteristics and radiofrequency ablation of right atrial flutter

    Directory of Open Access Journals (Sweden)

    Yoga Yuniadi

    2007-09-01

    Full Text Available This study aimed to elaborate the electrophysiology characteristics and radiofrequency ablation (RFA results of atrial flutter (AFL which has not been established in Indonesia. Three multipolar catheters were inserted percutaneously and positioned into coronary sinus (CS, His bundle area and around tricuspid annulus. Eight mm ablation catheter was used to make linear ablation at CTI of typical and reverse typical AFL. Bidirectional block was confirmed by conduction time prolongation of more than 90 msec from low lateral to CS ostium and vice versa, and/or by means of differential pacing. Thirty AFL from 27 patients comprised of 19 typical AFL, 5 reverse typical AFL and 6 atypical AFL enrolled the study. Mean tachycardia cycle length (TCL were 261.8 ± 42.84, 226.5 ± 41.23, and 195.4 ± 9.19 msec, respectively (p = 0.016. CTI conduction time occupied up to 60% of TCL with mean conduction time of 153.0 ± 67.37 msec. CS activation distributed to three categories which comprised of proximal to distal, distal to proximal and fusion activation. Only nine of 27 patients had no structural heart disease. RFA of symptomatic typical and reverse typical AFL demonstrated 96% success and 4.5 % recurrence rate during 13 ± 8 months follow up. Typical AFL is the predominant type of AFL in our population. The majority of AFL cases suffered from structural heart disease. RFA was highly effective to cure typical and reverse typical AFL. (Med J Indones 2007; 16:151-8 Keywords: atrial flutter, electrophysiology, ablation

  2. Fourier analysis of a gated blood-pool study during atrial flutter

    International Nuclear Information System (INIS)

    First-harmonic Fourier analysis of a gated blood-pool study is based on the assumption that the cardiac chambers contract once per cardiac cycle. In atrial arrhythmias this condition may not exist for the atria. We recently studied a patient with atrial flutter and 2:1 artioventricular conduction. There were predictable alterations in the first-harmonic Fourier phase and amplitude images. The observed changes from first-harmonic Fourier analysis were: (a) very low atrial amplitude values, and (b) absence of identifiable atrial regions on the phase image

  3. INCIDENCE AND CLINICAL-SIGNIFICANCE OF ST SEGMENT ELEVATION AFTER ELECTRICAL CARDIOVERSION OF ATRIAL-FIBRILLATION AND ATRIAL-FLUTTER

    NARCIS (Netherlands)

    VANGELDER, IC; CRIJNS, HJ; VANDERLAARSE, A; VANGILST, WH; LIE, KI

    1991-01-01

    To study the incidence and clinical significance of postshock ST segment elevations, we recorded 12-lead ECGs immediately after transthoracic direct-current electrical cardioversion in 146 patients with atrial fibrillation or flutter. Among 23 patients (19%), acute ST segment elevations amounted to

  4. Fetal cardiac arrhythmia: antepartum diagnosis of a case of congenital atrial flutter.

    OpenAIRE

    Anderson, K. J.; Simmons, S. C.; Hallidie-Smith, K A

    1981-01-01

    A case of antepartum atrial tachyarrhythmia was detected in the 36th week of pregnancy. Cardiotocograph recordings done twice daily enabled close surveillance of the fetal condition after oxytoxin challenge testing had failed to show evidence of hypoxia. After a diagnosis of fetal cardiac arrhythmia had been made, elective caesarean section in the 40th week of pregnancy resulted in delivery of an infant in atrial flutter and cardiac failure. Both these problems were soon resolved by cardiover...

  5. Transesophageal cardioversion of atrial flutter and atrial fibrillation using an electric balloon electrode system

    Institute of Scientific and Technical Information of China (English)

    郑方胜; 祁学文; 刘海峰; 康宁宁

    2003-01-01

    Objective To determine the feasibility and efficiency of terminating atrial flutter (AFL) and atrial fibrillation (AF) using synchronous low-energy shocks delivered through a novel transesophageal electric balloon electrode system.Methods By using a novel electric balloon electrode system, we attempted 91 transesophageal cardioversions in 52 patients, to treat 53 episodes of AFL and 38 episodes of AF.Results Of the 40 patients of AFL that failed to respond to drug therapy, 37 (92.5%) were successfully countershocked to sinus rhythm by transesophageal cardioversion, with a mean energy of (22.70±4.50) J (20-30 J). Of the 19 patients in AF, transesophageal cardioversion was successful in 16 (84.2%) cases, requiring a mean delivered energy of (17.38±8.58) J (3-30 J). There were no complications such as heart block or ventricular fibrillation, and no evidence of esophageal injury. Conclusions Transesophageal cardioversion using an electric balloon electrode system is an effective and feasible method for the treatment of AFL and AF. It requires low energy and no anesthesia, leads to less trauma, and shows a high cardioversion success rate that may prove valuable in the management of tachyarrhythmias.

  6. Successful termination of combined rapid atrial flutter/fibrillation and ventricular tachycardia by intravenous sotalol.

    OpenAIRE

    Ramsdale, D. R.; Peterson, C

    1987-01-01

    Combined rapid atrial flutter/fibrillation and recurrent ventricular tachycardia occurred in an 82 year old man with acute myocardial infarction. Both arrhythmias were promptly terminated by intravenous sotalol, suggesting another use for this unique drug in the absence of hypotension, heart block or cardiac failure.

  7. The occurrence and prognostic significance of atrial fibrillation/-flutter following acute myocardial infarction. TRACE Study group. TRAndolapril Cardiac Evalution

    DEFF Research Database (Denmark)

    Pedersen, O D; Bagger, H; Køber, L;

    1999-01-01

    AIMS: To investigate the occurrence and prognostic significance of atrial fibrillation/-flutter following acute myocardial infarction. METHODS AND RESULTS: The occurrence and prognostic significance of atrial fibrillation/-flutter were studied in 6676 consecutive patients with acute myocardial...... infarction screened in 27 centres in Denmark for inclusion into the TRAndolapril Cardiac Evaluation (TRACE) study. Information about occurrence of atrial fibrillation/-flutter during hospitalization was prospectively collected for the following three periods: day 1-2, day 3-4 and from day 5 until discharge...

  8. Effects of atrial fibrillation/atrial flutter on the short and medium-term prognosis of patients with acute myocardial infarction

    International Nuclear Information System (INIS)

    Objective: To evaluate the influnce of atrial fibrillation(AF)/atrial flutter on the mortality and prognosis of patients with AMI. Methods: A total of 297 consecutive patients were studied from Jan. 2001 to Dec. 2005 and were categorized into 2 groups according to the presence or absence of AF/atrial flutter. The 30 d and 6 mo mortalities, Killip Grades, cardiogenic shock, arrhythmia and left ventricular ejectory functional (LVEF) 6 months after AMI with Doppler US between the 2 groups were compared. Results: The incidence of AF/atrial fluttler was 12.5% with older age, higher Killip Gorade, higher CPK peak, higher rates of previous myocardial infarction and multivascular involvement than those without AF/ atrial flutter. The short and medium-term mortalities in AF/atriat flutter group were both significantly higher than those of non-AF/atrial flutter group (P<0.05). Conclusions: The short and medium-term mortalities increase obviously in AMI complicated with AF/atrial flutter, probably related to the severity of atherosclerosis. (authors)

  9. Work related physical activity and risk of a hospital discharge diagnosis of atrial fibrillation or flutter: the Danish Diet, Cancer, and Health Study

    OpenAIRE

    Frost, L.; Frost, P.; Vestergaard, P.

    2005-01-01

    Background and Aims: Excessive sporting activities have been associated with risk of atrial fibrillation. To study if work related physical activity also confers risk of atrial fibrillation or flutter, the association between work related physical strain and the risk of a hospital discharge diagnosis (inpatient as well as outpatient) of atrial fibrillation or flutter was examined.

  10. Acute success and short-term follow-up of catheter ablation of isthmus-dependent atrial flutter; a comparison of 8 mm tip radiofrequency and cryothermy catheters

    NARCIS (Netherlands)

    A.S. Thornton (Andrew); P. Janse (Petter); M. Alings (Marco); M.F. Scholten (Marcoen); J.M. Mekel; M. Miltenburg (Max); E. Jessurun; L.J.L.M. Jordaens (Luc)

    2008-01-01

    textabstractObjectives: To compare the acute success and short-term follow-up of ablation of atrial flutter using 8 mm tip radiofrequency (RF) and cryocatheters. Methods: Sixty-two patients with atrial flutter were randomized to RF or cryocatheter (cryo) ablation. Right atrial angiography was perfor

  11. Ablation of Post Transplant Atrial Flutter and Pseudo-fibrillation Using Magnetic Navigation via a Superior Approach

    OpenAIRE

    Tung, Roderick; Shivkumar, Kalyanam; Mandapati, Ravi

    2012-01-01

    Ablation of cavotricuspid ishtmus flutter and atrial tachycardia in a complex substrate has never been reported using remote navigation via superior approach. Venous access was obtained via right internal jugular for ablation and left subclavian for duodecapolar catheter placement into the coronary sinus. In a posttransplant patient presenting with both regular and irregular tachycardia, both cavotricuspid isthmus flutter in the donor and atrial tachycardia in the recipient was mapped using a...

  12. Neonatal atrial flutter after insertion of an intracardiac umbilical venous catheter

    Science.gov (United States)

    de Almeida, Marcos Moura; Tavares, Wládia Gislaynne de Sousa; Furtado, Maria Mônica Alencar Araripe; Fontenele, Maria Marcia Farias Trajano

    2016-01-01

    Abstract Objective: To describe a case of neonatal atrial flutter after the insertion of an intracardiac umbilical venous catheter, reporting the clinical presentation and reviewing the literature on this subject. Case description: A late-preterm newborn, born at 35 weeks of gestational age to a diabetic mother and large for gestational age, with respiratory distress and rule-out sepsis, required an umbilical venous access. After the insertion of the umbilical venous catheter, the patient presented with tachycardia. Chest radiography showed that the catheter was placed in the position that corresponds to the left atrium, and traction was applied. The patient persisted with tachycardia, and an electrocardiogram showed atrial flutter. As the patient was hemodynamically unstable, electric cardioversion was successfully applied. Comments: The association between atrial arrhythmias and misplaced umbilical catheters has been described in the literature, but in this case, it is noteworthy that the patient was an infant born to a diabetic mother, which consists in another risk factor for heart arrhythmias. Isolated atrial flutter is a rare tachyarrhythmia in the neonatal period and its identification is essential to establish early treatment and prevent systemic complications and even death. PMID:26525686

  13. Impact of congestive heart failure and left ventricular systolic function on the prognostic significance of atrial fibrillation and atrial flutter following acute myocardial infarction

    DEFF Research Database (Denmark)

    Pedersen, Ole Dyg; Bagger, Henning; Køber, Lars;

    2005-01-01

    BACKGROUND: Reports on the prognostic importance of atrial fibrillation following myocardial infarction have provided considerable variation in results. Thus, this study examined the impact of left ventricular systolic function and congestive heart failure on the prognostic importance of atrial...... congestive heart failure were prospectively collected. Mortality was followed for 5 years. RESULTS: In patients with left ventricular ejection fraction<0.25, atrial fibrillation/atrial flutter was associated with an increased in-hospital mortality (OR=1.8 (1.1-3.2); p<0.05) but not an increased 30-day...... mortality. In patients with 0.250.35. In patients with congestive heart failure, atrial fibrillation/atrial flutter was associated with an increased in-hospital mortality (OR=1.5 (1.2-1.9); p<0.001) and increased 30-day mortality (OR=1.4 (1.1-1.7); p<0.001) but not in patients without congestive heart...

  14. Interventional treatment of WPW syndrome and typical atrial flutter in the patient with nonischemic cardiomyopathy

    Directory of Open Access Journals (Sweden)

    Bockeria O. L.

    2012-12-01

    Full Text Available Myocardial noncompaction is associated with the development of heart failure and different arrhythmias. There are no typical arrhythmias for myocardial noncompaction. Various arrhythmias are clinically relevant because they may aggravate heart failure, may favor thromboembolism, like atrial fibrillation or flutter, or may lead to syncope or sudden cardiac death. In accumulated data we didn’t find description of left ventricular myocardial noncompaction, atrial flutter and intermittent Wolff–Parkinson–White (WPW syndrome. During electrophysiology study in patient with intermittent WPW syndrome programmed ventricular stimulation S1 = 500 ms, S2 = 260 ms was performed. Nonsustained ventricular tachycardia was induced. Then as a result of stimulation S1 = 500 ms, S2 = 240 ms fast ventricular tachycardia and ventricular fibrillation was induced. Then ventricular fibrillation was spontaneously terminated and converted into atrial fibrillation transmitted through the bypass tract with self-termination in 40 s. Cardiac contrast-enhanced magnetic resonanse imaging revealed left ventricular (LV myocardial noncompaction in apical and anterior segments of LV. There is no specific management of left ventricular myocardial noncompaction. In the present state of knowledge, an implantable cardioverterdefibrillator (ICD should be implanted in patients with myocardial noncompaction presenting with syncope and symptomatic ventricular arrhythmias in order to prevent sudden cardiac death. In this case patient refused from implanting an ICD.

  15. ECG artefacts mimicking atrial flutter in posterior fossa surgery.

    Science.gov (United States)

    Rudigwa, Priya; Elakkumanan, Lenin Babu; Rajan, Sakthi P; Prakash, M V Satya

    2015-01-01

    ECG artefacts are defined as abnormalities in the monitored ECG, which result from measurement of cardiac potentials on the body surface and are not related to the electrical activity of the heart. In the operation theatre, the use of various types of electrical equipment may interfere with ECG interpretation. We describe our experience with artefacts resembling atrial fibrillation when a nerve integrity monitoring device was used on a patient undergoing posterior fossa surgery for epidermoid tumour. These artefacts resemble serious arrhythmias and may result in unwanted interventions. To enable better identification of such artefacts, a 12-lead ECG should be considered as it will display rhythm in all the leads; while artefacts will present in only a few leads, true arrhythmia will be present in all the 12 leads. Our case report aims to increase awareness regarding ECG artefacts and to explain how to distinguish them from actual arrhythmias. PMID:26021382

  16. Alteration of fatal 1:1 conducted atrial flutter to less conducted ratio by landiolol infusion.

    Science.gov (United States)

    Takata, Junko; Haruyama, Naoko; Arashi, Tomoko; Mae, Tomoko

    2016-08-01

    An 84-year-old male patient with a past history of atrial-flutter-fibrillation and dementia underwent an urgent femoral neck fracture surgery. Preoperative electrocardiography demonstrated atrial flutter (AFL) with ventricular conduction at a ratio of 2:1-4:1, and transthoracic echocardiography showed severe left ventricular dysfunction with Ejection Fraction of 14.6 %. Femoral nerve block and Lateral femoral cutaneous nerve block with sedation was planned for the surgery. Upon entry to the operating room, ECG showed 2:1 conducted AFL at the rate of 128 beats min(-1). Due to the stimulation of urethral catheter insertion, it has altered to 1:1 conducted AFL. Loading dose of landiolol hydrochloride 7.5 mg followed by 1.5-3 μg/kg/min continuous administration was given, which had decreased the conduction ratio to 2:1 without causing hypotension. A further episode of 1:1 conducted AFL occurred when the pin was inserted to the thighbone, which caused circulatory collapse. Additional bolus dose of landiolol immediately altered it to 2:1 before operating cardioversion and stabilized the hemodynamics. He maintained AFL with 2:1 conduction thereafter, and 1:1 conduction was never seen postoperatively even after discontinuation of landiolol. PMID:27085543

  17. Successful Ablation of Cavotricuspid Isthmus-dependent Atrial Flutter Guided by Contact Force Vector in a Patient After a Tricuspid Valve Replacement

    OpenAIRE

    Goto, Eri; Nakamura, Kohki; Sasaki, Takehito; Naito, Shigeto

    2014-01-01

    A 46-year-old man after a tricuspid valve replacement due to traumatic severe tricuspid regurgitation developed cavotricuspid isthmus-dependent counterclockwise atrial flutter. During a linear ablation using a contact force-sensing irrigated ablation catheter, the flutter could be terminated by a radiofrequency application within a deep pouch just below the bioprosthetic tricuspid valve.

  18. Atrial flutter in a Tetralogy of Fallot operated patient: importance of a rapid and curative treatment

    Directory of Open Access Journals (Sweden)

    Alberto Cresti; Francesco De Sensi; Gennaro Miracapillo; Ait-Ali Lamia; Pierluigi Festa.

    2015-08-01

    Full Text Available A 51 male, affected by Tetralogy of Fallot, underwent a left Blalock-Taussig anastomosis at the age of two years and an aorto - right pulmonary artery tube graft when 8 years old. Complete surgical correction was performed at age 21 with closure of the ventricular septal defect and a large patch over the right outflow tract, shunts were discontinued. Then it was well up to 51 years old when he began to suffer shortness of breath with minimal exertion. A typical atrial flutter of the common type was diagnosed and a cavo-tricuspid isthmus ablation was successfully performed. Echocardiographic and magnetic resonance imaging and ergospirometry provided complete informations on anatomic and hemodynamic conditions but no other interventional procedure was necessary.

  19. Atrial Flutter

    Science.gov (United States)

    ... heart (atria and the ventricles) work together to pump blood through the heart. A normal heartbeat begins as ... AFL makes it harder for the heart to pump blood effectively. With the blood moving more slowly, it ...

  20. PREDICTION OF UNEVENTFUL CARDIOVERSION AND MAINTENANCE OF SINUS RHYTHM FROM DIRECT-CURRENT ELECTRICAL CARDIOVERSION OF CHRONIC ATRIAL-FIBRILLATION AND FLUTTER

    NARCIS (Netherlands)

    VANGELDER, IC; CRIJNS, HJ; VANGILST, WH; LIE, KI

    1991-01-01

    The present study was undertaken to reassess prospectively the immediate and long-term results of direct-current electrical cardioversion in chronic atrial fibrillation or atrial flutter, and to determine factors predicting clinical outcome of the arrhthmia after direct-current cardioversion. Two-hu

  1. Post-parathyroidectomy thyrotoxicosis and atrial flutter: a case for caution.

    Science.gov (United States)

    Asmar, Abdo; Ross, Edward A

    2011-04-01

    Despite transient hyperthyroidism reportedly occurring in ∼30% of post-parathyroidectomy (PTX) patients with primary hyperparathyroidism, it has rarely been described in the internal medicine literature. It occurs within days of surgery, is usually clinically mild or silent, and typically spontaneously resolves within weeks. Patients can, however, unusually present with symptoms and signs of thyrotoxicosis, including arrhythmias. We report a case of a hemodialysis patient who developed self-limited hyperthyroidism after intra-operative thyroid manipulation and excision during PTX surgery for secondary hyperparathyroidism that failed medical management. The patient was symptomatic with agitation, restlessness and new-onset atrial flutter, which required electrical cardioversion and temporary beta blockade. It is important that clinicians be aware of this potential surgical complication, so as to not attribute manifestations to post-PTX divalent cation disorders (i.e. hungry bone syndrome), thereby allowing prompt diagnosis and treatment. Post-operative monitoring of thyroid function is warranted for at least some subsets of patients: individuals who undergo thyroid exploration and palpation as part of their surgery to localize the parathyroid glands, as well as those with underlying cardiac disease or who are otherwise at high risk from even mild states of hyperthyroidism. PMID:25984129

  2. Typical Atrial Flutter - When Do You Say You Have Got It

    Directory of Open Access Journals (Sweden)

    Michaël Peyrol, MD

    2012-10-01

    Full Text Available Right Atrial Flutter (AFL is a common form of macro reentrant arrhythmia.1–3 In absence of previous cardiac surgery, the reentry circuit is usually bounded anteriorly by the tricuspid annulus (TA and posteriorly by the ostia of vena cava and Eustachian ridge. In this case, AFL is consensually called "typical" AFL and is highly dependent of the cavotricuspid isthmus (CTI.2 The CTI is a critical channel which represents the predominant area of slow conduction of the circuit. Therefore, this narrow isthmus has become the universally accepted target for ablation of typical AFL.2–4If ablation is carried out during AFL the first "intuitive" procedure endpoint is arrhythmia termination. Although this latter was initially thought to be an acceptable endpoint for ablation procedure, bidirectional CTI conduction block is actually considered as the gold standard endpoint for elimination of typical AFL recurrence.5,6 Indeed, Schumacher et al. found a 9% recurrence rate after bidirectional CTI block achievement, 54% recurrence rate after unidirectional CTI block and 100% recurrence rate when persistent slow conduction across CTI was noted after RF application on the CTI.

  3. Safety and efficacy of cryothermal and radiofrequency catheter ablation in treatment of typical atrial flutter

    Institute of Scientific and Technical Information of China (English)

    WANG Fang; HUANG Cong-xin; CHEN Gang; ZHANG Feng; MENG Wei-dong; SUN Bao-gui

    2007-01-01

    @@ Radiofrequency (RF) ablation of the critical isthmus between the tricuspid annulus and the inferior vena cava is commonly used to treat typical atrial flutter (AFL).1 This has become the first line therapy in Europe and in the US due to its high success rate and significant improvement in quality of life compared with conventional medical therapy.2 Sizeable lesions are required to achieve persistent bidirectional conduction block (BCB), which is the best endpoint to ensurelong-term success.3,4 Cooling the ablation electrode by irrigation has been shown to prevent both overheating of the electrode-tissue interface and impedance rise during RF delivery, allowing greater power delivery and larger,deeper lesion.5 Recent studies showed that pain-free cryoablation was comparable to RF ablation regardingthe short and long-term clinical success rate and safety.6However, no studies have shown that cryoablation is superior to the irrigation RF ablation. In this study, we compared the efficacy and safety of cryoablation with the irrigation radiofrequency ablation technologies for typical AFL.

  4. Alta dose de amiodarona em curto período reduz incidência de fibrilação atrial e flutter atrial no pós-operatório de cirurgia de revascularização miocárdica High dose of amiodarone in a short-term period reduces the incidence of postoperative atrial fibrillation and atrial flutter

    Directory of Open Access Journals (Sweden)

    Rafael Vieira Alcalde

    2006-09-01

    Full Text Available OBJETIVOS: Avaliar se a administração de amiodarona, em doses altas e curso rápido, reduz a incidência de fibrilação ou flutter atrial, após cirurgia de revascularização miocárdica e se reduz, também, o tempo de internação hospitalar. MÉTODOS: A amostra se constituiu de 93 pacientes randomizados, em estudo duplo-cego, para receberem amiodarona (46 pacientes ou placebo (47 pacientes. A terapia consistia na aplicação de 600mg de amiodarona, três vezes ao dia, iniciada no mínimo 30 horas e no máximo 56 horas antes da cirurgia. RESULTADOS: Fibrilação ou flutter atrial no pós-operatório ocorreu em 8 dos 46 pacientes no grupo amiodarona (17,4% e em 19 dos 47 pacientes no grupo placebo (40,4% (p=0,027. A dose média de amiodarona foi de 2,8g. Os pacientes do grupo amiodarona ficaram hospitalizados por 8,9±3,1 dias, enquanto a internação dos pacientes do grupo placebo foi de 11,4± 8,7 dias (p=0,07. O tempo de internação foi significativamente prolongado nos pacientes que desenvolveram fibrilação ou flutter atrial após a cirurgia, independente do grupo randomizado. CONCLUSÃO: Esta nova alternativa de administração de amiodarona em alta dose e por um curto período, antes da cirurgia de revascularização miocárdica, reduz a incidência de fibrilação ou flutter atrial no pós-operatório desta cirurgia.OBJECTIVE: To investigate wheter oral amiodarone administered before surgery for a short period in high dose would reduce the incidence of postoperative atrial fibrillation or atrial flutter and reduces the lenght of hospital stay. METHODS: In the double-blind, randomized study, 93 patients were given either oral amiodarone (46 patients or placebo (47 patients. Therapy consisted of 600mg of amiodarone three times a day, started at mininum 30 hours and at maximum 56 hours before surgery. RESULTS: Postoperative atrial fibrillation or atrial flutter occurred in 8 of 46 patients in the amiodarone group (17.4% and 19 of the

  5. Impact of dronedarone in atrial fibrillation and flutter on stroke reduction

    Directory of Open Access Journals (Sweden)

    Christine Benn Christiansen

    2010-03-01

    Full Text Available Christine Benn Christiansen1, Christian Torp-Pedersen1, Lars Køber21Department of Cardiology, Gentofte Hospital, University of Copenhagen, Hellerup, Denmark; 2Department of Cardiology, Rigshospitalet, University of Copenhagen, Copenhagen, DenmarkBackground: Dronedarone has been developed for treatment of atrial fibrillation (AF or atrial flutter (AFL. It is an amiodarone analogue but noniodinized and without the same adverse effects as amiodarone.Objective and methods: This is a review of 7 studies (DAFNE, ADONIS, EURIDIS, ATHENA, ANDROMEDA, ERATO and DIONYSOS on dronedarone focusing on efficacy, safety and prevention of stroke. There was a dose-finding study (DAFNE, 3 studies focusing on maintenance of sinus rhythm (ADONIS, EURIDIS and DIONYSOS, 1 study focusing on rate control (ERATO and 2 studies investigating mortality and morbidity (ANDROMEDA and ATHENA.Results: The target dose for dronedarone was established in the DAFNE study to be 400 mg twice daily. Both EURIDIS and ADONIS studies demonstrated that dronedarone was superior to placebo for maintaining sinus rhythm. However, DIONYSOS found that dronedarone is less efficient at maintaining sinus rhythm than amiodarone. ERATO concluded that dronedarone reduces ventricular rate in patients with chronic AF. The ANDROMEDA study in patients with severe heart failure was discontinued because of increased mortality in dronedarone group. Dronedarone reduced cardiovascular hospitalizations and mortality in patients with AF or AFL in the ATHENA trial. Secondly, according to a post hoc analysis a significant reduction in stroke was observed (annual rate 1.2% on dronedarone vs 1.8% on placebo, respectively [hazard ratio 0.66, confidence interval 0.46 to 0.96, P = 0.027]. In total, 54 cases of stroke occurred in 3439 patients (crude rate 1.6% receiving dronedarone compared to 76 strokes in 3048 patients on placebo (crude rate 2.5%, respectively.Conclusion: Dronedarone can be used for maintenance of

  6. Catheter selection for ablation of the cavotricuspid isthmus for treatment of typical atrial flutter.

    Science.gov (United States)

    Da Costa, Antoine; Jamon, Yann; Romeyer-Bouchard, Cécile; Thévenin, Jérôme; Messier, Marc; Isaaz, Karl

    2006-11-01

    Radiofrequency catheter ablation (RFA) represents the first line therapy of the cavotricuspid isthmus-dependent atrial flutter (CTI-AFL) with a high efficacy and low secondary effects. RFA of CTI-dependent AFL can be performed by using various types of ablation catheters. Recent evaluations comparing externally cooled tip RFA (ecRFA) catheters and large-tip (8 mm) catheters have revealed that these catheters have a higher efficacy for CTI-AFL ablation compared to 4-mm catheters. The reliability of RFA catheters for AFL is variable and an optimal catheter selection may enhance the RFA effectiveness. The main goal of this article is to review the elements that improve the management of CTI RFA. Preliminary examinations of histopathologic and anatomical elements that may interfere with conventional CTI RFA are presented. Experimental studies concerning the electrobiology of large-tip and cooled-tip catheters are compared. The different catheter designs between cooled-tip and 8-mm-tip catheters are examined (size of the deflectable curve, rotation stability, and size of the distal nonsteerable catheter part) because of their critical role in CTI RFA results. A thorough review of clinical trials of each catheter is presented, and comparison of both catheters in this clinical setting is analyzed. In addition, the role of CTI morphology on AFL RF duration is underlined such as the value of right atrial angiography as an adjunct tool for CTI RFA catheter selection. Based on randomized studies, 8-mm-tip catheters seem to be more effective for ablation in case of straight angiographic isthmus morphology. On the other hand, ecRFA catheters appear to be more effective in cases of complex CTI anatomy or difficult CTI RFA. To reduce X-ray exposition and RFA application time, few studies report that CTI angiographic evaluation before RFA allows a catheter selection based on both CTI morphology and length. Moreover, preliminary data of randomized studies showed that an

  7. : Emergency Physician Patterns Related to Anticoagulation of Patients with Recent-Onset Atrial Fibrillation and Flutter

    Directory of Open Access Journals (Sweden)

    Paraish Misra, MD

    2013-04-01

    Full Text Available Guidelines strongly recommend long-term anticoagulation with warfarin for patients with newly recognized AF who have high embolic risk by virtue of a CHADS2 (Congestive Heart Failure, Hypertension, Age >65, Diabetes, History of Stroke score ≥ 2. The goal of this study was to determine patterns of emergency department-initiated anticoagulation among eligible patients discharged from Canadian centers with an episode of recent-onset atrial fibrillation and flutter (RAFF and determine if decision-making is driven by the CHADS2 score or other factors. This was accomplished by examining health records using uniform case identification and data abstraction as well as centralized quality control; it was conducted in 8 Canadian university emergency departments over a 12-month period. Eligible patients for this analysis demonstrated RAFF requiring emergency management, were not already taking warfarin and were not admitted to hospital. Univariate analyses were conducted using T-test or Chi-square to select factors associated with anticoagulation initiation at a significance level of p < 0.15 and multiple logistic regression was employed to evaluate independent predictors after adjustment for confounders. Among 633 eligible patients, only 21 out of 120 patients (18% with a CHADS2 score ≥ 2 received anticoagulation and among 70 patients who were given anticoagulation only 21 (30% had a CHADS2 score ≥ 2. Independent predictors of anticoagulation included age by 10-year strata: (OR = 1.7; 95% CI 1.3 – 2.1, heparin use in the anticoagulation (OR = 9.6; 95% CI 4.9 – 18.9, a new prescription for metoprolol (OR = 9.6; 95% CI 4.9 – 18.9 and being referred to cardiology for follow-up (OR = 5.6; 95% CI 2.6 – 12.0. CHADS2 ≥ 2 doubled the likelihood of being prescribed anticoagulation (OR= 2.0; 95% CI 1.5 – 3.5 but was not an independent predictor. It was thus determined that patients discharged from the emergency department in this study were not

  8. Age as a Risk factor for Atrial Fibrillation and Flutter after Coronary Artery Bypass Grafting

    Directory of Open Access Journals (Sweden)

    Prashant Bhave MD

    2012-02-01

    Full Text Available Atrial fibrillation affects approximately 3 million people in the United States and creates a huge burden on the health care system, both in terms of morbidity, mortality, and cost.1 The prevalence of atrial fibrillation rises sharply with increases in age. It is estimated that 8% of people above 70 years of age have atrial fibrillation.2-4 Atrial fibrillation has long been recognized as a powerful risk factor for stroke,5 heart failure,6 and mortality.7 Advancing age amplifies the risk of all of these sequelae of atrial fibrillation.

  9. Age as a Risk factor for Atrial Fibrillation and Flutter after Coronary Artery Bypass Grafting

    OpenAIRE

    Prashant Bhave MD; Rod Passman MD, MSCE

    2012-01-01

    Atrial fibrillation affects approximately 3 million people in the United States and creates a huge burden on the health care system, both in terms of morbidity, mortality, and cost.1 The prevalence of atrial fibrillation rises sharply with increases in age. It is estimated that 8% of people above 70 years of age have atrial fibrillation.2-4 Atrial fibrillation has long been recognized as a powerful risk factor for stroke,5 heart failure,6 and mortality.7 Advancing age amplifies the risk of al...

  10. Electrophysiologic and anatomical characteristics of the right atrial posterior wall in patients with and without atrial flutter. Analysis by intracardiac echocardiography

    International Nuclear Information System (INIS)

    The posterior right atrial transverse conduction capability during typical atrial flutter (AFL) is well known, but its relationship to the anatomical characteristics remains controversial. Thirty-four AFL and 16 controls underwent intracardiac echocardiography after placement of a 20-polar catheter at the posterior block site during AFL or pacing. In 31 patients, the effective refractory period (ERP) at the block site was determined as the longest coupling interval that resulted in double potentials during extrastimuli from the mid-septal (SW) and free (FW) walls. The block site was located 3.0-29.0 mm posterior to the crista terminalis (CT) in each AFL and control patient. The CT area indexed to the body surface area was larger in AFL patients than in control patients (16.4±6.5 mm2/m2 vs 11.3±6.4 mm2/m2, p=0.01), and was positively correlated to age (r=0.34, p=0.02). The ERP was longer in the AFL patients than in controls (SW: median value 600 [270-725] ms vs 220 [200-253] ms; FW: 280 [230-675] ms vs 215 [188-260] ms, p<0.05 for each). A functional block line was located on the septal side of the CT in all patients. A limited conduction capability and age-related CT enlargement might have important implications for the pathogenesis in AFL. (author)

  11. 心房颤动或心房扑动引发心源性卒中后抗凝血治疗分析%Anticoagulant therapy analysis of cardiogenic stroke caused by atrial fibrillation or atrial flutter

    Institute of Scientific and Technical Information of China (English)

    李志斐

    2016-01-01

    Objective:To explore the anticoagulant therapy method of cardiogenic stroke caused by atrial fibrillation or atrial flutter.Methods:We analyzed the anticoagulant therapy data of 200 patients with cardiogenic stroke caused by atrial fibrillation or atrial flutter.Results:52%of the patients received at least 1 time doses of warfarin.Compared with those who received aspirin,the bleeding conversion rate of warfarin treatment patients was low(P=0.03);16 patients were admitted to hospital within 3 months after discharge.Conclusion:Warfarin is an important drug for the prevention of atrial fibrillation or atrial flutter in patients with a high risk of stroke,and without increasing the incidence of adverse events.%目的:探讨心房颤动或心房扑动引发心源性卒中后抗凝血治疗方法。方法:分析200例心房颤动或心房扑动引发脑卒中患者的抗凝血治疗资料。结果:52%的患者接受至少1次剂量的华法林,接受华法林与接受阿司匹林者相比,接受华法林者出血转换率较低(P=0.03);16例患者在出院3个月内再次因卒中住院。结论:华法林是心房颤动或心房扑动卒中高风险患者的重要预防药物,不增加不良事件发生率。

  12. High Incidence of Atrial Fibrillation or Flutter in Stroke Patients Who Have the Clinical Risk Factors for Stroke

    Directory of Open Access Journals (Sweden)

    Jacob I. Haft; Louis E. Teichholz

    2013-08-01

    Full Text Available The incidence of stroke in patients with atrial fibrillation or flutter (AF is well known and depends on the presence of risk factors. The incidence of AF in patients who have a stroke and its relationship to risk factors is not clear, however, because many stroke patients may have occult intermittent AF that is not present at the time of stroke and is not diagnosed. To better assess the incidence of AF, we studied the clinical records and all the 12 lead ECGs in a 14 year medical center data base of 985 patients admitted with ischemic stroke over a 3 year period and correlated the incidence of AF with the presence of the stroke risk factors. Of the stroke patients with congestive heart failure 61.9% had AF (95%CL 54.4, 68.9, with age >/= 75 years 45.2% had AF (CL 41.0,49.4, with coronary artery disease 42.9 had AF (CL 36.8, 49.2, with diabetes 39.2% had AF (CL 32.8,46.1 and with hypertension 33.7% had AF (CL 30.5, 37.1, all significantly higher than without these risk factors. Patients with more than one risk factor or with echo abnormalities, especially left atrial enlargement, had an even higher incidence of AF. These findings suggest that AF may be a very common mechanism whereby the stroke risk factors cause stroke. Stroke patients in normal sinus rhythm with these risk factors should be monitored for AF so they can receive anticoagulation to prevent a subsequent stroke if AF is diagnosed.

  13. Increased risk of sudden and non-sudden cardiovascular death in patients with atrial fibrillation/flutter following acute myocardial infarction

    DEFF Research Database (Denmark)

    Pedersen, Ole Dyg; Abildstrøm, Steen Z; Ottesen, Michael M; Rask-Madsen, Christian; Bagger, Henning; Køber, Lars; Torp-Pedersen, Christian

    2005-01-01

    AF facilitates induction of ventricular arrhythmias, which may increase the risk of sudden cardiovascular death (SCD). A close examination of the mode of death could potentially provide useful knowledge to guide further investigations and treatments. METHODS AND RESULTS: We analysed the relation......AIMS: Atrial fibrillation (AF) is a common complication in patients with acute myocardial infarction and is associated with an increase in the risk of death. The excess mortality associated with AF complicating acute myocardial infarction has not been studied in detail. Observations indicate that...... between AF/atrial flutter (AFL) and modes of death in 5983 consecutive patients discharged alive after an acute myocardial infarction screened in the TRAndolapril Cardiac Evaluation registry. This cohort of patients with an enzyme-verified acute myocardial infarction was admitted to 27 centres in 1990...

  14. Randomized comparison of the continuous vs point-by-point radiofrequency ablation of the cavotricuspid isthmus for atrial flutter

    International Nuclear Information System (INIS)

    Achievement of complete conduction block in the cavotricuspid isthmus (CTI) is a curative ablation technique in patients with common atrial flutter (AFL). The present study was a prospective comparison of the efficacy of 2 ablation strategies in patients with common AFL: the continuous and point-by-point radiofrequency (RF) delivery techniques. Forty patients with common AFL were randomly assigned to either a group treated with a continuous RF delivery or to a group undergoing point-by-point RF ablation. In the first group, the RF energy was continuously delivered during a slow drag of the catheter tip from the tricuspid annulus to the inferior vena cava without stopping the application. In the second group, the RE ablation was performed using a point-by-point approach for 60 s at each point. All patients underwent ablation with an 8-mm-tip ablation catheter with a power limit of 50 W and a target temperature of 55 degC. Complete CTI conduction block was achieved in all patients. The patient characteristics, including the anatomy of the CTI estimated by 3-dimensional computed tomography, were no different between the 2 groups. The procedure time (time from the start of RF delivery to the completion of CTI block), fluoroscopic time and total RF energy required to create the CTI block between the continuous and point-by-point groups were 7.3±5.6 vs 21.2±22.2 min (p<0.01), 7.2±4.4 vs 16.2±14.1 min (p<0.05), and 15,631±6,001 vs 24,072±16,140 joules (p<0.05), respectively. There were no complications or recurrences of AFL during the follow-up period in any of the patients. In the curative treatment of common AFL, the continuous RF delivery approach could shorten the procedure and fluoroscopic time and reduce the total RF energy compared with the point-by-point RF ablation approach. (author)

  15. Fibrilação atrial e flutter após operação de revascularização do miocárdio: fatores de risco e resultados Atrial fibrillation and flutter following coronary artery bypass graft surgery: risk factors and results

    Directory of Open Access Journals (Sweden)

    Marco Aurélio Vilela Borges LIMA

    2001-09-01

    Full Text Available OBJETIVO: Determinar a incidência de fibrilação atrial e flutter (FAF no pós-operatório de revascularização do miocárdio (RM, bem como os fatores preditivos e a influência destas arritmias sobre o período de internação hospitalar. CASUÍSTICA E MÉTODOS: Foram analisados 275 pacientes submetidos à operação de revascularização do miocárdio isolada ou associada à correção de aneurisma de ventrículo esquerdo. A idade variou de 26 a 83 anos, com média de idade de 58,7 ± 9,5 anos. Cento e noventa e seis pacientes (71,3% eram do sexo masculino. RESULTADOS: A incidência total de fibrilação atrial e flutter pós-operatórios foi 16,4% com pico de incidência ocorrendo no segundo e terceiro dia de pós-operatório. Idade avançada, sexo masculino e história de fibrilação atrial ou flutter no pré-operatório foram identificados como fatores preditivos independentes de fibrilação atrial ou flutter no pós-operatório. Os pacientes que apresentaram FA ou flutter no pós-operatório em média 36 horas a mais na Unidade de Terapia Intensiva (UTI e 4,8 dias a mais hospitalizados. CONCLUSÃO: A FA e flutter são arritmias comuns no pós-operatório de revascularização do miocárdio, tendo efeito significativo sobre os tempos de permanência na UTI e de internação hospitalar.OBJECTIVE: The aim of this study was to determine the overall incidence and predictors of atrial fibrillation and flutter (AFF following CABG, as well as the influence of these arrhythmia on the hospital length of stay. MATERIAL AND METHODS: Two hundred and seventy-five patients, who had undergone coronary artery bypass graft (CABG surgery at the Beneficência Portuguesa Hospital in São Paulo, had their data collected and analyzed. The age range was from 26 to 83 years old with mean age of 58.7 and standard deviation of 9.5 years. One hundred and ninety six patients (71.3% were male. RESULTS: The outcomes of this analysis were: the overall incidence of

  16. Rationale and design of ATHENA: A placebo-controlled, double-blind, parallel arm trial to assess the efficacy of dronedarone 400 mg bid for the prevention of cardiovascular hospitalization or death from any cause in PatiENts with atrial fibrillation/atrial flutter

    DEFF Research Database (Denmark)

    Hohnloser, S.H.; Connolly, S.J.; Crijns, H.J.G.M.;

    2008-01-01

    Rationale and Design of ATHENA. Background: Atrial fibrillation (AF) is the most commonly encountered clinical arrhythmia, predominantly affecting elderly patients. There is a continued need for new antiarrhythmic drugs to treat the ever-increasing number of patients with this arrhythmia......ENts with Atrial fibrillation/atrial flutter) is the largest single antiarrhythmic drug trial ever conducted. More than 4,600 patients with a history of AF or atrial flutter (AFL) have been randomized to receive dronedarone 400 mg bid or matching placebo. The primary study endpoint is time to first....... Dronedarone is a new antiarrhythmic compound currently being developed for treatment of AF. Methods: The ATHENA trial (A placebo-controlled, double-blind, parallel arm Trial to assess the efficacy of dronedarone 400 mg bid for the prevention of cardiovascular Hospitalization or death from any cause in pati...

  17. Case report of surgical treatment of abnormal atrial flutter (incisional atrial tachycardia in the patient after mitral valve replacement and radiofrequency modification of Maze procedure

    Directory of Open Access Journals (Sweden)

    Revishvili А. Sh.

    2012-12-01

    Conclusion. This type of tachycardia following after an atrial fibrillation surgery may be considered as a failing transmural myocardial damage during the procedure. The catheter method can be used succesfully unless there are no effects of antiarrhythmic therapy. The catheter method enables not only to verify the disconnection between the left atrial pulmonary veins and left atrium myocardium but also to perform the ablation in zones of the atrial myocardium that are anatomic substrates of post surgery tachyarrhythmias.

  18. Ablação do flutter atrial típico: estudo prospectivo e randomizado do cateter irrigado fechado versus cateter com eletrodo distal de 8 mm Ablation of typical atrial flutter: a prospective randomized study of cooled-tip versus 8-mm-tip catheters

    Directory of Open Access Journals (Sweden)

    Sissy L. Melo

    2007-03-01

    Full Text Available OBJETIVOS: Trabalho prospectivo, randomizado para comparar a eficácia e a segurança do cateter irrigado em relação ao cateter com eletrodo distal de 8 mm para ablação com radiofreqüência (RF do flutter atrial. MÉTODOS: Em 52 pacientes consecutivos referidos para tratamento do flutter atrial típico, a ablação do istmo cavotricuspídeo (Ist-CT foi realizada com cateter de irrigação fechada (n=26 ou com cateter de eletrodo distal de 8 mm (n=26. Os pulsos de RF foram aplicados ponto a ponto por 60 segundos com potência limitada a 50 w com o cateter irrigado e por controle de temperatura (60ºC, 70 w com cateter de 8 mm. O critério de fim do procedimento foi a obtenção de bloqueio bidirecional do Ist-CT. RESULTADOS: O bloqueio Ist-CT foi obtido em 98,1% dos pacientes. O "crossover" ocorreu em quatro pacientes do grupo com cateter irrigado. Não se encontrou diferença estatística significante em relação aos parâmetros da ablação, tais como tempo total de aplicação de RF (591,1±309,0s vs 486,2±250,8s, duração do procedimento (86,4 ± 23,6 vs 78,1±22,5min e tempo de fluoroscopia (17,0±6,7 vs 15,4±4,6min entre os dois grupos. Durante seguimento médio de 10,6 meses, um paciente do grupo irrigado apresentou recorrência do flutter atrial típico. CONCLUSÃO: A ablação do Ist-CT resultou ser efetiva e segura para o controle do flutter atrial com ambas as técnicas empregadas (cateter com eletrodo distal de 8 mm e cateter irrigado. A complexidade técnica do cateter irrigado proporciona menor competitividade.OBJECTIVES: Both ablation catheters with closed irrigated system and 8mm tip-catheters have been shown to be more effective for typical atrial flutter radiofrequency (RF ablation when compared to conventional 4 mm tip catheter. Considering the differences in complexity and costs of both systems, a prospective study was designed to compare the efficacy and safety of cooled-tip and 8mm-tip catheters for atrial flutter

  19. Atrial Tachycardias Occurring Late After Open Heart Surgery

    OpenAIRE

    Kohári, Mária; Pap, Róbert

    2015-01-01

    Atrial tachycardias are common after open heart surgery. Most commonly these are macro-reentrant including cavotricuspid isthmus dependent atrial flutter, incisional right atrial flutter and left atrial flutter. Focal atrial tachycardias occur less frequently. The specific type of atrial tachycardia highly depends on the type of surgical incision. Catheter ablation can be very effective, however requires a thorough understanding of anatomy and surgical technique.

  20. Analysis of stroke in ATHENA: a placebo-controlled, double-blind, parallel-arm trial to assess the efficacy of dronedarone 400 mg BID for the prevention of cardiovascular hospitalization or death from any cause in patients with atrial fibrillation/atrial flutter

    DEFF Research Database (Denmark)

    Connolly, Stuart J; Crijns, Harry J G M; Torp-Pedersen, Christian;

    2009-01-01

    stroke has been evaluated in a randomized, double-blind clinical trial, ATHENA (A placebo-controlled, double-blind, parallel-arm Trial to assess the efficacy of dronedarone 400 mg BID for the prevention of cardiovascular Hospitalization or death from any cause in patiENts with Atrial fibrillation......BACKGROUND: Many patients with atrial fibrillation are at high risk for stroke and require antithrombotic therapy. Antiarrhythmic drugs have not previously been shown to reduce the risk of stroke in atrial fibrillation. The effect of dronedarone, a new multichannel-blocking antiarrhythmic drug, on....../atrial flutter). METHODS AND RESULTS: Patients with persistent or paroxysmal atrial fibrillation and at least 1 risk factor for cardiovascular hospitalization were randomized to receive dronedarone (400 mg BID) or double-blind matching placebo and followed up for a minimum of 1 year to a common termination at 30...

  1. 硫酸镁对伊布利特转复心房颤动/心房扑动疗效的影响%Influence of magnesium sulfate on conversion effect of ibutilide on atrial fibrillation or flutter

    Institute of Scientific and Technical Information of China (English)

    吕薇; 牛铁生; 曹乾

    2013-01-01

    AIM To investigate the influence of pre-injected magnesium sulfate on the conversion effect of ibutilide on atrial fibrillation or flutter. METHODS Sixty -four patients who has atrial fibrillation or flutter were randomized to give placebo plus ibutilide group (control group) or magnesium sulfate plus ibutilide group (trial group) , receive either an infusion of 100 mL of 0.9% sodium chloride or the same amount of sodium chloride with 20 mL of 25% magnesium sulfate in one hour. After 10 min, ibutilide was infused. The conversion rate of atrial fibrillation or flutter and adverse events were observed. RESULTS Conversion rate of ibutilide for atrial fibrillation or flutter in the control group and the trial group is 50% and 84% respectively (P < 0.05). Adverse events are not significantly different between the two groups. CONCLUSION Pre - injection of mag -nesium sulfate enhances the ability of ibutilide for the conversion of atrial fibrillation or flutter.%目的 观察预先静脉给予硫酸镁对伊布利特转复心房颤动/心房扑动的影响.方法 选择符合条件的心房颤动/心房扑动患者64例,随机单盲法分为安慰剂+伊布利特组(对照组)和硫酸镁+伊布利特组(试验组),分别在1h内静脉滴注氯化钠注射液100 mL或氯化钠注射液100 mL加25%硫酸镁20 mL,10 min后给予伊布利特静脉注射,观察两组患者的心房颤动/心房扑动转复率及不良事件发生情况.结果 对照组与试验组对于心房颤动/心房扑动的转复率分别为50%及84%,两组比较差异显著(P<0.05);两组间不良反应发生率无显著差异(P>0.05).结论 预先静脉给予硫酸镁可显著提高伊布利特转复心房颤动/心房扑动的成功率.

  2. Ablação por cateter do flutter atrial. Caracterização eletrofisiológica da interrupção da condução pelos istmos posterior e septal Catheter ablation of atrial flutter. Electrophysiological characterization of posterior and septal isthmus block

    Directory of Open Access Journals (Sweden)

    José Marcos Moreira

    1998-07-01

    Full Text Available OBJETIVO: Avaliar os tipos de bloqueio obtidos nos istmos posterior (entre o anel tricuspídeo e veia cava inferior e septal (entre o anel tricuspídeo e óstio do seio coronário, após ablação do flutter atrial (FLA. MÉTODOS: Foram submetidos à ablação por radiofreqüência (RF 14 pacientes com FLA tipo I (9 homens em 16 procedimentos. A ativação atrial ao redor do anel tricuspídeo foi avaliada em ritmo sinusal utilizando-se cateter "Halo" com 10 pares de eletrodos (H1-2 a H19-20, durante estimulação do seio coronário proximal (SCP e região póstero-lateral do átrio direito (H1-2, antes e após ablações lineares. De acordo com a frente de programação do impulso definiu-se: ausência de bloqueio (condução bidirecional, bloqueio incompleto (condução bidirecional com retardo num dos sentidos e bloqueio completo (ausência de condução pelo istmo. O intervalo desta ativação (deltaSCP/H1-2 foi analisado. RESULTADOS: Bloqueio completo foi obtido em 7 procedimentos (44% e incompleto em 4 (25%. O deltaSCP/H1-2 foi de 74 ± 26ms no primeiro grupo e de 30,5 ± 7,5ms no segundo (pPURPOSE: Evaluate the different types of conduction blocks obtained between inferior vena cava-tricuspid annulus (posterior isthmus and between tricuspid annulus-coronary sinus ostium (septal isthmus after radiofrequency (RF catheter ablation of atrial flutter (AFL METHODS: In 16 procedures, 14 patients (pts, 9 male, with type I AFL underwent RF ablation. Atrial activation around tricuspid annulus was performed with a 10-bipole "Halo" catheter (H1-2; H19-20. In sinus rhythm, isthmus conduction was evaluated during proximal coronary sinus (PCS and low lateral right atrium (H1-2 pacing, before and after linear ablation. According to the wave front of impulse propagation we assessed absence of block (bidirectional conduction; incomplete block (bidirectional conduction with delay in one front of impulse propagation and complete block (absence of conduction

  3. Efficacy of i.v. amiodarone in converting rapid atrial fibrillation and flutter to sinus rhythm in intensive care patients.

    Science.gov (United States)

    Faniel, R; Schoenfeld, P

    1983-03-01

    Twenty-six consecutive patients (14 males, 12 females--mean age 66.6) were admitted to an intensive care unit (ICU) because of a rapid ventricular response to atrial fibrillation (RAF). Fourteen of them had been unsuccessfully treated by drugs (other than amiodarone) and/or DC shock before admission. A loading dose of i.v. amiodarone was administered (repeated boluses of 3 mg/kg in 3 min, or 30 min-infusions of 5 to 7.5 mg/kg), followed by continuous infusion, in order to reach a maximal total dosage of 1500 mg in 24 h. This treatment was considered efficacious if a reversion to stable sinus rhythm (SSR) occurred within 24 h and was maintained for more than 48 h. This was achieved in 21 out of 26 patients (80.8%). The mean time between the administration of therapy and the occurrence of SSR was 171 min. The total dose of amiodarone delivered to effect SSR was 6.9 +/- 2.3 mg/kg. No adverse reactions were encountered during the bolus injection but we recommend that continuous infusion be carried out through a central venous catheter to avoid phlebitis. The administration of 7 mg/kg of intravenous amiodarone delivered in 30 min proved a safe and successful first choice of management in atrial fibrillation with a rapid ventricular response. PMID:6861767

  4. Radiofrequency catheter ablation of Type 1 atrial flutter using a large-tip electrode catheter and high-power radiofrequency energy generator.

    Science.gov (United States)

    Feld, Gregory K

    2004-11-01

    Recent studies have demonstrated a high degree of efficacy of 8 mm electrode-tipped or saline-irrigated-tip catheters for ablation of atrial flutter (AFL). These catheters have a theoretical advantage as they produce a large ablation lesion. However, large-tip ablation catheters have a larger surface area and require a higher power radiofrequency (RF) generator with up to 100 W capacity to produce adequate ablation temperatures (50-60 degrees C). The potential advantages of a large-tip ablation catheter and high-power RF generator include the need for fewer energy applications, shorter procedure and fluoroscopy times, and greater efficacy. Therefore, the safety and efficacy of AFL ablation using 8 or 10 mm electrode catheters and a 100-W RF generator was studied using the Boston Scientific, Inc., EPT-1000 XP cardiac ablation system. There were 169 patients, aged 61 +/- 12 years involved. Acute end points were bidirectional isthmus block and no inducible AFL. Following ablation, patients were seen at 1, 3 and 6 months, with event monitoring performed weekly and for any symptoms. Three quality of life surveys were completed during follow-up. Acute success was achieved in 158 patients (93%), with 12 +/- 11 RF energy applications. The efficacy of 8 and 10 mm electrodes did not differ significantly. The number of RF energy applications (10 +/- 8 vs. 14 +/- 8) and ablation time (0.5 +/- 0.4 vs. 0.8 +/- 0.6 h) were less with 10 mm compared with 8 mm electrodes (p free of symptoms at 12 and 24 months, respectively. Ablation of AFL improved quality of life scores (p generator was safe, effective and improved quality of life. The number and duration of RF applications was lower with 10 mm compared with 8 mm electrode catheters. PMID:16293039

  5. 伊布利特和胺碘酮转复心房扑动及心房颤动的临床观察%Efficacy of ibutilide and amiodarone for termination of atrial fibrillation and flutter

    Institute of Scientific and Technical Information of China (English)

    王磊

    2011-01-01

    目的 观察新一代Ⅲ类抗心律失常药物伊布利特和经典Ⅲ类抗心律失常药物胺碘酮转复心房颤动(房颤)和心房扑动(房扑)的成功率及安全性.方法 选择40 ~ 75岁,持续时间≤90 d的房颤和房扑患者38例,按入院顺序随机分为伊布利特组19例和胺碘酮组19例,伊布利特组体质量≥60 kg者首剂1 mg、体质量<60 kg者首剂0.01 mg/kg,如无效10 min后再给予1 mg或0.01 mg/kg;胺碘酮组首剂150 mg,如无效10 min后再给予150 mg,观察转复率和转复时间,记录不良反应.结果 伊布利特和胺碘酮组4h内转复窦律分别为78.9%和31.5%,24 h内转复窦律分别为84.2%和52.6%,平均转复时间分别为(19±12)min和(48 ±17)min (P<0.01).两组均未发生致命性不良反应.结论 伊布利特与胺碘酮均能终止房颤和房扑,伊布利特转复房颤、房扑的疗效高于胺碘酮,转复时间短于胺碘酮,但须在严格监控下进行.%Objective To investigate the efficacy,safety and tolerance of intravenous ibutilide and amiodarone for conversion of atrial fibrillation( AF) and flutter( AFL) to normal sinus rhythm.Methods Thirty - eight consecutive patients aged 40 - 75 years with AF/AFL were included.The duration of arrhythmia were less than 90 days (ranged from 3 hours to 90 days),and ventricular rate(VR) were more than 60 beats/min.Two groups were assigned randomly.Patients in the ibutilide group( 19 cases) received ibutilide 1 mg if body weight ≥60 kg or 0.01 mg/kg if body weight < 60 kg; Treatment was repeated if atrial fibrillation or flutter was not converted after 10 min of the first dosage.Patients in the amiodarone group( 19 cases) received amiodarone 150 mg,followed by amiodarone 150 mg if atrial fibrillation or flutter persisted after 10 min of the first dosage.Results In 4 hours AF/AFL were converted in 15 of 19 patients(78.9% )in ibutilide group and in 6 of 19 patients(31.5% )in amiodarone group (P < 0.05),and in 24

  6. An Unusual Mechanism Of Sustained Right Atrial Tachycardia

    OpenAIRE

    Nair, Krishna Kumar Mohanan; Namboodiri, Narayanan; Thajudeen, Anees; Valaparambil, Ajitkumar; Jaganmohan A Tharakan

    2011-01-01

    Lower loop re-entry (LLR) flutter is a rare type of atypical right atrial flutter. Most of the reported cases occurred in association with typical flutter patterns as a transient arrhythmia. Our case is unique in the fact the LLR was sustained and persisted independently.

  7. Ablação com radiofreqüência do flutter atrial tipo I. Importância do bloqueio bidirecional do istmo entre a veia cava inferior e o anel da valva tricúspide

    Directory of Open Access Journals (Sweden)

    Scanavacca Mauricio

    1998-01-01

    Full Text Available OBJETIVO: Estudar a importância clínica da determinação eletrofisiológica da presença de bloqueio bidirecional na condução pelo istmo localizado entre a veia cava inferior e o anel da valva tricúspide (VCI - AT, após a ablação do flutter atrial tipo I (FL com radiofreqüência (RF. MÉTODOS: Quarenta pacientes consecutivos (idade média 51±11 anos com FL foram submetidos a ablação do istmo VCI-AT com RF. Em 30 pacientes (GI, o sucesso foi avaliado pela interrupção e não reindução do FL com estimulação atrial programada. Nos últimos 10 pacientes foi avaliada também a condução bidirecional pelo istmo, com cateteres posicionados na sua entrada e saída e em cada lado da linha de bloqueio. O bloqueio foi considerado bidirecional quando ocorrido nos dois sentidos e unidirecional quando ocorrido em um só sentido. RESULTADOS: Vinte e seis (86% pacientes do GI e 10 (100% do GII tiveram sucesso imediato (p= 0,5558. Durante o seguimento, 7 (30% de 23 pacientes do GI e 3 (30% de 9 do GII tiveram recorrência de FL (p= NS. Os três pacientes do GII que apresentaram recorrência tinham bloqueio unidirecional, enquanto os seis casos sem recorrência tinham bloqueio bidirecional (p=0,012. CONCLUSÃO: A demonstração de bloqueio bidirecional no istmo VCI-AT, obtida imediatamente após a ablação do FL com RF, relaciona-se a menor índice de recorrência clínica, devendo ser o critério preferencial para término do procedimento.

  8. 环磷腺苷葡胺联合地尔硫治疗慢性肺心病心衰合并快速房扑房颤的临床观察%Clinical Observation of Adenosine Cyclophosphate Combined with Diltiazem in the Treatment of Chronic Pul-monary Heart Disease Heart Failure Complicated with Rapid Atrial Fibrillation and Atrial Flutter

    Institute of Scientific and Technical Information of China (English)

    毛庆录; 徐梅

    2015-01-01

    目的:观察环磷腺苷葡胺联合地尔硫治疗慢性肺心病心衰合并快速房扑房颤的临床疗效及安全性。方法:选择慢性肺心病心衰合并快速房扑房颤患者100例,按随机数字表法分为观察组和对照组,各50例。对照组患者给予常规治疗,观察组在常规治疗的基础上口服地尔硫,30 mg/次,1次/d,同时加用环磷腺苷葡胺180 mg加入5%葡萄糖注射液200 ml中静脉滴注,1次/d,疗程均为10 d。观察两组患者给药前后的心率、肺动脉压、左室射血分数以及临床疗效。结果:治疗后观察组和对照组分别有43、31例患者临床症状明显改善、心率达标,两组比较差异有统计学意义(P<0.05);观察组患者肺动脉压下降幅度、左室射血分数较对照组均有明显好转,差异有统计学意义(P<0.05)。两组患者均未出现心动过缓、低血压、哮喘及心衰加重等副作用。结论:环磷腺苷葡胺联合地尔硫治疗慢性肺心病心衰合并快速房扑房颤,能显著改善患者心功能、控制心率、加快病情的好转,且安全性好。%OBJECTIVE:To observe clinical efficacy and safety of adenosine cyclophosphate combined with diltiazem in the treatment of chronic pulmonary heart disease heart failure complicated with atrial fibrillation and atrial flutter. METHODS:100 cas-es of chronic pulmonary heart disease heart failure complicated with rapid atrial fibrillation and atrial flutter were randomly divided into observation group and control group,with 50 cases in each group. The control group was given conventional treatment,and the observation group was additionally given diltiazem orally,30 mg/time,once a day,and adenosine cyclophosphate 180 mg add-ed into 5% Glucose injection 200 ml intravenously,once a day,for 10 days,on the basis of conventional treatment. The heart rate,the pressure of pulmonary artery and left ventricular ejection fraction(LVEF)before and

  9. Stochastic Flutter Analysis

    OpenAIRE

    Verhoosel, C.V.; Gutiérrez, M. A.; Hulshoff, S.J.

    2006-01-01

    The field of fluid-structure interaction is combined with the field of stochastics to perform a stochastic flutter analysis. Various methods to directly incorporate the effects of uncertainties in the flutter analysis are investigated. The panel problem with a supersonic fluid flowing over it is considered as a testcase. The stochastic moments (mean, standard deviation, etc.) of the flutter point are computed by an uncertainty analysis. Sensitivity-based methods are used to determine the stoc...

  10. Atrial Ectopics Precipitating Atrial Fibrillation

    OpenAIRE

    Johnson Francis

    2015-01-01

    Holter monitor tracing showing blocked atrial ectopics and atrial ectopic precipitating atrial fibrillation is being demonstrated. Initially it was coarse atrial fibrillation, which rapidly degenerated into fine atrial fibrillation.

  11. The Development of Atrial Flutter and Fibrillation

    Directory of Open Access Journals (Sweden)

    Rustam G. Habchabov

    2013-01-01

    Full Text Available Reasons of development of life-threatening arrhythmias that lead to sudden and total death in cases of cardiovascular diseases are still unclear, though cardiac research of this problem is conducted throughout the world. Damage of connective tissues insulation cover of the heart’s conductive pathways with oxidation of ectopic nodes can lead to life-threatening arrhythmias. This damage has never been considered before as a cause of electrical instability of the heart. Accordingly, treatment of such patients should change, and consequently should reduce the total number of sudden deaths due to cardiovascular diseases.The speed of electricity conduction from the heart to the nervous system and its distribution throughout the body remains underestimated. Slowdown of electric magnetic induction (acceleration between the heart and the central nervous system as well as slowdown of its distribution results in insufficient speed of electric flow and reduction of bioelectric processes of the body. This leads to activation of the sympathetic nervous system with the subsequent cascade of pressor mechanisms and development of essential hypertension.

  12. Intra-atrial course of right coronary artery – case report

    International Nuclear Information System (INIS)

    Intra-atrial course of the right coronary artery is a rare anomaly. The recognition of this entity is crucial to avoid potential hazards related to vessel injury during interventional procedures such as right heart catheterization, pacemaker implantation, invasive electrophysiology testing or atrial flutter ablation. We present a case of a 62-year old female with paroxysmal atrial flutter and atrial fibrillation, whose cardiac computed tomography revealed an anomalous course of the right coronary artery through the right atrium. Cardiac computed tomography examination enables an accurate assessment of morphology and location of the anomalous vessel course

  13. Geared-elevator flutter study. [transonic flutter characteristics of empennage

    Science.gov (United States)

    Ruhlin, C. L.; Doggett, R. V., Jr.; Gregory, R. A.

    1976-01-01

    The paper describes an experimental and analytical study of the transonic flutter characteristics of an empennage flutter model having an all-movable horizontal tail with a geared elevator. Two configurations were flutter tested: one with a geared elevator and one with a locked elevator with the model cantilever-mounted on a sting in the wind tunnel. The geared-elevator configuration fluttered experimentally at about 20% higher dynamic pressures than the locked-elevator configuration. The experimental flutter boundary was nearly flat at transonic speeds for both configurations. It was found that an analysis which treated the elevator as a discrete surface predicted flutter dynamic pressure levels better than analyses which treated the stabilizer and elevator as a warped surface. Warped-surface methods, however, predicted more closely the experimental flutter frequencies and Mach number trends.

  14. Mapping strategy for multiple atrial tachyarrhythmias in a transplant heart

    DEFF Research Database (Denmark)

    Jin, Qi; Pehrson, Steen; Jacobsen, Peter Karl;

    2015-01-01

    BACKGROUND: Different atrial arrhythmias can coexist in the recipient and donor atria after heart transplantation. CASE PRESENTATION: We report an unusual case of a patient with three different types of atrial arrhythmia after heart transplantation: an atrial fibrillation in the recipient atria......, and a cavotricuspid isthmus dependent atrial flutter and a focal atrial tachycardia in the donor atria. 3D electroanatomical mapping and ablation were guided by remote magnetic navigation (RMN). Atrial fibrillation continued in the recipient atria even after the donor heart was converted to sinus...... rhythm by ablation. CONCLUSIONS: It is critical to understand the surgical anatomy of a bi-atrial anastomosis and its relevant electrical activation pattern before ablation. Appropriate electroanatomical mapping strategy with RMN can facilitate the successful ablation of post-transplant atrial...

  15. STUDIES ON FLUTTER PREDICTION

    Directory of Open Access Journals (Sweden)

    Irina-Carmen ANDREI

    2012-03-01

    Full Text Available The purpose of this paper is to study the instability of the dynamic flutter. The justification is expressed by the fact that the occurrence of flutter within the aircraft’s flight envelope results in irreversible structural deformation which consequently leads to serious damage. Therefore the mathematical modeling of this phenomenon and its validation are very important. The instability of the dynamic flutter is characterized by critical speed and critical pulsation of oscillatory movements. In this paper, the quasi-stationary model and the Theodorsen model have been analyzed for calculating the aerodynamic forces and torques, and a comparison of them has been carried out. The fluid-structure coupling is done by rewriting the equations, considering that the forces are given by closed formulas. For the mathematical modeling of the flutter there have been used the p-k and V-g methods based on the Theodorsen model and the quasi-stationary model. In order to modeling the free vortices aerodynamic forces and moments, the equations which describe both the motion of the structure and the fluid flow had to be integrated simultaneously in time. The fluid-structure coupling is considered as a combination of two systems that describe the aeroelastic behavior of the structure.

  16. Active Flutter Suppression Combining the Receptance Method and Flutter Margin

    OpenAIRE

    Wu, Zhigang; Cooper, Jonathan

    2016-01-01

    Active flutter suppression is used to prevent flutter throughout the flight envelope by supplying active control forces in response to vehicle motions. In recent years, studies have been conducted on active flutter suppression using the receptance method. The advantage of the receptance method is that the feedback control gains are purely based upon measured receptances, without any need to evaluate or know the mass, damping, and stiffness matrices of the system. However, determination of the...

  17. Mathematical modeling approaches for the diagnosis and treatment of reentrant atrial tachyarrhythmias

    OpenAIRE

    Liberos Mascarell, Alejandro

    2016-01-01

    [EN] Atrial tachyarrhythmias present a high prevalence in the developed world, and several studies predict that in the coming decades it will be increased. Micro or macro-reentrant mechanisms of the electrical wavefronts that govern the mechanical behavior of the heart are one of the main responsibles for the maintenance of these arrhythmias. Atrial flutter is maintained by a macro-reentry around an anatomical or functional obstacle located in the atria. In the case of atrial fibrillation, th...

  18. An alternative to the flutter derivatives

    DEFF Research Database (Denmark)

    Andersen, Michael Styrk; Brandt, Anders

    A new simplified framework to study flutter and assess the full scale flutter wind speed is suggested. The flutter instability problem is reduced from a problem involving 8 flutter derivatives to only 4 coefficients. With this method it is possible to estimate the self-excited forces with increased...... precision by using stability diagrams. Furthermore, the physical transparency of the aerodynamic damping and stiffness terms is increased because the development in vertical and torsional damping and stiffness is analysed instead of flutter derivatives....

  19. Analysis of flutter and flutter suppression via an energy method

    OpenAIRE

    York, Darrell L.

    1980-01-01

    The design of modern high-performance aircraft is toward increased aerodynamic efficiency, decreased structural weight, and higher flight speeds. Preliminary designs often exhibit a flutter instability within the desired operating envelope of the aircraft. Passive methods which have been used to solve the flutter problem include added structural stiffness, mass balancing, and speed restrictions. These methods may result in significant weight penalties. Studies by Boeing (ref. 1) show that wei...

  20. Flutter of a Flag

    CERN Document Server

    Argentina, M; Argentina, Mederic

    2004-01-01

    We give an explanation for the onset of wind-induced flutter in a flag. Our theory accounts for the various physical mechanisms at work: the finite length and the small but finite bending stiffness of the flag, the unsteadiness of the flow, the added mass effect and vortex shedding from the trailing edge. Our analysis allows us to predict a critical speed for the onset of flapping as well as the frequency of flapping. We find that in a particular limit corresponding to a low density fluid flowing over a soft high density flag, the flapping instability is akin to a resonance between the mode of oscillation of a rigid pivoted airfoil in a flow and a hinged-free elastic filament vibrating in its lowest mode.

  1. Transonic blade flutter: A survey of new developments

    OpenAIRE

    Platzer, M.F.

    1982-01-01

    This paper presents a review of current work in transonic blade flutter research. Aerodynamic analyses for the prediction of attached flow flutter, choke flutter, and stall flutter are described. Also reviewed are unsteady aerodynamic measurement and flutter test programs that have recently been completed or are in progress to investigate transonic blade flutter phenomena.

  2. FLUTTER SUPPRESSION USING DISTRIBUTEDPIEZOELECTRIC ACTUATORS

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A piezoelectric actuator has the benefits of flexibility of its position, without time lag and wide bandpass characteristics. The early results of the wind tunnel flutter suppression test using the piezoeletric actuator were presented in Ref.[1]. A rigid rectangular wing model is constrained by a plunge spring and a pitch spring, and a pair of piezoelectric actuators is bonded on both sides of the plunge spring so as to carry out the active control. Refs.[2,3] reported two flutter suppression wind tunnel tests where the distributed piezoelectric actuators were used. In Ref.[2] low speed wind tunnel tests were conducted with aluminum and composite plate-like rectangular models fully covered by piezoelectric actuators. Flutter speed is increased by 11%. In Ref.[3] a composite plate-like swept back model with piezoceramic actuators bonded on the inboard surface was tested in a transonic wind tunnel and a 12% increment of flutter dynamic pressure was achieved.  In the present investigation, an aluminum plate-like rectangular model with inboard bonded piezoceramic actuators is adopted. Active flutter suppression control law has been designed. A series of analyses and ground tests and, finally, low-speed wind tunnel tests with the active control system opened and closed are conducted. Reasonable results have been obtained.

  3. Association between CHADS2 score and long-term atrial fibrillation recurrence rate after catheter ablation

    Institute of Scientific and Technical Information of China (English)

    胡晓锋

    2014-01-01

    Objective To investigate the association between CHADS2score and long-term(≥3 years)outcomes post catheter ablation in patients with atrial fibrillation(AF).Methods AF patients who received single catheter ablation in our hospital from January 2004 to March 2009 in our department were included and patients received regular follow-up.AF recurrence was defined as the occurrence of atrial arrhythmias(AF,atrial flutter and atrial tachycardia)recorded by electrocardiogram monitor(≥30 seconds)after ablation during follow-up period(after

  4. Applying non-linear dynamics to atrial appendage flow data to understand and characterize atrial arrhythmia

    International Nuclear Information System (INIS)

    The aim of this study was to better understand and characterize left atrial appendage flow in atrial fibrillation. Atrial fibrillation and flutter are the most common cardiac arrhythmias affecting 15% of the older population. The pulsed Doppler velocity profile data was recorded from the left atrial appendage of patients using transesophageal echocardiography. The data was analyzed using Fourier analysis and nonlinear dynamical tools. Fourier analysis showed that appendage mechanical frequency (ff) for patients in sinus rhythm was always lower (around1 Hz) than that in atrial fibrillation (5-8 Hz). Among patients with atrial fibrillation spectral power below ff was significantly different suggesting variability within this group of patients. Results that suggested the presence of nonlinear dynamics were: a) the existence of two arbitrary peak frequencies f1, f2, and other peak frequencies as linear combinations thereof (mf1±nf2), and b) the similarity between the spectrum of patient data and that obtained using the Lorenz equation. Nonlinear analysis tools, including Phase plots and differential radial plots, were also generated from the velocity data using a delay of 10. In the phase plots, some patients displayed a torus-like structure, while others had a more random-like pattern. In the differential radial plots, the first set of patients (with torus-like phase plots) showed fewer values crossing an arbitrary threshold of 10 than did the second set (8 vs. 27 in one typical example). The outcome of cardioversion was different for these two set of patients. Fourier analysis helped to: differentiate between sinus rhythm and atrial fibrillation, understand the characteristics of the wide range of atrial fibrillation patients, and provide hints that atrial fibrillation could be a nonlinear process. Nonlinear dynamical tools helped to further characterize and sub-classify atrial fibrillation

  5. Flutter at a low velocity

    Czech Academy of Sciences Publication Activity Database

    Vlček, Václav; Kozánek, Jan; Zolotarev, Igor

    Brno: Brno University of Technology, 2014 - (Fuis, V.), s. 688-691 ISBN 978-80-214-4871-1. ISSN 1805-8248. [Engineering Mechanics 2014 /20./. Svratka (CZ), 12.05.2014-15.05.2014] R&D Projects: GA ČR GA13-10527S Institutional support: RVO:61388998 Keywords : aeroelasticity * flutter * interferometry * subsonic flow Subject RIV: BI - Acoustics

  6. 对比普通与灌注冷却射频消融电极在Ⅰ型心房扑动消融中的作用%Comparing the effects of common ablation catheter and irrigated ablation catheter on common atrial flutter

    Institute of Scientific and Technical Information of China (English)

    彭景添

    2001-01-01

    目的 对比普遍与灌注冷却射频消融电极在Ⅰ型心房扑动(CAFL)消融中的作用。方法 60例CAFL患者随机分为两组:普通射频消融电极治疗组(CRF)和灌注冷却射频消融电极治疗组(IRF),分别比较两组取得下腔静脉与三尖瓣环峡部双向阻滞的手术时间、X线照射时间、射频消融放电次数及放电时间、并观察消融时电能、阻抗以及温度的改变。结果 IRF组的手术时间、X线照射时间、射频消融时间均较CRF组短(P<0.01),放电次数也少(P<0.05),IRF组消融过程中阻抗变化小、电能稳定,温度差异不明显,而CRF组则相反,且有19例出现碳化现象,两组痛感差异无显著性,均无心包填塞、栓塞等并发症。结论 灌注冷却射频消融电极在CAFL消融中优越于普通射频消融电极。%Objective To compare the effects of common ablation catheter and irrigated ablation catheter on common atrial flutter (CAFL). Methods 60 patients with CAFL were randomly dividied into common catheter group (CRF, 30cases) and irrigated catheter group (IRF, 30 cases). The procedure duration, fluoroscopy duration and radio frequeney duration were studied. The RF energy, impedance and temparature during the ablation were observed. Results The duration of procedure, fluoroscopy time and radio frequency ablation time were significantly shorter in IRF group than those in CRF group (P<0.01), there was also a difference in the times of ablation between two groups (P<0.05). In IRF group, the variation of impedance, RF-energy and temperature during the ablation was small, but in CRF group, the variation was obvious and there were 19 cases with coagulum formation. The degree of the chest pain was similar between two groups, there were no serious complications such as pericardial effusion, thrombi etc. Conclusion Irrigated ablation catheter should be superior to common ablation catheter in CAFL ablation.

  7. Atrial Fibrillation: Diagnosis

    Science.gov (United States)

    ... of this page please turn JavaScript on. Feature: Atrial Fibrillation Atrial Fibrillation: Diagnosis Past Issues / Winter 2015 Table of Contents ... of your body's cells and organs. Read More "Atrial Fibrillation" Articles Atrial Fibrillation / Who Is at Risk for ...

  8. Efficacy and safety of vernakalant in patients with atrial flutter

    DEFF Research Database (Denmark)

    Camm, A. John; Toft, Egon; Torp-Pedersen, Christian;

    2012-01-01

    , 3%) converted to sinus rhythm. A reduced mean absolute ventricular response rate occurred within 50 min in patients receiving vernakalant (mean change from baseline -8.2 b.p.m.) vs. patients receiving placebo (-0.2 b.p.m.) (P = 0.037). A post-hoc analysis revealed that vernakalant increased AFL...

  9. Complete Isolation of the Left Atrial Posterior Wall (Box Lesion to Treat Longstanding Persistent Atrial Fibrillation

    Directory of Open Access Journals (Sweden)

    Eduardo B. Saad, MD, PhD, FHRS; Charles Slater, MD, FHRS, RCES, CCDS, CEPS Meet the expert doctor Doctor Do You want to talk to a Electro physiologist about your AFIB..?? Then ask now! Now It's Free* Dr. Y Madhu Reddy, MD, FACC, FHRS Introduction to AFib Click here for more Videos..! Upcoming Events

    2014-12-01

    Full Text Available Introduction: The left atrial posterior wall has been shown to play na important role in AF pathophysiology. Objective: Evaluate the efficacy of an ablation strategy designed to completely isolate the LA posterior wall, on top of PV isolation. Methods and Results: 25 pts (72% male age 65 ± 12 years undergoing AF ablation for persistent or long term persistent AF. Mean AF duration was 11 ± 3 months and mean LA diameter was 4.8 ± 0.4 mm. After complete PVI, a “Roof Line” was created between the top of each contralateral set of lesions and a “floor line” closed the posterior wall in a “Box” fashion, connecting the bottom of each set of contralateral lesions. After an average follow-up of 16 ± 2 months, 20 patients (80% were free of any atrial arrhythmia recurrences (18 of whom off drugs. Five patients (20% had sustained atypical flutter and required a new ablation procedure. All these patients had mitral isthmus dependent flutters and no electrical conduction in the PVs or posterior wall were detected. Conclusions: Complete LA posterior wall isolation on top of PV is associated with good outcomes in patients with persistent and long-standing persistent AF when performed using meticulous bidirectional isolation criteria and adenosine infusion. Recurrences occur predominately as perimitral flutter, without gaps in the posterior wall.

  10. Computational investigation of subsonic torsional airfoil flutter

    OpenAIRE

    Kakkavas, Constantinos

    1998-01-01

    In this thesis single-degree-of-freedom torsional airfoil flutter is investigated using an incompressible potential flow code, a compressible inviscid Euler code and a compressible viscous Navier-Stokes code. It is found that the classical linearized incompressible and compressible flow theories yield unconservative flutter estimates. The computations based on the non-linear codes show for NACA 0006, NACA 0009, NACA 0012 and NACA 0015 airfoils, that the regions of torsional flutter instabilit...

  11. Fluttering Analysis in Wind Turbine Blade

    OpenAIRE

    Elangovan, Prabaharan

    2012-01-01

    The wind turbine blades often subjected by a phenomenon fluttering which leads to a structural damage. Therefore, it is necessary for design engineers to predict the fluttering behavior while designing the blades. The main scope of the thesis is to analyze and study the fluttering behavior by conducting structural analysis, modal analysis, Aeroelastic stability analysis and FSI of standard wind turbine blade. The analysis is carried out in ANSYS work bench and the preliminary results shows th...

  12. Temporary neonatal atrial pacing through the umbilical venous route: A novel technique

    Directory of Open Access Journals (Sweden)

    Hiren N Doshi

    2011-01-01

    Full Text Available Atrial pacing in the neonate is rarely done due to constraints of equipment, technical knowhow, and risk of complications. We describe a novel method of atrial pacing in the new born using equipment readily available in any intensive care unit. Atrial pacing can be achieved using an adult bipolar pacing wire directly introduced through the umbilical venous route. We have used this method in 5 neonates, and achieved atrial capture in 4 patients. Temporary atrial pacing is a therapeutic option in a few neonatal arrhythmias, such as atrial flutter, a few types of re-entrant tachycardias, such as accessory pathway mediated tachycardia and junctional reciprocating tachycardia, and has a limited role in cardiopulmonary resuscitation where sinoatrial node dysfunction is suspected.

  13. Piezoelectric Energy Harvesting From Flutter

    OpenAIRE

    Norouzi, Soroush

    2012-01-01

    With the increasing need for alternative sources of energy, a great deal of attention is drawn to harvesting energy from ambient vibration. These vibrations may be caused by fluid forces acting upon a structure. When a flexible structure is subject to a fluid flow, it loses stability at a certain flow velocity and starts to vibrate. This self-induced motion is called flutter where energy is continuously transferred from the fluid to the structure. In this study a piezoelectric film sensor is ...

  14. Impact of dronedarone on hospitalization burden in patients with atrial fibrillation

    DEFF Research Database (Denmark)

    Torp-Pedersen, Christian; Crijns, Harry J G M; Gaudin, Christophe;

    2011-01-01

    Hospitalization or death from any cause in patiENTs with Atrial fibrillation/atrial flutter (ATHENA), a composite of first CV hospitalization or death from any cause, was significantly reduced by dronedarone. This post hoc analysis evaluated the secondary endpoint of CV hospitalization and the clinical benefit of...... dronedarone on the number and duration of CV hospitalizations in patients with atrial fibrillation (AF).......Cardiovascular (CV) hospitalization is a predictor of CV mortality and has a negative impact on patients' quality of life. The primary endpoint of A placebo-controlled, double-blind, parallel-arm Trial to assess the efficacy of dronedarone 400 mg bid for the prevention of cardiovascular...

  15. Acute treatment of atrial fibrillation.

    Science.gov (United States)

    Kowey, P R; Marinchak, R A; Rials, S J; Filart, R A

    1998-03-12

    Atrial fibrillation (AFib) is a common clinical entity, responsible for significant morbidity and mortality, but it also accounts for a large percentage of healthcare dollar expenditures. Efforts to treat this arrhythmia in the past have focused on subacute antithrombotic therapy and eventually use of antiarrhythmic drugs for maintenance of sinus rhythm. However, there has been a growing interest in the concept of acute electrical and pharmacologic conversion. This treatment strategy has a number of benefits, including immediate alleviation of patient symptoms, avoidance of antithrombotic therapy, and prevention of electrophysiologic remodeling, which is thought to contribute to the perpetuation of the arrhythmia. There is also increasing evidence that this is a cost-effective strategy in that it may obviate admission to the hospital and the cost of long-term therapy. This article represents a summary of the treatments that may be used acutely to control the ventricular response to AFib, prevent thromboembolic events, and provide for acute conversion either pharmacologically or electrically. It includes information on modalities that are currently available and those that are under active development. We anticipate that an active, acute treatment approach to AFib and atrial flutter will become the therapeutic norm in the next few years, especially as the benefits of these interventions are demonstrated in clinical trials. PMID:9525568

  16. Atrial fibrillation

    NARCIS (Netherlands)

    Lip, Gregory Y H; Fauchier, Laurent; Freedman, Saul B; Van Gelder, Isabelle; Natale, Andrea; Gianni, Carola; Nattel, Stanley; Potpara, Tatjana; Rienstra, Michiel; Tse, Hung-Fat; Lane, Deirdre A

    2016-01-01

    Atrial fibrillation (AF) is the most common sustained cardiac rhythm disorder, and increases in prevalence with increasing age and the number of cardiovascular comorbidities. AF is characterized by a rapid and irregular heartbeat that can be asymptomatic or lead to symptoms such as palpitations, dys

  17. Atrial fibrillation

    DEFF Research Database (Denmark)

    Olesen, Morten S; Nielsen, Morten W; Haunsø, Stig;

    2014-01-01

    Atrial fibrillation (AF) is the most common cardiac arrhythmia affecting 1-2% of the general population. A number of studies have demonstrated that AF, and in particular lone AF, has a substantial genetic component. Monogenic mutations in lone and familial AF, although rare, have been recognized...

  18. Atrial Fibrillation and Stroke

    Science.gov (United States)

    ... Find People About NINDS NINDS Atrial Fibrillation and Stroke Information Page Table of Contents (click to jump ... done? Clinical Trials What is Atrial Fibrillation and Stroke? Atrial fibrillation (AF) describes the rapid, irregular beating ...

  19. Atrial Fibrillation: Treatment

    Science.gov (United States)

    ... of this page please turn JavaScript on. Feature: Atrial Fibrillation Atrial Fibrillation: Treatment Past Issues / Winter 2015 Table of Contents Treatment for atrial fibrillation depends on how often you have symptoms, how ...

  20. Living with Atrial Fibrillation

    Science.gov (United States)

    ... Topics » Atrial Fibrillation » Living With Atrial Fibrillation Explore Atrial Fibrillation What Is... Types Other Names Causes Who Is at Risk Signs & Symptoms Diagnosis Treatments Prevention Living With Clinical Trials Links Related Topics Arrhythmia ...

  1. Does conversion and prevention of atrial fibrillation enhance survival in patients with left ventricular dysfunction? Evidence from the Danish Investigations of Arrhythmia and Mortality ON Dofetilide/(DIAMOND) study

    DEFF Research Database (Denmark)

    Pedersen, Ole Dyg; Brendorp, Bente; Elming, Hanne;

    2003-01-01

    BACKGROUND: Atrial fibrillation is a common arrhythmia in patients with left ventricular dysfunction associated with increased morbidity and mortality. The present study investigated the potential of dofetilide to restore and maintain sinus rhythm in patients with left ventricular dysfunction......, which might reduce mortality and hospitalizations. METHODS AND RESULTS: In the Danish Investigations of Arrhythmia and Mortality ON Dofetilide (DIAMOND) studies, 506 patients were in atrial fibrillation (AF) or atrial flutter (AFl) at baseline. Over the course of study, cardioversion occurred in 148 (59...

  2. Leading-Edge Flutter of Supercavitating Hydrofoils

    OpenAIRE

    Brennen, C.; Oey, K. T.; Babcock, C. D.

    1980-01-01

    This paper presents the results of experiments and analysis of the phenomenon of leading-edge flutter which has been observed to occur for supercavitating hydrofoils. The experiments confirmed the existence of such a single-degree-of-freedom flutter involving chordwise bending and indicated that for long, natural (or vapor-filled) cavities the reduced flutter speed, [formula], was in the range 0.15 to 0.23. Secondary effects observed were the variation with the angle of attack (a minimum fl...

  3. Automatic Detection of Atrial Fibrillation for Mobile Devices

    Science.gov (United States)

    Kaiser, Stefanie; Kirst, Malte; Kunze, Christophe

    Two versions of a new detector for automatic real-time detection of atrial fibrillation in non-invasive ECG signals are introduced. The methods are based on beat to beat variability, tachogram analysis and simple signal filtering. The implementation on mobile devices is made possible due to the low demand on computing power of the employed analysis procedures. The proposed algorithms correctly identified 436 of 440 five minute episodes of atrial fibrillation or flutter and also correctly identified up to 302 of 342 episodes of no atrial fibrillation, including normal sinus rhythm as well as other cardiac arrhythmias. These numbers correspond to a sensitivity of 99.1 % and a specificity of 88.3%.

  4. The Relationship between physical activity and risk of atrial fibrillation-A systematic review and meta-Analysis

    DEFF Research Database (Denmark)

    Nielsen, Jens Erik Rokkedal; Wachtell, K; Abdulla, J

    2013-01-01

    The aim of this systematic literature review and meta-Analyses was to explore the relationship between physical activity and risk of new-onset atrial fibrillation (AF) or flutter (AFlu).Results: The search revealed 10 published studies that were eligible for three different meta-Analyses. A meta-...

  5. Atrial Arrhythmias in Astronauts - Summary of a NASA Summit

    Science.gov (United States)

    Barr, Yael R.; Watkins, Sharmila D.; Polk, J. D.

    2010-01-01

    Background and Problem Definition: To evaluate NASA s current standards and practices related to atrial arrhythmias in astronauts, Space Medicine s Advanced Projects Section at the Johnson Space Center was tasked with organizing a summit to discuss the approach to atrial arrhythmias in the astronaut cohort. Since 1959, 11 cases of atrial fibrillation, atrial flutter, or supraventricular tachycardia have been recorded among active corps crewmembers. Most of the cases were paroxysmal, although a few were sustained. While most of the affected crewmembers were asymptomatic, those slated for long-duration space flight underwent radiofrequency ablation treatment to prevent further episodes of the arrhythmia. The summit was convened to solicit expert opinion on screening, diagnosis, and treatment options, to identify gaps in knowledge, and to propose relevant research initiatives. Summit Meeting Objectives: The Atrial Arrhythmia Summit brought together a panel of six cardiologists, including nationally and internationally renowned leaders in cardiac electrophysiology, exercise physiology, and space flight cardiovascular physiology. The primary objectives of the summit discussions were to evaluate cases of atrial arrhythmia in the astronaut population, to understand the factors that may predispose an individual to this condition, to understand NASA s current capabilities for screening, diagnosis, and treatment, to discuss the risks associated with treatment of crewmembers assigned to long-duration missions or extravehicular activities, and to discuss recommendations for prevention or management of future cases. Summary of Recommendations: The summit panel s recommendations were grouped into seven categories: Epidemiology, Screening, Standards and Selection, Treatment of Atrial Fibrillation Manifesting Preflight, Atrial Fibrillation during Flight, Prevention of Atrial Fibrillation, and Future Research

  6. Performing the Left Atrial Maze Ablation Pattern Without Atriotomy.

    Science.gov (United States)

    Weimar, Timo; Gaynor, Sydney L; Seubert, Daniela Y; Damiano, Ralph J; Doll, Nicolas

    2016-02-01

    The need to perform an additional atriotomy is a major concern that keeps many surgeons from performing an extended left atrial lesion set in patients with atrial fibrillation during procedures such as aortic valve replacement. This does result either in a suboptimal lesion set or even in ignoring the rhythm disorder, leaving the patient exposed to an increased risk of stroke and possible hemodynamic compromises. This report describes a technique how pulmonary vein isolation, an isolation of the posterior left atrial wall and an anterior mitral annular line, which substitutes for the mitral isthmus line in order to prevent perimitral atrial flutter, can be performed during aortic valve replacement without the need for an atriotomy. This technique allows for an optimal time management by minimizing additional cardiopulmonary bypass-time and cross-clamp-time; however, its equivalent efficacy in successfully treating atrial fibrillation compared to the left atrial Maze IV ablation pattern needs to be revealed in future trials. PMID:26777943

  7. Nonlinear Characteristics of Randomly Excited Transonic Flutter

    DEFF Research Database (Denmark)

    Christiansen, Lasse Engbo; Lehn-Schiøler, Tue; Mosekilde, Erik;

    2002-01-01

    The paper describes the effects of random external excitations on the onset and dynamical characteristics of transonic flutter (i.e. large-amplitude, self-sustained oscillations) for a high aspect ratio wing. Wind tunnel experiments performed at the National Aerospace Laboratory (NAL) in Japan have...... reproduce several of the experimentally observed modifications of the flutter transition. In particular, the models display the characteristic phenomena of coherence resonance....

  8. Flutter behaviour of composite aircraft wings

    OpenAIRE

    Ashawesh, Gamal Mohamed

    1999-01-01

    This research work presents series of investigations into the structural dynamics and dynamic aeroelastic (flutter) behaviour of composite and metal wings. The study begins with a literature review where the development and an over view of the previous investigations in this field are presented. Static stiffness is very important to any type of analysis, especially in both dynamic and flutter analysis as in this case. Therefore, different methods are presented and used for the ...

  9. ATRIAL FIBROSIS IS A MORPHOLOGICAL BASIS OF ATRIAL FIBRILLATION

    OpenAIRE

    DRAPKINA O.M.; A. V. Emelyanov

    2015-01-01

    Mechanisms of atrial fibrosis including the role of serotonin in the development of this lesion in patients with atrial fibrillation are presented. New approaches to the treatment of atrial fibrillation aimed at atrial fibrosis reduction are discussed.

  10. Detection of Acute Atrial-Ventricular Arrhythmias Based on ECG Delineator: Evaluation on MIT/BIH Standard Databases

    Directory of Open Access Journals (Sweden)

    Katayoun Shojaian‎

    2008-03-01

    Full Text Available In this paper we use an efficient arrhythmia algorithm based on wavelet transform. In first step, QRS complexes are detected. Then each QRS is delineated by detecting and identifying the peaks of the individual waves, complex onset and end. Then the determination of P and T wave peaks, onset and ends are performed. Finally the Ventricular flutter, ventricular tachycardia, supra ventricular tachycardia, ventricular fibrillation, atrial fibrillation and atrial flutter that are kinds of acute ventricular-atrial arrhythmias are detected. In the proposed algorithm, we used a second order spline as mother wavelet and improved the previous algorithms proposed by other investigators. We evaluated the algorithm on some manually annotated single ECG signals selected from MIT-BIH arrhythmia databases. This algorithm may achieve the mean detection accuracy of about 80% in these arrhythmias.

  11. Numerical modeling of flutter in a transonic fan

    OpenAIRE

    Milandre, Olivier

    2014-01-01

    Flutter is a self-feeding and potentially destructive vibration that can lead to devastating effects such as broken blades. Using accurate numerical models to predict flutter in the conception of an engine is essential to avoid huge waste of money. The software 2, using the elsA CFD package developed by the French Aerospace Lab, ONERA, is used to perform unsteady calculations and predict flutter margin. The current methodology does not systematically manage to reproduce the expected flutter p...

  12. Simplified flutter prediction for bridges with bluff cross-section

    OpenAIRE

    Starossek, Uwe

    1994-01-01

    Wind-induced flutter of bridges occurs as coupled torsional and vertical oscillation, or uncoupled torsional oscillation. Bridges with bluff, non-streamlined sections are prone to torsional flutter. Prediction of torsional flutter on the basis of measured aerodynamic derivatives essentially corresponds to the prediction of coupled flutter, although, compared to the latter, it can be largely simplified. The theoretical background is discussed and the given formulae are checked against empirica...

  13. Atrial fibrillation.

    Science.gov (United States)

    Lip, Gregory Y H; Fauchier, Laurent; Freedman, Saul B; Van Gelder, Isabelle; Natale, Andrea; Gianni, Carola; Nattel, Stanley; Potpara, Tatjana; Rienstra, Michiel; Tse, Hung-Fat; Lane, Deirdre A

    2016-01-01

    Atrial fibrillation (AF) is the most common sustained cardiac rhythm disorder, and increases in prevalence with increasing age and the number of cardiovascular comorbidities. AF is characterized by a rapid and irregular heartbeat that can be asymptomatic or lead to symptoms such as palpitations, dyspnoea and dizziness. The condition can also be associated with serious complications, including an increased risk of stroke. Important recent developments in the clinical epidemiology and management of AF have informed our approach to this arrhythmia. This Primer provides a comprehensive overview of AF, including its epidemiology, mechanisms and pathophysiology, diagnosis, screening, prevention and management. Management strategies, including stroke prevention, rate control and rhythm control, are considered. We also address quality of life issues and provide an outlook on future developments and ongoing clinical trials in managing this common arrhythmia. PMID:27159789

  14. Detached tip of a transseptal sheath during left atrial ablation.

    Science.gov (United States)

    El-Damaty, Ahmed; Love, Michael; Parkash, Ratika

    2012-02-15

    Left atrial ablation has become more commonplace with the advent of catheter ablation for atrial fibrillation. A number of transseptal sheaths have been produced to enhance safe and efficient catheter manipulation in the left atrium (LA) for these procedures. Some of the sheaths have been subject to recall due to partial or complete detachment of its radiopaque tip. We report a case of a 46 year-old female diagnosed with idiopathic dilated cardiomyopathy that presented with atypical left atrial flutter. During electrophysiologic study, a Swartz braided SL1 (SL-1) transseptal sheath was used to introduce the ablation catheter to the left atrium. During left atrial mapping, the radiopaque tip of the sheath detached from the rest of the sheath and was seen floating in the LA. After exchanging the SL-1 sheath with a deflectable sheath, the detached segment was retrieved out of the LA and eventually out of the vascular system using an angioplasty balloon advanced over a wire and inflated distal to the lumen of the detached tip. The root cause of this malfunction was found to be lack of a secondary bonding process that these sheaths generally undergo during the manufacturing process. We describe the case of a left atrial ablation procedure where a novel percutaneous method was able to successfully retrieve the detached tip of a transseptal sheath from the vascular system, thereby avoiding a potential catastrophic complication or thoracotomy. This method may be useful in other cases where similar circumstances may present. PMID:22162088

  15. Managing atrial fibrillation in the elderly: critical appraisal of dronedarone

    Directory of Open Access Journals (Sweden)

    Trigo P

    2011-12-01

    Full Text Available Paula Trigo, Gregory W FischerDepartment of Anesthesiology, Mount Sinai School of Medicine, New York, NY, USAAbstract: Atrial fibrillation is the most commonly seen arrhythmia in the geriatric population and is associated with increased cardiovascular morbidity and mortality. Treatment of the elderly with atrial fibrillation remains challenging for physicians, because this unique subpopulation is characterized by multiple comorbidities requiring chronic use of numerous medications, which can potentially lead to severe drug interactions. Furthermore, age-related changes in the cardiovascular system as well as other physiological changes result in altered drug pharmacokinetics. Dronedarone is a new drug recently approved for the treatment of arrhythmias, such as atrial fibrillation and/or atrial flutter. Dronedarone is a benzofuran amiodarone analog which lacks the iodine moiety and contains a methane sulfonyl group that decreases its lipophilicity. These differences in chemical structure are responsible for making dronedarone less toxic than amiodarone which, in turn, results in fewer side effects. Adverse events for dronedarone include gastrointestinal side effects and rash. No dosage adjustments are required for patients with renal impairment. However, the use of dronedarone is contraindicated in the presence of severe hepatic dysfunction.Keywords: atrial fibrillation, elderly, antiarrhythmic agents, amiodarone, dronedarone

  16. Perturbed panel flutter : a simple model

    International Nuclear Information System (INIS)

    The effects of small periodic disturbances on the response of a two-degree-of-freedom, non-conservative, mechanical system are analyzed. The system is a simple model for panel flutter. The disturbance simulates the pressure fluctuations of a turbulent boundary layer on the panel. Asymptotic expansions of the solutions are obtained for small amplitude disturbances. The qualitative features of the response depend on the prescribed variation of the disrurbance frequency with the magnitude of the non-conservative applied force. The disturbance can induce a smooth transition to the fluttering states of the rods; or it may induce jump transitions. The results suggest a possible technique for delaying panel flutter, by applying periodic forcing functions with appropriate frequencies. (Author)

  17. Flutter analysis of the IAR 99 SOIM aircraft

    Directory of Open Access Journals (Sweden)

    Dorin LOZICI-BRINZEI

    2013-06-01

    Full Text Available Flutter analysis is considered for the minimum altitude at which the minimum designed Mach number is achieved, for the maximum altitude at which the maximum designed dynamic pressure is obtained and for the minimum altitude at which transonic effects begin occurring. Moreover, analyzes is performed for any other altitudes considered necessary. Flutter analysis results is graphically presented in equivalent speed with the curves of structural damping coefficient g required for flutter according to the flutter speed. Flutter analysis aims to determine the speeds of IAR 99 SOIM.

  18. Implementation of the non-flutter design principle

    DEFF Research Database (Denmark)

    Andersen, Michael Styrk; Sahin, Emrah; Laustsen, Benjamin;

    2014-01-01

    The non-flutter design principle is introduced. Aerodynamically stable section model tests performed by three different research groups indicate, that flutter might be avoided if the torsional-to-vertical frequency ratio is kept below 1. A case study of a suspension bridge spanning 3:7 km with a...... torsional-to-vertical frequency ratio = 0.89 is presented. Using a multimodal flutter approach and bridge deck flutter derivatives equal to those of a thin airfoil, classical flutter was shown not to occur....

  19. FLUTTER SUPPRESSION USING DISTRIBUTED PIEZOELECTRIC ACTUATORS

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The Flutter suppression using distributed piezoelectric actuators has been analyzed and tested. In constructing the finite element equation, effects of piezoelectric matrices are investigated. LQG method is used in designing the control law. In reducing the order of the control law, both balance realization and LK methods are used. For the rational approximation of the unsteady aerodynamic forces LS method is improved. In determining the piezoelectric constants d31 a new dynamic response method is developed. Laser vibrameter is used to pick up the model response and in ground resonance test the model is excited by piezoelectric actuators. Reasonable agreement of the wind tunnel flutter suppression test with calculated results is obtained.

  20. Coupled-flutter of two slender flags

    Science.gov (United States)

    Jérôme, Mougel; Sébastien, Michelin; Olivier, Doaré

    2015-11-01

    A flag in axial flow is subject to flutter instability that leads to large-amplitude flapping of the structure. When two flags are placed parallel to each other, they interact hydrodynamically leading to coupled dynamics of the system. The understanding of the possible dynamical regimes is crucial in the recent context of energy harvesting using piezoelectric fags. In this study, we consider coupled-flutter of two slender flags. Based on an extension of the famous model by Lighthill commonly called Large Amplitude Elongated Body Theory to the two-flags case, both linear and large-amplitude dynamics of such a coupled system will be presented.

  1. Atrial fibrillation - discharge

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/patientinstructions/000237.htm Atrial fibrillation - discharge To use the sharing features on this ... have been in the hospital because you have atrial fibrillation . This condition occurs when your heart beats faster ...

  2. Atrial fibrillation (acute onset)

    OpenAIRE

    Lip, Gregory Y. H.; Watson, Timothy

    2008-01-01

    Acute atrial fibrillation is rapid, irregular, and chaotic atrial activity of less than 48 hours' duration. It resolves spontaneously within 24 to 48 hours in over 50% of people. In this review we have included studies on patients with onset up to 7 days previously. Risk factors for acute atrial fibrillation include increasing age, CVD, alcohol abuse, diabetes, and lung disease.Acute atrial fibrillation increases the risk of stroke and heart failure.

  3. Atrial Fibrillation and Hyperthyroidism*

    OpenAIRE

    2005-01-01

    Atrial fibrillation occurs in 10 – 15% of patients with hyperthyroidism. Low serum thyrotropin concentration is an independent risk factor for atrial fibrillation. Thyroid hormone contributes to arrythmogenic activity by altering the electrophysiological characteristics of atrial myocytes by shortening the action potential duration, enhancing automaticity and triggered activity in the pulmonary vein cardio myocytes. Hyperthyroidism results in excess mortality from increased incidence of circu...

  4. Atrial Fibrillation: Complications

    Science.gov (United States)

    ... of this page please turn JavaScript on. Feature: Atrial Fibrillation Atrial Fibrillation: Complications Past Issues / Winter 2015 Table of Contents ... has two major complications—stroke and heart failure. Atrial Fibrillation and Stroke Click to enlarge image This illustration ...

  5. Atrial Fibrillation in Children

    Science.gov (United States)

    ... Pressure High Blood Pressure Tools & Resources Stroke More Atrial Fibrillation in Children Updated:Jul 18,2016 Does your ... content was last reviewed on 04/16/14. Atrial Fibrillation • Introduction • What is Atrial Fibrillation? • Why AFib Matters • ...

  6. Atrial Fibrillation Factsheet

    Science.gov (United States)

    Atrial Fibrillation Atrial fibrillation, often called AFib or AF, is the most common type of heart arrhythmia. An arrhythmia is when the ... Atrium Sinoatrial Node (pacemaker) Atrioventricular Node Left Atrium Atrial Fibrillation AFib Facts 1 • An estimated 2.7–6. ...

  7. Magnetic-flutter-induced pedestal plasma transport

    International Nuclear Information System (INIS)

    Plasma toroidal rotation can limit reconnection of externally applied resonant magnetic perturbation (RMP) fields δB on rational magnetic flux surfaces. Hence it causes the induced radial perturbations δBρ to be small there, thereby inhibiting magnetic island formation and stochasticity at the top of pedestals in high (H-mode) confinement tokamak plasmas. However, the δBρs induced by RMPs increase away from rational surfaces and are shown to induce significant sinusoidal radial motion (flutter) of magnetic field lines with a radial extent that varies linearly with δBρ and inversely with distance from the rational surface because of the magnetic shear. This produces a radial electron thermal diffusivity that is (1/2)(δBρ/B0)2 times a kinetically derived, electron-collision-induced, magnetic-shear-reduced, effective parallel electron thermal diffusivity in the absence of magnetic stochasticity. These low collisionality flutter-induced transport processes and thin magnetic island effects are shown to be highly peaked in the vicinity of rational surfaces at the top of low collisionality pedestals. However, the smaller but finite level of magnetic-flutter-induced electron heat transport midway between rational surfaces is the primary factor that determines the electron temperature difference between rational surfaces at the pedestal top. The magnetic-flutter-induced non-ambipolar electron density transport can be large enough to push the plasma toward an electron density transport root. Requiring ambipolar density transport is shown to determine the radial electric field, the plasma toroidal rotation (via radial force balance), a reduced electron thermal diffusivity and increased ambipolar density transport in the pedestal. At high collisionality the various flutter effects are less strongly peaked at rational surfaces and generally less significant. They are thus less likely to exhibit flutter-induced resonant behaviour and transition toward an electron

  8. Cibenzoline versus flecainide in the prevention of paroxysmal atrial arrhythmias: a double-blind randomized study.

    Science.gov (United States)

    Babuty, D; D'Hautefeuille, B; Scheck, F; Mycinsky, C; Pruvost, P; Peraudeau, P

    1995-05-01

    In a randomized, double-blind, parallel clinical trial, the authors tested and compared flecainide and cibenzoline, a new antiarrhythmic drug, on atrial arrhythmias. Sixty-eight patients (36 men, 32 women, mean age 62.5 +/- 1.6 years) with documented symptomatic paroxysmal atrial arrhythmias (fibrillation in 56, flutter in 12) were recruited and received either cibenzoline 260 mg/day (n = 33) or flecainide 200 mg/day (n = 35). Patients were assessed with physical examination, resting ECG, 24-hour ambulatory ECG recording, two-dimensional echocardiography, and standard biologic titrations before the inclusion day, and 3 months and 6 months after the randomization day. Sixteen patients were withdrawn (7 were lost to follow-up, 7 had side effects, 2 had another medical event). Seventeen patients had documented recurrence of atrial arrhythmia (9 in the cibenzoline group, 8 in the flecainide group) during the study. The efficacy of cibenzoline and flecainide for preventing recurrence of atrial arrhythmias was not significantly different (62.5% versus 71.4%). Eleven patients complained of one or more side effects (cibenzoline, n = 6; flecainide, n = 5), justifying leaving the trial in 6 cases (cibenzoline, n = 3; flecainide, n = 3). Two ventricular proarrhythmic effects were observed. No atrial proarrhythmic effects were reported. The efficacy of cibenzoline and flecainide for preventing atrial arrhythmia is good and similar during a follow-up period of 6 months. In view of these results, cibenzoline may be administered first to prevent atrial arrhythmia. PMID:7657846

  9. Flutter Speed Limits of Cantilever Rectangular and Tapered Plates

    Directory of Open Access Journals (Sweden)

    Kusay H. Jabir

    2007-01-01

    Full Text Available The aerodynamic and elastic forces may cause an oscillation of the structure such as the high frequency of the airfoil surfaces and the dynamic instability occurring in an aircraft in flight and failure may occur at a speed called flutter speed. In this work, analytical and numerical investigations of flutter limits of thin plates have been carried out. The flutter speed of rectangular plates were obtained and compared with some published results. Different design parameters were investigated such as aspect ratio, thickness and their effects on flutter velocity. It was found that the structural mode shape plays an important role in the determination of the flutter speed and the coupling between the bending and torsional mode is the main cause of flutter.

  10. Prediction of early-onset atrial tachyarrhythmia after successful trans-catheter device closure of atrial septal defect.

    Science.gov (United States)

    Park, Kyoung-Min; Hwang, Jin Kyung; Chun, Kwang Jin; Park, Seung-Jung; On, Young Keun; Kim, June Soo; Park, Seung Woo; Kang, I-Seok; Song, Jinyoung; Huh, June

    2016-08-01

    Atrial tachyarrhythmia is a well-known long-term complication of atrial septal defect (ASD) in adults, even after successful trans-catheter closure. However, the risk factors for early-onset atrial tachyarrhythmia after trans-catheter closure remain unclear. This retrospective study enrolled adults with secundum ASD undergoing trans-catheter closure from January 2000 to March 2014. We analyzed the clinical characteristics of patients and assessed risk factors for new-onset atrial tachyarrhythmia defined as a composite of atrial fibrillation or flutter (AF/AFL) after ASD closure. We enrolled a total of 427 patients; 123 were male (28.8%) and the median age was 37.0 (interquartile range [IQR]: 18.3-49.0). Nineteen (4.4%) patients had documented atrial tachyarrhythmia during the follow-up period (median: 11.4 months [IQR: 5.4-24]). Patients with transient AF/AFL during closure showed a greater incidence of new-onset atrial tachyarrhythmia during the follow-up period than patients with consistent sinus rhythm during closure (27.3% vs 3.8%; P = 0.01). Most new-onset atrial tachyarrhythmias were documented within 6 months (median: 2.6 [IQR: 1.2-4.1] months) of closure. In the multivariate analysis, the risk for new-onset atrial tachyarrhythmia was significant in patients with AF/AFL during closure (hazard ratio [HR]: 9.90, 95% confidence interval [CI]: 2.86-34.20; P < 0.001), deficient posteroinferior rim (HR: 5.48, 95% CI: 1.15-25.72; P = 0.04), and age of closure over 48 years (HR: 3.30, 95% CI: 1.30-8.38; P = 0.01). In conclusion, transient AF/AFL during trans-catheter closure of ASD as well as deficient posteroinferior rim and age of closure over 48 years may be useful for predicting early new-onset atrial tachyarrhythmia after device closure. PMID:27583905

  11. Flutter analysis of the IAR 99 SOIM aircraft

    OpenAIRE

    Dorin LOZICI-BRINZEI; Simion TATARU; Daniela BARAN

    2013-01-01

    Flutter analysis is considered for the minimum altitude at which the minimum designed Mach number is achieved, for the maximum altitude at which the maximum designed dynamic pressure is obtained and for the minimum altitude at which transonic effects begin occurring. Moreover, analyzes is performed for any other altitudes considered necessary. Flutter analysis results is graphically presented in equivalent speed with the curves of structural damping coefficient g required for flutter accordin...

  12. Flutter Speed Limits of Cantilever Rectangular and Tapered Plates

    OpenAIRE

    Kusay H. Jabir

    2007-01-01

    The aerodynamic and elastic forces may cause an oscillation of the structure such as the high frequency of the airfoil surfaces and the dynamic instability occurring in an aircraft in flight and failure may occur at a speed called flutter speed. In this work, analytical and numerical investigations of flutter limits of thin plates have been carried out. The flutter speed of rectangular plates were obtained and compared with some published results. Different design parameters were investigated...

  13. AEROELASTIC FLUTTER ANALYSIS OF SUPERSONIC WING WITH MULTIPLE EXTERNAL STORES

    OpenAIRE

    Nur Azam; Erwin Sulaeman

    2014-01-01

    ABSTRACT: Flutter may be considered to be one of the most dangerous aeroelastic failure phenomenon. The flutter characteristic differs for each aircraft type, and depends on the wing geometry as well as its operational region of subsonic, transonic or supersonic speeds. Prior to performing a flight flutter test, extensive numerical simulations and Ground Vibration Test should be conducted where the structural finite element modes and the experimentation results should be matched, otherwise th...

  14. How Is Atrial Fibrillation Treated?

    Science.gov (United States)

    ... page from the NHLBI on Twitter. How Is Atrial Fibrillation Treated? Treatment for atrial fibrillation (AF) depends on ... too much thyroid hormone). Who Needs Treatment for Atrial Fibrillation? People who have AF but don't have ...

  15. How Is Atrial Fibrillation Diagnosed?

    Science.gov (United States)

    ... Atrial Fibrillation » How Is Atrial Fibrillation Diagnosed? Explore Atrial Fibrillation What Is... Types Other Names Causes Who Is at Risk Signs & Symptoms Diagnosis Treatments Prevention Living With Clinical Trials Links Related Topics Arrhythmia ...

  16. Detection of Rapid Atrial Arrhythmias in SQUID Magnetocardiography

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ki Woong; Kwon, Hyuk Chan; Kim, Ki Dam; Lee, Yong Ho; Kim, Jin Mok; Kim, In Seon; Lim, Hyun Kyoon; Park, Yong Ki [Biomagnetism Research, Korea Research Institute of Standards and Science, Daejeon (Korea, Republic of); Kim, Doo Sang [Seoul Veterans Hospital, Seoul (Korea, Republic of); Lim, Seung Pyung [Chungnam National University Hospital, Daejeon (Korea, Republic of)

    2005-10-15

    We propose a method to measure atrial arrhythmias (AA) such as atrial fibrillation (Afb) and atrial flutter (Afl) with a SQUID magnetocardiograph (MCG) system. To detect AA is one of challenging topics in MCG. As the AA generally have irregular rhythm and atrio-ventricular conduction, the MCG signal cannot be improved by QRS averaging; therefore a SQUID MCG system having a high SNR is required to measure informative atrial excitation with a single scan. In the case of Afb, diminished f waves are much smaller than normal P waves because the sources are usually located on the posterior wall of the heart. In this study, we utilize an MCG system measuring tangential field components, which is known to be more sensitive to a deeper current source. The average noise spectral density of the whole system in a magnetic shielded room was 10 fT/Hz(a) 1 Hz and 5 fT/Hz(a) 100 Hz. We measured the MCG signals of patients with chronic Afb and Afl. Before the AA measurement, the comparison between the measurements in supine and prone positions for P waves has been conducted and the experiment gave a result that the supine position is more suitable to measure the atrial excitation. Therefore, the AA was measured in subject's supine position. Clinical potential of AA measurement in MCG is to find an aspect of a reentry circuit and to localize the abnormal stimulation noninvasively. To give useful information about the abnormal excitation, we have developed a method, separative synthetic aperture magnetometry (sSAM). The basic idea of sSAM is to visualize current source distribution corresponding to the atrial excitation, which are separated from the ventricular excitation and the Gaussian sensor noises. By using sSAM, we localized the source of an Afl successfully.

  17. Atrial Fibrillation and Pacing Algorithms

    OpenAIRE

    Terranova, Paolo; Severgnini, Barbara; Valli, Paolo; Dell'Orto, Simonetta; Greco, Enrico Maria

    2006-01-01

    Pacing prevention algorithms have been introduced in order to maximize the benefits of atrial pacing in atrial fibrillation prevention. It has been demonstrated that algorithms actually keep overdrive atrial pacing, reduce atrial premature contractions, and prevent short-long atrial cycle phenomenon, with good patient tolerance. However, clinical studies showed inconsistent benefits on clinical endpoints such as atrial fibrillation burden. Factors which may be responsible for neutral results ...

  18. Nonlinear Characteristics of Randomly Excited Transonic Flutter

    DEFF Research Database (Denmark)

    Christiansen, Lasse Engbo; Lehn-Schiøler, Tue; Mosekilde, Erik;

    2002-01-01

    shown that the self-sustained oscillations arise in a subcritical Hopf bifurcation. However, analysis of the experimental data also reveals that this bifurcation is modified in various ways. We present an outline of the construction of a 6 DOF model of the aeroelastic behavior of the wing structure...... reproduce several of the experimentally observed modifications of the flutter transition. In particular, the models display the characteristic phenomena of coherence resonance....

  19. Stall Flutter Control of a Smart Blade Section Undergoing Asymmetric Limit Oscillations

    Directory of Open Access Journals (Sweden)

    Nailu Li

    2016-01-01

    Full Text Available Stall flutter is an aeroelastic phenomenon resulting in unwanted oscillatory loads on the blade, such as wind turbine blade, helicopter rotor blade, and other flexible wing blades. Although the stall flutter and related aeroelastic control have been studied theoretically and experimentally, microtab control of asymmetric limit cycle oscillations (LCOs in stall flutter cases has not been generally investigated. This paper presents an aeroservoelastic model to study the microtab control of the blade section undergoing moderate stall flutter and deep stall flutter separately. The effects of different dynamic stall conditions and the consequent asymmetric LCOs for both stall cases are simulated and analyzed. Then, for the design of the stall flutter controller, the potential sensor signal for the stall flutter, the microtab control capability of the stall flutter, and the control algorithm for the stall flutter are studied. The improvement and the superiority of the proposed adaptive stall flutter controller are shown by comparison with a simple stall flutter controller.

  20. Risk of atrial fibrillation associated with use of bisphosphonates and other drugs against osteoporosis: a cohort study

    DEFF Research Database (Denmark)

    Vestergaard, Peter; Schwartz, Kristoffer; Pinholt, Else Marie; Rejnmark, Lars; Mosekilde, Leif

    2010-01-01

    flutter was present for any drug except for etidronate (OR = 1.22, 95% CI 1.15-1.29). After initiation of treatment, raloxifene was not associated with any excess risk of atrial fibrillation (OR = 0.98, 95% CI 0.72-1.33). Etidronate (HR = 1.08, 95% CI 1.02-1.14) and alendronate (HR = 1.09, 95% CI 1...

  1. Ocular flutter in suspected multiple sclerosis: a presenting paroxysmal manifestation.

    OpenAIRE

    D. A. Francis; Heron, J. R.

    1985-01-01

    A patient with suspected multiple sclerosis is described who presented with attacks of blurring of vision and ocular flutter. This has not previously been reported as an isolated paroxysmal manifestation of brain stem demyelination. As with other paroxysmal disturbances ocular flutter may present as the first sign of the disease.

  2. The Investigation of Flutter of Viscoelastic of Orthotropic Plates

    OpenAIRE

    Khudayarov B.A.

    2010-01-01

    The flutter of viscoelastic of orthotropic plates streamlined by a gas current are investigated. The basic direction of the present work consists in taking into account of viscoelastic material properties at supersonic speeds. An algorithm of the numerical solution for the problem has been worked out on the basic of the method. The results of the flutter critical speed calculations have been given.

  3. Transport from magnetic flutter: gordian knot or granny

    International Nuclear Information System (INIS)

    A quasilinear theory of particle and energy flux by magnetic flutter associated with drift waves is presented. It is shown that magnetic flutter can enhance the energy flux. However, particle diffusion is ambipolar and runaway electrons do not escape along the field lines. (author)

  4. Mathematical modeling of flutter of viscoelastic plates and cylindrical panels

    OpenAIRE

    B. A. Khudayarov

    2006-01-01

    The flutter of viscoelastic plates and cylindrical panels streamlined by a gas current are investigated. The basic direction of the present work consists in taking into account of viscoelastic material properties at supersonic speeds. An algorithm of the numerical solution for the problem has been worked out on the basic of the method. The results of the flutter critical speed calculations have been given.

  5. Analysis of tiltrotor whirl flutter in time and frequency domain

    DEFF Research Database (Denmark)

    Kim, Taeseong; Shin, SanJoon; Kim, Taehyoun

    2009-01-01

    The whirl flutter phenomenon in a rotor is induced by in-plane hub forces, and imposes a serious limit on the forward speed. In this paper, based on Greenberg’s model, quasi-steady and unsteady aerodynamic forces are formulated to examine the whirl flutter stability for a three-bladed rotor witho...

  6. Characterization of Left Atrial Tachyarrhythmias in Patients Following Atrial Fibrillation Ablation: Correlation of surface ECG with Intracardiac Mapping

    Directory of Open Access Journals (Sweden)

    Sanjay Dixit

    2010-05-01

    Full Text Available With expected success rates in excess of 80% for achieving long term arrhythmia control, catheter based ablation has become a popular treatment strategy in the management of patients with atrial fibrillation (AF. However, the success of AF ablation has been tempered by the occurrence of post procedure left atrial tachycardias and / or flutters, which can be seen in up to 30% of the patients. These arrhythmias are perpetuated either due to abnormalities of impulse formation (abnormal automaticity / triggered activity, or abnormalities of impulse conduction (micro / macroreentry. Regardless of the underlying mechanism, these tachycardias manifest distinct “P” or flutter waves on the surface ECG, recognition of which may facilitate their characterization / localization. However, because of the frequent overlap in the morphology of P waves, intracardiac mapping is often the only way to distinguish them apart. This is accomplished using a combination of activation, entrainment and electroanatomic mapping techniques. Tachycardias resulting from abnormalities of impulse formation and / or microreentry are characteristically focal and usually confined in and around pulmonary vein (PV segments which have reconnected (septal aspect of right PVs and anterior aspect of left PVs. In contrast, macroreentrant tachycardias manifest a large circuit dimension involving zone(s of slow conduction. These are most commonly seen to occur around the mitral valve but can develop in any part of the left atrium where “gaps” across prior ablation lesion sets create altered conduction. Successful ablation of focal tachycardias is usually accomplished by isolating the reconnected PV segment(s. In case of macroreentrant arrhythmias however, a more extensive ablation approach is typically required in order to achieve conduction block across isthmus of the circuit. Using these strategies, the majority of left atrial tachycardias occurring post AF ablation can be

  7. Optical detection of blade flutter. [in YF-100 turbofan engine

    Science.gov (United States)

    Nieberding, W. C.; Pollack, J. L.

    1977-01-01

    The paper examines the capabilities of photoelectric scanning (PES) and stroboscopic imagery (SI) as optical monitoring tools for detection of the onset of flutter in the fan blades of an aircraft gas turbine engine. Both optical techniques give visual data in real time as well as video-tape records. PES is shown to be an ideal flutter monitor, since a single cathode ray tube displays the behavior of all the blades in a stage simultaneously. Operation of the SI system continuously while searching for a flutter condition imposes severe demands on the flash tube and affects its reliability, thus limiting its use as a flutter monitor. A better method of operation is to search for flutter with the PES and limit the use of SI to those times when the PES indicates interesting blade activity.

  8. Flutter of Finite-Span Flexible Plates in Uniform Flow

    International Nuclear Information System (INIS)

    The flutter instability and response of finite-span flexible plates in uniform flow are investigated experimentally. The effects of the plate aspect ratio on its dynamic responses are mainly analyzed. A hysteretic phenomenon is observed and can be described such that the plate flutters spontaneously as the flow velocity is greater than a critical value U*C and the plate returns to its stable state as the flow velocity is slowly decreased to another critical one U*D. We find that the aspect ratio has a greater effect on U*C than on U*D. The flutter frequency decreases and the amplitude increases with the increase in the flow velocity. When the flutter instability of the plate occurs, three typical flutter modes are identified and are associated with the aspect ratio and the flow velocity. (fundamental areas of phenomenology (including applications))

  9. Exploiting periodicity to extract the atrial activity in atrial arrhythmias

    OpenAIRE

    Llinares Llopis, Raúl; Igual García, Jorge

    2011-01-01

    [EN] Atrial fibrillation disorders are one of the main arrhythmias of the elderly. The atrial and ventricular activities are decoupled during an atrial fibrillation episode, and very rapid and irregular waves replace the usual atrial P-wave in a normal sinus rhythm electrocardiogram (ECG). The estimation of these wavelets is a must for clinical analysis. We propose a new approach to this problem focused on the quasiperiodicity of these wavelets. Atrial activity is characterized by...

  10. Real-time flutter analysis of an active flutter-suppression system on a remotely piloted research aircraft

    Science.gov (United States)

    Gilyard, G. B.; Edwards, J. W.

    1983-01-01

    Flight flutter-test results of the first aeroelastic research wing (ARW-1) of NASA's drones for aerodynamic and structural testing program are presented. The flight-test operation and the implementation of the active flutter-suppression system are described as well as the software techniques used to obtain real-time damping estimates and the actual flutter testing procedure. Real-time analysis of fast-frequency aileron excitation sweeps provided reliable damping estimates. The open-loop flutter boundary was well defined at two altitudes; a maximum Mach number of 0.91 was obtained. Both open-loop and closed-loop data were of exceptionally high quality. Although the flutter-suppression system provided augmented damping at speeds below the flutter boundary, an error in the implementation of the system resulted in the system being less stable than predicted. The vehicle encountered system-on flutter shortly after crossing the open-loop flutter boundary on the third flight and was lost. The aircraft was rebuilt. Changes made in real-time test techniques are included.

  11. Unsteady aerodynamics of fluttering and tumbling plates

    Science.gov (United States)

    Andersen, A.; Pesavento, U.; Wang, Z. Jane

    2005-10-01

    We investigate the aerodynamics of freely falling plates in a quasi-two-dimensional flow at Reynolds number of 10(3) , which is typical for a leaf or business card falling in air. We quantify the trajectories experimentally using high-speed digital video at sufficient resolution to determine the instantaneous plate accelerations and thus to deduce the instantaneous fluid forces. We compare the measurements with direct numerical solutions of the two-dimensional Navier Stokes equation. Using inviscid theory as a guide, we decompose the fluid forces into contributions due to acceleration, translation, and rotation of the plate. For both fluttering and tumbling we find that the fluid circulation is dominated by a rotational term proportional to the angular velocity of the plate, as opposed to the translational velocity for a glider with fixed angle of attack. We find that the torque on a freely falling plate is small, i.e. the torque is one to two orders of magnitude smaller than the torque on a glider with fixed angle of attack. Based on these results we revise the existing ODE models of freely falling plates. We get access to different kinds of dynamics by exploring the phase diagram spanned by the Reynolds number, the dimensionless moment of inertia, and the thickness-to-width ratio. In agreement with previous experiments, we find fluttering, tumbling, and apparently chaotic motion. We further investigate the dependence on initial conditions and find brief transients followed by periodic fluttering described by simple harmonics and tumbling with a pronounced period-two structure. Near the cusp-like turning points, the plates elevate, a feature which would be absent if the lift depended on the translational velocity alone.

  12. Wavelet Applications for Flight Flutter Testing

    Science.gov (United States)

    Lind, Rick; Brenner, Marty; Freudinger, Lawrence C.

    1999-01-01

    Wavelets present a method for signal processing that may be useful for analyzing responses of dynamical systems. This paper describes several wavelet-based tools that have been developed to improve the efficiency of flight flutter testing. One of the tools uses correlation filtering to identify properties of several modes throughout a flight test for envelope expansion. Another tool uses features in time-frequency representations of responses to characterize nonlinearities in the system dynamics. A third tool uses modulus and phase information from a wavelet transform to estimate modal parameters that can be used to update a linear model and reduce conservatism in robust stability margins.

  13. RMP-Flutter-Induced Pedestal Plasma Transport

    International Nuclear Information System (INIS)

    Full text: Plasma toroidal rotation can prevent or limit reconnection of externally applied resonant magnetic perturbation (RMP) fields δB on rational magnetic flux surfaces. Hence, it causes the induced radial perturbations to vanish or be small there, and thereby inhibits magnetic island formation and stochasticity in the edge of high (H-mode) confinement tokamak plasmas. However, the radial component of the spatial magnetic flutter induced by RMP fields off rational surfaces causes a radial electron thermal diffusivity of (1/2)(δBp/B)2 times a magnetic-shear-influenced effective parallel electron thermal diffusivity. The resultant RMP-flutter-induced electron thermal diffusivity can be comparable to experimentally inferred values at the top of H-mode pedestals. This process also causes a factor of about 3 smaller RMP-induced electron density diffusivity there. Because this electron density transport is non-ambipolar, it produces a toroidal torque on the plasma, which is usually in the co-current direction. Kinetic-based cylindrical screw-pinch and toroidal models of these RMP-flutter-induced plasma transport effects have been developed. The RMP-induced increases in these diffusive plasma transport processes are typically spatially inhomogeneous in that they are strongly peaked near the rational surfaces in low collisionality pedestals, which may lead to resonant sensitivities to the local safety factor q. The effects can be large enough to reduce the radially averaged gradients of the electron temperature and density at the top of H-mode edge pedestals, and modify the plasma toroidal rotation and radial electric field there. At high collisionality the various effects are less strongly peaked at rational surfaces and thus less likely to exhibit RMP-induced resonant behavior. These RMP-flutter-induced plasma transport processes provide a new paradigm for developing an understanding of how RMPs modify the pedestal structure to stabilize peeling-ballooning modes

  14. Stochastic Characterization of Flutter using Historical Wind Tunnel Data

    Science.gov (United States)

    Heeg, Jennifer

    2007-01-01

    Methods for predicting the onset of flutter during an experiment are traditionally applied treating the data as deterministic values. Uncertainty and variation in the data is often glossed over by using best-fit curves to represent the information. This paper applies stochastic treatments to wind tunnel data obtained for the Piezoelectric Aeroelastic Response Tailoring Investigation model. These methods include modal amplitude tracking, modal frequency tracking and several applications of the flutter margin method. The flutter margin method was developed by Zimmerman and Weissenburger, and extended by Poirel, Dunn and Porter to incorporate uncertainty. Much of the current work follows the future work recommendations of Poirel, Dunn and Porter.

  15. AEROELASTIC FLUTTER ANALYSIS OF SUPERSONIC WING WITH MULTIPLE EXTERNAL STORES

    Directory of Open Access Journals (Sweden)

    Nur Azam

    2014-12-01

    Full Text Available ABSTRACT: Flutter may be considered to be one of the most dangerous aeroelastic failure phenomenon. The flutter characteristic differs for each aircraft type, and depends on the wing geometry as well as its operational region of subsonic, transonic or supersonic speeds. Prior to performing a flight flutter test, extensive numerical simulations and Ground Vibration Test should be conducted where the structural finite element modes and the experimentation results should be matched, otherwise the numerical simulation model must be rejected. In this paper, the analysis of simulation of a supersonic wing equipped with external missiles loaded on the wing is presented. The structural mode shapes at each generated frequency are also visually presented. The analysis is carried out using MSC Nastran FEM software. The wing flutter with the external stores was simulated at different altitudes. The result shows that the flutter velocity is sensitive to the flight altitude. For this reason, the flutter analysis is conducted also for a negative altitude. The negative altitude is obtained by considering the constant equivalent speed-Mach number rule at the flutter speed boundary as a requirement in standard regulation of transport aircraft. ABSTRAK: Salah satu fenomena kegagalan aeroelastik yang paling membahayakan adalah kipasan (flutter. Ciri-ciri kegagalan kipasan (flutter adalah berbeza untuk setiap jenis pesawat bergantung pada geometri sayap dan regim operasi sama ada subsonik, transonik atau supersonik. Sebelum melakukan ujian penerbangan kipasan , simulasi berangka luas dan ujian getaran peringkat bawahan (darat perlu dijalankan di mana struktur mod unsur terhingga dan keputusan eksperimen harus dipadankan, sebaliknya model simulasi berangka boleh ditolak. Dalam kertas kerja ini, simulasi sayap supersonik dilengkapi dengan beban luaran peluru berpandu di sayap telah dianalisis di daerah supersonik tinggi. Bentuk mod struktur pada setiap mod frekuensi

  16. Flutter analysis of side vanes for wind mills. Flutter analyse van zijvanen voor windmolens

    Energy Technology Data Exchange (ETDEWEB)

    Bierbooms, W.; Rodenburg, R. (Instituut voor Windenergie, Vakgroep Mechanica en Constructies, Faculteit der Civiele Techniek, Technische Univ. Delft (Netherlands))

    1992-09-01

    One of the problems in the research on the dynamic stability of wind turbines is the stability of a rotor with side vane. Such wind mills are developed by the Eindhoven University of Technology in the Netherlands for the use of water pumps in developing countries. The function of the side vane is to keep the rotor wind-oriented. During stormy weather on the test field in Almere, Netherlands, in January 1990 flutter phenomenons were observed for the vane of the CWD 2000 mill. A simple model has been developed to describe the flutter phenomenon by means of two degrees of freedom (torsion and pitch). The impact of some relevant parameters can be investigated by this model. 7 figs., 3 refs.

  17. Anticoagulation in atrial fibrillation

    OpenAIRE

    Steinberg, Benjamin A; Piccini, Jonathan P.

    2014-01-01

    Atrial fibrillation increases the risk of stroke, which is a leading cause of death and disability worldwide. The use of oral anticoagulation in patients with atrial fibrillation at moderate or high risk of stroke, estimated by established criteria, improves outcomes. However, to ensure that the benefits exceed the risks of bleeding, appropriate patient selection is essential. Vitamin K antagonism has been the mainstay of treatment; however, newer drugs with novel mechanisms are also availabl...

  18. Flutter margin with non-linearities: real-time prediction of flutter onset speed

    OpenAIRE

    Casado Corpas, José; López Díez, Jesús

    2008-01-01

    The present article shows a procedure to predict the flutter speed based on real-time tuning of a quasi non-linear aeroelastic model. A two-dimensional non-linear (freeplay) aeroeslastic model is implemented inMatLab/Simulink with incompressible aerodynamic conditions. A comparison with real compressible conditions is provided. Once the numerical validation is accomplished, a parametric aeroelastic model is built in order to describe the proposed procedure and contribute to reduce the number ...

  19. Prevention of Recurrent Atrial Fibrillation and Bi-Atrial Resynchronization

    OpenAIRE

    Evrard, P.; Sakalihasan, Natzi; R. Garcia; Van Laere, Anne-Sophie; Patterson, B.

    1999-01-01

    After conversion of atrial fibrillation, it is important to maintain sinus rhythm. In addition antiarrhythmic drugs, biatrial resynchronization seems to prevent recurrences of atrial fibrillation in patients with interatrial conduction block: local experience.

  20. Effect of chronic kidney diseases on mortality among digoxin users treated for non-valvular atrial fibrillation

    DEFF Research Database (Denmark)

    Sessa, Maurizio; Mascolo, Annamaria; Andersen, Mikkel Porsborg;

    2016-01-01

    PURPOSE: This study investigated the impact of chronic kidney disease on all-causes and cardiovascular mortality in patients with atrial fibrillation treated with digoxin. METHODS: All patients with non-valvular atrial fibrillation and/or atrial flutter as hospitalization diagnosis from January 1......, 1997 to December 31, 2012 were identified in Danish nationwide administrative registries. Cox proportional hazard model was used to compare the adjusted risk of all-causes and cardiovascular mortality among patients with and without chronic kidney disease and among patients with different chronic...... kidney disease stages within 180 days and 2 years from the first digoxin prescription. RESULTS: We identified 37,981 patients receiving digoxin; 1884 patients had the diagnosis of chronic kidney disease. Cox regression analysis showed no statistically significant differences in all-causes (Hazard Ratio...

  1. A dynamical interpretation of flutter instability in a continuous medium

    CERN Document Server

    Piccolroaz, Andrea; Willis, John R

    2010-01-01

    Flutter instability in an infinite medium is a form of material instability corresponding to the occurrence of complex conjugate squares of the acceleration wave velocities. Although its occurrence is known to be possible in elastoplastic materials with nonassociative flow law and to correspond to some dynamically growing disturbance, its mechanical meaning has to date still eluded a precise interpretation. This is provided here by constructing the infinite-body, time-harmonic Green's function for the loading branch of an elastoplastic material in flutter conditions. Used as a perturbation, it reveals that flutter corresponds to a spatially blowing-up disturbance, exhibiting well-defined directional properties, determined by the wave directions for which the eigenvalues become complex conjugate. Flutter is shown to be connected to the formation of localized deformations, a dynamical phenomenon sharing geometrical similarities with the well-known mechanism of shear banding occurring under quasi-static loading....

  2. GVT-Based Ground Flutter Test without Wind Tunnel Project

    Data.gov (United States)

    National Aeronautics and Space Administration — ZONA Technology, Inc (ZONA) and Arizona State University (ASU) propose a R&D effort to further develop the ground flutter testing system in place of a wind...

  3. GVT-Based Ground Flutter Test without Wind Tunnel Project

    Data.gov (United States)

    National Aeronautics and Space Administration — ZONA Technology, Inc (ZONA) and Arizona State University (ASU) propose a R&D effort to develop a ground flutter testing system without wind tunnel, called the...

  4. Modern wing flutter analysis by computational fluid dynamics methods

    Science.gov (United States)

    Cunningham, Herbert J.; Batina, John T.; Bennett, Robert M.

    1988-01-01

    The application and assessment of the recently developed CAP-TSD transonic small-disturbance code for flutter prediction is described. The CAP-TSD code has been developed for aeroelastic analysis of complete aircraft configurations and was previously applied to the calculation of steady and unsteady pressures with favorable results. Generalized aerodynamic forces and flutter characteristics are calculated and compared with linear theory results and with experimental data for a 45 deg sweptback wing. These results are in good agreement with the experimental flutter data which is the first step toward validating CAP-TSD for general transonic aeroelastic applications. The paper presents these results and comparisons along with general remarks regarding modern wing flutter analysis by computational fluid dynamics methods.

  5. Flutter Analysis of the Shuttle Tile Overlay Repair Concept

    Science.gov (United States)

    Bey, Kim S.; Scott, Robert C.; Bartels, Robert E.; Waters, William A.; Chen, Roger

    2007-01-01

    The Space Shuttle tile overlay repair concept, developed at the NASA Johnson Space Center, is designed for on-orbit installation over an area of damaged tile to permit safe re-entry. The thin flexible plate is placed over the damaged area and secured to tile at discreet points around its perimeter. A series of flutter analyses were performed to determine if the onset of flutter met the required safety margins. Normal vibration modes of the panel, obtained from a simplified structural analysis of the installed concept, were combined with a series of aerodynamic analyses of increasing levels of fidelity in terms of modeling the flow physics to determine the onset of flutter. Results from these analyses indicate that it is unlikely that the overlay installed at body point 1800 will flutter during re-entry.

  6. Atrial Fibrosis and the Mechanisms of Atrial Fibrillation

    OpenAIRE

    Everett, Thomas H; Olgin, Jeffrey E.

    2006-01-01

    Atrial fibrillation (AF) is commonly associated with congestive heart failure (CHF), and CHF has been shown to be associated with atrial structural remodeling resulting in fibrosis. This atrial interstitial fibrosis has been seen in patients with CHF and animal models of pacing induced heart failure. With atrial fibrosis, conduction abnormalities result in an increase in AF vulnerability. The mechanism of AF that is associated with CHF is still under debate as both focal and reentrant mechani...

  7. Practical applicability of landiolol, an ultra-short-acting β1-selective blocker, for rapid atrial and ventricular tachyarrhythmias with left ventricular dysfunction

    OpenAIRE

    Wada, Yuko; Aiba, Takeshi; Tsujita, Yasuyuki; Itoh, Hideki; Wada, Mitsuru; Nakajima, Ikutaro; Ishibashi, Kohei; Okamura, Hideo; Miyamoto, Koji; Noda, Takashi; Sugano, Yasuo; Kanzaki, Hideaki; Anzai, Toshihisa; Kusano, Kengo; Yasuda, Satoshi

    2015-01-01

    Background Landiolol effectively controls rapid heart rate in atrial fibrillation or flutter (AF/AFL) patients with left ventricular (LV) dysfunction. However, predicting landiolol Responders and Non-Responders and patients who will experience adverse effects remains a challenge. The aim of this study was to clarify the potential applicability of landiolol for rapid AF/AFL and refractory ventricular tachyarrhythmias (VTs) in patients with heart failure. Methods A total of 39 patients with AF/...

  8. Mathematical modeling of flutter of viscoelastic plates and cylindrical panels

    Directory of Open Access Journals (Sweden)

    B. A. Khudayarov

    2006-03-01

    Full Text Available The flutter of viscoelastic plates and cylindrical panels streamlined by a gas current are investigated. The basic direction of the present work consists in taking into account of viscoelastic material properties at supersonic speeds. An algorithm of the numerical solution for the problem has been worked out on the basic of the method. The results of the flutter critical speed calculations have been given.

  9. Non-Flutter Design Principle for long Span Bridges

    DEFF Research Database (Denmark)

    Johansson, Jens; Andersen, Michael Styrk; Starch Øvre, Michele

    The case of flutter on a sharp edged flat plate section model, with a height-to-width ratio of 1:10, has been investigated at four different torsional-to-vertical frequency ratios equal to 0.71, 0.88, 1.19 and 2.10. At a torsional-to-vertical frequency ratio of approximately 1.1 the flutter wind...

  10. Can Atrial Fibrillation Be Prevented?

    Science.gov (United States)

    ... page from the NHLBI on Twitter. How Can Atrial Fibrillation Be Prevented? Following a healthy lifestyle and taking ... risk for heart disease may help you prevent atrial fibrillation (AF). These steps include: Following a heart healthy ...

  11. Atrial remodeling, fibrosis, and atrial fibrillation.

    Science.gov (United States)

    Jalife, José; Kaur, Kuljeet

    2015-08-01

    The fundamental mechanisms governing the perpetuation of atrial fibrillation (AF), the most common arrhythmia seen in clinical practice, are poorly understood, which explains in part why AF prevention and treatment remain suboptimal. Although some clinical parameters have been identified as predicting a transition from paroxysmal to persistent AF in some patients, the molecular, electrophysiological, and inflammation changes leading to such a progression have not been described in detail. Oxidative stress, atrial dilatation, calcium overload, inflammation, microRNAs, and myofibroblast activation are all thought to be involved in AF-induced atrial remodeling. However, it is unknown to what extent and at which time points such alterations influence the remodeling process that perpetuates AF. Here we postulate a working model that might open new pathways for future investigation into mechanisms of AF perpetuation. We start from the premise that the progression to AF perpetuation is the result of interplay among manifold signaling pathways with differing kinetics. Some such pathways have relatively fast kinetics (e.g., oxidative stress-mediated shortening of refractory period); others likely depend on molecular processes with slower kinetics (e.g., transcriptional changes in myocyte ion channel protein expression mediated through inflammation and fibroblast activation). We stress the need to fully understand the relationships among such pathways should one hope to identify novel, truly effective targets for AF therapy and prevention. PMID:25661032

  12. Wing flutter boundary prediction using unsteady Euler aerodynamic method

    Science.gov (United States)

    Lee-Rausch, Elizabeth M.; Batina, John T.

    1993-01-01

    Modifications to an existing 3D implicit upwind Euler/Navier-Stokes code for the aeroelastic analysis of wings are described. These modifications include the incorporation of a deforming mesh algorithm and the addition of the structural equations of motion for their simultaneous time-integration with the governing flow equations. The paper gives a brief description of these modifications and presents unsteady calculations which check the modifications to the code. Euler flutter results for an isolated 45 deg swept-back wing are compared with experimental data for seven freestream Mach numbers which define the flutter boundary over a range of Mach number from 0.499 to 1.14. These comparisons show good agreement in flutter characteristics for freestream Mach numbers below unity. For freestream Mach numbers above unity, the computed aeroelastic results predict a premature rise in the flutter boundary as compared with the experimental boundary. Steady and unsteady contours of surface Mach number and pressure are included to illustrate the basic flow characteristics of the time-marching flutter calculations and to aid in identifying possible causes for the premature rise in the computational flutter boundary.

  13. On-Line Flutter Prediction Tool for Wind Tunnel Flutter Testing using Parameter Varying Estimation Methodology Project

    Data.gov (United States)

    National Aeronautics and Space Administration — ZONA Technology, Inc. (ZONA) proposes to develop an on-line flutter prediction tool using the parameter varying estimation (PVE) methodology, called the PVE...

  14. On-Line Flutter Prediction Tool for Wind Tunnel Flutter Testing using Parameter Varying Estimation Methodology Project

    Data.gov (United States)

    National Aeronautics and Space Administration — ZONA Technology, Inc. (ZONA) proposes to develop an on-line flutter prediction tool for wind tunnel model using the parameter varying estimation (PVE) technique to...

  15. Risk Factors for Atrial Fibrillation

    OpenAIRE

    Krijthe, Bouwe

    2013-01-01

    textabstractAtrial fibrillation is a common cardiac arrhythmia that is characterized by rapid disorganized atrial electrical activity resulting in absence of atrial contractions. It is diagnosed on the basis of typical findings on an electrocardiogram (ECG). The characteristic ECG findings are absence of P-waves, and an irregular heart rate. Symptoms of atrial fibrillation include palpitations, dyspnea, reduced exercise capacity, chest pain and dizziness, but it often goes without symptoms. A...

  16. Stroke prevention in atrial fibrillation.

    NARCIS (Netherlands)

    Verheugt, F.W.A.

    2006-01-01

    The only major and potentially fatal risk for patients with atrial fibrillation is the development of systemic thromboembolism. Stroke occurs five times more frequently in patients with atrial fibrillation than in comparable patients in sinus rhythm. The yearly incidence of stroke in atrial fibrilla

  17. Atrial Fibrillation (AF or AFib)

    Science.gov (United States)

    ... Pressure High Blood Pressure Tools & Resources Stroke More Atrial Fibrillation (AF or AFib) Updated:Feb 10,2016 What ... to the Terms and Conditions and Privacy Policy Atrial Fibrillation • Introduction • What is Atrial Fibrillation? • Why AFib Matters • ...

  18. Left atrial appendage occlusion

    Directory of Open Access Journals (Sweden)

    Ahmad Mirdamadi

    2013-01-01

    Full Text Available Left atrial appendage (LAA occlusion is a treatment strategy to prevent blood clot formation in atrial appendage. Although, LAA occlusion usually was done by catheter-based techniques, especially percutaneous trans-luminal mitral commissurotomy (PTMC, it can be done during closed and open mitral valve commissurotomy (CMVC, OMVC and mitral valve replacement (MVR too. Nowadays, PTMC is performed as an optimal management of severe mitral stenosis (MS and many patients currently are treated by PTMC instead of previous surgical methods. One of the most important contraindications of PTMC is presence of clot in LAA. So, each patient who suffers of severe MS is evaluated by Trans-Esophageal Echocardiogram to rule out thrombus in LAA before PTMC. At open heart surgery, replacement of the mitral valve was performed for 49-year-old woman. Also, left atrial appendage occlusion was done during surgery. Immediately after surgery, echocardiography demonstrates an echo imitated the presence of a thrombus in left atrial appendage area, although there was not any evidence of thrombus in pre-pump TEE. We can conclude from this case report that when we suspect of thrombus of left atrial, we should obtain exact history of previous surgery of mitral valve to avoid misdiagnosis clotted LAA, instead of obliterated LAA. Consequently, it can prevent additional evaluations and treatments such as oral anticoagulation and exclusion or postponing surgeries including PTMC.

  19. Anticoagulation in atrial fibrillation.

    Science.gov (United States)

    Steinberg, Benjamin A; Piccini, Jonathan P

    2014-01-01

    Atrial fibrillation increases the risk of stroke, which is a leading cause of death and disability worldwide. The use of oral anticoagulation in patients with atrial fibrillation at moderate or high risk of stroke, estimated by established criteria, improves outcomes. However, to ensure that the benefits exceed the risks of bleeding, appropriate patient selection is essential. Vitamin K antagonism has been the mainstay of treatment; however, newer drugs with novel mechanisms are also available. These novel oral anticoagulants (direct thrombin inhibitors and factor Xa inhibitors) obviate many of warfarin's shortcomings, and they have demonstrated safety and efficacy in large randomized trials of patients with non-valvular atrial fibrillation. However, the management of patients taking warfarin or novel agents remains a clinical challenge. There are several important considerations when selecting anticoagulant therapy for patients with atrial fibrillation. This review will discuss the rationale for anticoagulation in patients with atrial fibrillation; risk stratification for treatment; available agents; the appropriate implementation of these agents; and additional, specific clinical considerations for treatment. PMID:24733535

  20. Integrin β1 Participates in Atrial Remodeling in Rapid Atrial Pacing Induced Canine Atrial Fibrillation Model

    Institute of Scientific and Technical Information of China (English)

    Zhang wei; Yang guirong; Zheng zhaotong; Wang sujia; Zhang yun

    2004-01-01

    @@ Objective Integrin β1 regulates cell to cell and cell to extracellualr matrix interaction in heart. however, its pathop hysiological role in atrial fibrillation is unclear. The purpose of t his study was to determine whether atrial structural remodeling during atrial fibrillation is associated with altered integrinβ1.

  1. RELATION BETWEEN LEFT ATRIAL SIZE AND ATRIAL FIBRILLATION IN DIFFERENT DISEASES

    OpenAIRE

    Rajith; Divya

    2014-01-01

    BACKGROUND: Atrial fibrillation is the most common cardiac dysrhythmia and left atrial size is an important factor in the development of atrial fibrillation. In the presence of atrial fibrillation an increase in left atrial size is associated with increased risk of stroke as well as increased morbidity and mortality. In this context, this study entitled “relation between left atrial size and atrial fibrillation in different diseases” was undertaken to study the left atrial size in different d...

  2. Complex Mode Frequency Iteration Method for Flutter Analysis of 2-DOF Systems

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    For a vibration system with 2-DOF of bend and torsion, itscritical flutter wind speed can be calculated by using complex mode frequency iteration (CMFI) method based on MatLab 5.2, the results of which are in agree with those acquired by wind tunnel test. Not only critical flutter wind speed, but also vibration characteristic of a system under different wind speeds can be determined. CMFI method is suitable for both of separated-flow torsional flutter and classic coupling flutter analysis, which is presented by flutter analysis of an ideal thin plate and a bluff bridge deck. Furthermore, it is proved through the investigation of the relationship between flutter derivatives and its critical flutter wind speed that coupling aerodynamic derivatives are necessary for classic coupling flutter to occur.

  3. Flutter prediction, suppression and control in aircraft composite wings as a design prerequisite: a survey

    OpenAIRE

    Njuguna, James A. K.

    2007-01-01

    Emergence of flutter compromises not only the long-term durability of the wing structure, but also the operational safety, flight performance and energy efficiency of the aircraft. Effectual means of flutter prevention are, therefore, mandatory in the certification of new flight vehicles. This work intends to address the flutter phenomenon highlighting the above issues, and reviews some of the most recent theoretical and experimental developments in flutter analyses. In the ...

  4. Supersonic Flutter Utilization for Effective Energy-Harvesting Based on Piezoelectric Switching Control

    OpenAIRE

    Kanjuro Makihara; Shigeru Shimose

    2012-01-01

    The harvesting of electrical energy generated from the flutter phenomenon of a plate wing is studied using the quasi-steady aerodynamic theory and the finite element method. The example of supersonic flutter structure comes from sounding rockets’ wings. Electrical energy is harvested from supersonic flutter by using piezoelectric patches and switching devices. In order to evaluate the harvesting performance, we simulate flutter dynamics of the plate wing to which piezoelectric patches are att...

  5. Fluid Structural Modal Coupled Numerical Investigation of Transonic Fluttering Of Axial Flow Compressor Blades

    OpenAIRE

    Rio Melvin Aro. T; EZHILMARAN G

    2015-01-01

    Flutter is an unstable oscillation which can lead to destruction. Flutter can occur on fixed surfaces, such as blades, wing or the stabilizer. By self-excited aeroelastic instability, flutter can lead to mechanical or structural failure of aircraft engine blades. The modern engines have been designed with increased pressure ratio and reduced weight in order to improve aerodynamic efficiency, resulting in severe aeroelastic problems. Particularly flutter in axial compressors with t...

  6. Exploiting periodicity to extract the atrial activity in atrial arrhythmias

    Science.gov (United States)

    Llinares, Raul; Igual, Jorge

    2011-12-01

    Atrial fibrillation disorders are one of the main arrhythmias of the elderly. The atrial and ventricular activities are decoupled during an atrial fibrillation episode, and very rapid and irregular waves replace the usual atrial P-wave in a normal sinus rhythm electrocardiogram (ECG). The estimation of these wavelets is a must for clinical analysis. We propose a new approach to this problem focused on the quasiperiodicity of these wavelets. Atrial activity is characterized by a main atrial rhythm in the interval 3-12 Hz. It enables us to establish the problem as the separation of the original sources from the instantaneous linear combination of them recorded in the ECG or the extraction of only the atrial component exploiting the quasiperiodic feature of the atrial signal. This methodology implies the previous estimation of such main atrial period. We present two algorithms that separate and extract the atrial rhythm starting from a prior estimation of the main atrial frequency. The first one is an algebraic method based on the maximization of a cost function that measures the periodicity. The other one is an adaptive algorithm that exploits the decorrelation of the atrial and other signals diagonalizing the correlation matrices at multiple lags of the period of atrial activity. The algorithms are applied successfully to synthetic and real data. In simulated ECGs, the average correlation index obtained was 0.811 and 0.847, respectively. In real ECGs, the accuracy of the results was validated using spectral and temporal parameters. The average peak frequency and spectral concentration obtained were 5.550 and 5.554 Hz and 56.3 and 54.4%, respectively, and the kurtosis was 0.266 and 0.695. For validation purposes, we compared the proposed algorithms with established methods, obtaining better results for simulated and real registers.

  7. Post-parathyroidectomy thyrotoxicosis and atrial flutter: a case for caution

    OpenAIRE

    Asmar, Abdo; Ross, Edward A.

    2011-01-01

    Despite transient hyperthyroidism reportedly occurring in ∼30% of post-parathyroidectomy (PTX) patients with primary hyperparathyroidism, it has rarely been described in the internal medicine literature. It occurs within days of surgery, is usually clinically mild or silent, and typically spontaneously resolves within weeks. Patients can, however, unusually present with symptoms and signs of thyrotoxicosis, including arrhythmias. We report a case of a hemodialysis patient who developed self-l...

  8. Successful ablation of atypical atrial flutter in a young patient after Senning procedure

    Directory of Open Access Journals (Sweden)

    E.A. Artyukhina

    The follow-up period was 3 years. After 6 months antiarrhythmic drugs (cordarone were cancelled, the patient no complains, at the control daily monitorings of an electrocardiogram by Holter methods rhythm disturbances haven’t been reported.

  9. What Is Atrial Fibrillation?

    Science.gov (United States)

    ... regular beat. Certain cells in your heart make electric signals that cause the heart to contract and pump blood. These electrical signals show up on an elec- trocardiogram (ECG) recording. Your doctor can read your ECG to find out if the electric signals are normal. In atrial fibrillation (AFib), the ...

  10. Lesson Five Atrial fibrillation

    Institute of Scientific and Technical Information of China (English)

    鲁端; 吴文烈

    2003-01-01

    @@ Atrial fibrillation(AF) may occur in paroxysmaland persistent forms. It may be seen in normal subjects,particularly during emotional stress or follow-ing surgery,exercise, or acute alcoholic intoxication.It also may occur in patients with heart or lungdisease who develop acute hypoxia, hypercapnia,ormetabolic or hemodynamic derangements.

  11. Surface Acoustic Wave Vibration Sensors for Measuring Aircraft Flutter

    Science.gov (United States)

    Wilson, William C.; Moore, Jason P.; Juarez, Peter D.

    2016-01-01

    Under NASA's Advanced Air Vehicles Program the Advanced Air Transport Technology (AATT) Project is investigating flutter effects on aeroelastic wings. To support that work a new method for measuring vibrations due to flutter has been developed. The method employs low power Surface Acoustic Wave (SAW) sensors. To demonstrate the ability of the SAW sensor to detect flutter vibrations the sensors were attached to a Carbon fiber-reinforced polymer (CFRP) composite panel which was vibrated at six frequencies from 1Hz to 50Hz. The SAW data was compared to accelerometer data and was found to resemble sine waves and match each other closely. The SAW module design and results from the tests are presented here.

  12. Missile flutter experiment and data analysis using wavelet transform

    Science.gov (United States)

    Yu, Kaiping; Ye, Jiyuan; Zou, Jingxiang; Yang, Bingyuan; Yang, Hua

    2004-01-01

    A modal parameter identification method of impulse response function, based on a modulated Gaussian wavelet transform, is presented. The factors influencing the identification accuracy and the required conditions of using this parameter identification method are discussed. Numerical verification of the proposed method is presented for several two-degree-of-freedom examples. A wind tunnel flutter experiment on a wing model of missiles is introduced. The data set from the flutter test is analyzed by using the proposed wavelet transform method. The first two order modal parameters of the wing model are identified, and then the critical dynamic stress is predicted by using the flutter stability parameter method. Finally, the results are compared with the results of FFT analysis.

  13. Equivalent linearization method for limit cycle flutter analysis of plate-type structure in axial flow

    International Nuclear Information System (INIS)

    The responses and limit cycle flutter of a plate-type structure with cubic stiffness in viscous flow were studied. The continuous system was dispersed by utilizing Galerkin Method. The equivalent linearization concept was performed to predict the ranges of limit cycle flutter velocities. The coupled map of flutter amplitude-equivalent linear stiffness-critical velocity was used to analyze the stability of limit cycle flutter. The theoretical results agree well with the results of numerical integration, which indicates that the equivalent linearization concept is available to the analysis of limit cycle flutter of plate-type structure. (authors)

  14. Large Scale Flutter Data for Design of Rotating Blades Using Navier-Stokes Equations

    Science.gov (United States)

    Guruswamy, Guru P.

    2012-01-01

    A procedure to compute flutter boundaries of rotating blades is presented; a) Navier-Stokes equations. b) Frequency domain method compatible with industry practice. Procedure is initially validated: a) Unsteady loads with flapping wing experiment. b) Flutter boundary with fixed wing experiment. Large scale flutter computation is demonstrated for rotating blade: a) Single job submission script. b) Flutter boundary in 24 hour wall clock time with 100 cores. c) Linearly scalable with number of cores. Tested with 1000 cores that produced data in 25 hrs for 10 flutter boundaries. Further wall-clock speed-up is possible by performing parallel computations within each case.

  15. Summary of Flutter Experiences as a Guide to the Preliminary Design of Lifting Surfaces on Missiles

    Science.gov (United States)

    Martin, Dennis J

    1958-01-01

    Presented is a limited review of some experiences in flight testing of missiles and of wing flutter investigations that may be of interest in missile design. Several types of flutter of concern in missile studies are briefly described. Crude criteria are presented for two of the most common types of flutter to permit a rapid estimate to be made of the probability of the occurrence of flutter. Many of the details of the flutter problem have been omitted, and only the broader elements have been retained so as to give the designer an overall view of the subject.

  16. Gradient catastrophe and flutter in vortex filament dynamics

    CERN Document Server

    Konopelchenko, B G

    2011-01-01

    Gradient catastrophe and flutter instability in the motion of vortex filament within the localized induction approximation are analyzed. It is shown that the origin if this phenomenon is in the gradient catastrophe for the dispersionless Da Rios system which describes motion of filament with slow varying curvature and torsion. Geometrically this catastrophe manifests as a rapid oscillation of a filament curve in a point that resembles the flutter of airfoils. Analytically it is the elliptic umbilic singularity in the terminology of the catastrophe theory. It is demonstrated that its double scaling regularization is governed by the Painlev\\'e-I equation.

  17. Aeroelastic Instability and Flutter for a 10 MW Wind Turbine

    OpenAIRE

    Vatne, Sigrid Ringdalen

    2011-01-01

    The goal of this thesis is to evaluate if flutter is a challenge to a 10 MW wind turbine. Flutter is an aeroelastic instability which occurs due to the interaction between the aerodynamic forces and the elasticity of the blade. Torsional motions of the blade lead to variations in the aerodynamic forces due to changes in the angle of attack of the airfoil. The variation in aerodynamic forces creates flapwise vibration of the blade. When the vibrations of the blades are in an unfavourable phase...

  18. Gradient catastrophe and flutter in vortex filament dynamics

    International Nuclear Information System (INIS)

    Gradient catastrophe and flutter instability in the motion of a vortex filament within the localized induction approximation are analyzed. It is shown that the origin of this phenomenon is in the gradient catastrophe for the dispersionless Da Rios system which describes the motion of a filament with slow varying curvature and torsion. Geometrically, this catastrophe manifests as a rapid oscillation of a filament curve in a point that resembles the flutter of airfoils. Analytically, it is the elliptic umbilic singularity in the terminology of the catastrophe theory. It is demonstrated that its double scaling regularization is governed by the Painleve-I equation. (fast track communication)

  19. Gradient catastrophe and flutter in vortex filament dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Konopelchenko, B G [Dipartimento di Fisica, Universita del Salento and INFN, Sezione di Lecce, 73100 Lecce (Italy); Ortenzi, G, E-mail: giovanni.ortenzi@unimib.it [Dipartimento di Matematica Pura ed Applicazioni, Universita di Milano Bicocca, 20125 Milano (Italy)

    2011-10-28

    Gradient catastrophe and flutter instability in the motion of a vortex filament within the localized induction approximation are analyzed. It is shown that the origin of this phenomenon is in the gradient catastrophe for the dispersionless Da Rios system which describes the motion of a filament with slow varying curvature and torsion. Geometrically, this catastrophe manifests as a rapid oscillation of a filament curve in a point that resembles the flutter of airfoils. Analytically, it is the elliptic umbilic singularity in the terminology of the catastrophe theory. It is demonstrated that its double scaling regularization is governed by the Painleve-I equation. (fast track communication)

  20. Hacking the Body 2.0: Flutter/Stutter

    OpenAIRE

    Baker, Camille; Sicchio, Kate; Mooney, Tara Baoth; Stewart, Rebecca

    2016-01-01

    Flutter/Stutter is an improvisational dance piece, part of the Hacking the Body 2.0 project, that uses networked soft circuit sensors to trigger sound and haptic actuators in the form of a small motor that tickles the performers. Dancers embody the flutter of the motor and respond with their own movement that reflects this feeling. This research explores using the concept of hacking data to repurpose and re-imagine biofeedback from the body. It investigates understandings of states of the bo...

  1. Hacking the Body 2.0 performance: Flutter/Stutter

    OpenAIRE

    Baker, Camille; Sicchio, Kate; Mooney, Tara Baoth; Stewart, Rebecca

    2016-01-01

    Flutter/Stutter is an improvisational dance piece, part of the Hacking the Body 2.0 project, that uses networked soft circuit sensors to trigger sound and haptic actuators in the form of a small motor that tickles the performers. Dancers embody the flutter of the motor and respond with their own movement that reflects this feeling. This research explores using the concept of hacking data to repurpose and re-imagine biofeedback from the body. It investigates understandings of states of the bod...

  2. Flight test results of an active flutter suppression system installed on a remotely piloted research vehicle

    Science.gov (United States)

    Edwards, J. W.

    1981-01-01

    Flight flutter test results of the first aeroelastic research wing of NASA's Drones for Aerodynamic and Structural Testing (DAST) program are presented. The implementation of the flutter suppression system and the flight test operation are described. The conduct of the flutter testing and the near-real time damping estimation algorithm are also described in detail. Flight data was obtained at Mach numbers up to 0.91 and was of high quality. Response to fast frequency sweep excitation provided reliable damping estimates and the open-loop flutter boundary was well defined. Evidence of angle-of-attack effects upon damping at high transonic Mach numbers is also presented. While the flutter suppression system provided augmented damping at speeds below the flutter boundary, an error in the implementation of the system gain caused the system to be less stable than predicted and the vehicle encountered system-on flutter on the third flight.

  3. Atrial fibrillation in the elderly

    Institute of Scientific and Technical Information of China (English)

    Roberto A.Franken; Ronaldo F.Rosa; Silvio CM Santos

    2012-01-01

    This review discusses atrial fibrillation according to the guidelines of Brazilian Society of Cardiac Arrhythmias and the Brazilian Cardiogeriatrics Guidelines. We stress the thromboembolic burden of atrial fibrillation and discuss how to prevent it as well as the best way to conduct cases of atrial fibrillatios in the elderly, reverting the arrhythmia to sinus rhythm, or the option of heart rate control. The new methods to treat atrial fibrillation, such as radiofrequency ablation, new oral direct thrombin inhibitors and Xa factor inhibitors, as well as new antiarrhythmic drugs, are depicted.

  4. The relationship between physical activity and risk of atrial fibrillation -a systematic review and meta-analysis

    OpenAIRE

    ens Rokkedal Nielsen, MD; Kristian Wachtel, MD PhD; Jawdat Abdulla, MD, PhD

    2013-01-01

    Aim: The aim of this systematic literature review and meta-analyses was to explore the relationship between physical activity and risk of new-onset atrial fibrillation (AF) or flutter (AFlu). Results: The search revealed 10 published studies that were eligible for three different meta-analyses. A meta-analysis of six case-control studies showed that risk of AF increased more than 5-fold in athletes compared to non-athletic controls, OR=5.3 [(3.6, 7.9; 95% confidence interval (CI)], p

  5. Management of atrial fibrillation

    OpenAIRE

    Vergara, Pasquale; Della Bella, Paolo

    1997-01-01

    Atrial fibrillation (AF) is associated with increases in the risk of mortality, congestive heart failure, and stroke. Medical treatment is aimed at preventing thrombo-embolic complications and reducing symptoms and consequences related to the arrhythmia. In the first section of this review, we discuss the principles of mainstream oral anticoagulant therapy and the possible advantages of the new oral anticoagulants. In the second section, we review the catheter ablation approaches to paroxysma...

  6. Right atrial lipoma

    Directory of Open Access Journals (Sweden)

    Pêgo-Fernandes Paulo M.

    2003-01-01

    Full Text Available Benign cardiac tumors are rare, and lipomas are among those less frequently found. We report the case of a 48-year-old male complaining of high blood pressure and epistaxis in the last 2 months, with a diagnosis of right atrial lipoma established on echocardiography, magnetic resonance imaging, and anatomicopathological examination. The tumor was successfully removed, and up to 42 months after surgical excision, no evidence of tumor relapse was observed.

  7. Anticoagulation in Atrial Fibrillation

    OpenAIRE

    Ahmad, Yousif; YH Lip, Gregory

    2012-01-01

    Patients with atrial fibrillation (AF) are at increased thromboembolic risk, and they suffer more severe strokes with worse outcomes. Most thromboembolic complications of AF are eminently preventable with oral anticoagulation, and the increasing numbers of AF patients mean antithrombotic therapy is the most crucial management aspect of this common arrhythmia. Despite the proven efficacy of warfarin, a string of limitations have meant that it is underused by physicians and patients alike. This...

  8. Rivaroxaban in atrial fibrillation

    OpenAIRE

    Giorgi MA; Miguel LS

    2012-01-01

    Mariano A Giorgi,1,2 Lucas San Miguel31Cardiology Service, Centro de Educación Médica e Investigaciones Clínicas “Norberto Quirno”, 2Department of Pharmacology, School of Medicine, Universidad Austral, 3Department of Cardiology and Cardiovascular Surgery, FLENI, Buenos Aires, ArgentinaAbstract: Warfarin is the traditional therapeutic option available to manage thromboembolic risk in atrial fibrillation. The hemorrhagic risk with warfarin de...

  9. Evaluation of Atrial Fibrillation

    Directory of Open Access Journals (Sweden)

    Francis E. Marchlinski

    2008-05-01

    Full Text Available Atrial fibrillation (AF is a supraventricular tachyarrhythmia characterized by uncoordinated atrial activation. On the ECG fibrillatory (f waves (rapid oscillations with variable amplitude, shape and timing replace normal P waves. Ventricular response becomes irregular and rapid depending of the intrinsic electrophysiological properties of the AV node1 and the balance between vagal and sympathetic tone1. The presence of an irregularly pulse is a clinical sign that can be quickly and reliably identified in any healthcare situation and, indicates AF with a high sensitivity and specificity (95% and 75%, respectively. If the irregularity last for more than 20 seconds the specificity reaches 98% 2-4. Identification of AF can be done by using manual pulse palpation in those presenting with a variety of symptoms. It is desirable to check the blood pressure and pulse in all patients who present with breathlessness, dyspnea, palpitations, syncope, dizziness or chest discomfort. Furthermore, many patients presenting with an acute stroke are found to be in AF albeit asymptomatic with respect to non-neurologic complaints. The finding of a sustained irregular wide QRS complex tachycardia may be suspicious of AF conducted with bundle brunch aberrancy or over an accessory pathway, and in patients with A-V sequential pacemakers can reflect an inadequate configuration with ventricular tracking of sensed atrial activity.

  10. Hyperuricemia and Atrial Fibrillation.

    Science.gov (United States)

    Maharani, Nani; Kuwabara, Masanari; Hisatome, Ichiro

    2016-07-27

    The importance of atrial fibrillation (AF) as a cause of mortality and morbidity has prompted research on its pathogenesis and treatment. Recognition of AF risk factors is essential to prevent it and reduce the risk of death. Hyperuricemia has been widely accepted to be associated with the incidence of paroxysmal or persistent AF, as well as to the risk of AF in post cardiovascular surgery patients. The possible explanations for this association have been based on their relation with either oxidative stress or inflammation. To investigate the link between hyperuricemia and AF, it is necessary to refer to hyperuricemia-induced atrial remodeling. So far, both ionic channel and structural remodeling caused by hyperuricemia might be plausible explanations for the occurrence of AF. Inhibition of xanthine oxidase and nicotinamide adenine dinucleotide phosphate (NADPH)-oxidase, or the use of antioxidants, along with serum uric acid (SUA) level reduction to prevent inflammation, might be useful. Uric acid transporters (UATs) play a key role in the regulation of intracellular uric acid concentration. Intracellular rather than serum uric acid level is considered more important for the pathogenesis of AF. Identification of UATs expressed in cells is thus important, and targeting UATs might become a potential strategy to reduce the risk of hyperuricemia-induced atrial fibrillation. PMID:27396561

  11. Hypercoagulability causes atrial fibrosis and promotes atrial fibrillation

    NARCIS (Netherlands)

    Spronk, Henri M H; De Jong, Anne Margreet; Verheule, Sander; De Boer, Hetty C; Maass, Alexander H; Lau, Dennis H; Rienstra, Michiel; van Hunnik, Arne; Kuiper, Marion; Lumeij, Stijn; Zeemering, Stef; Linz, Dominik; Kamphuisen, Pieter Willem; Ten Cate, Hugo; Crijns, Harry J; Van Gelder, Isabelle C; van Zonneveld, Anton Jan; Schotten, Ulrich

    2016-01-01

    AIMS: Atrial fibrillation (AF) produces a hypercoagulable state. Stimulation of protease-activated receptors by coagulation factors provokes pro-fibrotic, pro-hypertrophic, and pro-inflammatory responses in a variety of tissues. We studied the effects of thrombin on atrial fibroblasts and tested the

  12. Left atrial appendage occlusion for stroke prevention in atrial fibrillation

    DEFF Research Database (Denmark)

    Tzikas, Apostolos; Shakir, Samera; Gafoor, Sameer;

    2015-01-01

    Aims: To investigate the safety, feasibility, and efficacy of left atrial appendage occlusion (LAAO) with the AMPLATZER Cardiac Plug (ACP) for stroke prevention in patients with atrial fibrillation (AF). Methods and results: Data from consecutive patients treated in 22 centres were collected. A...

  13. Flutter-driven triboelectrification for harvesting wind energy.

    Science.gov (United States)

    Bae, Jihyun; Lee, Jeongsu; Kim, SeongMin; Ha, Jaewook; Lee, Byoung-Sun; Park, YoungJun; Choong, Chweelin; Kim, Jin-Baek; Wang, Zhong Lin; Kim, Ho-Young; Park, Jong-Jin; Chung, U-In

    2014-01-01

    Technologies to harvest electrical energy from wind have vast potentials because wind is one of the cleanest and most sustainable energy sources that nature provides. Here we propose a flutter-driven triboelectric generator that uses contact electrification caused by the self-sustained oscillation of flags. We study the coupled interaction between a fluttering flexible flag and a rigid plate. In doing so, we find three distinct contact modes: single, double and chaotic. The flutter-driven triboelectric generator having small dimensions of 7.5 × 5 cm at wind speed of 15 ms(-1) exhibits high-electrical performances: an instantaneous output voltage of 200 V and a current of 60 μA with a high frequency of 158 Hz, giving an average power density of approximately 0.86 mW. The flutter-driven triboelectric generation is a promising technology to drive electric devices in the outdoor environments in a sustainable manner. PMID:25247474

  14. Flutter of buckled shape memory alloy reinforced laminates

    International Nuclear Information System (INIS)

    The effect of shape memory alloys (SMA) on the linear and nonlinear flutter behaviors of buckled cross-ply and angle-ply laminates was investigated in the frequency and time domains using the finite element method. In particular, this study takes the first move toward examining the effect of varying the SMA fiber spacing. Von Karman large deformation assumptions and quasi-steady aerodynamic theory were employed. The flutter boundary, stability boundary, time history response, and phase plane plots of SMA reinforced cross-ply and angle-ply laminates are presented. The numerical results show that increase in the SMA fiber volume fraction and prestrain may generate more recovery stress, and increase the stiffness of the SMA reinforced laminates. Therefore, the flutter boundary and critical load of the plate may be increased significantly. All five types of panel behavior, namely flat, buckled, limit-cycle, periodic, and chaotic motion, are clearly displayed and successively identified. This study sheds light on improving the flutter boundary efficiently by increasing the SMA fiber volume fraction to reinforce the center of the plate. (paper)

  15. The effect of magnetic flutter on residual flow

    International Nuclear Information System (INIS)

    The hypothesis that stochastic magnetic fields disrupt zonal flows associated with ion temperature gradient turbulence saturation is investigated analytically with a residual flow calculation in the presence of magnetic flutter. The calculation starts from the time-asymptotic zero-beta residual flow of Rosenbluth and Hinton [Phys. Rev. Lett. 80, 724 (1998)] with the sudden application of an externally imposed, fixed magnetic field perturbation. The short-time electron response from radial charge loss due to magnetic flutter is calculated from the appropriate gyrokinetic equation. The potential evolution has quadratic behavior, with a zero crossing at finite time. The crossing time and its parametric dependencies are compared with numerical results from a gyrokinetic simulation of residual flow in the presence of magnetic flutter. The numerical and analytical results are in good agreement and support the hypothesis that the high-beta runaway of numerical simulations is a result of the disabling of zonal flows by finite-beta charge losses associated with magnetic flutter

  16. The effect of magnetic flutter on residual flow

    Energy Technology Data Exchange (ETDEWEB)

    Terry, P. W.; Pueschel, M. J.; Carmody, D. [Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States); Nevins, W. M. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States)

    2013-11-15

    The hypothesis that stochastic magnetic fields disrupt zonal flows associated with ion temperature gradient turbulence saturation is investigated analytically with a residual flow calculation in the presence of magnetic flutter. The calculation starts from the time-asymptotic zero-beta residual flow of Rosenbluth and Hinton [Phys. Rev. Lett. 80, 724 (1998)] with the sudden application of an externally imposed, fixed magnetic field perturbation. The short-time electron response from radial charge loss due to magnetic flutter is calculated from the appropriate gyrokinetic equation. The potential evolution has quadratic behavior, with a zero crossing at finite time. The crossing time and its parametric dependencies are compared with numerical results from a gyrokinetic simulation of residual flow in the presence of magnetic flutter. The numerical and analytical results are in good agreement and support the hypothesis that the high-beta runaway of numerical simulations is a result of the disabling of zonal flows by finite-beta charge losses associated with magnetic flutter.

  17. Suspension Bridge Flutter for Girder with Separate Control Flaps

    DEFF Research Database (Denmark)

    Huynh, T.; Thoft-Christensen, Palle

    Active vibration control of long span suspension bridge flutter using separated control flaps (SFSC) has shown to increase effectively the critical wind speed of bridges. In this paper, an SFSC calculation based on modal equations of the vertical and torsional motions of the bridge girder includi...

  18. Flight test of passive wing/store flutter suppression

    Science.gov (United States)

    Cazier, F. W., Jr.; Kehoe, M. W.

    1986-01-01

    Flight tests were performed on an F-16 airplane carrying on each wing an AIM-9J wingtip missile, a GBU-8 bomb near midspan, and an external fuel tank. Baseline flights with the GBU-8 mounted on a standard pylon established that this configuration is characterized by an antisymmetric limited amplitude flutter oscillation within the operational envelope. The airplane was then flown with GBU-8 mounted on the decoupler pylon. The decoupler pylon is a NASA concept of passive wing-store flutter suppression achieved by providing a low store-pylon pitch frequency. The decoupler pylon successfully suppressed wing-store flutter throughout the flight envelope. A 37 percent increase in flutter velocity over the standard pylon was demonstrated. Maneuvers with load factors to 4g were performed. Although the static store displacements during maneuvers were not sufficiently large to be of concern, a store pitch alignment system was tested and performed successfully. One GBU-8 was ejected demonstrating that weapon separation from the decoupler pylon is normal.

  19. Selective reinforcement of wing structure for flutter prevention.

    Science.gov (United States)

    Cooper, P. A.; Stroud, W. J.

    1972-01-01

    The results of an analytical study are presented on the use of boron polyimide filamentary composite material for the purpose of increasing the flutter speed of a simple titanium full depth sandwich wing structure designed for strength. The results clearly demonstrate that selective reinforcement of wing surfaces, using judiciously placed filamentary composites, promises sizable mass savings in the design of advanced aircraft structures.

  20. Persistent atrial fibrillation in a goat model of chronic left atrial overload.

    NARCIS (Netherlands)

    Remes, J.; Brakel, T.J. van; Bolotin, G.; Garber, C.; Jong, MM de; Veen, FH van der; Maessen, J.G.

    2008-01-01

    OBJECTIVES: Atrial dilatation predisposes to atrial fibrillation. Although several animal models focus on the initiating mechanisms of atrial fibrillation in dilated atria, a model of left atrial overload resulting in persistent atrial fibrillation in nonanesthetized animals has not been presented t

  1. Effects of trimetazidine on atrial structural remodeling and platelet activation in dogs with atrial fibrillation

    Institute of Scientific and Technical Information of China (English)

    HAN Wei; LI Wei-min; ZHOU Hong-yan; HUO Hong; WEI Na; DONG Guo; CAO Yong; ZHOU Guo; YANG Shu-sen

    2009-01-01

    @@ Atrial fibrillation (AF) is one of the most common arrhythmias in clinical practice. AF results in electrophysiological alterations which involve increased atrial effective refractory period and atrial effective refractory period dispersion, reduced rate adaptation of atrial effective refractory period, and slowed atrial conduction.

  2. Sinus Node and Atrial Arrhythmias.

    Science.gov (United States)

    John, Roy M; Kumar, Saurabh

    2016-05-10

    Although sinus node dysfunction (SND) and atrial arrhythmias frequently coexist and interact, the putative mechanism linking the 2 remain unclear. Although SND is accompanied by atrial myocardial structural changes in the right atrium, atrial fibrillation (AF) is a disease of variable interactions between left atrial triggers and substrate most commonly of left atrial origin. Significant advances have been made in our understanding of the genetic and pathophysiologic mechanism underlying the development and progression of SND and AF. Although some patients manifest SND as a result of electric remodeling induced by periods of AF, others develop progressive atrial structural remodeling that gives rise to both conditions together. The treatment strategy will thus vary according to the predominant disease phenotype. Although catheter ablation will benefit patients with predominantly AF and secondary SND, cardiac pacing may be the mainstay of therapy for patients with predominant fibrotic atrial cardiomyopathy. This contemporary review summarizes current knowledge on sinus node pathophysiology with the broader goal of yielding insights into the complex relationship between sinus node disease and atrial arrhythmias. PMID:27166347

  3. Rhythm- and Rate-Controlling Effects of Dronedarone in Patients With Atrial Fibrillation (from the ATHENA Trial)

    DEFF Research Database (Denmark)

    Page, Richard L; Connolly, Stuart J; Crijns, Harry J G M;

    2011-01-01

    Dronedarone is a multi-channel-blocking drug for the treatment of patients with atrial fibrillation (AF) or atrial flutter (AFL) with rate- and rhythm-controlling properties. A Placebo-Controlled, Double-Blind, Parallel Arm Trial to Assess the Efficacy of Dronedarone 400 mg b.i.d. for the...... rate-controlling properties of dronedarone in the ATHENA trial. Patients were randomized to dronedarone 400 mg twice daily (n 2,301) or placebo (n 2,327). Electrocardiographic tracings were classified for AF or AFL or sinus rhythm. Patients with AF or AFL on every postbaseline electrocardiogram were......, dronedarone demonstrated both rhythm- and rate-controlling properties in ATHENA. These effects are likely to contribute to the reduction of important clinical outcomes observed in this trial....

  4. Connexin Remodeling Contributes to Atrial Fibrillation

    OpenAIRE

    Michelle M Jennings; J Kevin Donahue

    2013-01-01

    Atrial fibrillation significantly contributes to mortality and morbidity through increased risk of stroke, heart failure and myocardial infarcts. Investigations of mechanisms responsible for the development and maintenance of atrial fibrillation have highlighted the importance of gap junctional remodeling. Connexins 40 and 43, the major atrial gap junctional proteins, undergo considerable alterations in expression and localization in atrial fibrillation, creating an environment conducive to s...

  5. Raised plasma concentrations of atrial natriuretic peptide are independent of left atrial dimensions in patients with chronic atrial fibrillation.

    OpenAIRE

    Berglund, H; Boukter, S; Theodorsson, E; Vallin, H; Edhag, O

    1990-01-01

    The aim of the present study was to determine whether left atrial size--a likely indicator of atrial stretching--correlates with the plasma concentration of atrial natriuretic peptide and whether this relation is different in patients in sinus rhythm and in those with atrial fibrillation. Arterial plasma concentrations of immunoreactive atrial natriuretic peptide (ir-ANP), adrenaline, noradrenaline, aldosterone, and vasopressin were measured in 13 patients in sinus rhythm without apparent hea...

  6. No incremental benefit of multisite atrial pacing compared with right atrial pacing in patients with drug refractory paroxysmal atrial fibrillation

    OpenAIRE

    Levy, T; Walker, S; Rex, S; Rochelle, J; Paul, V.

    2001-01-01

    OBJECTIVE—To evaluate the incremental antifibrillatory effect of multisite atrial pacing compared with right atrial pacing in patients with drug refractory paroxysmal atrial fibrillation paced for arrhythmia prevention alone.
METHODS—In 20 of these patients (mean (SD) age 64 (8) years; 14 female, six male), a single blinded randomised crossover study was performed to investigate the incremental benefit of one month of multisite atrial pacing compared with one month of right atrial pacing. Out...

  7. Atrial Cardiopathy: A Broadened Concept of Left Atrial Thromboembolism Beyond Atrial Fibrillation

    Science.gov (United States)

    Kamel, Hooman; Okin, Peter M.; Longstreth, W. T.; Elkind, Mitchell S.V.; Soliman, Elsayed Z.

    2016-01-01

    Atrial fibrillation (AF) has long been associated with a heightened risk of ischemic stroke and systemic thromboembolism, but recent data require a re-evaluation of our understanding of the nature of this relationship. New findings about the temporal connection between AF and stroke, alongside evidence linking markers of left atrial abnormalities with stroke in the absence of apparent AF, suggest that left atrial thromboembolism may occur even without AF. These observations undermine the hypothesis that the dysrhythmia that defines AF is necessary and sufficient to cause thromboembolism. In this commentary, we instead suggest that the substrate for thromboembolism may often be the anatomic and physiological atrial derangements associated with AF. Therefore, our understanding of cardioembolic stroke may be more complete if we shift our representation of its origin from AF to the concept of atrial cardiopathy. PMID:26021638

  8. Supersonic Flutter Utilization for Effective Energy-Harvesting Based on Piezoelectric Switching Control

    Directory of Open Access Journals (Sweden)

    Kanjuro Makihara

    2012-01-01

    Full Text Available The harvesting of electrical energy generated from the flutter phenomenon of a plate wing is studied using the quasi-steady aerodynamic theory and the finite element method. The example of supersonic flutter structure comes from sounding rockets’ wings. Electrical energy is harvested from supersonic flutter by using piezoelectric patches and switching devices. In order to evaluate the harvesting performance, we simulate flutter dynamics of the plate wing to which piezoelectric patches are attached. We demonstrate that our harvesting system can generate much more electrical energy from wing flutter than conventional harvesting systems can. This flutter utilization changes our perception to a useful one in various fruitful applications from a destructive phenomenon.

  9. Stall Flutter Control of a Smart Blade Section Undergoing Asymmetric Limit Oscillations

    OpenAIRE

    Nailu Li; Balas, Mark J.; Pourya Nikoueeyan; Hua Yang; Naughton, Jonathan W.

    2016-01-01

    Stall flutter is an aeroelastic phenomenon resulting in unwanted oscillatory loads on the blade, such as wind turbine blade, helicopter rotor blade, and other flexible wing blades. Although the stall flutter and related aeroelastic control have been studied theoretically and experimentally, microtab control of asymmetric limit cycle oscillations (LCOs) in stall flutter cases has not been generally investigated. This paper presents an aeroservoelastic model to study the microtab control of the...

  10. Experimental Methods Applied in a Study of Stall Flutter in an Axial Flow Fan

    OpenAIRE

    John D. Gill; Capece, Vincent R.; Ronald B. Fost

    2004-01-01

    Flutter testing is an integral part of aircraft gas turbine engine development. In typical flutter testing blade mounted sensors in the form of strain gages and casing mounted sensors in the form of light probes (NSMS) are used. Casing mounted sensors have the advantage of being non-intrusive and can detect the vibratory response of each rotating blade. Other types of casing mounted sensors can also be used to detect flutter of rotating blades. In this investigation casing mounted high freque...

  11. Supersonic panel flutter in the presence of the concentrated inertial masses and the moments

    OpenAIRE

    Belubekyan M.V.; Martirosyan S.R.

    2016-01-01

    By analyzing, as an example, a thin elastic rectangular plate streamlined by supersonic gas flows, we study the phenomenon of divergence and of panel flutter of the overrunning of the gas flow at is free edge under the assumption of presence of concentrated inertial masses and moments at the free and fixed edges respectively. Its solution shows that the divergence or the localized divergence and the flutter are possible. The corresponding critical velocities of divergence and panel flutter ar...

  12. Parameter sensitivities affecting the flutter speed of a MW-sized blade.

    Energy Technology Data Exchange (ETDEWEB)

    Lobitz, Donald Wayne, Jr.

    2005-08-01

    With the current trend toward larger and larger horizontal axis wind turbines, classical flutter is becoming a more critical issue. Recent studies have indicated that for a single blade turning in still air the flutter speed for a modern 35 m blade occurs at approximately twice its operating speed (2 per rev), whereas for smaller blades (5-9 m), both modern and early designs, the flutter speeds are in the range of 3.5-6 per rev. Scaling studies demonstrate that the per rev flutter speed should not change with scale. Thus, design requirements that change with increasing blade size are producing the concurrent reduction in per rev flutter speeds. In comparison with an early small blade design (5 m blade), flutter computations indicate that the non rotating modes which combine to create the flutter mode change as the blade becomes larger (i.e., for the larger blade the second flapwise mode, as opposed to the first flapwise mode for the smaller blade, combines with the first torsional mode to produce the flutter mode). For the more modern smaller blade design (9 m blade), results show that the non rotating modes that couple are similar to those of the larger blade. For the wings of fixed-wing aircraft, it is common knowledge that judicious selection of certain design parameters can increase the airspeed associated with the onset of flutter. Two parameters, the chordwise location of the center of mass and the ratio of the flapwise natural frequency to the torsional natural frequency, are especially significant. In this paper studies are performed to determine the sensitivity of the per rev flutter speed to these parameters for a 35 m wind turbine blade. Additional studies are performed to determine which structural characteristics of the blade are most significant in explaining the previously mentioned per rev flutter speed differences. As a point of interest, flutter results are also reported for two recently designed 9 m twist/coupled blades.

  13. Parameter sensitivities affecting the flutter speed of a MW-sized blade.

    Energy Technology Data Exchange (ETDEWEB)

    Lobitz, Donald Wayne, Jr.

    2004-10-01

    With the current trend toward larger and larger horizontal axis wind turbines, classical flutter is becoming a more critical issue. Recent studies have indicated that for a single blade turning in still air the flutter speed for a modern 35 m blade occurs at approximately twice its operating speed (2 per rev), whereas for smaller blades (5-9 m), both modern and early designs, the flutter speeds are in the range of 3.5-6 per rev. Scaling studies demonstrate that the per rev flutter speed should not change with scale. Thus, design requirements that change with increasing blade size are producing the concurrent reduction in per rev flutter speeds. In comparison with an early small blade design (5 m blade), flutter computations indicate that the non rotating modes which combine to create the flutter mode change as the blade becomes larger (i.e., for the larger blade the second flapwise mode, as opposed to the first flapwise mode for the smaller blade, combines with the first torsional mode to produce the flutter mode). For the more modern smaller blade design (9 m blade), results show that the non rotating modes that couple are similar to those of the larger blade. For the wings of fixed-wing aircraft, it is common knowledge that judicious selection of certain design parameters can increase the airspeed associated with the onset of flutter. Two parameters, the chordwise location of the center of mass and the ratio of the flapwise natural frequency to the torsional natural frequency, are especially significant. In this paper studies are performed to determine the sensitivity of the per rev flutter speed to these parameters for a 35 m wind turbine blade. Additional studies are performed to determine which structural characteristics of the blade are most significant in explaining the previously mentioned per rev flutter speed differences. As a point of interest, flutter results are also reported for two recently designed 9 m twist/coupled blades.

  14. Experimental Investigation of Three-Dimensional Mechanisms in Low-Pressure Turbine Flutter

    OpenAIRE

    Vogt, Damian

    2005-01-01

    The continuous trend in gas turbine design towards lighter, more powerful and more reliable engines on one side and use of alternative fuels on the other side renders flutter problems as one of the paramount challenges in engine design. Flutter denotes a self-excited and self-sustained aeroelastic instability phenomenon that can lead to material fatigue and eventually damage of structure in a short period of time unless properly damped. The design for flutter safety involves the prediction of...

  15. Aeroservoelastic Pitch Control of Stall-Induced Flap/Lag Flutter of Wind Turbine Blade Section

    OpenAIRE

    Tingrui Liu

    2015-01-01

    The aim of this paper is to analyze aeroelastic stability, especially flutter suppression for aeroelastic instability. Effects of aeroservoelastic pitch control for flutter suppression on wind turbine blade section subjected to combined flap and lag motions are rarely studied. The work is dedicated to solving destructive flapwise and edgewise instability of stall-induced flutter of wind turbine blade by aeroservoelastic pitch control. The aeroelastic governing equations combine a flap/lag str...

  16. Development and application of an optimization procedure for flutter suppression using the aerodynamic energy concept

    Science.gov (United States)

    Nissim, E.; Abel, I.

    1978-01-01

    An optimization procedure is developed based on the responses of a system to continuous gust inputs. The procedure uses control law transfer functions which have been partially determined by using the relaxed aerodynamic energy approach. The optimization procedure yields a flutter suppression system which minimizes control surface activity in a gust environment. The procedure is applied to wing flutter of a drone aircraft to demonstrate a 44 percent increase in the basic wing flutter dynamic pressure. It is shown that a trailing edge control system suppresses the flutter instability over a wide range of subsonic mach numbers and flight altitudes. Results of this study confirm the effectiveness of the relaxed energy approach.

  17. Supersonic panel flutter in the presence of the concentrated inertial masses and the moments

    Directory of Open Access Journals (Sweden)

    Belubekyan M.V.

    2016-03-01

    Full Text Available By analyzing, as an example, a thin elastic rectangular plate streamlined by supersonic gas flows, we study the phenomenon of divergence and of panel flutter of the overrunning of the gas flow at is free edge under the assumption of presence of concentrated inertial masses and moments at the free and fixed edges respectively. Its solution shows that the divergence or the localized divergence and the flutter are possible. The corresponding critical velocities of divergence and panel flutter are obtained. It is shown that depending on the relation between parameters of the problem, the critical flutter velocity can be either smaller or larger than the critical velocity of divergence.

  18. Application of a flight test and data analysis technique to flutter of a drone aircraft

    Science.gov (United States)

    Bennett, R. M.

    1981-01-01

    Modal identification results presented were obtained from recent flight flutter tests of a drone vehicle with a research wing (DAST ARW-1 for Drones for Aerodynamic and Structural Testing, Aeroelastic Research Wing-1). This vehicle is equipped with an active flutter suppression system (FSS). Frequency and damping of several modes are determined by a time domain modal analysis of the impulse response function obtained by Fourier transformations of data from fast swept sine wave excitation by the FSS control surface on the wing. Flutter points are determined for two different altitudes with the FSS off. Data are given for near the flutter boundary with the FSS on.

  19. Aerofoil flutter: fluid-mechanical analysis and wind tunnel testing

    International Nuclear Information System (INIS)

    This paper describes a three dimensional wing model, which has been developed for the purpose of studying flutter, both computationally and through wind tunnel testing. A three dimensional, laminar flow aerofoil wing, based on the NACA aerofoil has been designed. The natural frequencies for this aerofoil were obtained through modal analysis. A scale model wing, without taper was manufactured in the laboratory and tested in a wind tunnel. The pressure data was obtained from fluid flow analysis and the deformation results obtained through structural analysis. The analysis was performed in the ANSYS Workbench Environment, accessing FLUENT CFX for the computational fluid dynamics analysis and the ANSYS FEA package for the mechanical analysis. The computational results obtained are compared with the experimental data obtained in the wind tunnel. Comparison of the analysis and test results provides further understanding of the flutter characteristics.

  20. The influence of trailed vorticity on flutter speed estimations

    DEFF Research Database (Denmark)

    Pirrung, Georg; Aagaard Madsen, Helge; Kim, Taeseong

    2014-01-01

    This paper briefly describes the implementation of a coupled near and far wake model for wind turbine rotor induction in the aeroelastic code HAWC2 and its application for flutter analysis of the NREL 5 MW wind turbine. The model consists of a far wake part based on Blade Element Momentum (BEM...... influence of the near wake model on the aeroelastic stability of the blades of the NREL 5 MW turbine in overspeed conditions is investigated in the second part of the paper. The analysis is based on a runaway case in which the turbine is free to speed up without generator torque and vibrations start...... building up at a critical rotor speed. Blades with modified torsional and flapwise stiffness are also investigated. A flutter analysis is often part of the stability investigations for new blades but is normally carried out with engineering models that do not include the influence of unsteady trailed...

  1. Comparative study between two different active flutter suppression systems

    Science.gov (United States)

    Nissim, E.

    1978-01-01

    An activated leading-edge (LE)-tailing-edge (TE) control system is applied to a drone aircraft with the objective of enabling the drone to fly subsonically at dynamic pressures which are 44% above the open-loop flutter dynamic pressure. The control synthesis approach is based on the aerodynamic energy concept and it incorporates recent developments in this area. A comparison is made between the performance of the activated LE-TE control system and the performance of a TE control system, analyzed in a previous work. The results obtained indicate that although all the control systems achieve the flutter suppression objectives, the TE control system appears to be somewhat superior to the LE-TE control system, in this specific application. This superiority is manifested through reduced values of control surface activity over a wide range of flight conditions.

  2. Some atypical flutter characteristics of the NACA0015 profile

    Czech Academy of Sciences Publication Activity Database

    Vlček, Václav; Zolotarev, Igor; Kozánek, Jan; Štěpán, M.

    Prague: Institute of Thermomechanics ASCR, v. v. i., 2016 - (Zolotarev, I.; Pešek, L.), s. 65-72 ISBN 978-80-87012-60-4. [DYMAMESI 2016. Prague (CZ), 01.03.2016-02.03.2016] R&D Projects: GA ČR GA13-10527S Institutional support: RVO:61388998 Keywords : aeroelasticity * flutter * interferometry * subsonic flow Subject RIV: BI - Acoustics

  3. Flutter phenomena in the control of civil engineering structures

    International Nuclear Information System (INIS)

    Structural control is often beneficial only up to a certain gain limit and may cause instabilities beyond that limit. This is shown analytically for a simple structure, the king post truss, for which previous experimental investigations have established the occurrence of instability through mode interaction under certain circumstances. In this paper an attempt is made to explain these instabilities, which are either caused by resonance or by flutter

  4. Stability Assessment of Flutter - Type Vibration Using Lyapunov Function

    Czech Academy of Sciences Publication Activity Database

    Náprstek, Jiří

    Žďár nad Sázavou : ŽĎAS, 2000 - (Náprstek, J.; Minster, J.), s. 17-24 ISBN 80-86246-03-5. [Engineering Mechanics 2000. Svratka (CZ), 15.05.2000-18.05.2000] R&D Projects: GA ČR GA103/99/0122 Keywords : bending - torsional flutter * nonlinear differential equations * Lyapunov function Subject RIV: JM - Building Engineering

  5. Nonlinear Stability of Flutter - Type Vibration in Wind

    Czech Academy of Sciences Publication Activity Database

    Náprstek, Jiří

    Rotterdam : Balkema, 2000 - (Ziada, S.; Staubli, T.), s. 445-454 ISBN 90-5809-129-5. [Flow Induced Vibration /7./. Luzern (CH), 19.06.2000-22.06.2000] R&D Projects: GA ČR GA103/99/0122; GA ČR GA103/99/0756 Keywords : bending-torsional flutter, Lyapunov function, cross section. Subject RIV: JN - Civil Engineering

  6. Unsteady Aerodynamic Forces Measured on a Fluttering Profile

    Czech Academy of Sciences Publication Activity Database

    Zolotarev, Igor; Vlček, Václav; Kozánek, Jan

    Anaheim: ASME, 2014, V004T04A056-V004T04A056. ISBN 978-0-7918-4601-8. [ASME 2014 Pressure Vessels & Piping Conference. Anaheim, California (US), 20.07.2014-24.07.2014] R&D Projects: GA ČR GA13-10527S Institutional support: RVO:61388998 Keywords : flutter * profile * kinematics of motion * aerodynamic forces * interferometric measurements * lift ing forces * aeroelastic stability Subject RIV: BI - Acoustics

  7. Unsteady aerodynamic forces measured on a fluttering profil

    Czech Academy of Sciences Publication Activity Database

    Vlček, Václav; Zolotarev, Igor; Kozánek, Jan

    Praha: Insitute of Thermomechanics ASCR, v. v. i., 2013 - (Zolotarev, I.). s. 167-168 ISBN 978-80-87012-46-8. ISSN 1805-8248. [Engineering Mechanics 2013 /19./. 13.05.2013-16.05.2013, Svratka] R&D Projects: GA ČR GA13-10527S Institutional support: RVO:61388998 Keywords : aeroelastic experiments * self-excited vibrations * fluttering profile Subject RIV: JU - Aeronautics, Aerodynamics, Aircrafts

  8. Unsteady aerodynamic forces measured on a fluttering profil

    Czech Academy of Sciences Publication Activity Database

    Vlček, Václav; Zolotarev, Igor; Kozánek, Jan

    Prague: Institute of Thermomechanics, Academy of Sciences of the Czech Republic, v. v. i., 2013 - (Zolotarev, I.), s. 650-658 ISBN 978-80-87012-47-5. ISSN 1805-8256. [Engineering Mechanics 2013 /19./. Svratka (CZ), 13.05.2013-16.05.2013] R&D Projects: GA ČR GA13-10527S Institutional support: RVO:61388998 Keywords : aeroelastic experiments * self-excited vibrations * fluttering profile * wind tunnel Subject RIV: JU - Aeronautics, Aerodynamics, Aircrafts

  9. Vibrating profile kinematics in the start of flutter

    Czech Academy of Sciences Publication Activity Database

    Kozánek, Jan; Vlček, Václav; Zolotarev, Igor

    Lodž: Lodž University of Technology, 2013 - (Awrejcewicz, J.), s. 667-676 ISBN 978-83-7283-589-5. [Dynamical Systems – Theory and Application /12./. Lodž (PL), 02.12.2013-05.12.2013] R&D Projects: GA ČR GA13-10527S Institutional support: RVO:61388998 Keywords : NACA0015 profile * flutter * identification * Mach number * stability Subject RIV: BI - Acoustics

  10. The influence of trailed vorticity on flutter speed estimations

    International Nuclear Information System (INIS)

    This paper briefly describes the implementation of a coupled near and far wake model for wind turbine rotor induction in the aeroelastic code HAWC2 and its application for flutter analysis of the NREL 5 MW wind turbine. The model consists of a far wake part based on Blade Element Momentum (BEM) theory, which is coupled with Beddoes' near wake model for trailed vorticity. The first part of this work outlines the implementation in HAWC2, with a focus on the interaction of the induction from the blade based near wake model with the induction from the polar grid based BEM model in HAWC2. The influence of the near wake model on the aeroelastic stability of the blades of the NREL 5 MW turbine in overspeed conditions is investigated in the second part of the paper. The analysis is based on a runaway case in which the turbine is free to speed up without generator torque and vibrations start building up at a critical rotor speed. Blades with modified torsional and flapwise stiffness are also investigated. A flutter analysis is often part of the stability investigations for new blades but is normally carried out with engineering models that do not include the influence of unsteady trailed vorticity. Including this influence results in a slightly increased safety margin against classical flutter in all simulated cases

  11. Atrial Fibrillation and Heart Failure

    Directory of Open Access Journals (Sweden)

    William G. Stevenson, M.D

    2008-07-01

    Full Text Available Atrial fibrillation is common in heart failure patients and is associated with increased mortality. Pharmacologic trials have not shown any survival benefit for a rhythm control over a rate control strategy. It has been suggested that sinus rhythm is associated with a survival benefit, but that the risks of anti-arrhythmic drug treatment and poor efficacy offset the beneficial effect. Catheter ablation for atrial fibrillation can establish sinus rhythm without the risks of anti-arrhythmic drug therapy. Data from randomized trials demonstrating a survival benefit for patients undergoing an ablation procedure for atrial fibrillation are still lacking. Ablation of the AV junction and permanent pacing remain a treatment alternative in otherwise refractory cases. Placement of a biventricular system may prevent or reduce negative consequences of chronic right ventricular pacing. Current objectives and options for treatment of atrial fibrillation in heart failure patients are reviewed.

  12. Atrial Septal Defect (For Parents)

    Science.gov (United States)

    ... Video) Going to the Hospital Your Heart & Circulatory System Quiz: Heart & Circulatory System EKG (Video) What's It Like to Have Surgery? Atrial Septal Defect Ventricular Septal Defect Heart and Circulatory System Anesthesia Basics Contact Us Print Resources Send to ...

  13. Atrial Fibrillation and Heart Failure

    OpenAIRE

    Jens Seiler; Tedrow, Usha B.; Stevenson, William G

    2008-01-01

    Atrial fibrillation is common in heart failure patients and is associated with increased mortality.  Pharmacologic trials have not shown any survival benefit for a rhythm control over a rate control strategy.  It has been suggested that sinus rhythm is associated with a survival benefit, but that the risks of anti-arrhythmic drug treatment and poor efficacy offset the beneficial effect.  Catheter ablation for atrial fibrillation can establish sinus rhythm without the risks of a...

  14. Atrial Fibrillation and Heart Failure

    OpenAIRE

    William G. Stevenson, M.D; Usha B. Tedrow, M.D; Jens Seiler, M.D

    2008-01-01

    Atrial fibrillation is common in heart failure patients and is associated with increased mortality. Pharmacologic trials have not shown any survival benefit for a rhythm control over a rate control strategy. It has been suggested that sinus rhythm is associated with a survival benefit, but that the risks of anti-arrhythmic drug treatment and poor efficacy offset the beneficial effect. Catheter ablation for atrial fibrillation can establish sinus rhythm without the risks of anti-arrhythmic dru...

  15. Surgical Ablation of Atrial Fibrillation

    OpenAIRE

    Ramlawi, Basel; Abu Saleh, Walid K.

    2015-01-01

    The Cox-maze procedure for the restoration of normal sinus rhythm, initially developed by Dr. James Cox, underwent several iterations over the years. The main concept consists of creating a series of transmural lesions in the right and left atria that disrupt re-entrant circuits responsible for propagating the abnormal atrial fibrillation rhythm. The left atrial appendage is excluded as a component of the Maze procedure. For the first three iterations of the Cox- maze procedure, these lesions...

  16. Antithrombotic therapy in atrial fibrillation.

    OpenAIRE

    Chin, B.; Lip, G. Y.

    1996-01-01

    OBJECTIVE: To review the evidence for antithrombotic therapy in patients with nonrheumatic atrial fibrillation. QUALITY OF EVIDENCE: Five primary prevention trials and one secondary prevention trial compare antithrombotic therapy with placebo or no treatment. Two trials also determine the efficacy and safety of acetylsalicylic acid. MAIN FINDINGS: Warfarin reduces the risk of stroke by 68%. The effect is consistent in all identifiable groups of patients with nonrheumatic atrial fibrillation, ...

  17. Stroke prevention in atrial fibrillation.

    OpenAIRE

    Michael Katsnelson,; Sebastian Koch; Tatjana Rundek

    1997-01-01

    Non-valvular atrial fibrillation is a common and from a neurological perspective the most significant cardiac arrhythmia with a growing world-wide incidence. It also carries a significant associated morbidity and mortality, with cardioembolic strokes arguably being the most disabling sequelae. This brief review will highlight the important studies and the latest treatment modalities available for stroke prevention in patients with non-valvular atrial fibrillation.

  18. Idiopathic giant right atrial aneurysm

    International Nuclear Information System (INIS)

    A 2-year-old boy with an incidental finding of massive cardiomegaly on a chest X-ray was diagnosed with a giant right atrial aneurysm upon further investigation with echocardiography. The patient underwent successful surgical reduction of the right atrium and closure of the patent foramen ovale to prevent thromboembolic complications and to lower the risk of atrial arrhythmias. The resected atrium had paper-thin walls and pathological features of interstitial fibrosis with endocardial thickening

  19. Probucol attenuates atrial autonomic remodeling in a canine model of atrial fibrillation produced by prolonged atrial pacing

    Institute of Scientific and Technical Information of China (English)

    GONG Yong-tai; LI Wei-min; LI Yue; YANG Shu-sen; SHENG Li; YANG Ning; SHAN Hong-bo; XUE Hong-jie; LIU Wei; YANG Bao-feng; DONG De-li; LI Bao-xin

    2009-01-01

    Background We hypothesize that increased atrial oxidative stress and inflammation may play an important role in atrial nerve sprouting and heterogeneous sympathetic hyperinnervation during atrial fibrillation (AF). To test the hypothesis, we examined whether the antioxidant and anti-inflammatory treatment with probucol attenuates atrial autonomic remodeling in a canine model of AF produced by prolonged rapid right atrial pacing. Methods Twenty-one dogs were divided into a sham-operated group, a control group and a probucol group. Dogs in the control group and probucol group underwent right atrial pacing at 400 beats per minute for 6 weeks, and those in the probucol group received probucol 1 week before rapid atrial pacing until pacing stopped. After 6-week rapid atrial pacing, general properties including left atrial structure and function, atrial hemodynamics and the inducibility and duration of AF were measured in all the groups. Atrial oxidative stress markers and serum C-reactive protein (CRP) concentration were estimated. The degree of nerve sprouting and sympathetic innervation at the right atrial anterior wall (RAAW) and the left atrial anterior wall (LAAW) were quantified by immunohistochemistry, atdal norepinephrine contents were also detected. Atrial beta-nerve growth factor (beta-NGF) mRNA and protein expression at the RAAW and LAAW were assessed by real-time quantitative RT-PCR and Western blotting respectively. Results Atrial tachypacing induced significant nerve sprouting and heterogeneous sympathetic hyperinnervation, and the magnitude of nerve sprouting and hyperinnervation was higher in the RAAW than in the LAAW. Atrial beta-NGF mRNA and protein levels were significantly increased at the RAAW and LAAW, and the upregulation of beta-NGF expression was greater at the RAAW than at the LAAW in the control group. The beta-NGF protein level was positively correlated with the density of sympathetic nerves in all groups. Probucol decreased the increase of

  20. Giant right atrial myxoma

    International Nuclear Information System (INIS)

    Primary tumors of the heart are rare, their estimated incidence ranging between 0.0017-0.19%, and among them cardiac myxomas are the most common (50%). Right atrial localization is uncommon, occurring only in 15-20% of cases. Their clinical presentation ranges from an asymptomatic status to the presence of constitutional symptoms or symptoms pointing to the presence of cardiac obstruction or pulmonary embolism. A case is presented of a 36-year-old male patient with a history of asthenia, palpitations and reduced functional capacity. Transthoracic echocardiography revealed a large mass in the right atrium which prolapsed into the right ventricle and obstructed the tricuspid valve. The patient underwent cardiopulmonary bypass surgery and the mass (9x9 cm) was removed without any complication. Histological examination confirmed the diagnosis of myxoma.

  1. Labyrinth Seal Flutter Analysis and Test Validation in Support of Robust Rocket Engine Design

    Science.gov (United States)

    El-Aini, Yehia; Park, John; Frady, Greg; Nesman, Tom

    2010-01-01

    High energy-density turbomachines, like the SSME turbopumps, utilize labyrinth seals, also referred to as knife-edge seals, to control leakage flow. The pressure drop for such seals is order of magnitude higher than comparable jet engine seals. This is aggravated by the requirement of tight clearances resulting in possible unfavorable fluid-structure interaction of the seal system (seal flutter). To demonstrate these characteristics, a benchmark case of a High Pressure Oxygen Turbopump (HPOTP) outlet Labyrinth seal was studied in detail. First, an analytical assessment of the seal stability was conducted using a Pratt & Whitney legacy seal flutter code. Sensitivity parameters including pressure drop, rotor-to-stator running clearances and cavity volumes were examined and modeling strategies established. Second, a concurrent experimental investigation was undertaken to validate the stability of the seal at the equivalent operating conditions of the pump. Actual pump hardware was used to construct the test rig, also referred to as the (Flutter Rig). The flutter rig did not include rotational effects or temperature. However, the use of Hydrogen gas at high inlet pressure provided good representation of the critical parameters affecting flutter especially the speed of sound. The flutter code predictions showed consistent trends in good agreement with the experimental data. The rig test program produced a stability threshold empirical parameter that separated operation with and without flutter. This empirical parameter was used to establish the seal build clearances to avoid flutter while providing the required cooling flow metering. The calibrated flutter code along with the empirical flutter parameter was used to redesign the baseline seal resulting in a flutter-free robust configuration. Provisions for incorporation of mechanical damping devices were introduced in the redesigned seal to ensure added robustness

  2. Theory of particle and energy flux from the magnetic flutter of drift waves

    International Nuclear Information System (INIS)

    A quasi-linear theory of particle and energy flux by magnetic flutter associated with drift waves is presented. It is shown that magnetic flutter can enhance the energy flux. However, particle diffusion is ambipolar and runaway electrons do not escape along the field lines

  3. Nonlinear dynamics approach of modeling the bifurcation for aircraft wing flutter in transonic speed

    DEFF Research Database (Denmark)

    Matsushita, Hiroshi; Miyata, T.; Christiansen, Lasse Engbo;

    2002-01-01

    The procedure of obtaining the two-degrees-of-freedom, finite dimensional. nonlinear mathematical model. which models the nonlinear features of aircraft flutter in transonic speed is reported. The model enables to explain every feature of the transonic flutter data of the wind tunnel tests...

  4. Nonlinear dynamics approach of modeling the bifurcation for aircraft wing flutter in transonic speed

    DEFF Research Database (Denmark)

    Matsushita, Hiroshi; Miyata, T.; Christiansen, Lasse Engbo; Lehn-Schiøler, Tue; Mosekilde, Erik

    The procedure of obtaining the two-degrees-of-freedom, finite dimensional. nonlinear mathematical model. which models the nonlinear features of aircraft flutter in transonic speed is reported. The model enables to explain every feature of the transonic flutter data of the wind tunnel tests...

  5. Who Is at Risk for Atrial Fibrillation?

    Science.gov (United States)

    ... Who Is at Risk for Atrial Fibrillation? Explore Atrial Fibrillation What Is... Types Other Names Causes Who Is at Risk Signs & Symptoms Diagnosis Treatments Prevention Living With Clinical Trials Links Related Topics Arrhythmia ...

  6. Surgical Ablation of Atrial Fibrillation.

    Science.gov (United States)

    Ramlawi, Basel; Abu Saleh, Walid K

    2015-01-01

    The Cox-maze procedure for the restoration of normal sinus rhythm, initially developed by Dr. James Cox, underwent several iterations over the years. The main concept consists of creating a series of transmural lesions in the right and left atria that disrupt re-entrant circuits responsible for propagating the abnormal atrial fibrillation rhythm. The left atrial appendage is excluded as a component of the Maze procedure. For the first three iterations of the Cox- maze procedure, these lesions were performed using a surgical cut-and-sew approach that ensured transmurality. The Cox-Maze IV is the most currently accepted iteration. It achieves the same lesion set of the Cox- maze III but uses alternative energy sources to create the transmural lesions, potentially in a minimally invasive approach on the beating heart. High-frequency ultrasound, microwave, and laser energy have all been used with varying success in the past. Today, bipolar radiofrequency heat or cryotherapy cooling are the most accepted sources for creating linear lesions with consistent safety and transmurality. The robust and reliable nature of these energy delivery methods has yielded a success rate reaching 90% freedom from atrial fibrillation at 12 months. Such approaches offer a significant long-term advantage over catheter-based ablation, especially in patients having longstanding, persistent atrial fibrillation with characteristics such as dilated left atrial dimensions, poor ejection fraction, and failed catheter ablation. Based on these improved results, there currently is significant interest in developing a hybrid ablation strategy that incorporates the superior transmural robust lesions of surgical ablation, the reliable stroke prevention potential of epicardial left atrial appendage exclusion, and sophisticated mapping and confirmatory catheter-based ablation technology. Such a minimally invasive hybrid strategy for ablation may lead to the development of multidisciplinary "Afib teams" to

  7. Parametric Flutter Analysis of the TCA Configuration and Recommendation for FFM Design and Scaling

    Science.gov (United States)

    Baker, Myles; Lenkey, Peter

    1997-01-01

    The current HSR Aeroelasticity plan to design, build, and test a full span, free flying transonic flutter model in the TDT has many technical obstacles that must be overcome for a successful program. One technical obstacle is the determination of a suitable configuration and point in the sky to use in setting the scaling point for the ASE models program. Determining this configuration and point in the sky requires balancing several conflicting requirements, including model buildability, tunnel test safety, and the ability of the model to represent the flutter mechanisms of interest. As will be discussed in detail in subsequent sections, the current TCA design exhibits several flutter mechanisms of interest. It has been decided that the ASE models program will focus on the low frequency symmetric flutter mechanism, and will make no attempt to investigate high frequency flutter mechanisms. There are several reasons for this choice. First, it is believed that the high frequency flutter mechanisms are similar in nature to classical wing bending/torsion flutter, and therefore there is more confidence that this mechanism can be predicted using current techniques. The low frequency mode, on the other hand, is a highly coupled mechanism involving wing, body, tail, and engine motion which may be very difficult to predict. Second, the high frequency flutter modes result in very small weight penalties (several hundred pounds), while suppression of the low frequency mechanism inside the flight envelope causes thousands of pounds to be added to the structure. In order to successfully test the low frequency flutter mode of interest, a suitable starting configuration and point in the sky must be identified. The configuration and point in the sky must result in a wind tunnel model that (1) represents the low-frequency wing/body/engine/empennage flutter mechanisms that are unique to HSCT configurations, (2) flutters at an acceptably low frequency in the tunnel, (3) flutters at an

  8. Evaluation of somatosensory cortical differences between flutter and vibration tactile stimuli.

    Science.gov (United States)

    Han, Sang Woo; Chung, Yoon Gi; Kim, Hyung-Sik; Chung, Soon-Cheol; Park, Jang-Yeon; Kim, Sung-Phil

    2013-01-01

    In parallel with advances in haptic-based mobile computing systems, understanding of the neural processing of vibrotactile information becomes of great importance. In the human nervous system, two types of vibrotactile information, flutter and vibration, are delivered from mechanoreceptors to the somatosensory cortex through segregated neural afferents. To investigate how the somatosensory cortex differentiates flutter and vibration, we analyzed the cortical responses to vibrotactile stimuli with a wide range of frequencies. Specifically, we examined whether cortical activity changed most around 50 Hz, which is known as a boundary between flutter and vibration. We explored various measures to evaluate separability of cortical activity across frequency and found that the hypothesis margin method resulted in the greatest separability between flutter and vibration. This result suggests that flutter and vibration information may be processed by different neural processes in the somatosensory cortex. PMID:24110709

  9. Intravenous heparin dosing strategy in hospitalized patients with atrial dysrhythmias.

    Science.gov (United States)

    Roswell, Robert O; Greet, Brian; Shah, Sunny; Bernard, Samuel; Milin, Alexandra; Lobach, Iryna; Guo, Yu; Radford, Martha J; Berger, Jeffrey S

    2016-08-01

    Patients with non-valvular atrial fibrillation (AF) have an elevated stroke risk that is 2-7 times greater than in those without AF. Intravenous unfractionated heparin (UFH) is commonly used for hospitalized patients with atrial fibrillation and atrial flutter (AFL) to prevent stroke. Dosing strategies exist for intravenous anticoagulation in patients with acute coronary syndromes and venous thromboembolic diseases, but there are no data to guide providers on a dosing strategy for intravenous anticoagulation in patients with AF/AFL. 996 hospitalized patients with AF/AFL on UFH were evaluated. Bolus dosing and initial infusion rates of UFH were recorded along with rates of stroke, thromboemobolic events, and bleeding events as defined by the International Society on Thrombosis and Haemostasis criteria. Among 226 patients included in the analysis, 76 bleeding events occurred. Using linear regression analysis, initial rates of heparin infusion ranging from 9.7 to 11.8 units/kilogram/hour (U/kg/h) resulted in activated partial thromboplastin times that were within therapeutic range. The median initial infusion rate in patients with bleeding was 13.3 U/kg/h, while in those without bleeding it was 11.4 U/kg/h; p = 0.012. An initial infusion rate >11.0 U/kg/h yielded an OR 1.95 (1.06-3.59); p = 0.03 for any bleeding event. Using IV heparin boluses neither increased the probability of attaining a therapeutic aPTT (56.1 vs 56.3 %; p = 0.99) nor did it significantly increase bleeding events in the study (35.7 vs 31.3 %; p = 0.48). The results suggest that higher initial rates of heparin are associated with increased bleeding risk. From this dataset, initial heparin infusion rates of 9.7-11.0 U/kg/h without a bolus can result in therapeutic levels of anticoagulation in hospitalized patients with AF/AFL without increasing the risk of bleeding. PMID:26951166

  10. Low atrial septum pacing in pacemaker patients

    NARCIS (Netherlands)

    Voogt, Willem Gijsbert de

    2006-01-01

    In patients with an indication for anti bradycardia pacing, atrial fibrillation (AF) is a common arrhythmia (30-50%) even in the absence of atrial tachy arrhythmias before pacemaker implantation. Pace prevention and pace intervention for atrial tachy arrhythmias could be an interesting adjuvant trea

  11. Obstructive sleep apnea in atrial fibrillation patients.

    Science.gov (United States)

    Arias, Miguel A; Alonso-Fernández, Alberto; García-Río, Francisco; Sánchez, Ana; López, Juana M; Pagola, Carlos

    2006-06-28

    A high prevalence of obstructive sleep apnea has been demonstrated in patients with atrial fibrillation. Our comments want to emphasize the importance of identifying and treating a large proportion of patients with atrial fibrillation who have undiagnosed obstructive sleep apnea as an additional preventive strategy for atrial fibrillation patients. PMID:16309764

  12. Atrial fibrillation post cardiac bypass surgery

    OpenAIRE

    Mostafa, Ashraf; EL-Haddad, Mohamed A.; Shenoy, Maithili; Tuliani, Tushar

    2012-01-01

    Atrial fibrillation occurs in 5-40% patients after coronary artery bypass graft surgery. Atrial fibrillation increases mortality and morbidity in the post-operative period. We sought to conduct a comprehensive review of literature focusing on pathophysiology, risk factors, prevention and treatment of post coronary artery bypass graft atrial fibrillation.

  13. The influence of trailed vorticity on flutter speed estimations

    OpenAIRE

    Pirrung, Georg; Aagaard Madsen , Helge; Kim, Taeseong

    2014-01-01

    This paper briefly describes the implementation of a coupled near and far wake model for wind turbine rotor induction in the aeroelastic code HAWC2 and its application for flutter analysis of the NREL 5 MW wind turbine. The model consists of a far wake part based on Blade Element Momentum (BEM) theory, which is coupled with Beddoes' near wake model for trailed vorticity. The first part of this work outlines the implementation in HAWC2, with a focus on the interaction of the induction from the...

  14. Forces and Moments acting on the Fluttering Profile

    Czech Academy of Sciences Publication Activity Database

    Kozánek, Jan; Vlček, Václav; Zolotarev, Igor

    Vol. 8. Dordrecht: Springer, 2012 - (Beran, J.; Bílek, M.; Hejnová, M.; Žabka, P.), s. 217-222 ISBN 978-94-007-5124-8. ISSN 2211-0984. [International Conference on the Theory and Mechanisms /11./. Liberec (CZ), 04.09.2012-06.09.2012] R&D Projects: GA ČR GA101/09/1522 Institutional research plan: CEZ:AV0Z20760514 Keywords : fluttering profile * interferometry * drag and lift forces * moments Subject RIV: BI - Acoustics

  15. Impact of the origin of sinus node artery on recurrence after pulmonary vein isolation in patients with paroxysmal atrial fibrillation

    Institute of Scientific and Technical Information of China (English)

    ZHANG Zhi-jun; CHEN Ke; TANG Ri-bo; gANG Cai-hua; Edmundo Patricio Lopes Lao; YAN Qian; HE Xiao-nan

    2013-01-01

    Background Major atrial coronary arteries,including the sinus node artery (SNA),were commonly found in the areas involved in atrial fibrillation (AF) ablation and could cause difficulties in achieving linear block at the left atrial (LA) roof.The SNA is a major atrial coronary artery of the atrial coronary circulation.This study aimed to determine impact of the origin of SNA on recurrence of AF after pulmonary vein isolation (PVI) in patients with paroxysmal AF.Methods Seventy-eight patients underwent coronary angiography for suspected coronary heart disease,followed by catheter ablation for paroxysmal AF.According to the origin of SNA from angiographic findings,they were divided into right SNA group (SNA originating from the right coronary artery) and left SNA group (SNA originating from the left circumflex artery).Guided by an electroanatomic mapping system,circumferential pulmonary vein ablation (CPVA) was performed in both groups and PVI was the procedural endpoint.All patients were followed up at 1,3,6,9 and 12 months post-ablation.Recurrence was defined as any episode of atrial tachyarrhythmias (ATAs),including AF,atrial flutter or atrial tachycardia,that lasted longer than 30 seconds after a blanking period of 3 months.Results The SNA originated from the right coronary artery in 34 patients (43.6%) and the left circumflex artery in 44 patients (56.4%).Freedom from AF and antiarrhythmic drugs (AADs) at 1 year was 67.9 % (53/78) for all patients.After 1 year follow-up,79.4% (27/34) in right SNA group and 59.1% (26/44) in left SNA group (P=0.042) were in sinus rhythm.On multivariate analysis,left atrium size (HR=1.451,95%CI:1.240-1.697,P <0.001) and a left SNA (HR=6.22,95%CI:2.01-19.25,P=0.002)were the independent predictors of AF recurrence.Conclusions The left SNA is more frequent in the patients with paroxysmal AF.After one year follow-up,the presence of a left SNA was identified as an independent predictor of AF recurrence after CPVA in

  16. Atrial fibrillation and delayed gastric emptying.

    Directory of Open Access Journals (Sweden)

    Isadora C Botwinick

    Full Text Available BACKGROUND: Atrial fibrillation and delayed gastric emptying (DGE are common after pancreaticoduodenectomy. Our aim was to investigate a potential relationship between atrial fibrillation and DGE, which we defined as failure to tolerate a regular diet by the 7(th postoperative day. METHODS: We performed a retrospective chart review of 249 patients who underwent pancreaticoduodenectomy at our institution between 2000 and 2009. Data was analyzed with Fisher exact test for categorical variables and Mann-Whitney U or unpaired T-test for continuous variables. RESULTS: Approximately 5% of the 249 patients included in the analysis experienced at least one episode of postoperative atrial fibrillation. Median age of patients with atrial fibrillation was 74 years, compared with 66 years in patients without atrial fibrillation (p = 0.0005. Patients with atrial fibrillation were more likely to have a history of atrial fibrillation (p = 0.03. 92% of the patients with atrial fibrillation suffered from DGE, compared to 46% of patients without atrial fibrillation (p = 0.0007. This association held true when controlling for age. CONCLUSION: Patients with postoperative atrial fibrillation are more likely to experience delayed gastric emptying. Interventions to manage delayed gastric function might be prudent in patients at high risk for postoperative atrial fibrillation.

  17. An Interactive Software for Conceptual Wing Flutter Analysis and Parametric Study

    Science.gov (United States)

    Mukhopadhyay, Vivek

    1996-01-01

    An interactive computer program was developed for wing flutter analysis in the conceptual design stage. The objective was to estimate the flutter instability boundary of a flexible cantilever wing, when well-defined structural and aerodynamic data are not available, and then study the effect of change in Mach number, dynamic pressure, torsional frequency, sweep, mass ratio, aspect ratio, taper ratio, center of gravity, and pitch inertia, to guide the development of the concept. The software was developed for Macintosh or IBM compatible personal computers, on MathCad application software with integrated documentation, graphics, data base and symbolic mathematics. The analysis method was based on non-dimensional parametric plots of two primary flutter parameters, namely Regier number and Flutter number, with normalization factors based on torsional stiffness, sweep, mass ratio, taper ratio, aspect ratio, center of gravity location and pitch inertia radius of gyration. The parametric plots were compiled in a Vought Corporation report from a vast data base of past experiments and wind-tunnel tests. The computer program was utilized for flutter analysis of the outer wing of a Blended-Wing-Body concept, proposed by McDonnell Douglas Corp. Using a set of assumed data, preliminary flutter boundary and flutter dynamic pressure variation with altitude, Mach number and torsional stiffness were determined.

  18. Fluttering energy harvesters in the wind: A review

    Science.gov (United States)

    McCarthy, J. M.; Watkins, S.; Deivasigamani, A.; John, S. J.

    2016-01-01

    The growing area of harvesting energy by aerodynamically induced flutter in a fluid stream is reviewed. Numerous approaches were found to understand, demonstrate and [sometimes] optimise harvester performance based on Movement-Induced or Extraneously Induced Excitation. Almost all research was conducted in smooth, unidirectional flow domains; either experimental or computational. The power outputs were found to be very low when compared to conventional wind turbines, but potential advantages could be lower noise levels. A consideration of the likely outdoor environment for fluttering harvesters revealed that the flow would be highly turbulent and having a mean flow angle in the horizontal plane that could approach a harvester from any direction. Whilst some multiple harvester systems in smooth, well-aligned flow found enhanced efficiency (due to beneficial wake interaction) this would require an invariant flow approach angle. It was concluded that further work needs to be performed to find a universally accepted metric for efficiency and to understand the effects of the realities of the outdoors, including the highly variable and turbulent flow conditions likely to be experienced.

  19. Chirality-dependent flutter of Typha blades in wind.

    Science.gov (United States)

    Zhao, Zi-Long; Liu, Zong-Yuan; Feng, Xi-Qiao

    2016-01-01

    Cattail or Typha, an emergent aquatic macrophyte widely distributed in lakes and other shallow water areas, has slender blades with a chiral morphology. The wind-resilient Typha blades can produce distinct hydraulic resistance for ecosystem functions. However, their stem may rupture and dislodge in excessive wind drag. In this paper, we combine fluid dynamics simulations and experimental measurements to investigate the aeroelastic behavior of Typha blades in wind. It is found that the chirality-dependent flutter, including wind-induced rotation and torsion, is a crucial strategy for Typha blades to accommodate wind forces. Flow visualization demonstrates that the twisting morphology of blades provides advantages over the flat one in the context of two integrated functions: improving wind resistance and mitigating vortex-induced vibration. The unusual dynamic responses and superior mechanical properties of Typha blades are closely related to their biological/ecosystem functions and macro/micro structures. This work decodes the physical mechanisms of chirality-dependent flutter in Typha blades and holds potential applications in vortex-induced vibration suppression and the design of, e.g., bioinspired flight vehicles. PMID:27432079

  20. An electret-based aeroelastic flutter energy harvester

    International Nuclear Information System (INIS)

    This paper presents a new airflow energy harvester exploiting fluttering effects coupled to an electret-based conversion to turn the flow-induced movements of a membrane into electricity. The proposed device is made of a polymer membrane placed between two parallel flat electrodes coated with 25 μm thick Teflon PTFE electret layers; a bluff body is placed at the inlet of the device to induce vortex shedding. When the wind or airstream of any kind flows through the harvester, the membrane enters in oscillation due to fluttering and successively comes into contact with the two Teflon-coated fixed electrodes. This periodic motion is directly converted into electricity thanks to the electret-based conversion process. Various geometries have been tested and have highlighted a 2.7 cm3 device, with an output power of 481 μW (178 μW cm−3) at 15 m s−1 and 2.1 mW (782 μW cm−3) at 30 m s−1 with an electret charged at −650 V. The power coefficient Cp of the device reaches 0.54% at 15 m s−1 which is low, but compares favorably with the other small-scale airflow energy harvesters. (paper)

  1. Effects of large bending deflections on blade flutter limits

    Energy Technology Data Exchange (ETDEWEB)

    Kallesoee, Bjarne Skovmose; Hartvig Hansen, Morten

    2008-04-15

    The coupling of bending and torsion due to large blade bending are assumed to have some effects of the flutter limits of wind turbines. In the present report, the aeroelastic blade model suggested by Kallesoee, which is similar to a second order model, is used to investigate the aeroelastic stability limits of the RWT blade with and without the effects of the large blade deflection. The investigation shows no significant change of the flutter limit on the rotor speed due to the blade deflection,whereas the first edgewise bending mode becomes negatively damped due to the coupling with blade torsion which causes a change of the effective direction of blade vibration. These observations are confirmed by nonlinear aeroelastic simulations using HAWC2. This work is part of the UpWind project funded by the European Commission under the contract number SES6-CT-2005-019945 which is gratefully acknowledged. This report is the deliverable D2.3 of the UpWind project. (au)

  2. Flutter of wings involving a locally distributed flexible control surface

    Science.gov (United States)

    Mozaffari-Jovin, S.; Firouz-Abadi, R. D.; Roshanian, J.

    2015-11-01

    This paper undertakes to facilitate appraisal of aeroelastic interaction of a locally distributed, flap-type control surface with aircraft wings operating in a subsonic potential flow field. The extended Hamilton's principle serves as a framework to ascertain the Euler-Lagrange equations for coupled bending-torsional-flap vibration. An analytical solution to this boundary-value problem is then accomplished by assumed modes and the extended Galerkin's method. The developed aeroelastic model considers both the inherent flexibility of the control surface displaced on the wing and the inertial coupling between these two flexible bodies. The structural deformations also obey the Euler-Bernoulli beam theory, along with the Kelvin-Voigt viscoelastic constitutive law. Meanwhile, the unsteady thin-airfoil and strip theories are the tools of producing the three-dimensional airloads. The origin of aerodynamic instability undergoes analysis in light of the oscillatory loads as well as the loads owing to arbitrary motions. After successful verification of the model, a systematic flutter survey was conducted on the theoretical effects of various control surface parameters. The results obtained demonstrate that the flapping modes and parameters of the control surface can significantly impact the flutter characteristics of the wings, which leads to a series of pertinent conclusions.

  3. LCO flutter of cantilevered woven glass/epoxy laminate in subsonic flow

    Institute of Scientific and Technical Information of China (English)

    Dayang Laila Abang Haji Abdul Majid; ShahNor Basri

    2008-01-01

    The paper presents aeroelastic characteristics of a cantilevered composite wing,idealized as a composite flat plate laminate.The composite laminate was made from woven glass fibers with epoxy matrix.The elastic and dynamic properties of the laminate were determined experimentally for aeroelastic calculations.Aeroelastic wind tunnel testing of the laminate was performed and the result showed that flutter,a dynamic instability occurred.The cantilevered laminate also displayed limit cycle amplitude,post-flutter oscillation.The experimental flutter velocity and frequency were verified by our computational analysis.

  4. Subsonic flutter analysis addition to NASTRAN. [for use with CDC 6000 series digital computers

    Science.gov (United States)

    Doggett, R. V., Jr.; Harder, R. L.

    1973-01-01

    A subsonic flutter analysis capability has been developed for NASTRAN, and a developmental version of the program has been installed on the CDC 6000 series digital computers at the Langley Research Center. The flutter analysis is of the modal type, uses doublet lattice unsteady aerodynamic forces, and solves the flutter equations by using the k-method. Surface and one-dimensional spline functions are used to transform from the aerodynamic degrees of freedom to the structural degrees of freedom. Some preliminary applications of the method to a beamlike wing, a platelike wing, and a platelike wing with a folded tip are compared with existing experimental and analytical results.

  5. Thinking outside the Box: Rotor Modulation in the Treatment of Atrial Fibrillation

    Directory of Open Access Journals (Sweden)

    : Ruchir Sehra MD FHRS; Sanjiv M. Narayan, MD, PHD; FHRS,John Humme, MD

    2013-06-01

    Full Text Available Ablation for atrial fibrillation (AF is an important and exciting therapy whose results remain suboptimal. Although most clinical trials show that ablation eliminates AF more effectively than medications, it is disappointing that the continued single procedural success remains ≈50% despite the substantial advances that have taken place in imaging, catheter positioning and energy delivery. Focal impulse and rotor modulation (FIRM, on the other hand, offers the opportunity to precisely define and then ablate patient-specific sustaining mechanisms for AF, rather than trying to eliminate all possible AF triggers. For over a decade, electrophysiologists have described cases in which AF terminates after only limited ablation – usually that cannot be explained by ‘random’ meandering wavelets. Indeed, recent studies from several laboratories show that all forms of clinical AF are typically ‘driven’ by stable electrical rotors and focal sources, not by multiple meandering waves. FIRM mapping enables an operator to place a catheter at typically 1-3 predicted sites in the atria, and with 80% of patients with persistent and paroxysmal AF and increase the single procedure rate of AF elimination from 50% with PV isolation alone to >80%. Ongoing studies hint that FIRM only ablation, enabling ablation times in the range observed for typical atrial flutter, may also achieve these high success rates without subsequent trigger ablation. This review summarizes the current state-of-the-art on FIRM mapping and ablation.

  6. Dronedarone For Atrial Fibrillation: Unbridled Enthusiasm Or Just Another Small Step Forward?

    Directory of Open Access Journals (Sweden)

    James A. Reiffel, M.D.

    2009-08-01

    Full Text Available In July 2009, the federal Food and Drug Administration (FDA approved the marketing of dronedarone (Multaq, sanofi-aventis for use in patients with atrial fibrillation (AF or flutter (AFL [with a requirement for a recent episode] that is paroxysmal or persistent – the latter having been converted to sinus rhythm or with conversion planned – who have, in addition to AF, certain “high-risk” markers for adverse outcomes that were derived from the enrollment criteria for the landmark ATHENA trial.1 These markers include one or more of: age >70 yrs, hypertension, diabetes mellitus, prior cerebrovascular accident, left atrial size of 50 mm or larger, or LVEF <40%. Contraindications include class IV heart failure or symptomatic heart failure with a recent decompensation; second or third degree AV block without a functioning pacemaker; bradycardia < 50 bpm; concomitant use of a strong CYP3A inhibitor or a QT prolonging agent that may induce torsades de pointes; QTc Bazett interval of 500 ms or longer; or severe hepatic impairment.

  7. Surgical Treatment of Atrial Fibrillation

    Directory of Open Access Journals (Sweden)

    Naghmeh Moshtaghi

    2008-12-01

    Full Text Available Atrial fibrillation is the most prevalent permanent arrhythmia. It may be associated with other cardiac pathologies which need surgical treatment. Various types of surgery including the traditional cut-sew operations and operations using different energy sources are currently in use. In comparison with medical treatment, surgery is safe, effective, and has reliable results.

  8. Atrial Fibrillation and Heart Failure

    Directory of Open Access Journals (Sweden)

    Jens Seiler

    2008-07-01

    Full Text Available Atrial fibrillation is common in heart failure patients and is associated with increased mortality.  Pharmacologic trials have not shown any survival benefit for a rhythm control over a rate control strategy.  It has been suggested that sinus rhythm is associated with a survival benefit, but that the risks of anti-arrhythmic drug treatment and poor efficacy offset the beneficial effect.  Catheter ablation for atrial fibrillation can establish sinus rhythm without the risks of anti-arrhythmic drug therapy.  Data from randomized trials demonstrating a survival benefit for patients undergoing an ablation procedure for atrial fibrillation are still lacking.  Ablation of the AV junction and permanent pacing remain a treatment alternative in otherwise refractory cases.  Placement of a biventricular system may prevent or reduce negative consequences of chronic right ventricular pacing.  Current objectives and options for treatment of atrial fibrillation in heart failure patients are reviewed. 

  9. Personalized management of atrial fibrillation

    DEFF Research Database (Denmark)

    Kirchhof, Paulus; Breithardt, Günter; Aliot, Etienne;

    2013-01-01

    The management of atrial fibrillation (AF) has seen marked changes in past years, with the introduction of new oral anticoagulants, new antiarrhythmic drugs, and the emergence of catheter ablation as a common intervention for rhythm control. Furthermore, new technologies enhance our ability to de...

  10. Supercavitation hydrofoil performance and torsional flutter margin; Supercavitation yokugata no teijo hiteijo tokusei to nejiri flutter genkai

    Energy Technology Data Exchange (ETDEWEB)

    Matsudaira, Y.; Obara, H. [Tokyo Metropolitan Institute of Technology, Tokyo (Japan); Nakagawa, H. [Sumitomo Heavy Industries, Ltd., Tokyo (Japan); Yoshida, H. [Tokyo Metropolitan Institute of Technology, Tokyo (Japan)

    2000-08-25

    Supercavitation hydrofoil applied to high-speed marine propeller or hydro-machinery blade runs into unsteady behaviors such as cavitation breakdown and hydraulic flutter in some operation range. The hydrofoil performance was experimentally estimated and compared with the wedge performance using the cavitation tunnel and the torsional vibration apparatus with three component load cells, This experiment was carried out at several angles of attack in the region from subcavitation to supercavitation. At a general steady state but including some cavitation breakdowns, the hydrofoil has the most superior time mean lift/drag ratio about 6 < C{sub l}/C{sub d} < 8 at in all cavitation regions. But, the ratio drastically decreases as the angle of attack increases. Fluctuating lift coefficient C{sub l}{sup '} due to the cavitation breakdown reaches up to about 10% of time mean lift coefficient C{sub l}. At the hydrofoil pitching motion, the torsional flutter margin of the hydrofoil extends to higher reduced frequency side as the angle of attack increases and has the nearly same margin of the wedge in all cavitation regions. (author)

  11. Subclinical Atrial Fibrillation and the Risk of Stroke

    NARCIS (Netherlands)

    Healey, Jeff S.; Connolly, Stuart J.; Gold, Michael R.; Israel, Carsten W.; Van Gelder, Isabelle C.; Capucci, Alessandro; Lau, C. P.; Fain, Eric; Yang, Sean; Bailleul, Christophe; Morillo, Carlos A.; Carlson, Mark; Themeles, Ellison; Kaufman, Elizabeth S.; Hohnloser, Stefan H.

    2012-01-01

    BACKGROUND One quarter of strokes are of unknown cause, and subclinical atrial fibrillation may be a common etiologic factor. Pacemakers can detect subclinical episodes of rapid atrial rate, which correlate with electrocardiographically documented atrial fibrillation. We evaluated whether subclinica

  12. What Are the Signs and Symptoms of Atrial Fibrillation?

    Science.gov (United States)

    ... Twitter. What Are the Signs and Symptoms of Atrial Fibrillation? Atrial fibrillation (AF) usually causes the heart's lower ... Chest pain Dizziness or fainting Fatigue (tiredness) Confusion Atrial Fibrillation Complications AF has two major complications— stroke and ...

  13. Match Point Solution for Robust Flutter Analysis in Constant-Mach Prediction

    Institute of Scientific and Technical Information of China (English)

    Yun Haiwei; Han Jinglong

    2008-01-01

    This paper presents a method for robust flutter computation which uses flight altitude as the perturbation variable in order to obtain a match point solution. The air density and sound speed of standard atmosphere model are approximated as the polynomial function of altitude, such that the flight altitude becomes the single perturbation variable that describes the aeroelastic system. The uncertainties of generalized stiffness and damping are considered and the uncertain aeroelastic system can be formulated as linear fractional transforma- tion (LFT) representation which is suitable for μ analysis framework. Finally, the match point solutions of robust flutter margins can be computed with structured singular value (SSV) theory. The robust flutter analysis method provided in this paper is suitable for con- stant-Mach flight flutter test and provides valuable reference for flight envelope expansion.

  14. Experimental Model Based Feedback Control for Flutter Suppression and Gust Load Alleviation Project

    Data.gov (United States)

    National Aeronautics and Space Administration — ZONA Technology, Inc. (ZONA) proposes an R&D effort to develop an Experimental Model Based Feedback Control (EMBFC) Framework for the flutter suppression and...

  15. A Conceptual Wing Flutter Analysis Tool for Systems Analysis and Parametric Design Study

    Science.gov (United States)

    Mukhopadhyay, Vivek

    2003-01-01

    An interactive computer program was developed for wing flutter analysis in the conceptual design stage. The objective was to estimate flutt er instability boundaries of a typical wing, when detailed structural and aerodynamic data are not available. Effects of change in key flu tter parameters can also be estimated in order to guide the conceptual design. This userfriendly software was developed using MathCad and M atlab codes. The analysis method was based on non-dimensional paramet ric plots of two primary flutter parameters, namely Regier number and Flutter number, with normalization factors based on wing torsion stiffness, sweep, mass ratio, taper ratio, aspect ratio, center of gravit y location and pitch-inertia radius of gyration. These parametric plo ts were compiled in a Chance-Vought Corporation report from database of past experiments and wind tunnel test results. An example was prese nted for conceptual flutter analysis of outer-wing of a Blended-Wing- Body aircraft.

  16. Uso da radiofrequência bipolar para o tratamento da fibrilação atrial durante cirurgia cardíaca Uso de la radiofrecuencia bipolar para el tratamiento de la fibrilación atrial durante cirugía cardíaca Use of bipolar radiofrequency for the treatment of atrial fibrillation during cardiac surgery

    Directory of Open Access Journals (Sweden)

    Leonardo Secchin Canale

    2011-06-01

    Full Text Available FUNDAMENTO: O tratamento da fibrilação atrial com dispositivo de ablação de tecidos por radiofrequência bipolar em concomitância à cirurgia cardíaca tem se mostrado método eficaz no tratamento desta arritmia. OBJETIVO: Descrever a experiência inicial do Instituto Nacional de Cardiologia no tratamento cirúrgico da fibrilação atrial com uso de dispositivo de radiofrequência bipolar em pacientes submetidos à cirurgia cardíaca, relatando o resultado de acompanhamento pós-operatório de um ano. MÉTODOS: Entre janeiro de 2008 e março de 2009, 47 pacientes (36 mulheres consecutivos, com idade média de 53,7 ± 10,6 anos, apresentando fibrilação atrial por um período médio de 34,6 meses (3 a 192 meses foram submetidos à ablação cirúrgica desta arritmia, por radiofrequência bipolar, durante o procedimento que motivou a indicação da cirurgia. Oito apresentavam fibrilação atrial intermitente e 39, contínua. Oitenta e um por cento foram submetidos à cirurgia valvar como procedimento principal. Esta é uma análise retrospectiva, observacional, com avaliação de um ano de pós-operatório das variáveis clínicas e de Holter 24 h. RESULTADOS: Dos 47 pacientes, 40 sobreviveram um ano. Desses, 33 foram submetidos a Holter 24 h, em um intervalo médio de 401 dias após a cirurgia. Encontrou-se a seguinte distribuição de ritmos: 24 (73% sinusal, 5 (15% fibrilação atrial, três (9% Flutter atrial e um (3% ritmo juncional. Foram observados dois acidentes vasculares encefálicos, sendo um associado à arritmia supraventricular. CONCLUSÃO: A ablação cirúrgica de fibrilação atrial com dispositivo de radiofrequência bipolar concomitante à cirurgia cardíaca é método eficaz para o tratamento desta arritmia.FUNDAMENTO: El tratamiento de la fibrilación atrial con dispositivo de ablación de tejidos por radiofrecuencia bipolar en concomitancia con la cirugía cardíaca se muestra un método eficaz en el tratamiento de esta

  17. Risk of atrial fibrillation in diabetes mellitus

    DEFF Research Database (Denmark)

    Pallisgaard, Jannik L.; Schjerning, Anne-Marie; Lindhardt, Tommi B.;

    2016-01-01

    AIM: Diabetes has been associated with atrial fibrillation but the current evidence is conflicting. In particular knowledge regarding young diabetes patients and the risk of developing atrial fibrillation is sparse. The aim of our study was to investigate the risk of atrial fibrillation in patients...... with diabetes compared to the background population in Denmark. METHODS AND RESULTS: Through Danish nationwide registries we included persons above 18 years of age and without prior atrial fibrillation and/or diabetes from 1996 to 2012. The study cohort was divided into a background population without...... diabetes and a diabetes group. The absolute risk of developing atrial fibrillation was calculated and Poisson regression models adjusted for sex, age and comorbidities were used to calculate incidence rate ratios of atrial fibrillation. The total study cohort included 5,081,087 persons, 4,827,713 (95%) in...

  18. Vurdering av flutter stabilitetsgrensen til Hålogalandsbroen med en probabilistisk metode

    OpenAIRE

    Kvamstad, Tori Høyland

    2011-01-01

    The present work is a study of the aeroelastic stability limit of the Hålogaland Bridge. The state-of-the-art theory concerning determination of flutter stability limits in modern bridge design is presented. The self-excited loads are modeled using aerodynamic derivatives obtained in a free vibration wind tunnel test of a section model. The bimodal flutter limit of all relevant mode pairs are evaluated, by considering frequency separation and mode shape similarity of the respective modes. The...

  19. Assessment of the flutter stability limit of the Hålogaland Bridge using aprobabilistic approach

    OpenAIRE

    Kvamstad, Tori Høyland

    2011-01-01

    The present work is a study of the aeroelastic stability limit of the Hålogaland Bridge. The state-of-the-art theory concerning determination of flutter stability limits in modern bridge design is presented. The self-excited loads are modeled using aerodynamic derivatives obtained in a free vibration wind tunnel test of a section model.The bimodal flutter limit of all relevant mode pairs are evaluated, by considering frequency separation and mode shape similarity of the respective modes. The ...

  20. Investigating Stall Flutter using a DS model-An application for HAWTs

    International Nuclear Information System (INIS)

    As wind turbine blades become larger there is a tendency for the blade torsional stiffness to reduce, producing the possibility of dynamic instability at moderate windspeeds. While linearised methods can assess the envelope of allowable blade properties for avoiding classical flutter with attached flow aerodynamics, wind turbine aerofoils can experience stalled flow. Therefore, it is necessary to explore the possible effects of stall-flutter on blade stability. This paper aims to address methods for judging the stability of blade designs during both attached flow and stalled flow behaviour. This paper covers the following areas: i) Attached flow model A Beddoes-Leishman indicial model is presented and the choice of coefficients is explained in the context of Theodorsen's theory for flat-plate aerofoils and experimental results by Beddoes and Leishman. Special attention is given to the differing dynamic behaviour of the pitching moment due to flapping motion, pitching motion and dynamically varying inflow. (ii) Classical flutter analysis The time domain attached flow model is verified against a linear flutter analysis by comparing time domain results for a 3D model of a representative multi-megawatt turbine blade, varying the position of the centre of mass along the chord. The results show agreement to within 6% for a range of flutter onset speeds. (iii) Dynamic stall model On entering the stalled region, damping of torsional motion of an aerofoil section can become negative. A dynamic stall model which encompasses the effects of trailing edge separation and leading edge vortex detachment is presented and validated against published experimental data. (iv) Stall flutter The resulting time domain model is used in simulations validating the prediction of reduced flutter onset for stalled aerofoils. Representative stalled conditions for a multi-megawatt wind turbine blade are investigated to assess the possible reduction in flutter speed. A maximum reduction of 17

  1. Modeling and experimental characterization of a fluttering windbelt for energy harvesting

    International Nuclear Information System (INIS)

    Wind energy harvesters based on fluttering offer a valuable and efficient alternative to the traditional wind turbines. A longer life expectancy and cheaper fabrication is attained through the absence of gears or bearings. This article presents the theoretical and experimental study of a novel windbelt-based energy harvester, designed to harvest from continuously changing low-speed winds. A theoretical model is derived to explore the scaling effect on the critical flutter frequency, and experimental results validate the theoretical predictions

  2. A preliminary theoretical flutter analysis of the JS1 glider / J.A. de Bruyn

    OpenAIRE

    De Bruyn, Jan Adriaan

    2004-01-01

    A preliminary theoretic flutter analysis of the new JS1 18m-class glider was performed by means of analytic methods. This analysis consisted of a detailed modal analysis using finite element modelling followed by the flutter prediction. The modal analysis was computed with the aid of the commercial FE-code ANSYS in which a model of the complete glider was generated. This model was created in such a way as to effectively simulate the composite characteristics, while also ensurin...

  3. Classical Flutter and Active Control of Wind Turbine Blade Based on Piezoelectric Actuation

    OpenAIRE

    Tingrui Liu

    2015-01-01

    The aim of this article is to analyze classical flutter and active control of single-cell thin-walled composite wind turbine blade beam based on piezoelectric actuation. Effects of piezoelectric actuation for classical flutter suppression on wind turbine blade beam subjected to combined transverse shear deformation, warping restraint effect, and secondary warping are investigated. The extended Hamilton’s principle is used to set up the equations of motion, and the Galerkin method is applied t...

  4. Stability analysis of nonlinear autonomous systems - General theory and application to flutter

    Science.gov (United States)

    Smith, L. L.; Morino, L.

    1975-01-01

    The analysis makes use of a singular perturbation method, the multiple time scaling. Concepts of stable and unstable limit cycles are introduced. The solution is obtained in the form of an asymptotic expansion. Numerical results are presented for the nonlinear flutter of panels and airfoils in supersonic flow. The approach used is an extension of a method for analyzing nonlinear panel flutter reported by Morino (1969).

  5. Nonlinear flutter wind tunnel test and numerical analysis of folding fins with freeplay nonlinearities

    OpenAIRE

    Yang Ning; Wang Nan; Zhang Xin; Liu Wei

    2016-01-01

    The flutter characteristics of folding control fins with freeplay are investigated by numerical simulation and flutter wind tunnel tests. Based on the characteristics of the structures, fins with different freeplay angles are designed. For a 0° angle of attack, wind tunnel tests of these fins are conducted, and vibration is observed by accelerometers and a high-speed camera. By the expansion of the connected relationships, the governing equations of fit for the nonlinear aeroelastic analysis ...

  6. Finite Element Simulation of Aerofoil Fluttering in Turbulent or Laminar Flow

    Czech Academy of Sciences Publication Activity Database

    Horáček, Jaromír; Sváček, P.; Feistauer, M.

    Taipei : Chinese Society of Mechanism and Machine Theory, 2015 - (Shuo Hung Chang) ISBN 978-986-04-6098-8. [IFToMM World Congress /14./. Taipei (TW), 25.10.2015-30.10.2015] R&D Projects: GA ČR(CZ) GAP101/11/0207 Institutional support: RVO:61388998 Keywords : aeroelasticity * flutter * post-flutter vibrations * RANS equations Subject RIV: BI - Acoustics http://www.iftomm2015.tw/IFToMM2015CD/PDF/OS19-002.pdf

  7. Aeroelastic flutter of feathers, flight and the evolution of non-vocal communication in birds.

    Science.gov (United States)

    Clark, Christopher J; Prum, Richard O

    2015-11-01

    Tonal, non-vocal sounds are widespread in both ordinary bird flight and communication displays. We hypothesized these sounds are attributable to an aerodynamic mechanism intrinsic to flight feathers: aeroelastic flutter. Individual wing and tail feathers from 35 taxa (from 13 families) that produce tonal flight sounds were tested in a wind tunnel. In the wind tunnel, all of these feathers could flutter and generate tonal sound, suggesting that the capacity to flutter is intrinsic to flight feathers. This result implies that the aerodynamic mechanism of aeroelastic flutter is potentially widespread in flight of birds. However, the sounds these feathers produced in the wind tunnel replicated the actual flight sounds of only 15 of the 35 taxa. Of the 20 negative results, we hypothesize that 10 are false negatives, as the acoustic form of the flight sound suggests flutter is a likely acoustic mechanism. For the 10 other taxa, we propose our negative wind tunnel results are correct, and these species do not make sounds via flutter. These sounds appear to constitute one or more mechanism(s) we call 'wing whirring', the physical acoustics of which remain unknown. Our results document that the production of non-vocal communication sounds by aeroelastic flutter of flight feathers is widespread in birds. Across all birds, most evolutionary origins of wing- and tail-generated communication sounds are attributable to three mechanisms: flutter, percussion and wing whirring. Other mechanisms of sound production, such as turbulence-induced whooshes, have evolved into communication sounds only rarely, despite their intrinsic ubiquity in ordinary flight. PMID:26385327

  8. Atrial ultrastructural changes during experimental atrial tachycardia depend on high ventricular rate

    NARCIS (Netherlands)

    Schoonderwoerd, BA; Ausma, J; Crijns, HJGM; Van Veldhuisen, DJ; Blaauw, EH; Van Gelder, IC

    2004-01-01

    Atrial Ultrastructural Remodeling. Introduction: Atrial structural and electrophysiologic changes occur during atrial tachycardia. The role of high ventricular rate in these processes remains to be established. Methods and Results: Six goats were subjected to 4 weeks of rapid atrioventricular (AV) p

  9. Kinetic mesh-free method for flutter prediction in turbomachines

    Indian Academy of Sciences (India)

    V Ramesh; S M Deshpande

    2014-02-01

    The present paper deals with the development and application of a kinetic theory-based mesh-free method for unsteady flows. The method has the capability to compute on any arbitrary distribution of moving nodes. In general, computation of unsteady flow past multiple moving boundaries using conventional finite volume solvers are quite involved. They invariably require repeated grid generation or an efficient grid movement strategy. This approach becomes more difficult when there are many moving boundaries. In the present work, we propose a simple and an effective node movement strategy for the mesh-free solver. This can tackle the unsteady problems with moving boundaries in a much easier way. Using the present method we have computed unsteady flow in oscillating turbomachinery blades. A simple energy method has been used to predict flutter using the unsteady computations. The results compare well with the available experiments and other computations.

  10. Flutter of rods with artificial roughness in axial flow

    International Nuclear Information System (INIS)

    The experimental investigation results on the vibration characteristics of the rods with artificial roughness in the axial flow are presented. It is shown that the roughness plays an important role in the mechanism of vibrations excitation. For the rods having artificial roughness with a relative size of 0.075+0.2 the phenomenon of dynamic instability has been revealed at the flowrates being by the order of magnitude smaller than those predicted by the Paidoussis theory. It is experimentally obtained that for the rods similar to those used as a nuclear reactor fuel element and heat exchanger tubes the critical velocities resulting in the vibration amplitude increase by the one or two order of magnitude are the values as much as 6-12 m/s. It is shown that the phenomenon revealed differs from a classic flutter by a number of attributes. (author)

  11. Supersonic flutter analysis of thin cracked functionally graded material plates

    CERN Document Server

    Natarajan, S; Bordas, S

    2012-01-01

    In this paper, the flutter behaviour of simply supported square functionally graded material plates immersed in a supersonic flow is studied. An enriched 4-noded quadrilateral element based on field consistency approach is used for this study and the crack is modelled independent of the underlying mesh. The material properties are assumed to be temperature dependent and graded only in the thickness direction. The effective material properties are estimated using the rule of mixtures. The formulation is based on the first order shear deformation theory and the shear correction factors are evaluated employing the energy equivalence principle. The influence of the crack length, the crack orientation, the flow angle and the gradient index on the aerodynamic pressure and the frequency are numerically studied. The results obtained here reveal that the critical frequency and the critical pressure decreases with increase in crack length and it is minimum when the crack is aligned to the flow angle.

  12. Left Atrial Appendage Exclusion for Stroke Prevention in Atrial Fibrillation

    OpenAIRE

    Patel, Taral K.; Yancy, Clyde W; Knight, Bradley P.

    2012-01-01

    The public health burden of atrial fibrillation (AF) and associated thromboembolic stroke continues to grow at alarming rates. AF leads to a fivefold increase in the risk of stroke. Therefore, stroke prevention remains the most critical aspect of AF management. Current standard of care focuses on oral systemic anticoagulation, most commonly with warfarin and now with newer agents such as dabigatran, rivaroxaban, and apixaban. However, the challenges and limitations of oral anticoagulation hav...

  13. Low atrial septum pacing in pacemaker patients

    OpenAIRE

    Voogt, Willem Gijsbert de

    2006-01-01

    In patients with an indication for anti bradycardia pacing, atrial fibrillation (AF) is a common arrhythmia (30-50%) even in the absence of atrial tachy arrhythmias before pacemaker implantation. Pace prevention and pace intervention for atrial tachy arrhythmias could be an interesting adjuvant treatment in the prevention of the arrhythmia related complications. These treatment modalities when available in pacemaker systems could come at a relative low cost as the indication for pacemaker imp...

  14. Almanac 2015: atrial fibrillation research in Heart.

    Science.gov (United States)

    Jawad-Ul-Qamar, Muhammad; Kirchhof, Paulus

    2016-04-15

    Atrial fibrillation continues to attract interest in the cardiovascular community and inHeart Over 60 original research and review papers published inHeartin 2014-2015 cover various aspects of atrial fibrillation, from associated conditions and precipitating factors to new approaches to management. Here, we provide an overview of articles on atrial fibrillation published inHeartin 2014-2015, highlighting new developments, emerging concepts and novel approaches to treatment. PMID:26791994

  15. Minimally Invasive Surgical Therapies for Atrial Fibrillation

    OpenAIRE

    Chu, Michael W.A.; Yoshitsugu Nakamura; Bob Kiaii

    2012-01-01

    Atrial fibrillation is the most common sustained arrhythmia and is associated with significant risks of thromboembolism, stroke, congestive heart failure, and death. There have been major advances in the management of atrial fibrillation including pharmacologic therapies, antithrombotic therapies, and ablation techniques. Surgery for atrial fibrillation, including both concomitant and stand-alone interventions, is an effective therapy to restore sinus rhythm. Minimally invasive surgical ablat...

  16. Postoperative atrial fibrillation, oxidative stress, and inflammation

    OpenAIRE

    ÖZAYDIN, Mehmet

    2011-01-01

    Postoperative atrial fibrillation is the most common complication of cardiac surgery. It is associated with increased complication rates. Recent trials have suggested that inflammation and oxidative stress have key roles in the pathophysiology of atrial fibrillation. Current evidence evaluating the use of antiinflammatory and antioxidant agents, including statins, corticosteroids, N-acetylcysteine, vitamin C, and fish oil, to prevent postoperative atrial fibrillation is promising. However, la...

  17. Implementation of antithrombotic management in atrial fibrillation

    OpenAIRE

    Lairikyengbam, S; Davies, A; Jones, P.

    2000-01-01

    The aim of the study was to assess the extent to which published recommendations on the antithrombotic management of atrial fibrillation had been adopted into clinical practice in a busy district general hospital, and the impact of clinical audit on subsequent management. In the initial audit, 185 consecutive patients with atrial fibrillation were studied using their case notes to identify any further clinical risk factors for stroke. A management algorithm stratified patients with atrial fib...

  18. Sensitivity Analysis of Flutter Response of a Wing Incorporating Finite-Span Corrections

    Science.gov (United States)

    Issac, Jason Cherian; Kapania, Rakesh K.; Barthelemy, Jean-Francois M.

    1994-01-01

    Flutter analysis of a wing is performed in compressible flow using state-space representation of the unsteady aerodynamic behavior. Three different expressions are used to incorporate corrections due to the finite-span effects of the wing in estimating the lift-curve slope. The structural formulation is based on a Rayleigh-Pitz technique with Chebyshev polynomials used for the wing deflections. The aeroelastic equations are solved as an eigen-value problem to determine the flutter speed of the wing. The flutter speeds are found to be higher in these cases, when compared to that obtained without accounting for the finite-span effects. The derivatives of the flutter speed with respect to the shape parameters, namely: aspect ratio, area, taper ratio and sweep angle, are calculated analytically. The shape sensitivity derivatives give a linear approximation to the flutter speed curves over a range of values of the shape parameter which is perturbed. Flutter and sensitivity calculations are performed on a wing using a lifting-surface unsteady aerodynamic theory using modules from a system of programs called FAST.

  19. Flutter Instability Speeds of Guided Splined Disks: An Experimental and Analytical Investigation

    Directory of Open Access Journals (Sweden)

    Ahmad Mohammadpanah

    2015-01-01

    Full Text Available “Guided splined disks” are defined as flat thin disks in which the inner radius of the disk is splined and matches a splined arbor that provides the driving torque for rotating the disk. Lateral constraint for the disk is provided by space fixed guide pads. Experimental lateral displacement of run-up tests of such a system is presented, and the flutter instability zones are identified. The results indicate that flutter instability occurs at speeds when a backward travelling wave of a mode meets a reflected wave of a different mode. Sometimes, the system cannot pass a flutter zone, and transverse vibrations of the disk lock into that flutter instability zone. The governing linear equations of transverse motion of such a spinning disk, with assumed free inner and outer boundary conditions, are derived. A lateral constraint is introduced and modeled as a linear spring. Rigid body translational and tilting degrees of freedom are included in the analysis of the total motion of the spinning disk. The eigenvalues of the system are computed numerically, and the flutter instability zones are defined. The results show that the mathematical model can predict accurately the flutter instability zones measured in the experimental tests.

  20. Fluid Structural Modal Coupled Numerical Investigation of Transonic Fluttering Of Axial Flow Compressor Blades

    Directory of Open Access Journals (Sweden)

    Rio Melvin Aro.T

    2015-05-01

    Full Text Available Flutter is an unstable oscillation which can lead to destruction. Flutter can occur on fixed surfaces, such as blades, wing or the stabilizer. By self-excited aeroelastic instability, flutter can lead to mechanical or structural failure of aircraft engine blades. The modern engines have been designed with increased pressure ratio and reduced weight in order to improve aerodynamic efficiency, resulting in severe aeroelastic problems. Particularly flutter in axial compressors with transonic flow can be characterized by a number of aerodynamic nonlinear effects such as shock boundary layer interaction, rotating stall, and tip vortex instability. Rotating blades operating under high centrifugal forces may also encounter structural nonlinearities due to friction damping and large deformations. In the future work a standard axial flow compressor blade will be taken for analysis, both Subsonic and Transonic range are taken for analysis. Fluid and Structure are two different domains which will be coupled by full system coupling technique to predict the fluttering effect on the compressor blade. ANSYS is a commercial simulation tool, which will be deployed in this work to perform FSI (Fluid Structure Interaction and FSI coupled Modal to predict the flutter in the compressor blades

  1. Automated preliminary design of simplified wing structures to satisfy strength and flutter requirements

    Science.gov (United States)

    Stroud, W. J.; Dexter, C. B.; Stein, M.

    1972-01-01

    A simple structural model of an aircraft wing is used to show the effects of strength (stress) and flutter requirements on the design of minimum-weight aircraft-wing structures. The wing is idealized as an isotropic sandwich plate with a variable cover thickness distribution and a variable depth between covers. Plate theory is used for the structural analysis, and piston theory is used for the unsteady aerodynamics in the flutter analysis. Mathematical programming techniques are used to find the minimum-weight cover thickness distribution which satisfies flutter, strength, and minimum-gage constraints. The method of solution, some sample results, and the computer program used to obtain these results are presented. The results indicate that the cover thickness distribution obtained when designing for the strength requirement alone may be quite different from the cover thickness distribution obtained when designing for either the flutter requirement alone or for both the strength and flutter requirements concurrently. This conclusion emphasizes the need for designing for both flutter and strength from the outset.

  2. Aspirin Often Wrongly Prescribed for Atrial Fibrillation

    Science.gov (United States)

    ... page: https://medlineplus.gov/news/fullstory_159459.html Aspirin Often Wrongly Prescribed for Atrial Fibrillation Blood thinners -- not aspirin -- dramatically cut the risk of stroke, researchers say ...

  3. Present treatment options for atrial fibrillation

    OpenAIRE

    Lairikyengbam, S; Anderson, M.,; Davies, A

    2003-01-01

    Atrial fibrillation is the commonest sustained cardiac arrhythmia. It accounts for >35% of all hospital admissions for cardiac arrhythmias in the United States. The presence of atrial fibrillation increases the mortality of a population by up to twofold. The risk of stroke increases from 1.5% in patients with atrial fibrillation from 50–59 years of age to up to 23.5% for such patients aged 80–89 years. Although the diagnosis of atrial fibrillation is usually straightforward, effective treatme...

  4. Atrial Fibrillation and Colonic Neoplasia in African Americans.

    Directory of Open Access Journals (Sweden)

    Mehdi Nouraie

    Full Text Available Colorectal cancer (CRC and atrial fibrillation/flutter (AF share several risk factors including increasing age and obesity. However, the association between CRC and AF has not been thoroughly examined, especially in African Americans. In this study we aimed to assess the prevalence of AF and its risk factors in colorectal neoplasia in an African American.We reviewed records of 527 African American patients diagnosed with CRC and 1008 patients diagnosed with benign colonic lesions at Howard University Hospital from January 2000 to December 2012. A control group of 731 hospitalized patients without any cancer or colonic lesion were randomly selected from the same time and age range, excluding patients who had diagnosis of both CRC and/or adenoma. The presence or absence of AF was based upon ICD-9 code documentation. The prevalence of AF in these three groups was compared by multivariate logistic regression.The prevalence of AF was highest among CRC patients (10% followed by adenoma patients (7.2% then the control group (5.4%, P for trend = 0.002. In the three groups of participants, older age (P<0.008 and heart failure (P<0.001 were significantly associated with higher risk of AF. After adjusting for these risk factors, CRC (OR: 1.4(95%CI:0.9-2.2, P = 0.2 and adenoma (OR: 1.1(95%CI:0.7-1.6, P = 0.7 were not significantly associated AF compared to control group.AF is highly prevalent among CRC patients; 1 in 10 patients had AF in our study. The predictors of AF in CRC was similar to that in adenoma and other patients after adjustment for potential confounders suggesting that the increased AF risk in CRC is explained by higher prevalence of AF risk factors.

  5. Atrial fibrillation: inflammation in disguise?

    Science.gov (United States)

    Lappegård, K T; Hovland, A; Pop, G A M; Mollnes, T E

    2013-08-01

    Atrial fibrillation is highly prevalent, and affected patients are at an increased risk of a number of complications, including heart failure and thrombo-embolism. Over the past years, there has been increasing interest in the role of inflammatory processes in atrial fibrillation, from the first occurrence of the arrhythmia to dreaded complications such as strokes or peripheral emboli. As the standard drug combination which aims at rate control and anticoagulation only offers partial protection against complications, newer agents are needed to optimize treatment. In this paper, we review recent knowledge regarding the impact of inflammation on the occurrence, recurrence, perpetuation and complications of the arrhythmia, as well as the role of anti-inflammatory therapies in the treatment for the disease. PMID:23672430

  6. Mapping Atrial Fibrillation: 2015 Update

    OpenAIRE

    Chirag R. Barbhayia; Saurabh Kumar; Gregory F. Michaud

    2015-01-01

    Atrial fibrillation requires a trigger that initiates the arrhythmia and substrate that favors perpetuation. Cardiac mapping is necessary to locate triggers and substrate so that an ablation strategy can be optimized. The most commonly used cardiac mapping approach is isochronal or activation mapping, which aims to create a spatial model of electrical wavefront propagation. Historically, activation mapping has been successful for mapping point source and single or double wave reentrant arr...

  7. Atrial fibrillation care improvement collaborative

    OpenAIRE

    Robelia, Paul; Kopecky, Stephen; Thacher, Tom

    2015-01-01

    Atrial fibrillation (AF) is an increasingly common cardiac arrhythmia. Many patients with new onset or recurrent AF present to the emergency department and are subsequently admitted to the hospital and seen by cardiology specialists for follow up. In an attempt to address this high utilization of acute health care resources, reduce costs, and improve patient care, our institution instituted a collaborative project between the departments of emergency medicine, cardiology, family medicine, and...

  8. Atrial fibrillation in the elderly

    Institute of Scientific and Technical Information of China (English)

    Roger Kerzner; Michael W. Rich

    2005-01-01

    Atrial fibrillation (AF) is an extremely common condition in the elderly, with increasing prevalence around the world as the population ages. AF may be associated with serious health consequences, including stroke, heart failure, and decreased quality of life, so that careful management of AF by geriatric health care providers is required. With careful attention to anticoagulation therapy, and prudent use of medications and invasive procedures to minimize symptoms, many of the adverse health consequences of AF can be prevented.

  9. Atrial tumors in cardiac MRI

    International Nuclear Information System (INIS)

    Cardiac magnetic resonance imaging (MRI) is an important tool for the diagnosis of cardiac masses. Various cardiac tumors are predisposed to occurring in atrial structures. The aim of this review article is the description of atrial tumors and their morphological features in MRI. In general, cardiac tumors are rare: approximately 0.001-0.03% in autopsy studies. About 75% of them are benign. The most common cardiac tumor is the myxoma. They are predisposed to occur in the atria and show a characteristically strong hyperintense signal on T2-wieghted images in MRI. In other sequences a heterogeneous pattern reflects its variable histological appearance. Lipomas exhibit a signal behavior identical to fatty tissue with a typical passive movement in cine imaging. Fibroelastomas are the most common tumors of the cardiac valves. Consisting of avascular fibrous tissue, they often present with hypointense signal intensities. Thrombi attached to their surface can cause severe emboli even in small tumors. Amongst primary cardiac malignancies, sarcomas are most common and favor the atria. Secondary malignancies of the heart are far more common than primary ones (20-40 times). In case of known malignancies, approximately 10% of patients develop cardiac metastasis at the end of their disease. Lymphogenic metastases favor the pericardium, while hematogenic spread prefers the myocardium. Since they are not real atrial tumors, thrombi and anatomical structures of the atria have to be differentiated from other pathologies. (orig.)

  10. Atrial fibrillation after cardiac surgery

    Directory of Open Access Journals (Sweden)

    Nair Suresh

    2010-01-01

    Full Text Available Once considered as nothing more than a nuisance after cardiac surgery, the importance of postoperative atrial fibrillation (POAF has been realized in the last decade, primarily because of the morbidity associated with the condition. Numerous causative factors have been described without any single factor being singled out as the cause of this complication. POAF has been associated with stroke, renal failure and congestive heart failure, although it is difficult to state whether POAF is directly responsible for these complications. Guidelines have been formulated for prevention of POAF. However, very few cardiothoracic centers follow any form of protocol to prevent POAF. Routine use of prophylaxis would subject all patients to the side effects of anti-arrhythmic drugs, while only a minority of the patients do actually develop this problem postoperatively. Withdrawal of beta blockers in the postoperative period has been implicated as one of the major causes of POAF. Amiodarone, calcium channel blockers and a variety of other pharmacological agents have been used for the prevention of POAF. Atrial pacing is a non-pharmacological measure which has gained popularity in the prevention of POAF. There is considerable controversy regarding whether rate control is superior to rhythm control in the treatment of established atrial fibrillation (AF. Amiodarone plays a central role in both rate control and rhythm control in postoperative AF. Newer drugs like dronedarone and ranazoline are likely to come into the market in the coming years.

  11. Physics-Based Identification, Modeling and Risk Management for Aeroelastic Flutter and Limit-Cycle Oscillations (LCO) Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The proposed research program will develop a physics-based identification, modeling and risk management infrastructure for aeroelastic transonic flutter and...

  12. Changes in plasma atrial natriuretic factor in patients with idiopathic atrial fibrillation

    International Nuclear Information System (INIS)

    To observe the changes in plasma atrial natriuretic factor (AFN) in patients with idiopathic atrial fibrillation and investigate its mechanism, plasma ANF, platelet count and hematocrit were detected in 21 cases with transient idiopathic atrial fibrillation (group A, A1 representing attack, while A2 termination), 28 with persistent idiopathic atrial fibrillation (group B), 27 suffered from rheumatic heart disease with mitral stenosis and persistent atrial fibrillation (group C), 32 with transient supraventricular tachycardia (group D) and 20 normal controls (group E). It was found that the level of ANF was significantly higher in patients with attacking transient idiopathic atrial fibrillation than that in group A2, D and E (P 0.05), while there was significant difference in hematocrit in group A1 compared with group A2, D, E (P < 0.01). It suggested that ANF and hematocrit play an important role in the attack of idiopathic atrial fibrillation

  13. A novel and simple atrial retractor.

    Science.gov (United States)

    Kofidis, Theo; Lee, Chuen Neng

    2011-05-01

    Minimally invasive cardiac operations require specialized equipment. Atrial retractors are a frequently used tool to expose heart valves for minimally invasive and open procedures. The models currently available in the market are efficient; however, they may be complex, bulky, or expensive. We introduce a novel, very simple atrial retractor we designed using ubiquitously available materials. PMID:21524488

  14. Refractory atrial fibrillation effectively treated with ranolazine

    OpenAIRE

    Vaishnav, Aditi; Vaishnav, Avani; Lokhandwala, Yash

    2014-01-01

    Atrial fibrillation is the most common sustained cardiac arrhythmia which is often troublesome to manage. Currently, rhythm and rate control medications are the mainstays of therapy. In 2 amiodarone-refractory highly symptomatic patients, an innovative approach using ranolazine, which selectively acts on Na+ channels and delays atrial depolarization, was tried successfully.

  15. PAROXYSMAL ATRIAL FIBRILLATION: CHOICE OF CARDIOVERSION THERAPY

    Directory of Open Access Journals (Sweden)

    B. A. Tatarskii

    2015-12-01

    Full Text Available Characteristics and classification of different patterns of paroxysmal atrial fibrillation are presented. Main indications to restoration of sinus rhythm are discussed. The features of main medications used to terminate of atrial fibrillation are given. The choice of antiarrhythmic drug is considerate. Necessity of individual approach to therapy tactics is proved.

  16. Blocked atrial bigeminy presenting with bradycardia.

    Science.gov (United States)

    Akdeniz, Celal; Tanidir, Ibrahim Cansaran; Tuzcu, Volkan

    2012-01-01

    Blocked premature atrial contractions can cause bradycardia by resetting sinoatrial node and prolonging the RR intervals. Herein, we report the management of a patient with frequent premature atrial contractions in bigeminal pattern. The patient presented with symptomatic bradycardia and was successfully treated with propafenone. PMID:22469245

  17. Galectin-3 in patients undergoing ablation of atrial fibrillation

    Directory of Open Access Journals (Sweden)

    Nicolas Clementy

    2014-11-01

    Conclusions: Persistent type of atrial fibrillation is an independent predictor of higher Galectin-3 concentration. This biomarker of fibrosis may be implied in the mechanisms of atrial remodeling and maintenance of atrial fibrillation, and thus be helpful for the design of therapeutic strategy in patients with atrial fibrillation.

  18. Aliskiren protecting atrial structural remodeling from rapid atrial pacing in a canine model.

    Science.gov (United States)

    Zhao, Zhiqiang; Chen, Yan; Li, Weimin; Wang, Xinghua; Li, Jian; Yang, Wansong; Cheng, Lijun; Liu, Tong; Liu, Enzhao; Li, Guangping

    2016-08-01

    Atrial fibrillation (AF) contributing to the increasing mortality risk is the most common disease in clinical practice. Owing to the side effects and relative inefficacy of current antiarrhythmic drugs, some research focuses on renin-angiotensin-aldosterone system (RAS) for finding out the new treatment of AF. The purpose of this study is to confirm whether aliskiren as a proximal inhibitor of renin, which completely inhibits RAS, has beneficial effects on atrial structural remodeling in AF. In this study, rapid atrial pacing was induced at 500 beats per minute for 2 weeks in a canine model. A different dose of aliskiren was given orally for 2 weeks before rapid atrial pacing. HE staining and Masson's staining were used for analysis of myocardial fibrosis. TGF-β1, signal pathways, and pro-inflammatory cytokines were shown for the mechanism of structural remodeling after the treatment of aliskiren. Serious atrial fibrosis was induced by rapid atrial pacing, followed by the elevated TGF-β1, upregulated MEK and ERK1/2, and increased inflammatory factors. Aliskiren could apparently improve myocardial fibrosis by reducing the expression of TGF-β1, inhibiting MEK and ERK1/2 signal pathways, and decreasing IL-18 and TLR4 in both serum and atrial tissue. In conclusion, aliskiren could prevent atrial structural remodeling from rapid atrial pacing for 2 weeks. Aliskiren may play a potential beneficial role in the treatment of AF induced by rapid atrial pacing. PMID:27118660

  19. T-tail flutter: Potential-flow modelling, experimental validation and flight tests

    Science.gov (United States)

    Murua, Joseba; Martínez, Pablo; Climent, Héctor; van Zyl, Louw; Palacios, Rafael

    2014-11-01

    Flutter of T-tail configurations is caused by the aeroelastic coupling between the vertical fin and the horizontal stabiliser. The latter is mounted on the fin instead of the fuselage, and hence the arrangement presents distinct characteristics compared to other typical empennage setups; specifically, T-tail aeroelasticity is governed by inplane dynamics and steady aerodynamic loading, which are typically not included in flutter clearance methodologies based on the doublet lattice method. As the number of new aircraft featuring this tail configuration increases, there is a need for precise understanding of the phenomenon, appropriate tools for its prediction, and reliable benchmarking data. This paper addresses this triple challenge by providing a detailed explanation of T-tail flutter physics, describing potential-flow modelling alternatives, and presenting detailed numerical and experimental results to compensate for the shortage of reproducible data in the literature. A historical account of the main milestones in T-tail aircraft development is included, followed by a T-tail flutter research review that emphasises the latest contributions from industry as well as academia. The physical problem is dissected next, highlighting the individual and combined effects that drive the phenomenon. Three different methodologies, all based on potential-flow aerodynamics, are considered for T-tail subsonic flutter prediction: (i) direct incorporation of supplementary T-tail effects as additional terms in the flutter equations; (ii) a generalisation of the boundary conditions and air loads calculation on the double lattice; and (iii) a linearisation of the unsteady vortex lattice method with arbitrary kinematics. Comparison with wind-tunnel experimental results evidences that all three approaches are consistent and capture the key characteristics in the T-tail dynamics. The validated numerical models are then exercised in easy-to-duplicate canonical test cases. These

  20. Differential gene expression during atrial structural remodeling in human left and right atrial appendages in atrial fibrillation

    Institute of Scientific and Technical Information of China (English)

    Hui Zhu; Wei Zhang; Ming Zhong; Gong Zhang; Yun Zhang

    2011-01-01

    Extracellular matrix (ECM) remodeling increases the vulnerability to atrial fibrillation (AF). Some gene expressions are crucial for the metabolism of ECM. The left atrium plays an important role in maintaining AF.However, most studies investigated only the right atrial tissue. We therefore chose human tissue samples from both the left and right atrial to detect the different gene expressions during structural remodeling in AF. The atrial appendages tissue samples from 24 patients with chronic AF and 12 patients with sinus rhythm were obtained when they were undergoing mitral/aortic valve replacement operation. The mRNA levels of matrix metalloproteinases-9 (MMP-9), tissue inhibitor of metalloproteinase-1 (TIMP-1), disintegrin, metalloproteases-15, and integrins β1 were determined by reverse transcriptionpolymerase chain reaction (RT-PCR). in AF group, the level of MMP-9 in left atrial appendage (LAA) was increased (P<0.001), while integrin β1 level was decreased (P< 0.05) compared with those expressed in right atrial appendage (RAA) tissue. The levels of disintegrin, metalloproteinases-15, and TIMP-1 genes in the LAA and RAA had no significant differences. The results demonstrated that the gene expressions in the LAA and RAA are different during AF, which implied that the mechanism of atrial structural remodeling in AF is due to multiple sources and is complicated.

  1. Towards Low Energy Atrial Defibrillation.

    Science.gov (United States)

    Walsh, Philip; Kodoth, Vivek; McEneaney, David; Rodrigues, Paola; Velasquez, Jose; Waterman, Niall; Escalona, Omar

    2015-01-01

    A wireless powered implantable atrial defibrillator consisting of a battery driven hand-held radio frequency (RF) power transmitter (ex vivo) and a passive (battery free) implantable power receiver (in vivo) that enables measurement of the intracardiac impedance (ICI) during internal atrial defibrillation is reported. The architecture is designed to operate in two modes: Cardiac sense mode (power-up, measure the impedance of the cardiac substrate and communicate data to the ex vivo power transmitter) and cardiac shock mode (delivery of a synchronised very low tilt rectilinear electrical shock waveform). An initial prototype was implemented and tested. In low-power (sense) mode, >5 W was delivered across a 2.5 cm air-skin gap to facilitate measurement of the impedance of the cardiac substrate. In high-power (shock) mode, >180 W (delivered as a 12 ms monophasic very-low-tilt-rectilinear (M-VLTR) or as a 12 ms biphasic very-low-tilt-rectilinear (B-VLTR) chronosymmetric (6ms/6ms) amplitude asymmetric (negative phase at 50% magnitude) shock was reliably and repeatedly delivered across the same interface; with >47% DC-to-DC (direct current to direct current) power transfer efficiency at a switching frequency of 185 kHz achieved. In an initial trial of the RF architecture developed, 30 patients with AF were randomised to therapy with an RF generated M-VLTR or B-VLTR shock using a step-up voltage protocol (50-300 V). Mean energy for successful cardioversion was 8.51 J ± 3.16 J. Subsequent analysis revealed that all patients who cardioverted exhibited a significant decrease in ICI between the first and third shocks (5.00 Ω (SD(σ) = 1.62 Ω), p power transfer and sensing of ICI during cardioversion are evidenced as key to the advancement of low-energy atrial defibrillation. PMID:26404298

  2. A Study on Aeroelastic Flutter Suppression and its Control Measures –Past and Future

    Directory of Open Access Journals (Sweden)

    Bruce Ralphin Rose J

    2014-05-01

    Full Text Available In a cruising mission, an airplane wing is subject to intense dynamic pressure changes with different magnitudes. The variable pressures exerted on the wing geometry will cause the redundant vibrations by flutter effect. The unkind Aeroelastic instabilities have an influence on the airplane performance and its structural life to a large extend. To overcome the instabilities, (particularly flutter modes an Active Flutter Suppression (AFS technique has been proposed during the year of 2002. In this review article, the contributions of different researchers in the field of AFS over the years are investigated. Mathematical models for various control designs provided are capable enough to link the response of wing structures against the oncoming airflow. It includes the structural and fluid dynamic properties required to design an active control to capture the effects of flutter frequency. Mass balancing and stiffness enhancement with control systems are the different methods available to implement AFS. In the critical flutter speed, the non linear characters play a vital role in the view of complex systems design and accuracy. Consequently, with the aid mass balancing, the non linear effects such as Limit Cycle Oscillations (LCO, baggy control system linkages and Internal Resonance are eliminated or reduced. Therefore, for increased airplane performance and efficiency, AFS is a key approach in the field of unconventional aeroelasticity.

  3. Flutter performance of bend-twist coupled large-scale wind turbine blades

    Science.gov (United States)

    Hayat, Khazar; de Lecea, Alvaro Gorostidi Martinez; Moriones, Carlos Donazar; Ha, Sung Kyu

    2016-05-01

    The bend-twist coupling (BTC) is proven to be effective in mitigating the fatigue loads for large-scale wind turbine blades, but at the same time it may cause the risk of flutter instability. The BTC is defined as a feature of twisting of the blade induced by the primary bending deformation. In the classical flutter, the BTC arises from the aerodynamic loads changing with the angle of attack. In this study, the effects of the structural BTC on the flutter are investigated by considering the layup unbalances (ply angle, material and thickness of the composite laminates) in the NREL 5-MW wind turbine rotor blade of glass fiber/epoxy [02/+45/-45]S laminates. It is numerically shown that the flutter speed may decrease by about 5 percent with unbalanced ply-angle only (one side angle, from 45° to 25°). It was then demonstrated that the flutter performance of the wind turbine blade can be increased by using lighter and stiffer carbon fibers which ensures the higher structural BTC at the same time.

  4. Flight test of a decoupler pylon for wing/store flutter suppression

    Science.gov (United States)

    Cazier, F. W., Jr.; Kehoe, M. W.

    1986-01-01

    The decoupler pylon is a NASA concept of passive wing-store flutter suppression achieved by providing a low store-pylon pitch frequency. Flight tests were performed on an F-16 aircraft carrying on each wing an AIM-9J wingtip missile, a GBU-8 bomb near midspan, and an external fuel tank. Baseline flights with the GBU-8 mounted on a standard pylon established that this configuration is characterized by an antisymmetric limited amplitude flutter oscillation within the operational envelope. The airplane was then flown with the GBU-8 mounted on the decoupler pylon. The decoupler pylon successfully suppressed wing-store flutter throughout the flight envelope. A 37-percent increase in flutter velocity over the standard pylon was demonstrated. Maneuvers with load factors to 4g were performed. Although the static store displacements during maneuvers were not sufficiently large to be of concern, a store pitch alignment system was tested and performed successfully. One GBU-8 was ejected demonstrating that weapon separation from the decoupler pylon is normal. Experience with the present decoupler pylon design indicated that friction in the pivoting mechanism could affect its proper functioning as a flutter suppressor.

  5. Automated procedure for design of wing structures to satisfy strength and flutter requirements

    Science.gov (United States)

    Haftka, R. T.

    1973-01-01

    A pilot computer program was developed for the design of minimum mass wing structures under flutter, strength, and minimum gage constraints. The wing structure is idealized by finite elements, and second-order piston theory aerodynamics is used in the flutter calculation. Mathematical programing methods are used for the optimization. Computation times during the design process are reduced by three techniques. First, iterative analysis methods used to reduce significantly reanalysis times. Second, the number of design variables is kept small by not using a one-to-one correspondence between finite elements and design variables. Third, a technique for using approximate second derivatives with Newton's method for the optimization is incorporated. The program output is compared witH previous published results. It is found that some flutter characteristics, such as the flutter speed, can display discontinous dependence on the design variables (which are the thicknesses of the structural elements). It is concluded that it is undesirable to use such quantities in the formulation of the flutter constraint.

  6. Current Issues in Atrial Fibrillation

    OpenAIRE

    Khaykin, Yaariv; Shamiss, Yana

    2012-01-01

    Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia. It places an enormous burden on the patients, caregivers, and the society at large. While the main themes in the care of an AF patient have not changed over the years and continue to focus on stroke prevention, control of the ventricular, rate and rhythm maintenance, there have been a number of new developments in each of these realms. This paper will discuss the “hot” topics in AF in 2012 including new and upcoming med...

  7. Vorticity Transport on a Flexible Wing in Stall Flutter

    Science.gov (United States)

    Akkala, James; Buchholz, James; Farnsworth, John; McLaughlin, Thomas

    2014-11-01

    The circulation budget within dynamic stall vortices was investigated on a flexible NACA 0018 wing model of aspect ratio 6 undergoing stall flutter. The wing had an initial angle of attack of 6 degrees, Reynolds number of 1 . 5 ×105 and large-amplitude, primarily torsional, limit cycle oscillations were observed at a reduced frequency of k = πfc / U = 0 . 1 . Phase-locked stereo PIV measurements were obtained at multiple chordwise planes around the 62.5% and 75% spanwise locations to characterize the flow field within thin volumetric regions over the suction surface. Transient surface pressure measurements were used to estimate boundary vorticity flux. Recent analyses on plunging and rotating wings indicates that the magnitude of the pressure-gradient-driven boundary flux of secondary vorticity is a significant fraction of the magnitude of the convective flux from the separated leading-edge shear layer, suggesting that the secondary vorticity plays a significant role in regulating the strength of the primary vortex. This phenomenon is examined in the present case, and the physical mechanisms governing the growth and evolution of the dynamic stall vortices are explored. This work was supported by the Air Force Office of Scientific Research through the Flow Interactions and Control Program monitored by Dr. Douglas Smith, and through the 2014 AFOSR/ASEE Summer Faculty Fellowship Program (JA and JB).

  8. Transition from Flutter to Tumble: Observations of a Falling Lamina

    Science.gov (United States)

    Belmonte, A.; Eisenberg, H.; Moses, E.

    1996-11-01

    We present an experimental study of a rigid thin strip (lamina) freely falling through a fluid confined in a two-dimensional vertical cell. We observe the asymptotic motion of laminae with a range of lengths and masses, using water, glycerol, or petroleum ether. We find that a well-defined transition from side-to-side motion (fluttering) to end-over-end motion (tumbling) occurs as a function of a dimensionless control parameter, the Froude number Fr. The motion does not depend on the fluid viscosity: the mean velocity of falling is determined by the pressure drag, which depends on the fluid density. The Froude number is given by the ratio of timescales characterizing the pendular motion of the lamina and the generation of lift. The transition is at Frc = 0.64 ± 0.03, above which tumbling occurs. Comparison is made with the transition to running or galloping in animals. Visualization using suspended alumina particles shows that a vortex is shed at each side-to-side excursion of the lamina, producing a zig-zag wake.

  9. Time simulation of flutter with large stiffness changes

    Science.gov (United States)

    Karpel, Mordechay; Wieseman, Carol D.

    1992-01-01

    Time simulation of flutter, involving large local structural changes, is formulated with a state-space model that is based on a relatively small number of generalized coordinates. Free-free vibration modes are first calculated for a nominal finite-element model with relatively large fictitious masses located at the area of structural changes. A low-frequency subset of these modes is then transformed into a set of structural modal coordinates with which the entire simulation is performed. These generalized coordinates and the associated oscillatory aerodynamic force coefficient matrices are used to construct an efficient time-domain, state-space model for a basic aeroelastic case. The time simulation can then be performed by simply changing the mass, stiffness, and damping coupling terms when structural changes occur. It is shown that the size of the aeroelastic model required for time simulation with large structural changes at a few apriori known locations is similar to that required for direct analysis of a single structural case. The method is applied to the simulation of an aeroelastic wind-tunnel model. The diverging oscillations are followed by the activation of a tip-ballast decoupling mechanism that stabilizes the system but may cause significant transient overshoots.

  10. Flutter Viscoelastic of a Cylindrical Shells taking into Account of a Boundary Layer in a Flow of Gas

    Directory of Open Access Journals (Sweden)

    Khudayarov B. A.

    2010-09-01

    Full Text Available In this work is investigated the flutter of visco-elastic cylindrical shells streamlined by gas current. The basic direction of work is consisted in taking into account of visco-elastic material’s properties at supersonic speeds. Critical speeds for shell flutter are defined.

  11. Flutter Viscoelastic of a Cylindrical Shells taking into Account of a Boundary Layer in a Flow of Gas

    OpenAIRE

    Khudayarov B.A.

    2010-01-01

    In this work is investigated the flutter of visco-elastic cylindrical shells streamlined by gas current. The basic direction of work is consisted in taking into account of visco-elastic material’s properties at supersonic speeds. Critical speeds for shell flutter are defined.

  12. Treatment of atrial fibrillation. Part II. Current realities and future prospects.

    Directory of Open Access Journals (Sweden)

    Bockeria L.A.

    Full Text Available Atrial fibrillation (AF is one of the most common arrhythmias in the world. It causes serious disturbances in cardiac hemodynamics and is dangerous because of its life-threatening consequences. The problem of treatment of AF is one the main and discussed problems in contemporary arrhythmology and cardiac surgery. Nowadays there are a lot of methods of treatment of atrial fibrillation, but their effectiveness and indications to them need a detailed analysis. Strategies of conservative therapy of AF help us to achieve sinus rhythm only in 50% cases. That's why the question of searching more effective surgical methods was obvious. First attempts in surgical treatment were made in 1980s. Such operations as left atrial isolation, His-bundle’s ablation and the “corridor” procedure were performed. But these operations were trying to isolate AF or to localize it in the certain part of atrium to minimize its negative effects on the ventricles, but the fibrillation was preserved. Fist operation eliminating AF was named Maze operation and was made in 1987 year. The conception of this operation is to create surgical incisions with cut and sew technique that helps us to divide atrial myocardium into the small segments that doesn’t allow macro-reentrant circuits to sustain. That's why the ability to fibrillate or to flutter is excluded. Later this operation had undergone several modifications what helped to correct its main disadvantages. Eventually Maze III operation became gold standard in AF treatment. But this operation was technically difficult and was not possible to be made by average surgeons. That’s why the necessity to search alternative energy sources to make ablation lines instead of surgical incisions and simplify the operation appeared. The main types of ablation used in this operation are cryoablation, radiofrequency, ultrasound and microwave ablation. In many investigations alternative energy sources are compared to each other to

  13. Numerical simulation and Hopf bifurcation of flutter-type oscillation of two-dimensional blade

    International Nuclear Information System (INIS)

    A numerical method is proposed to simulate the Flutter-type oscillation of the two-dimensional blades in a flow with low speed. The finite element method is used to solve numerically the Laplace equation, and then the aerodynamic forces can be obtained using the unsteady Bernoulli equation. A two-degree-of-freedom dynamic model is introduced to describe the blade oscillation, and Runge-Kutta method is applied to solve the equation of motion. The coupled fields can be solved alternately, and the oscillation orbit of the two-dimensional blade can be obtained. Furthermore, the results are presented in phase plane and studied based on Hopf bifurcation. The influence of the flow velocity on the blade flutter is studied, and it can be concluded that the appearance of flutter-type oscillation is the result of the occurrence of Hopf bifurcation, as the flow velocity increases

  14. Classical Flutter and Active Control of Wind Turbine Blade Based on Piezoelectric Actuation

    Directory of Open Access Journals (Sweden)

    Tingrui Liu

    2015-01-01

    Full Text Available The aim of this article is to analyze classical flutter and active control of single-cell thin-walled composite wind turbine blade beam based on piezoelectric actuation. Effects of piezoelectric actuation for classical flutter suppression on wind turbine blade beam subjected to combined transverse shear deformation, warping restraint effect, and secondary warping are investigated. The extended Hamilton’s principle is used to set up the equations of motion, and the Galerkin method is applied to reduce the aeroelastic coupled equations into a state-space form. Active control is developed to enhance the vibrational behavior and dynamic response to classical aerodynamic excitation and stabilize structures that might be damaged in the absence of control. Active optimal control scheme based on linear quadratic Gaussian (LQG controller is implemented. The research provides a way for rare study of classical flutter suppression and active control of wind turbine blade based on piezoelectric actuation.

  15. Nonlinear flutter analysis of stiffened composite panels in super-sonic flow

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The flutter instability of stiffened composite panels subjected to aerodynamic forces in the supersonic flow is investigated. Based on Hamilton’s principle,the aeroelastic model of the composite panel is established by using the von Karman large deflection plate theory,piston theory aerodynamics and the quasi-steady thermal stress theory. Then,using the finite element method along with Bogner-Fox-Schmit elements and three-dimensional beam elements,the nonlinear equations of motion are derived. The effect of stiffening scheme on the flutter critical dynamic pressure is demonstrated through the numerical example,and the nonlinear flutter characteristics of stiffened composite panels are also analyzed in the time domain. This will lay the foundation for design of panel structures employed in aerospace vehicles.

  16. Extracellular Matrix Remodeling in Atrial Fibrosis: Mechanisms and Implications in Atrial Fibrillation

    OpenAIRE

    Pellman, Jason; Lyon, Robert C.; Sheikh, Farah

    2009-01-01

    Atrial fibrosis has been strongly associated with the presence of heart diseases/arrhythmias, including congestive heart failure (CHF) and atrial fibrillation (AF). Inducibility of AF as a result of atrial fibrosis has been the subject of intense recent investigation, since it is the most commonly encountered arrhythmia in adults and can substantially increase the risk of premature death. Rhythm and rate control drugs as well as surgical interventions are used as therapies for AF; however, in...

  17. Impact of pulmonary vein isolation on atrial vagal activity and atrial electrical remodeling

    Institute of Scientific and Technical Information of China (English)

    Yingxue Dong; Shulong Zhang; Lianjun Gao; Hongwei Zhao; Donghui Yang; Yunlong Xia; Yanzong Yang

    2008-01-01

    Objective Mechanisms of pulmonary vein isolation (PVI) for atrial fibrillation remain controversy.This study aimed to investigate the impact of PVI on vagal modulation to atria.Methods Eighteen adult mongrel dogs under general anesthesia were randomly divided into two groups.Bilateral cervical sympathovagal trunks were decentralized and sympathetic effects was blocked by metoprolol administration.Atrial electrical remodeling (AER) was established by rapid right atrial pacing at the rate of 600 bpm for 30 minutes.PVI was performed in group A.Atrial effective refractory period (ERP),vulnerability window (VW) of atrial fibrillation,and sinus rhythm cycle length (SCL) were measured at baseline and during vagal stimulation before and after atrial rapid pacing with and without PVI at fight atrial appendage (RAA),left atrial appendage (LAA),distal coronary sinus (CSd) and proximal coronary sinus (CSp).Results (1) Effects of PVI on vagal modulation:Shortening of SCL during vagal stimulation decreased significantly after PVI compared with that before PVI in group A (P<0.001).Shortening of ERP during vagal stimulation decreaseed significantly after PVI compared with that before PVI (P<0.05).VW of atrial fibrillation during vagal stimulation decreased significantly after PVI compared with that before PVI (P<0.05).(2) Effects of PVI on AER:shortening of ERP before and after atrial rapid pacing increased significantly at baseline and vagal stimulation in group B compared with that in group A (P<0.05).VW during vagal stimulation increased significantly after atrial rapid pacing in group B (P<0.05).Conclusion PVI attenuates the vagal modulation to the atria,thereby decreases the susceptibility to atrial fibrillation mediated by vagal activity.PVI releases AER,which maybe contributes to the vagal denervation.Our study indicates that PVI not only can eradicate triggered foci but also modify substrates for AF.(J Geriatr Cardiol 2008;5:28-32)

  18. The Atrial Fibrillation Ablation Pilot Study

    DEFF Research Database (Denmark)

    Arbelo, Elena; Brugada, Josep; Hindricks, Gerhard;

    2014-01-01

    AIMS: The Atrial Fibrillation Ablation Pilot Study is a prospective registry designed to describe the clinical epidemiology of patients undergoing an atrial fibrillation (AFib) ablation, and the diagnostic/therapeutic processes applied across Europe. The aims of the 1-year follow-up were to analyse...... left atrial tachycardia, and 4 patients died (1 haemorrhagic stroke, 1 ventricular fibrillation in a patient with ischaemic heart disease, 1 cancer, and 1 of unknown cause). CONCLUSION: The AFib Ablation Pilot Study provided crucial information on the epidemiology, management, and outcomes of catheter...

  19. The totally thoracoscopic left atrial maze procedure for the treatment of atrial fibrillation.

    Science.gov (United States)

    van Laar, Charlotte; Geuzebroek, Guillaume S C; Hofman, Frederik N; Van Putte, Bart P

    2016-01-01

    The totally thoracoscopic left atrial maze (TT-maze) is a recent, minimally invasive surgical procedure for the treatment of atrial fibrillation, with promising results in terms of freedom from atrial fibrillation. The TT-maze consists of a bilateral, epicardial pulmonary vein isolation with the creation of a box using radiofrequency and exclusion of the left atrial appendage (LAA). In addition, the box is connected with the base of the LAA and furthermore with the mitral annulus with the so-called trigonum line. In this report, we describe our surgical approach and short-term results. PMID:26993056

  20. Ablation of the atrioventricular node executed after paranodal ablation of the atrioventricular node for the treatment of paroxysmal atrial-ventricular node of reentry tachycardia in conditions of artificial blood circulation

    Directory of Open Access Journals (Sweden)

    Melikulov A.Kh.

    2014-03-01

    Full Text Available In this clinical observation is shown the data of the patient who was previously undergone paranodal ablation of atrial-ventricular junction for the treatment of atrioventricular (AV nodal reentrant tachycardia. Radiofrequency ablation of right lower isthmus for treatment of the paroxysmal form of atrial flutter was made for the patient. Sick sinus node syndrome and paroxysmal form of atrial fibrillation were diagnosed. Then dual-chamber pacemaker was implanted. Antiarrhythmic therapy about the persistent form of atrial fibrillation had no effect. The decision for the implementation of radio frequency modification of atrioventricular connection using right ventriclar access failed because of the lack of verification of the His bundle's spike. Using retrograde access through the aorta we managed to create AV blockade of III degree. Taking into account the fact that in 1990-ies patients with atrioventricular nodal reentrant tachycardia were operated using paranodal ablation of the AV node using extracorporeal circulation, this case has a practical significance when endovascular catheter modification of AV nodal conduction in this category of patients is made.

  1. Flutter Instability Speeds of Guided Splined Disks: An Experimental and Analytical Investigation

    OpenAIRE

    Ahmad Mohammadpanah; Hutton, Stanley G.

    2015-01-01

    “Guided splined disks” are defined as flat thin disks in which the inner radius of the disk is splined and matches a splined arbor that provides the driving torque for rotating the disk. Lateral constraint for the disk is provided by space fixed guide pads. Experimental lateral displacement of run-up tests of such a system is presented, and the flutter instability zones are identified. The results indicate that flutter instability occurs at speeds when a backward travelling wave of a mode mee...

  2. Synthesis of active controls for flutter suppression on a flight research wing

    Science.gov (United States)

    Abel, I.; Perry, B., III; Murrow, H. N.

    1977-01-01

    This paper describes some activities associated with the preliminary design of an active control system for flutter suppression capable of demonstrating a 20% increase in flutter velocity. Results from two control system synthesis techniques are given. One technique uses classical control theory, and the other uses an 'aerodynamic energy method' where control surface rates or displacements are minimized. Analytical methods used to synthesize the control systems and evaluate their performance are described. Some aspects of a program for flight testing the active control system are also given. This program, called DAST (Drones for Aerodynamics and Structural Testing), employs modified drone-type vehicles for flight assessments and validation testing.

  3. Identification of Flutter Derivatives of Bridge Decks in Wind Tunnel Test by Stochastic Subspace Identification

    Directory of Open Access Journals (Sweden)

    T. Janesupasaeree

    2009-01-01

    Full Text Available Problem statement: Flutter derivatives are the essential parameters in the estimations of the flutter critical wind velocity and the responses of long-span cable supported bridges. These derivatives can be experimentally estimated from wind tunnel test results. Generally, wind tunnel test methods can be divided into free decay test and buffeting test. Compared with the free decay method, the buffeting test is simpler but its outputs appear random-like. This makes the flutter derivatives extraction from its outputs more difficult and then a more advanced system identification is required. Most of previous studies have used deterministic system identification techniques, in which buffeting forces and responses are considered as noises. These previous techniques were applicable only to the free decay method. They also confronted some difficulties in extracting flutter derivatives at high wind speeds and under turbulence flow cases where the buffeting responses dominate. Approach: In this study, the covariance-driven stochastic subspace identification technique (SSI-COV was presented to extract the flutter derivatives of bridge decks from the buffeting test results. An advantage of this method is that it considers the buffeting forces and responses as inputs rather than as noises. Numerical simulations and wind tunnel tests of a streamlined thin plate model conducted under smooth flow by the free decay and the buffeting tests were used to validate the applicability of the SSI-COV method. Then, wind tunnel tests of a two-edge girder blunt type of Industrial-Ring-Road Bridge deck (IRR were conducted under smooth and turbulence flow. Results: The identified flutter derivatives of the thin plate model by the SSI-COV technique agree well with those obtained theoretically. The results from the thin plate and the IRR Bridge deck validated the reliability and applicability of the SSI-COV technique to various experimental methods and conditions of wind flow

  4. Fluidic harvesters in free stream turbulence undergoing flow-induced vibrations or flutter

    Science.gov (United States)

    Gomez, Joan; Azadeh Ranjbar, Vahid; Goushcha, Oleg; Andreopoulos, Yiannis; Elvin, Niell

    2015-11-01

    In the present experimental work we investigated the performance of fluidic harvesters consisting of cylindrical body mounted of the tip of a flexible beam in the presence of nearly homogeneous and isotropic turbulence. Circular, semi-circular and square shapes have been tested. It was found that turbulence interferes with resonance conditions between the flow and the structure in the case of vortex induced vibrations and has absolutely no effect in flutter dominated case. As a result, turbulence increases the power output of non-linear harvesters subjected to vortex induces vibration and it has no effect in harvester under flutter conditions. Supported by NSF Grant: CBET #1033117.

  5. Computational fluid dynamic analysis of flutter characteristics for self-anchored suspension bridges

    Institute of Scientific and Technical Information of China (English)

    Zhiwen ZHU; Zhaoxiang WANG; Zhengqing CHEN

    2008-01-01

    This paper outlines the essentials and proce-dures of computational fluid dynamics (CFD) simulation applicable to evaluating flutter derivatives of bridge decks. An arbitrary Lagrangian-Eulerian (ALE) description of the flow around the moving rigid box girder combined with the finite volume discretization and multi-grid algorithm is pre-sented. The proposed methods are employed to identify flutter derivatives of the bridge deck of the Sanchaji Self-anchored Suspension Bridge. The results agree well with ones from wind tunnel tests. It demonstrates accuracy and efficiency of the present method.

  6. RADIOFREQUENCY CATHETER ABLATION OF PERMANENT ATRIAL FIBRILLATION UNDER GUIDANCE OF CARTO-MERGE TECHNIQUE

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Objective To investigate the feasibility and effectiveness of radiofrequency catheter ablation (RFCA) to treat permanent atrial fibrillation (AF) under the guidance of Carto-Merge technique.Methods Fifteen male patients with permanent AF underwent RFCA under the guidance of Carto-Merge technique. The mean age was 54. 00 ± 10. 44 years, and duration of AF was 23.66 ± 14. 93 months. Cardiac magnetic resonance angiography (MRA) was performed to obtain pre-procedural three-dimensional (3D) images on the anatomy of left atrium (LA) and pulmonary veins (PVs) before RFCA procedure. Then the electroanatomical map was integrated with 3D images of MRA to form Carto-Merge map that guided step-by-step ablation strategy of permanent AF. Circumferential PV ablation was performed first until complete PVs electric isolation confirmed by Lasso catheter. If AF was not terminated, lesion lines on roof of LA, mitral isthmus, and tricuspid isthmus were produced.Results The episodes of AF were terminated during RFCA in 2 patients, by direct current cardioversion in the remaining 13 patients. Transient AF occurred in 2 patients after ablation on 1st day and 1st week respectively, AF terminated spontaneously not long after taking metoprolol. One patient developed persistent atrial flutter (AFL) in 2 months after procedure and AFL was eliminated by the second ablation. Persistent AF recurred on 1st day, 1st and 5th week respectively in 3 patients, and did not terminate after 3 months even though amiodarone was given The remaining 12 patients were all free of AF during 2-11 months of follow-up. The recent success rate for RFCA of permanent AF was 80%.Conclusions Carto-Merge technique can effectively guide RFCA of permanent AF. When combined with single Lasso mapping, it can simplify the mapping, lower expenses, and enhance the success rate of RFCA of permanent AF.

  7. Towards Low Energy Atrial Defibrillation

    Directory of Open Access Journals (Sweden)

    Philip Walsh

    2015-09-01

    Full Text Available A wireless powered implantable atrial defibrillator consisting of a battery driven hand-held radio frequency (RF power transmitter (ex vivo and a passive (battery free implantable power receiver (in vivo that enables measurement of the intracardiac impedance (ICI during internal atrial defibrillation is reported. The architecture is designed to operate in two modes: Cardiac sense mode (power-up, measure the impedance of the cardiac substrate and communicate data to the ex vivo power transmitter and cardiac shock mode (delivery of a synchronised very low tilt rectilinear electrical shock waveform. An initial prototype was implemented and tested. In low-power (sense mode, >5 W was delivered across a 2.5 cm air-skin gap to facilitate measurement of the impedance of the cardiac substrate. In high-power (shock mode, >180 W (delivered as a 12 ms monophasic very-low-tilt-rectilinear (M-VLTR or as a 12 ms biphasic very-low-tilt-rectilinear (B-VLTR chronosymmetric (6ms/6ms amplitude asymmetric (negative phase at 50% magnitude shock was reliably and repeatedly delivered across the same interface; with >47% DC-to-DC (direct current to direct current power transfer efficiency at a switching frequency of 185 kHz achieved. In an initial trial of the RF architecture developed, 30 patients with AF were randomised to therapy with an RF generated M-VLTR or B-VLTR shock using a step-up voltage protocol (50–300 V. Mean energy for successful cardioversion was 8.51 J ± 3.16 J. Subsequent analysis revealed that all patients who cardioverted exhibited a significant decrease in ICI between the first and third shocks (5.00 Ω (SD(σ = 1.62 Ω, p < 0.01 while spectral analysis across frequency also revealed a significant variation in the impedance-amplitude-spectrum-area (IAMSA within the same patient group (|∆(IAMSAS1-IAMSAS3[1 Hz − 20 kHz] = 20.82 Ω-Hz (SD(σ = 10.77 Ω-Hz, p < 0.01; both trends being absent in all patients that failed to cardiovert

  8. Assessment of right atrial function analysis

    International Nuclear Information System (INIS)

    To assess the potential utility of right atrial function analysis in cardiac disease, reservoir function, pump function, and right atrial peak emptying rate (RAPER) were compared in 10 normal subjects, 32 patients with coronary artery disease, and 4 patients with primary pulmonary hypertension. Right atrial volume curves were obtained using cardiac radionuclide method with Kr-81m. In normal subjects, reservoir function index was 0.41+-0.05; pump function index was 0.25+-0.05. Both types of patients has decreased reservoir funcion and increased pump function. Pump function tended to decrease with an increase of right ventricular end-diastolic pressure. RAPER correlated well with right ventricular peak filling rate, probably reflecting right ventricular diastolic function. Analysis of right atrial function seemed to be of value in evaluating factors regulating right ventricular contraction and diastolic function, and cardiac output. (Namekawa, K)

  9. Genetics Home Reference: familial atrial fibrillation

    Science.gov (United States)

    ... or Free article on PubMed Central Roberts R. Mechanisms of disease: Genetic mechanisms of atrial fibrillation. Nat Clin Pract Cardiovasc Med. ... with a qualified healthcare professional . About Genetics Home Reference Site Map Contact Us Selection Criteria for Links ...

  10. Atrial Fibrillation - Multiple Languages: MedlinePlus

    Science.gov (United States)

    ... Supplements Videos & Tools You Are Here: Home → Multiple Languages → All Health Topics → Atrial Fibrillation URL of this page: https://medlineplus.gov/languages/atrialfibrillation.html Other topics A-Z A B ...

  11. Atrial Fibrillation During an Exploration Class Mission

    Science.gov (United States)

    Lipsett, Mark; Hamilton, Douglas; Lemery, Jay; Polk, James

    2011-01-01

    This slide presentation reviews a possible scenario of an astronaut having Atrial Fibrillation during a Mars Mission. In the case review the presentation asks several questions about the alternatives for treatment, medications and the ramifications of the decisions.

  12. Geared-elevator flutter study. [wind tunnel tests of transonic flutter effects on control surfaces of supersonic transport tail assemblies, conducted in a NASA-Langley transonic wind tunnel

    Science.gov (United States)

    Ruhlin, C. L.; Doggett, R. V., Jr.; Gregory, R. A.

    1976-01-01

    An experimental and analytical study was made of the transonic flutter characteristics of a supersonic transport tail assembly model having an all-movable, horizontal tail with a geared elevator. Two model configurations, namely, one with a gear-elevator (2.8 to 1.0 gear ratio) and one with locked-elevator (1.0 to 1.0 gear ratio), were flutter tested in the Langley transonic dynamics tunnel with an empennage cantilever-mounted on a sting. The geared-elevator configuration fluttered experimentally at about 20% higher dynamic pressures than the locked-elevator configuration. The experimental flutter dynamic pressure boundaries for both configurations were nearly flat over a Mach number range from 0.9 to 1.1. Flutter calculations (mathematical models) were made for the geared-elevator configuration using three subsonic lifting-surface methods. In one method, the elevator was treated as a discrete surface, and in the other two methods, the stabilizer and elevator were treated as a single warped-surface with the primary difference between these two methods being in the mathematical implementation used. A comparison of the experimental and analytical results shows that the discrete-elevator method predicted best the experimental flutter dynamic pressure level. However, the single warped-surface methods predicts more closely the experimental flutter frequencies and Mach number trends.

  13. Calpain I Inhibition prevents atrial structural remodeling in a canine model with atrial fibrillation

    Institute of Scientific and Technical Information of China (English)

    XUE Hong-jie; SHAN Hong-bo; LIU Jie; LI Wei-min; LI Yue; GONG Yong-tai; YANG Bao-feng; JIN Cheng-luo; SHENG Li; CHU Shan; ZHANG Li

    2008-01-01

    Background Atrial fibrillation (AF) is accompanied by atrial structural remodeling. Calpain activity is induced during AR To lest a causal relationship between calpain activation and atrial structural changes, N-acetyl-Leu-Leu-Met (ALLM), a calpain inhibitor, was utilized in a canine AF model.Methods Fifteen dogs were randomly divided into 3 groups: sham-operated group, control group and calpain inhibitor group; each with 5 dogs. Sustained AF was induced by rapid right atrium pacing at 600 beats per minute for 3 weeks. ALLM was administered at a dosage of 1.0 mg-kg-1·d-1 in the calpain inhibitor group. Three weeks later, the proteolysis, protein expression of TnT and myosin, calpain l localization and expression and structural changes were examined in left atrial free walls, right atrial free walls and the interatrial septum respectively. Atrial size and contractile function were also measured by echocardiography.Results Long-term rapid atrial pacing induced marked structural changes such as enlarged atrial volume, myolysis, degradation of TnT and myosin, accumulation of glycogen and changes in mitochondrial shape and size, which were paralleled by an increase in calpain activity. The positive correlation between calpain activity and the degree of myolysis (rs=0.90 961, P<0.0001) was demonstrated. In addition to structural abnormalities, pacing-induced atrial contractile dysfunction was observed in this study. The pacing-induced atrial structural alterations and loss of contractility were partially prevented by the calpain inhibitor ALLM.Conclusions Activation of calpain represents key features in the progression towards overt structural remodeling. Calpain inhibitor, ALLM, suppressed the increased calpain activity and reversed structural remodeling caused by sustained atrial fibrillation in the present model. Calpain Inhibition may therefore provide a possibility for therapeutic Intervention in AF.

  14. Atrial Fibrillation in Congestive Heart Failure

    OpenAIRE

    Lubitz, Steven A.; Benjamin, Emelia J.; Ellinor, Patrick T.

    2010-01-01

    Atrial fibrillation and congestive heart failure are morbid conditions that share common risk factors and frequently coexist. Each condition predisposes to the other, and the concomitant presence of the two identifies individuals at increased risk for mortality. Recent data have emerged which help elucidate the complex genetic and non-genetic pathophysiological mechanisms that contribute to the development of atrial fibrillation in individuals with congestive heart failure. Clinical trial res...

  15. The immediate future for the medical treatment of atrial fibrillation

    DEFF Research Database (Denmark)

    Pedersen, Ole Dyg; Brendorp, Bente; Køber, Lars;

    2002-01-01

    Atrial fibrillation is the most commonly sustained cardiac arrhythmia and a common reason for mortality and morbidity. Atrial fibrillation causes disease for three reasons: i) the ventricular rate is often high, which leads to symptoms ranging from discomfort to life threatening heart failure; ii......) the rhythm causes loss of atrioventricular synchrony, which reduces diastolic filling and may lead to heart failure; and iii) atrial contraction is lost leading to stagnant blood that again may lead to atrial thrombi and peripheral embolism. Thus, the treatment of atrial fibrillation is focused on the...... are in development, but to the author's knowledge only a single thrombin inhibitor is actively being developed for atrial fibrillation....

  16. Avaliação da atividade elétrica atrial em pacientes submetidos ao tratamento cirúrgico da valvopatia mitral Evaluation of atrial electrical activity in patients operated on mitral valve disease

    Directory of Open Access Journals (Sweden)

    Cesar Augusto Ferreira

    2002-01-01

    Full Text Available INTRODUÇÃO: O acesso cirúrgico por esternotomia mediana e atriotomia subseptal clássica pode, em certos casos, resultar em má exposição da valva mitral. Incisões atriais alternativas otimizam a exposição da valva mitral mas podem interferir na atividade elétrica atrial pós-operatória. OBJETIVO: Padronizar método para investigar a atividade elétrica atrial para emprego em estudos comparativos de diferentes atriotomias em cardiopatas sumetidos à cirurgia cardíaca. MÉTODOS: Análise com eletrocardiograma convencional e de 24 h (sistema Holter, pré e pós-operatória, e cardioestimulação epicárdica pós-operatória pelo método de Narula, em 10 pacientes submetidos à correção de valvopatias mitrais. RESULTADOS: No pré-op., os pacientes em ritmo sinusal apresentaram ectopias supraventriculares, com episódios de taquicardia supraventricular em 57% dos casos, "flutter" atrial em 10% e ritmo juncional em 10%. Todos apresentaram ectopias ventriculares, de baixa incidência em 70% dos casos, e taquicardia ventricular não sustentada foi detectada em 30% dos pacientes. No pós-operatório, houve 40% de novas arritmias supraventriculares (fibrilação atrial, ritmo juncional, ritmo atrial baixo e taquicardia supraventricular paroxística, mas não ocorreram arritmias ventriculares. No pós-op. a função do nó sinusal não se alterou, ocorreu redução significativa das ectopias supraventriculares, com reversão de FA para ritmo sinusal em 1 paciente, mas não houve redução significativa das ectopias ventriculares. O tempo de condução inter-atrial correlacionou-se com o tamanho do átrio esquerdo. CONCLUSÃO: A metodologia mostrou-se adequada e segura, e poderá ser empregada na comparação de diferentes incisões atriais para exposição valvar mitral.INTRODUCTION: The selection of the surgical approach to the mitral valve is a critical factor in obtaining good exposure and minimizing lesions of the surrounding structures

  17. The Autonomic Nervous System and Atrial Fibrillation: The Roles of Pulmonary Vein Isolation and Ganglionated Plexi Ablation

    Directory of Open Access Journals (Sweden)

    Benjamin J. Scherlag

    2009-08-01

    Full Text Available After the sequential successes of catheter ablation for the treatment of pre-excitation syndromes (WPW, junctional reentry (AVNRT atrial flutter (AFL and ventricular arrhythmias, clinical electrophysiologists have focused on the myocardial basis of atrial fibrillation (AF. Thus, the strategy for ablation of drug and cardioversion refractory AF was to isolate the myocardial connections from the focal firing pulmonary veins (PVs in addition to altering the atrial substrate maintaining AF. However, the overall success rates have not achieved those of the other types of ablation procedures. In this review we have summarized the favorable aspects and drawbacks of pulmonary vein isolation (PVI. As for the role of the Intrinsic Cardiac Autonomic Nervous System (ICANS, both basic and clinical evidence has shown that ganglionated plexi (GP stimulation promotes initiation and maintenance of AF, and that GP ablation reduces recurrence of AF following catheter or surgical ablation of these structures. Based on these findings, the GP Hyperactivity Hypothesis has been proposed to explain, at least in part, the mechanistic basis for the focal form of AF. For example, PV isolation may not always be necessary for elimination of AF, as in the early stages of paroxysmal AF. GP ablation alone, in these cases, may suffice for focal AF termination. In the persistent and long standing persistent forms the substrate for AF may be more extensive and therefore require GP ablation plus PV isolation and/or CFAE ablations. Clinical reports, both catheter based as well as minimally invasive surgical procedures, which include PVI plus GP ablation have shown relatively long-term success rates much closer to or equal to those achieved by myocardial ablation procedures in patients with WPW, AVNRT and AFL.

  18. The Autonomic Nervous System and Atrial Fibrillation:The Roles of Pulmonary Vein Isolation and Ganglionated Plexi Ablation

    Directory of Open Access Journals (Sweden)

    Benjamin J. Scherlag, PhD

    2009-08-01

    Full Text Available After the sequential successes of catheter ablation for the treatment of pre-excitation syndromes (WPW, junctional reentry (AVNRT atrial flutter (AFL and ventricular arrhythmias, clinical electrophysiologists have focused on the myocardial basis of atrial fibrillation (AF. Thus, the strategy for ablation of drug and cardioversion refractory AF was to isolate the myocardial connections from the focal firing pulmonary veins (PVs in addition to altering the atrial substrate maintaining AF. However, the overall success rates have not achieved those of the other types of ablation procedures. In this review we have summarized the favorable aspects and drawbacks of pulmonary vein isolation (PVI. As for the role of the Intrinsic Cardiac Autonomic Nervous System (ICANS, both basic and clinical evidence has shown that ganglionated plexi (GP stimulation promotes initiation and maintenance of AF, and that GP ablation reduces recurrence of AF following catheter or surgical ablation of these structures. Based on these findings, the GP Hyperactivity Hypothesis has been proposed to explain, at least in part, the mechanistic basis for the focal form of AF. For example, PV isolation may not always be necessary for elimination of AF, as in the early stages of paroxysmal AF. GP ablation alone, in these cases, may suffice for focal AF termination. In the persistent and long standing persistent forms the substrate for AF may be more extensive and therefore require GP ablation plus PV isolation and/or CFAE ablations. Clinical reports, both catheter based as well as minimally invasive surgical procedures, which include PVI plus GP ablation have shown relatively long-term success rates much closer to or equal to those achieved by myocardial ablation procedures in patients with WPW, AVNRT and AFL.

  19. Electrophysiological characteristics of paroxysmal atrial fibrillation originating from superior vena cava: a clinical analysis of 30 cases.

    Science.gov (United States)

    Shi, Xiang-Min; Yuan, Hong-Tao; Guo, Hong-Yang; Guo, Jian-Ping; Shan, Zhao-Liang; Wang, Yu-Tang

    2015-01-01

    To analyze characteristics of electrocardiogram (ECG), electrophysiological intracardiac mapping and radiofrequency ablation (RF) of paroxysmal atrial fibrillation (PAF) originating from superior vena cava (SVC), aiming to investigate electrophysiological characteristics of PAF with SVC origin. Clinical data of 30 subjects (18 men and 12 women, aged, 58.6 ± 15.5 years) with PAF of SVC origin were retrospectively analyzed; All patients underwent RF during 2006.9-2012.7. ECG of AF and atrial premature contractions (APCs), procedure and fluoroscopic time, numbers of ablation sites within SVC, complications and success rate were studied. Compared with P wave of sinus rhythm (SR), APCs of SVC origin exhibited higher amplitude in lead II (0.23 ± 0.11 vs. 0.15 ± 0.06 mv), III (0.19 ± 0.09 vs. 0.13 ± 0.08 mv), AVF (0.21 ± 0.13 vs. 0.14 ± 0.10 mv), V2 (0.24 ± 0.07 vs. 0.15 ± 0.09 mv) and V3 (0.21 ± 0.09 vs. 0.12 ± 0.05 mv) (P atrial flutter within 1 month after completion of ablation and were controlled by antiarrhythmic drugs. The APCs and AF of SVC origin manifested distinctive ECG features, which could be helpful to distinguish SVC from other foci before ablation, the completion of SVCI required shorter procedure and fluoroscopic time, as well as less ablation points, and meanwhile, the success rate was high with less complication. PMID:25784993

  20. Psychosomatic correlations in atrial fibrillations

    Directory of Open Access Journals (Sweden)

    Vladimir Ernstovich Medvedev

    2011-12-01

    Full Text Available Patients with atrial fibrillations (AF and comorbid mental disorders were examined. Two patient groups differing in the structure of psychosomatic ratios were identified. Group 1 comprised patients with AF and signs of reactivity lability that manifested itself as psychopathological reactions to the primary manifestations of AF; Group 2 included those who had developed mental disorders mainly in end-stage cardiovascular disease (predominantly a permanent form of AF in the presence of such events as chronic heart failure (CHF. The results of the study suggest that the patients with AF have frequently anxiety and hypochondriacal disorders, which agrees with the data available in the literature. In addition, end-stage AF is marked by depressive syndromes caused by the severe course of cardiovascular diseases resulting in CHF.

  1. Spontaneous onset of atrial fibrillation

    Science.gov (United States)

    Zemlin, Christian W.; Mitrea, Bogdan G.; Pertsov, Arkady M.

    2009-06-01

    Most commonly, atrial fibrillation is triggered by rapid bursts of electrical impulses originating in the myocardial sleeves of pulmonary veins (PVs). However, the nature of such bursts remains poorly understood. Here, we propose a mechanism of bursting consistent with the extensive empirical information about the electrophysiology of the PVs. The mechanism is essentially non-local and involves the spontaneous initiation of non-sustained spiral waves in the distal end of the muscle sleeves of the PVs. It reproduces the experimentally observed dynamics of the bursts, including their frequency, their intermittent character, and the unusual shape of the electrical signals in the pulmonary veins that are reminiscent of so-called early afterdepolarizations (EADs).

  2. Home Screening for Detecting Subclinical Atrial Fibrillation

    Directory of Open Access Journals (Sweden)

    Renato Pietro Ricci; Taya V. Glotzer

    2015-12-01

    Full Text Available The advent of cardiac implanted electronic devices with accurate atrial arrhythmia diagnostic capabilities has revealed a large burden of “silent “ atrial fibrillation that is present in the cardiac population. Many studies have been completed, and many more are ongoing, to determine the correct treatment course when these atrial arrhythmias are detected. Alongside the development of accurate atrial diagnostics within the devices, has been the growth an entire network of wireless home monitoring capability. It is now possible to see, over the internet, individual patients’ atrial arrhythmia burden on every day. This capability has tremendous promise for patient care, with the possibility of reducing strokes, decreasing heart failure, preventing cardiomyopathies, and likely substantially reducing health care costs. As this innovative diagnostic capability is generating large amounts of data, protocols for what should be done with the plethora of new information are being developed. In the pages that follow, we will present what is known about home monitoring for silent atrial fibrillation, and present the results of recent studies published in this arena.

  3. Uso da radiofrequência bipolar para o tratamento da fibrilação atrial durante cirurgia cardíaca

    Directory of Open Access Journals (Sweden)

    Leonardo Secchin Canale

    2011-06-01

    Full Text Available FUNDAMENTO: O tratamento da fibrilação atrial com dispositivo de ablação de tecidos por radiofrequência bipolar em concomitância à cirurgia cardíaca tem se mostrado método eficaz no tratamento desta arritmia. OBJETIVO: Descrever a experiência inicial do Instituto Nacional de Cardiologia no tratamento cirúrgico da fibrilação atrial com uso de dispositivo de radiofrequência bipolar em pacientes submetidos à cirurgia cardíaca, relatando o resultado de acompanhamento pós-operatório de um ano. MÉTODOS: Entre janeiro de 2008 e março de 2009, 47 pacientes (36 mulheres consecutivos, com idade média de 53,7 ± 10,6 anos, apresentando fibrilação atrial por um período médio de 34,6 meses (3 a 192 meses foram submetidos à ablação cirúrgica desta arritmia, por radiofrequência bipolar, durante o procedimento que motivou a indicação da cirurgia. Oito apresentavam fibrilação atrial intermitente e 39, contínua. Oitenta e um por cento foram submetidos à cirurgia valvar como procedimento principal. Esta é uma análise retrospectiva, observacional, com avaliação de um ano de pós-operatório das variáveis clínicas e de Holter 24 h. RESULTADOS: Dos 47 pacientes, 40 sobreviveram um ano. Desses, 33 foram submetidos a Holter 24 h, em um intervalo médio de 401 dias após a cirurgia. Encontrou-se a seguinte distribuição de ritmos: 24 (73% sinusal, 5 (15% fibrilação atrial, três (9% Flutter atrial e um (3% ritmo juncional. Foram observados dois acidentes vasculares encefálicos, sendo um associado à arritmia supraventricular. CONCLUSÃO: A ablação cirúrgica de fibrilação atrial com dispositivo de radiofrequência bipolar concomitante à cirurgia cardíaca é método eficaz para o tratamento desta arritmia.

  4. Left Atrial Sphericity Index Predicts Early Recurrence of Atrial Fibrillation After Direct-Current Cardioversion

    DEFF Research Database (Denmark)

    Osmanagic, Armin; Möller, Sören; Osmanagic, Azra;

    2016-01-01

    BACKGROUND: Attempts to achieve rhythm control using direct-current cardioversion (DCC) are common in those with persistent atrial fibrillation (AF). Although often successful, AF recurs within 1 month in as many as 57% of patients. The aim of this study was to assess whether a baseline left atrial...

  5. Robotic atrial septal defect repair and endoscopic treatment of atrial fibrillation.

    Science.gov (United States)

    Argenziano, Michael; Williams, Mathew R

    2003-04-01

    Computer (robotic) enhancement has emerged as a facilitator of minimally invasive cardiac surgery and has been used to perform portions of intracardiac procedures via thoracotomy incisions. This report describes the use of the da Vinci surgical system in two totally endoscopic ("closed chest") cardiac operations: atrial septal defect closure and pulmonary vein isolation of atrial fibrillation. ASD closure: Fifteen patients underwent repair of a secundum-type atrial septal defect or patent foramen ovale by a totally endoscopic approach, utilizing the da Vinci robotic system. Cardiopulmonary bypass (CPB) was achieved peripherally. Cardioplegia was administered via the distal port of the arterial cannula after endoballoon inflation. Via three port incisions in the right chest, the entire operation including pericardiotomy; bicaval occlusion; atriotomy; atrial septopexy; and atrial closure was performed by a surgeon seated at a computer console. A fourth 15 mm port was utilized for suction and suture passage by a patient-side assistant. In one case, a recurrent shunt was identified and repaired on POD 5. Median ICU length of stay (LOS) was 20 hours, and median hospital LOS was 4 days. Atrial fibrillation surgery: This report also describes the pathway that we have pursued in the development of a totally endoscopic operation for atrial fibrillation. Beginning with animal models, we tested various ablative energy sources; methods of ablation; and minimally invasive approaches. This work has led to the development of a variety of minimally invasive surgical approaches including a totally endoscopic, robotically assisted beating heart procedure for the treatment of atrial fibrillation. PMID:12838483

  6. Intra-atrial endothelial lesion resulting from transseptal puncture for catheter ablation of atrial fibrillation

    Directory of Open Access Journals (Sweden)

    Samir M. Said

    2012-06-01

    Full Text Available Thromboembolic events are known complications of left atrial ablation therapy. We describe a complication which may also lead to systemic thromboembolism that has not been reported so far: the formation of a moving structure attached to the fossa ovalis after an attempted transseptal puncture in a 66-year old patient with symptomatic paroxysmal atrial fibrillation.

  7. Predictors of left atrial appendage stunning after electrical cardioversion of non-valvular atrial fibrillation

    Institute of Scientific and Technical Information of China (English)

    杨沙宁; 黄从新; 胡晓军; 金立军; 李凤翥; 彭水先

    2003-01-01

    Objective To identify predictors of left atrial appendage stunning after the use of electrical cardioversion to restore sinus rhythm in patients with non-valvular atrial fibrillation.Methods A total of 68 consecutive patients (45 men, 23 women, 60.5±8.7 years of age) with non-valvular atrial fibrillation undergoing electrical cardioversion were enlisted in this study. Clinical and echocardiographic variables were analyzed by univariate regression and multivariate logistic regression to investigate the relationship between occurrences of left atrial appendage stunning and these factors. Results Univariate analysis revealed that, in comparing patients without and with left atrial appendage stunning, there were significant differences in the duration of atrial fibrillation > 8 weeks (32.3% vs 75.5%, P 50 mm (29.0% vs 54.1%, P 8 weeks (OR=7.249, 95%CI=1.998-26.304, P 50 mm (OR=3.896, 95%CI=1.105-13.734, P8 weeks, left atrial diameter >50 mm, left ventricular ejection fraction <50%, and cumulative energy of electrical cardioversion are independent predictors of left atrial appendage stunning. Anticoagulation treatment should be individualized for patients undergoing electrical cardioversion to reduce the risk of both cardioversion-related thromboembolic events and hemorrhagic complications caused by warfarin treatment.

  8. Percutaneous atrial appendage occlusion for stroke prevention in patients with atrial fibrillation

    DEFF Research Database (Denmark)

    Munkholm-Larsen, Stine; Cao, Christopher; Yan, Tristan D;

    2012-01-01

    This review aims to evaluate systematically the safety and efficacy of percutaneous left atrial appendage occlusion (PLAAO) in stroke prevention for patients with atrial fibrillation (AF). A systematic review of peer-reviewed journals on PLAAO before June 2011 was performed on three electronic...

  9. Symptomatic Bradycardia Caused By Premature Atrial Contractions Originating From Right Atrial Appendage

    OpenAIRE

    Alper, AT; Gungor, B; Turkkan, C; Tekkesin, AI

    2013-01-01

    Premature atrial contraction is a common form of supraventricular arrhythmias. In rare cases, severe symptoms other than palpitation may occur. In this report, we present a patient with symptomatic bradycardia which developed secondary to blocked premature atrial contractions and was successfully treated with radiofrequency ablation.

  10. Symptomatic bradycardia caused by premature atrial contractions originating from right atrial appendage.

    Science.gov (United States)

    Alper, At; Gungor, B; Turkkan, C; Tekkesin, Ai

    2013-05-01

    Premature atrial contraction is a common form of supraventricular arrhythmias. In rare cases, severe symptoms other than palpitation may occur. In this report, we present a patient with symptomatic bradycardia which developed secondary to blocked premature atrial contractions and was successfully treated with radiofrequency ablation. PMID:23840105

  11. Active aeroelastic flutter analysis and vibration control of supersonic beams using the piezoelectric actuator/sensor pairs

    International Nuclear Information System (INIS)

    The active vibration control of all kinds of structures by using the piezoelectric material has been extensively investigated. In this paper, the active aeroelastic flutter characteristics and vibration control of supersonic beams applying the piezoelectric material are studied further. The piezoelectric materials are bonded on the top and bottom surfaces of the beams to act as the actuator and sensor so that the active aeroelastic flutter suppression for the supersonic beams can be conducted. The supersonic piston theory is adopted to evaluate the aerodynamic pressure. Hamilton's principle with the assumed mode method is used to develop the dynamical model of the structural systems. By using the standard eigenvalue methodology, the solutions for the complex eigenvalue problem are obtained. A negative velocity feedback control strategy is used to obtain active damping. The aeroelastic flutter bounds are calculated and the active aeroelastic flutter characteristics are analyzed. The impulse responses of the structural system are obtained by using the Houbolt numerical algorithm to study the active aeroelastic vibration control. The influences of the non-dimensional aerodynamic pressure on the active flutter control are analyzed. From the numerical results it is observed that the aeroelastic flutter characteristics of the supersonic beams can be significantly improved and that the aeroelastic vibration amplitudes can be remarkably reduced, especially at the flutter points, by using the piezoelectric actuator/sensor pairs which can provide an active damping. Within a certain value of the feedback control gain, with the increase of it, the flutter aerodynamic pressure (or flutter velocity) can be increased and the control results are also improved

  12. The flow field acting on the fluttering profile, kinematics, forces and total moment

    Czech Academy of Sciences Publication Activity Database

    Kozánek, Jan; Vlček, Václav; Zolotarev, Igor

    2013-01-01

    Roč. 13, č. 7 (2013), s. 1-7. ISSN 0219-4554 R&D Projects: GA ČR GA101/09/1522 Institutional support: RVO:61388998 Keywords : fluttering profile * interferometry visualization * acting forces and moment Subject RIV: JU - Aeronautics, Aerodynamics, Aircrafts Impact factor: 1.059, year: 2013

  13. Measuring of the profile vibration on the flutter critic flow velocity

    Czech Academy of Sciences Publication Activity Database

    Zolotarev, Igor; Vlček, Václav; Kozánek, Jan

    2015-01-01

    Roč. 4, č. 2 (2015), s. 45-45. ISSN 2168-9792. [International Conference and Exhibition on MECHANICAL & AERO SPACE ENGINEERING /3./. 05.10.2015-07.10.2015, San Francisco] R&D Projects: GA ČR GA13-10527S Institutional support: RVO:61388998 Keywords : aero elasticity * flutter * subsonic flow Subject RIV: BI - Acoustics

  14. Active flutter suppression of a lifting surface using piezoelectric actuation and modern control theory

    Science.gov (United States)

    Han, Jae-Hung; Tani, Junji; Qiu, Jinhao

    2006-04-01

    This paper presents a numerical and experimental investigation on active flutter suppression of a swept-back cantilevered lifting surface using piezoelectric (PZT) actuation. A finite element method, a panel aerodynamic method, and the minimum state-space realization are involved in the development of the equation of motion in state-space, which is efficiently used for the analysis of the system and design of control laws with a modern control framework. PZT actuators, bonded symmetrically on the plate, are optimally grouped into two equivalent actuator sets using genetic algorithms to enhance controllability. H2- and μ-synthesized control laws are designed and the flutter suppression performance is evaluated via wind tunnel testing. In the μ-synthesis design, a simple parametric uncertainty model is used to take into account the system changes with respect to airflow speed. Both controllers show comparable flutter suppression performance around the flutter point. However, the μ-synthesized controller shows improved behavior over a wide flow speed range.

  15. Nonlinear flutter wind tunnel test and numerical analysis of folding fins with freeplay nonlinearities

    Directory of Open Access Journals (Sweden)

    Yang Ning

    2016-02-01

    Full Text Available The flutter characteristics of folding control fins with freeplay are investigated by numerical simulation and flutter wind tunnel tests. Based on the characteristics of the structures, fins with different freeplay angles are designed. For a 0° angle of attack, wind tunnel tests of these fins are conducted, and vibration is observed by accelerometers and a high-speed camera. By the expansion of the connected relationships, the governing equations of fit for the nonlinear aeroelastic analysis are established by the free-interface component mode synthesis method. Based on the results of the wind tunnel tests, the flutter characteristics of fins with different freeplay angles are analyzed. The results show that the vibration divergent speed is increased, and the divergent speed is higher than the flutter speed of the nominal linear system. The vibration divergent speed is increased along with an increase in the freeplay angle. The developed free-interface component mode synthesis method could be used to establish governing equations and to analyze the characteristics of nonlinear aeroelastic systems. The results of the numerical simulations and the wind tunnel tests indicate the same trends and critical velocities.

  16. Study and Analysis on the Influence of Flutter Frequency on Airplane Stability

    Directory of Open Access Journals (Sweden)

    B. Janarthanan

    2013-10-01

    Full Text Available In the nationwide requirement of the growth in commercial aviation safety and profit, the field of Aeroelastic science plays a vital role. Flutter is one of the dynamic aeroelastic problems, it mainly occurs at lifting surfaces when the airplane cruises at high speeds. At relatively low speeds, the torsional stiffness of the wing is enough to counteract the twisting. However, the variation in flutter frequency causes the instability motion on aircraft. Therefore, the wing displacement against the flow field plays a vital role in dynamic stability analysis. As per the commercial aviation concern, an aircraft which is able to overcome the significant aeroelastic problems can yield maximum running profit. In order to maintain the airplane stability in high-speed, wings can be designed to minimize the distance between aerodynamic centre and shear centre (on the elastic axis. The main focus of this project is to calculate the frequency of an aircraft wing while it is subjected to aeroelastic (flutter instability. The analytical process identified for this work is the Eigen value method. By using MATLAB solver, the optimization has been carried out along the span of real-time model. In future, the efficient structural model is then simulated and analysis is carried out to evaluate the longitudinal stability due to flutter phenomena.

  17. Aeroservoelastic Pitch Control of Stall-Induced Flap/Lag Flutter of Wind Turbine Blade Section

    Directory of Open Access Journals (Sweden)

    Tingrui Liu

    2015-01-01

    Full Text Available The aim of this paper is to analyze aeroelastic stability, especially flutter suppression for aeroelastic instability. Effects of aeroservoelastic pitch control for flutter suppression on wind turbine blade section subjected to combined flap and lag motions are rarely studied. The work is dedicated to solving destructive flapwise and edgewise instability of stall-induced flutter of wind turbine blade by aeroservoelastic pitch control. The aeroelastic governing equations combine a flap/lag structural model and an unsteady nonlinear aerodynamic model. The nonlinear resulting equations are linearized by small perturbation about the equilibrium point. The instability characteristics of stall-induced flap/lag flutter are investigated. Pitch actuator is described by a second-order model. The aeroservoelastic control is analyzed by three types of optimal PID controllers, two types of fuzzy PID controllers, and neural network PID controllers. The fuzzy controllers are developed based on Sugeno model and intuition method with good results achieved. A single neuron PID control strategy with improved Hebb learning algorithm and a radial basic function neural network PID algorithm are applied and performed well in the range of extreme wind speeds.

  18. Flutter and thermal buckling control for composite laminated panels in supersonic flow

    Science.gov (United States)

    Li, Feng-Ming; Song, Zhi-Guang

    2013-10-01

    Aerothermoelastic analysis for composite laminated panels in supersonic flow is carried out. The flutter and thermal buckling control for the panels are also investigated. In the modeling for the equation of motion, the influences of in-plane thermal load on the transverse bending deflection are taken into account, and the unsteady aerodynamic pressure in supersonic flow is evaluated by the linear piston theory. The governing equation of the structural system is developed applying the Hamilton's principle. In order to study the influences of aerodynamic pressure on the vibration mode shape of the panel, both the assumed mode method (AMM) and the finite element method (FEM) are used to derive the equation of motion. The proportional feedback control method and the linear quadratic regulator (LQR) are used to design the controller. The aeroelastic stability of the structural system is analyzed using the frequency-domain method. The effects of ply angle of the laminated panel on the critical flutter aerodynamic pressure and the critical buckling temperature change are researched. The flutter and thermal buckling control effects using the proportional feedback control and the LQR are compared. An effective method which can suppress the flutter and thermal buckling simultaneously is proposed.

  19. Effect of blade flutter and electrical loading on small wind turbine noise

    Science.gov (United States)

    The effect of blade flutter and electrical loading on the noise level of two different size wind turbines was investigated at the Conservation and Production Research Laboratory (CPRL) near Bushland, TX. Noise and performance data were collected on two blade designs tested on a wind turbine rated a...

  20. Nonlinear flutter wind tunnel test and numerical analysis of folding fins with freeplay nonlinearities

    Institute of Scientific and Technical Information of China (English)

    Yang Ning; Wang Nan; Zhang Xin; Liu Wei

    2016-01-01

    The flutter characteristics of folding control fins with freeplay are investigated by numer-ical simulation and flutter wind tunnel tests. Based on the characteristics of the structures, fins with different freeplay angles are designed. For a 0? angle of attack, wind tunnel tests of these fins are conducted, and vibration is observed by accelerometers and a high-speed camera. By the expansion of the connected relationships, the governing equations of fit for the nonlinear aeroelastic analysis are established by the free-interface component mode synthesis method. Based on the results of the wind tunnel tests, the flutter characteristics of fins with different freeplay angles are analyzed. The results show that the vibration divergent speed is increased, and the divergent speed is higher than the flutter speed of the nominal linear system. The vibration divergent speed is increased along with an increase in the freeplay angle. The developed free-interface component mode synthesis method could be used to establish governing equations and to analyze the characteristics of nonlinear aeroe-lastic systems. The results of the numerical simulations and the wind tunnel tests indicate the same trends and critical velocities.

  1. Concomitant surgical removal of left atrial myxoma and ablation of paroxysmal atrial fibrillation

    Directory of Open Access Journals (Sweden)

    Revishvili A. Sh.

    2013-03-01

    Full Text Available This article describes a clinical case of a patient with left atrial myxoma combined with paroxysmal atrial fibrillation. General practitioner considered symptoms of left ventricular insufficiency (shortness of breath, cough, palpitation, dizziness, blood spitting as lung pathology. When paroxysms of atrial fibrillation became more frequent the patient was send to cardiologist. Transthoracic echocardiography revealed a tumor (55 × 52 mm arising from the middle third of interatrial septum, floating and partially obstructing left atrioventricular orifice. Patient underwent Maze IV procedure combined with tumor resection. Histological study of the tumor showed typical for heart myxoma structure and cells. This case shows on-time diagnostics and successful surgical treatment of the patient with left atrial myxoma combined with paroxysmal atrial fibrillation.

  2. Effect of age on stroke prevention therapy in patients with atrial fibrillation: the atrial fibrillation investigators

    DEFF Research Database (Denmark)

    van Walraven, Carl; Hart, Robert G; Connolly, Stuart;

    2009-01-01

    BACKGROUND AND PURPOSE: Stroke risk increases with age in patients who have nonvalvular atrial fibrillation. It is uncertain whether the efficacy of stroke prevention therapies in atrial fibrillation changes as patients age. The objective of this study was to determine the effect of age on the...... relative efficacy of oral anticoagulants (OAC) and antiplatelet (AP) therapy (including acetylsalicylic acid and triflusal) on ischemic stroke, serious bleeding, and vascular events in patients with atrial fibrillation. METHODS: This is an analysis of the Atrial Fibrillation Investigators database, which...... contains patient level-data from randomized trials of stroke prevention in atrial fibrillation. We used Cox regression models with age as a continuous variable that controlled for sex, year of randomization, and history of cerebrovascular disease, diabetes, hypertension, and congestive heart failure...

  3. Risk of atrial fibrillation and stroke in rheumatoid arthritis

    DEFF Research Database (Denmark)

    Lindhardsen, Jesper; Ahlehoff, Ole; Gislason, Gunnar Hilmar;

    2012-01-01

    To determine if patients with rheumatoid arthritis have increased risk of atrial fibrillation and stroke.......To determine if patients with rheumatoid arthritis have increased risk of atrial fibrillation and stroke....

  4. A roadmap to improve the quality of atrial fibrillation management

    DEFF Research Database (Denmark)

    Kirchhof, Paulus; Breithardt, Günter; Bax, Jeroen;

    2016-01-01

    At least 30 million people worldwide carry a diagnosis of atrial fibrillation (AF), and many more suffer from undiagnosed, subclinical, or 'silent' AF. Atrial fibrillation-related cardiovascular mortality and morbidity, including cardiovascular deaths, heart failure, stroke, and hospitalizations,...

  5. Patient's Guide to Antithrombotic Therapy in Atrial Fibrillation

    Science.gov (United States)

    ... to Antithrombotic A Patient’s Guide to AntithromboticTherapy in Atrial Fibrillation AMERICAN COLLEGE OF CHEST PHYSICIANS Therapy in Atrial Fibrillation PATIENT EDUCATION GUIDE AMERICAN COLLEGE OF CHEST PHYSICIANS ...

  6. Who Is at Risk for Atrial Fibrillation (AF or AFib)?

    Science.gov (United States)

    ... living with AFib Atrial Fibrillation • Introduction • What is Atrial Fibrillation? • Why AFib Matters • Understand your Risk for AFib Children • Symptoms of AFib • Treatment & Prevention of AFib Treatment Guidelines of AFib Treatment Options ...

  7. On the numerical simulation of flutter and its suppression by active control

    International Nuclear Information System (INIS)

    The classic problem of predicting the motion (flutter) of a rigid airfoil mounted on an elastic support in a steady freestream is revisited. In the classic approach, the equations of motion were linearized, the supports were linear springs, the motion was assumed to be periodic, the aerodynamic loads were predicted by Wagner's function, and the solution was obtained in the so-called frequency domain. In the present approach, the equations of motion are in their fully nonlinear form, the supports may be nonlinear springs, the motion is not assumed to be periodic, the loads are predicted by a general unsteady vorticity-panel method, and the solution is obtained in the so-called time domain. After it is demonstrated that the present approach predicts the onset of flutter and the post-flutter behavior for flat-plate as well as thick airfoils, the airfoil -is modified by the addition of a flap at the trailing edge. The flap is part of an actively controlled servomechanism, and it is demonstrated that flutter can be readily controlled with very little effort by a variety of feedback-control laws. In the present approach, emphasis is placed on considering the airfoil, its supports, the flowing air and the control/servo mechanism collectively to be a single dynamic system. All the equations of motion and control laws are solved simultaneously and interactively; thus, complete interactions among the various subsystems are captured. The present simulation of an oscillating airfoil provides some characteristics of the flutter phenomenon that were missed in previous studies: for example, it is shown that, in the absence of flaps, the motion in heave (the translational part of the motion) is responsible for adding energy to (exciting) the structural subsystem while the motion in pitch is responsible for extracting energy from (damping) the structural subsystem. Below the critical speed, there is more dissipation than excitation and hence all initial disturbances decay

  8. Galectin-3 in patients undergoing ablation of atrial fibrillation

    OpenAIRE

    Nicolas Clementy; Eric Piver; Nazih Benhenda; Anne Bernard; Bertrand Pierre; Edouard Siméon; Laurent Fauchier; Jean-Christophe Pagès; Dominique Babuty

    2014-01-01

    Background: Mechanisms of maintenance of atrial fibrillation are known to include fibrosis. Galectin-3, as a biomarker of fibrosis, may be a valuable marker of atrial remodeling. We sought to find whether there was a link between clinical features and higher galectin-3 levels in patients with atrial fibrillation. Methods: Serum concentrations of Galectin-3 were determined in a consecutive series of patients addressed for ablation of atrial fibrillation. Results: One-hundred-and-eighty-s...

  9. Optimizing therapy in patients with atrial fibrillation and heart failure

    OpenAIRE

    Mulder, Bart Antonius

    2015-01-01

    Atrial fibrillation is the most common cardiac arrhythmia and the prevalence is expected to increase in the coming years. The same is true for heart failure. Atrial fibrillation may result in heart failure, and vice versa, but they can also exacerbate each other. The combination of atrial fibrillation and heart failure has important therapeutic implications to treat both diseases and create optimal outcomes for these patients. We started with patients with permanent atrial fibrillation. These...

  10. Heart failure and atrial fibrillation: current concepts and controversies

    OpenAIRE

    Berg, van den, T.J.T.P.; Tuinenburg, A. E.; Crijns, H. J. G. M.; Gelder, De; Gosselink, A. T.; Lie, K. I.

    1997-01-01

    Heart failure and atrial fibrillation are very common, particularly in the elderly. Owing to common risk factors both disorders are often present in the same patient. In addition, there is increasing evidence of a complex, reciprocal relation between heart failure and atrial fibrillation. Thus heart failure may cause atrial fibrillation, with electromechanical feedback and neurohumoral activation playing an important mediating role. In addition, atrial fibrillation may promote heart failure; ...

  11. Giant right atrial myxoma: characterization with cardiac magnetic resonance imaging.

    LENUS (Irish Health Repository)

    Ridge, Carole A

    2012-02-01

    A 53-year-old woman presented to the emergency department with a 2-week history of dyspnoea and chest pain. Computed tomography pulmonary angiography was performed to exclude acute pulmonary embolism (PE). This demonstrated a large right atrial mass and no evidence of PE. Transthoracic echocardiography followed by cardiac magnetic resonance imaging confirmed a mobile right atrial mass. Surgical resection was then performed confirming a giant right atrial myxoma. We describe the typical clinical, radiologic, and pathologic features of right atrial myxoma.

  12. A Case of Giant Right Atrial Aneurysm in a Child.

    Science.gov (United States)

    Pawar, Ravindra S; Tiwari, Ashish; Suresh, P V; Raj, Vimal; Kaushik, Pradeepkumar

    2016-07-01

    Giant right atrial aneurysm is a rare entity in infants and children. It needs to be distinguished from an atrial diverticulum, which can have similar presentation. Generally, an incidental finding in children, it can present with varied symptoms. We report a case of a giant right atrial aneurysm in an asymptomatic child with a large clot in the dilated right atrium, who underwent successful resection of the atrial aneurysm. PMID:26884450

  13. Atrial Ectopic Tachycardia in a Patient With Marfan Syndrome

    OpenAIRE

    Awerbach, Jordan D.; Khatib, Sammy; Moodie, Douglas S.; Snyder, Christopher S.

    2011-01-01

    The fibrillin defect central to Marfan syndrome is believed to affect myocardial conduction and predispose affected patients to various arrhythmias, including ventricular tachycardia, atrial fibrillation, and atrioventricular nodal reentry tachycardia. Here we describe an adult Marfan patient with atrial ectopic tachycardia. To our knowledge, this is the first reported case of atrial ectopic tachycardia in the setting of Marfan syndrome.

  14. Information Learned from Animal Models of Atrial Fibrillation

    OpenAIRE

    Finet, J. Emanuel; Rosenbaum, David S.; Donahue, J. Kevin

    2009-01-01

    Animal models of atrial fibrillation have taught us about mechanisms of this common disease. A variety of animal models exist, including models of lone atrial fibrillation and models of atrial fibrillation in the setting of heart failure, aging or pericardial inflammation. This chapter reviews these various models.

  15. Subclinical Hypothyroidism: An Overlooked Cause of Atrial Fibrillation?

    Directory of Open Access Journals (Sweden)

    Theofilos M. Kolettis, MD

    2012-12-01

    Full Text Available The association between clinical1 or subclinical2 hyperthyroidism and atrial fibrillation is established from large prospective cohort studies, with serum free thyroxin (T4 concentrations correlating with atrial fibrillation rates.3 However, the role of subclinical hypothyroidism as a causal factor for atrial fibrillation has not been elucidated.

  16. Cardiac Remodeling After Atrial Fibrillation Ablation

    Directory of Open Access Journals (Sweden)

    Li-Wei Lo, MD; Shih-Ann Chen, MD

    2013-06-01

    Full Text Available Radiofrequency catheter ablation procedures are considered a reasonable option for patients with symptomatic, drug refractory atrial fibrillation (AF. Ablation procedures have been reported to effectively restore sinus rhythm and provide long-term relief of symptoms. Both electrical and structural remodeling occurs with AF. A reversal of the electrical remodeling develops within 1 week after restoration to sinus rhythm following the catheter ablation. The recovery rate is faster in the right atrium than the left atrium. Reverse structural remodeling takes longer and is still present 2 to 4 months after restoration of sinus rhythm. The left atrial transport function also improves after successful catheter ablation of AF. Left atrial strain surveys from echocardiography are able to identify patients who respond to catheter ablation with significant reverse remodeling after ablation. Pre-procedural delayed enhancement magnetic resonance imaging is also able to determine the degree of atrial fibrosis and is another tool to predict the reverse remodeling after ablation. The remodeling process is complex if recurrence develops after ablation. Recent evidence shows that a combined reverse electrical and structural remodeling occurs after ablation of chronic AF when recurrence is paroxysmal AF. Progressive electrical remodeling without any structural remodeling develops in those with recurrence involving chronic AF. Whether progressive atrial remodeling is the cause or consequence during the recurrence of AF remains obscure and requires further study.

  17. ANTIARRHYTMIC EFFICACY OF SOTALOL IN PATIENTS WITH TACHY-BRADY SYNDROME HAVING ATRIAL PACEMAKER WITH DIFFERENT ATRIAL ELECTRODE POSITION

    OpenAIRE

    T. N. Novikova

    2016-01-01

    Aim. To evaluate efficacy of the combined therapy (sotalol and constant electric cardiostimulation in AAI regimen) at two atrial electrode position: in low back part of interatrial septum (IAS) and in right atrial auricle (RAA).Material and methods. 20 patients with tachy-brady syndrome were examined. They were randomized in 2 groups depending on atrial electrode position. Sotalol (160 mg daily) was prescribed to all patients in a month after implantation of constant atrial pacemaker (CAP). A...

  18. [Antithrombotic management in atrial fibrillation].

    Science.gov (United States)

    Fauchier, Laurent; Taillandier, Sophie; Clementy, Nicolas

    2013-02-01

    There is increasing recognition of the value of oral anticoagulation for stroke prevention in atrial fibrillation (AF), and the availability of new oral anticoagulants that overcome the limitations of vitamin K antagonists (VKA). Stroke risk assessment using the CHA2DS2-Vasc score allows identification of patients who are at truly low risk (score = 0) who should need no antithrombotic therapy, while all others (CHA2DS2-Vasc score > or = 1 with a risk of thromboembolic event > 1% per year) would be considered for oral anticoagulation. The HAS-BLED score has been recently proposed to easily assess bleeding risk in AF patients. A score of > or = 3 indicates "high risk" and some caution and regular review of the patient are needed. It also makes the clinician think of correctable common bleeding risk factors. The direct thrombin inhibitor dabigatran and factor Xa inhibitors rivaroxaban and apixaban are new oral anticoagulants that are at least as efficacious and safe as VKA in non valvular AF. Their advantages are easier use, predictable anticoagulant effects, low propensity for food and drug interactions, and lower rates of intracranial bleeding than with VKA, but they should not be used in patients with kidney disease at the present time. Overall, one may expect that more AF patients will be appropriately treated with oral anticoagulation in the next years. PMID:23513780

  19. Increased susceptibility to atrial fibrillation secondary to atrial fibrosis in transgenic goats expressing transforming growth factor - B1

    Science.gov (United States)

    Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia in people with significant morbidity and mortality. There is a strong association between atrial fibrosis and AF. Transforming growth factor B1 (TGF-B1) is an essential mediator of atrial fibrosis in animal models and human pat...

  20. Multirate Flutter Suppression System Design for the Benchmark Active Controls Technology Wing. Part 2; Methodology Application Software Toolbox

    Science.gov (United States)

    Mason, Gregory S.; Berg, Martin C.; Mukhopadhyay, Vivek

    2002-01-01

    To study the effectiveness of various control system design methodologies, the NASA Langley Research Center initiated the Benchmark Active Controls Project. In this project, the various methodologies were applied to design a flutter suppression system for the Benchmark Active Controls Technology (BACT) Wing. This report describes the user's manual and software toolbox developed at the University of Washington to design a multirate flutter suppression control law for the BACT wing.

  1. Determinants and importance of atrial pressure morphology in atrial septal defect.

    OpenAIRE

    Parikh, D N; J. Fisher; Moses, J W; Goldberg, H.L.; Levin, A. R.; Engle, M. A.; Borer, J S

    1984-01-01

    A prominent "v" wave relative to the "a" wave in the jugular vein and right atrial pressure tracing is considered to be a common haemodynamic sign of atrial septal defect. Since the prevalence, age relation, and haemodynamic determinants of the "v" greater than or equal to "a" wave configuration have not been studied the pressure recordings from 15 adults and 80 children with an isolated secundum atrial septal defect in sinus rhythm and from 40 adults and 55 children in sinus rhythm without s...

  2. Study on Effect of Compound Salvia Pellet in Preventing Atrial Fibrillation with Left Atrial Thrombosis

    Institute of Scientific and Technical Information of China (English)

    连耀植; 李玉光; 张汉灵; 张元春; 闫纯英; 林建才; 许端敏; 张钰; 郑宝群; 麦芒

    2004-01-01

    @@ Atrial fibrillation (AF) is a kind of common arrhythmia, which, besides affecting cardiac function, has another serious outcome, that is, it is easy to form atrial thrombosis and induce thrombus/embolus, especially cerebral embolus.The incidence of left atrial thrombosis (LAT)could reach 25%-30%(1), the incidence of embolic complication per year could reach 2. 98%-6.30%, even 20% or more(2,3). To prevent thrombosis so as to lower the incidence of cerebral stroke and other embolic complications has been so far the focal point of AF treatment.

  3. Effects of Persistent Atrial Fibrillation-Induced Electrical Remodeling on Atrial Electro-Mechanics – Insights from a 3D Model of the Human Atria

    OpenAIRE

    Adeniran, Ismail; Maclver, David H.; Garratt, Clifford J.; Ye, Jianqiao; Hancox, Jules C.; Zhang, Henggui

    2015-01-01

    Aims Atrial stunning, a loss of atrial mechanical contraction, can occur following a successful cardioversion. It is hypothesized that persistent atrial fibrillation-induced electrical remodeling (AFER) on atrial electrophysiology may be responsible for such impaired atrial mechanics. This simulation study aimed to investigate the effects of AFER on atrial electro-mechanics. Methods and Results A 3D electromechanical model of the human atria was developed to investigate the effects of AFER on...

  4. Nitric Oxide synthases and atrial fibrillation

    Directory of Open Access Journals (Sweden)

    CynthiaAnnCarnes

    2012-04-01

    Full Text Available Oxidative stress has been implicated in the pathogenesis of atrial fibrillation. There are multiple systems in the myocardium which contribute to redox homeostasis, and loss of homeostasis can result in oxidative stress. Potential sources of oxidants include nitric oxide synthases, which normally produce nitric oxide in the heart. Two nitric oxide synthase isoforms (1 and 3 are normally expressed in the heart. During pathologies such as heart failure, there is induction of nitric oxide synthase 2 in multiple cell types in the myocardium. In certain conditions, the NOS enzymes may become uncoupled, shifting from production of nitric oxide to superoxide anion, a potent free radical and oxidant. Multiple lines of evidence suggest a role for nitric oxide synthases in the pathogenesis of atrial fibrillation. Therapeutic approaches to reduce atrial fibrillation by modulation of nitric oxide synthase activity may be beneficial, although further investigation of this strategy is needed.

  5. Alcohol consumption and risk of atrial fibrillation

    DEFF Research Database (Denmark)

    Tolstrup, Janne Schurmann; Wium-Andersen, Marie Kim; Ørsted, David Dynnes;

    2016-01-01

    BACKGROUND: The aim of this study was to test the hypothesis that alcohol consumption, both observational (self-reported) and estimated by genetic instruments, is associated with a risk of atrial fibrillation and to determine whether people with high cardiovascular risk are more sensitive towards...... alcohol than people with low risk. METHODS: We used data for a total of 88,782 men and women from the Copenhagen City Heart Study 1991-1994 and 2001-2003 and the Copenhagen General Population Study 2003-2010. Information on incident cases of atrial fibrillation was obtained from a validated nationwide...... register. As a measure of alcohol exposure, both self-reported consumption and genetic variations in alcohol metabolizing genes (ADH1B/ADH1C) were used as instrumental variables. The endpoint was admission to hospital for atrial fibrillation as recorded in a validated hospital register. RESULTS: A total...

  6. Effects of irbesartan on atrial cell electrophysiology

    Institute of Scientific and Technical Information of China (English)

    HUANG Cong-xin; CAO Feng; JIANG Hong; WANG Teng; LI Xia

    2005-01-01

    @@ Atrial fibrillation (AF) is the most common sustained arrhythmia encountered in clinical practice.1 Its incidence increases with age and the presence of structural heart disease. It is a major cause of stroke, especially in the elderly. It has been shown that angiotensin converting enzyme inhibitor (ACEI) can reduce the incidence of AF after acute myocardial infarction.2 Several studies have shown that activation of the rennin-angiotensin system is associated with the mechanisms of AF. Irbesartan is a long-acting angiotensin Ⅱ type 1 receptor antagonist used widely in the treatment of hypertension.3 In recent years, it has been demonstrated that patients treated with amiodarone plus irbesartan had a lower rate of recurrence of atrial fibrillation than did patients treated with amiodarone alone.4 These findings suggest that the inhibition of angiotensin Ⅱ may prevent AF, but its underlying electrophysiological mechanisms are obscure. The purpose of this study is to investigate the effects of irbesartan on atrial cell electrophysiology.

  7. Atrial Electrical Remodeling and Sleep Disordered Breathing

    Directory of Open Access Journals (Sweden)

    Adrian Baranchuk; Diego Conde

    2013-08-01

    Full Text Available To the Editor: We read with interest the article from Bitter et al. (1 published in the last volume of JAFIB. This non-systematic review covers some of the most important physiopathological aspects of the link between sleep disordered breathing (SDB and atrial fibrillation (AFib. We do agree with the authors on the role of hypertension, endothelial dysfunction and inflammation. These topics were, to our understanding and perspective, very well covered by the authors on this review. However, despite that the authors mentioned atrial remodeling a couple of times during their review, we are not sure that this topic and specifically atrial electrical remodeling, was properly discussed and referenced. The pathophysiology linking SDB to AF is multifactorial and may involve repetitive hypoxemia, increased sympathetic drive, fluctuations in intrathoracic pressure and systemic inflammation (2. These physiologic changes may induce structural and electrical remodeling serving as a substrate to the development of AFib. An indirect marker for such electrical remodeling is the prolongation of atrial conduction time, represented by increased maximum P-wave duration in the surface ECG. In a prior study, we showed that an increased P-wave duration has been associated with SDB (3. Interatrial block (IAB, defined as a surface P-wave duration > 120 ms, was more prevalent in patients with moderate-severe SDB (34.7% SDB vs. 0% controls, p 25 were independent predictors of maximum P-wave duration (p=0.001 and p<0.001 respectively (3. Another non-invasive method to determine atrial electrical remodeling is the Signal-averaged P-wave (SAPW duration. The SAPW duration represents the average of all P-wave durations in a given number of consecutive heartbeats. We recently postulated that SAPW would be useful to identify atrial electrical remodeling in patients with severe SDB and that treatment with C-PAP for 4-6 weeks may induce reverse atrial electrical remodeling (4

  8. Antihypertensive treatment and risk of atrial fibrillation

    DEFF Research Database (Denmark)

    Marott, Sarah C W; Nielsen, Sune F; Benn, Marianne;

    2014-01-01

    AIMS: To examine the associations between antihypertensive treatment with angiotensin-converting enzyme inhibitors (ACEis) or angiotensin receptor blockers (ARBs), β-blockers, diuretics, or calcium-antagonists, and risk of atrial fibrillation. We examined these associations using the entire Danish...... population from 1995 through 2010. METHODS AND RESULTS: Excluding medication used in atrial fibrillation, we matched individuals on ACEi monotherapy 1:1 with individuals on β-blocker (n = 48 658), diuretic (n = 69 630), calcium-antagonist (n = 57 646), and ARB monotherapy (n = 20 158). Likewise, individuals...... on ARB monotherapy were matched 1:1 with individuals on β-blocker (n = 20 566), diuretic (n = 20 832), calcium-antagonist (n = 20 232), and ACEi monotherapy (n = 20 158). All were free of atrial fibrillation and of predisposing diseases like heart failure, ischaemic heart disease, diabetes mellitus...

  9. Wind-tunnel Measurement of Propeller Whirl-flutter Speeds and Static-stability Derivatives and Comparison with Theory

    Science.gov (United States)

    Bland, Samuel R.; Bennett, Robert M.

    1963-01-01

    Results of an experimental investigation of propeller whirl flutter are presented for a model consisting of an isolated, rigid system of propeller and simulated power plant mounted with flexibility in pitch and yaw on a rigid sting. A range of propeller blade angles, restraint stiffnesses, and restraint damping coefficients was investigated for a system symmetrical i n pitch and yaw with a windmilling propeller. Measurements of the static-stability derivatives were also made by using a simple balance and were compared with two sets of theoretical derivatives. Whirl-flutter calculations were made with the theoretical and measured derivatives. Some limited results were obtained for the whirl flutter of the model mounted on a cantilever semispan wing. The measured whirl-flutter speeds and frequencies of the isolated model were in very good agreement with those predicted by calculations in which measured derivatives and viscous damping were used. This agreement was better than that obtained by using structural damping. Predicted whirl-flutter speeds for the isolated model were lower when theoretical stability derivatives were used than when measured derivatives were used. The theoretical and experimental static-stability derivatives exhibited the same trends, but in certain instances differed appreciably in magnitude. the measured whirl-flutter boundary for the one configuration considered.

  10. Physical Insights, Steady Aerodynamic Effects, and a Design Tool for Low-Pressure Turbine Flutter

    Science.gov (United States)

    Waite, Joshua Joseph

    The successful, efficient, and safe turbine design requires a thorough understanding of the underlying physical phenomena. This research investigates the physical understanding and parameters highly correlated to flutter, an aeroelastic instability prevalent among low pressure turbine (LPT) blades in both aircraft engines and power turbines. The modern way of determining whether a certain cascade of LPT blades is susceptible to flutter is through time-expensive computational fluid dynamics (CFD) codes. These codes converge to solution satisfying the Eulerian conservation equations subject to the boundary conditions of a nodal domain consisting fluid and solid wall particles. Most detailed CFD codes are accompanied by cryptic turbulence models, meticulous grid constructions, and elegant boundary condition enforcements all with one goal in mind: determine the sign (and therefore stability) of the aerodynamic damping. The main question being asked by the aeroelastician, "is it positive or negative?'' This type of thought-process eventually gives rise to a black-box effect, leaving physical understanding behind. Therefore, the first part of this research aims to understand and reveal the physics behind LPT flutter in addition to several related topics including acoustic resonance effects. A percentage of this initial numerical investigation is completed using an influence coefficient approach to study the variation the work-per-cycle contributions of neighboring cascade blades to a reference airfoil. The second part of this research introduces new discoveries regarding the relationship between steady aerodynamic loading and negative aerodynamic damping. Using validated CFD codes as computational wind tunnels, a multitude of low-pressure turbine flutter parameters, such as reduced frequency, mode shape, and interblade phase angle, will be scrutinized across various airfoil geometries and steady operating conditions to reach new design guidelines regarding the influence

  11. Effect of catheter radiofrequency ablation on C-reactive protein, brain natriuretic peptide and echocardiograph in patients with persistent and permanent atrial fibrillation

    Institute of Scientific and Technical Information of China (English)

    Huang Qiong; Yuan Yiqiang; Qiu Chunguang; Zhao Yujie; Mao Youlin; Wang Ruimin; Wang Qian

    2014-01-01

    Background Radiofrequency catheter ablation (RFCA) for atrial fibrillation (AF) has developed rapidly,and is a commonly performed ablation in many major hospitals throughout the world,due to its satisfactory results.The aim of this study was to detect the effect of RFCA on C-reactive protein (CRP),brain natriuretic peptide (BNP),and echocardiograph in patients with persistent and permanent AF.Methods A total of 120 patients (71 males,mean age (50.8±12.0) years) with persistent and permanent AF undergoing RFCA under guidance of the Carto merge technique were studied.Left atrial diameter (LAD),right atrial diameter (RAD),left ventricular ejection fraction (LVEF),CRP,and BNP were observed 3,6 and 12 months after RFCA and compared with results before RFCA.The recurrence of atrial arrhythmias was observed 3 and 12 months after the procedure.Results Compared with that before RFCA,LAD and RAD decreased and LVEF increased significantly after RFCA.Meanwhile,the levels of CRP and BNP were reduced significantly at 3,6,and 12 months after RFCA (P<0.05).In the non-recurrent patients,LVEF was increased significantly compared with the recurrent patients at 3,6,and 12 months after RFCA (P<0.05).CRP and BNP levels were decreased significantly in the non-recurrent patients compared with the recurrent patients at 3,6,and 12 months after RFCA (P<0.05).After one or two applications of RFCA,during a follow-up of 12 months,12 patients (10.0%) had AF,10 patients (8.3%) had atrial flutter,and 5 patients had atrial tachycardia (4.2%).Conclusions Conversion of AF to sinus rhythm by RFCA,has been shown to reduce LA size and improve LVEF.It can also significantly decrease the levels of CRP and BNP in patients with persistent and permanent AF and reduce the risk of inflammation and developing heart failure.

  12. Contribution to Numerical and Experimental Studies of Flutter in Space Turbines. Aerodynamic Analysis of Subsonic or Supersonic Flows in Response to a Prescribed Vibratory Mode of the Structure.

    OpenAIRE

    Ferria, Hakim

    2011-01-01

    Modern turbomachines are designed towards thinner, lighter and highly loaded blades. This gives rise to increased sensitivity to flow induced vibrations such as flutter, which leads to structure failure in a short period of time if not sufficiently damped. Although numerical tools are more and more reliable, flutter prediction still depends on a large degree on simplified models. In addition, the critical nature of flutter, resulting in poor well-documented real cases in the open literature, ...

  13. Atrial fibrillation and the 4P medicine

    Directory of Open Access Journals (Sweden)

    Federica Censi

    2013-09-01

    Full Text Available Although the paradigm of the 4P medicine - Predictive, Personalized, Preemptive, and Participatory - has been suggested several years ago, its application to atrial fibrillation is still far away. Given the increasing prevalence and incidence of this pathology it is the time to promote preventive strategies, by identifying the risk factors associated to life style and by incentivizing innovative diagnostic technologies. The promotion of the correct life style and of the use of diagnostic devices based on innovative and reliable technologies, represent a first step towards the full realization of the revolution of 4P medicine in atrial fibrillation.

  14. [Obesity as a risk factor for atrial fibrillation].

    Science.gov (United States)

    Duraj, Iwona; Broncel, Marlena

    2016-01-01

    Atrial fibrillation (AF) and obesity is a growing problem of public health both in Poland and in the whole world. AF risk factors may be summarized as elderliness, male sex, smoking, hypertension, diabetes, obesity, coronary heart disease, heart failure, valvular heart disease, cardiac surgery. Once obesity is an independent, potentially modifiable risk factor for AF. The connection between obesity and atrial fibrillation is very up-to-date because of incremental prevalence, almost epidemic of obesity in the whole world. The probability of AF among obese patients increases with concomitant obstructive sleep apnea. Regardless many researches it hasn't been assessed yet how obesity itself predisposes to AF. It could be an effect of change in the atrial anatomy, the rise of atrial pressure, mechanical stretch, interstitial atrial fibrosis and disruption of atrial electric integrity. A great role is ascribed to inflammation, especially proinflammatory cytokines increased by adipocites of left atrial epicardial adiposity. PMID:26891428

  15. Reduced kidney function is a risk factor for atrial fibrillation.

    Science.gov (United States)

    Laukkanen, Jari A; Zaccardi, Francesco; Karppi, Jouni; Ronkainen, Kimmo; Kurl, Sudhir

    2016-08-01

    There is limited knowledge on the relationship between kidney function and incidence of atrial fibrillation. Thus, this prospective study was designed to evaluate whether various biomarkers of kidney function are associated to the risk of atrial fibrillation. The study population consisted of 1840 subjects (615 women and 1225 men) aged 61-82 years. Cystatin C- and creatinine-based estimation of glomerular filtration rate (eGFRcys and eGRFcreat , respectively) and urinary albumin/creatinine ratio (ACR) were assessed to investigate their relationship with the risk of atrial fibrillation. During a median follow-up of 3.7 years, a total of 159 incident atrial fibrillation cases occurred. After adjustment for potential confounders, the risk of atrial fibrillation was increased (hazard ratio 2.74, 95% confidence interval (CI) 1.56-4.81, P atrial fibrillation (hazard ratio 2.16, CI 1.35-2.82, P atrial fibrillation. PMID:26780558

  16. Management and prognosis of atrial fibrillation in the diabetic patient

    DEFF Research Database (Denmark)

    Pallisgaard, Jannik Langtved; Lindhardt, Tommi Bo; Olesen, Jonas Bjerring;

    2015-01-01

    The global burden of atrial fibrillation and diabetes mellitus (diabetes) is considerable, and prevalence rates are increasing. Diabetes is associated with an increased risk of developing atrial fibrillation; however, diabetes also influences the management and prognosis of atrial fibrillation. In...... the following article, the authors describe the association between diabetes and atrial fibrillation; specifically, the significance of diabetes on the risk of atrial fibrillation, ischemic stroke and bleeding complications associated with anticoagulation. In addition, the authors evaluate the risks...... and outcomes of heart failure and the success rates of both ablation and cardioversion in atrial fibrillation patients with diabetes. Finally, this article describes the association of HbA1c levels with the management and prognosis of atrial fibrillation patients....

  17. Atrial Fibrillation and Heart Failure Parallels: Lessons for Atrial Fibrillation Prevention

    OpenAIRE

    McManus, David D.; Shaikh, Amir Y; Abhishek, FNU; Vasan, Ramachandran S.

    2011-01-01

    Heart failure (HF) and atrial fibrillation (AF) are two of the most common cardiovascular diseases encountered in clinical practice, and the prevalence of these diseases continues to grow world-wide with the aging of the global population.

  18. Flutter analysis of an airfoil with nonlinear damping using equivalent linearization

    Directory of Open Access Journals (Sweden)

    Chen Feixin

    2014-02-01

    Full Text Available The equivalent linearization method (ELM is modified to investigate the nonlinear flutter system of an airfoil with a cubic damping. After obtaining the linearization quantity of the cubic nonlinearity by the ELM, an equivalent system can be deduced and then investigated by linear flutter analysis methods. Different from the routine procedures of the ELM, the frequency rather than the amplitude of limit cycle oscillation (LCO is chosen as an active increment to produce bifurcation charts. Numerical examples show that this modification makes the ELM much more efficient. Meanwhile, the LCOs obtained by the ELM are in good agreement with numerical solutions. The nonlinear damping can delay the occurrence of secondary bifurcation. On the other hand, it has marginal influence on bifurcation characteristics or LCOs.

  19. Flutter control of incompressible flow turbomachine blade rows by splitter blades

    International Nuclear Information System (INIS)

    Splitter blades as a passive flutter control technique are investigated by developing a mathematical model to predict the stability of an aerodynamically loaded splittered-rotor operating in an incompressible flow field. The splitter blades, positioned circumferentially in the flow passage between two principal blades, introduce aerodynamic and/or combined aerodynamic-structural detuning into the rotor. The two-dimensional oscillating cascade unsteady aerodynamics, including steady loading effects, are determined by developing a complete first-order unsteady aerodynamic analysis together with an unsteady aerodynamic influence coefficient technique. The torsion mode flutter of both uniformly spaced tuned rotors and detuned rotors are predicted by incorporating the unsteady aerodynamic influence coefficients into a single-degree-of-freedom aeroelastic model. This model is then utilized to demonstrate that incorporating splitters into unstable rotor configurations results in stable splittered-rotor configurations. (orig.)

  20. A Study on Fluid Self-Excited Flutter and Forced Response of Turbomachinery Rotor Blade

    Directory of Open Access Journals (Sweden)

    Chih-Neng Hsu

    2014-01-01

    Full Text Available Complex mode and single mode approach analyses are individually developed to predict blade flutter and forced response. These analyses provide a system approach for predicting potential aeroelastic problems of blades. The flow field properties of a blade are analyzed as aero input and combined with a finite element model to calculate the unsteady aero damping of the blade surface. Forcing function generators, including inlet and distortions, are provided to calculate the forced response of turbomachinery blading. The structural dynamic characteristics are obtained based on the blade mode shape obtained by using the finite element model. These approaches can provide turbine engine manufacturers, cogenerators, gas turbine generators, microturbine generators, and engine manufacturers with an analysis system to remedy existing flutter and forced response methods. The findings of this study can be widely applied to fans, compressors, energy turbine power plants, electricity, and cost saving analyses.

  1. Aeroelastic Flutter Behavior of Cantilever within a Nozzle-Diffuser Geometry

    Science.gov (United States)

    Tosi, Luis Phillipe; Colonius, Tim; Sherrit, Stewart; Lee, Hyeong Jae

    2015-11-01

    Aeroelastic flutter arises when the motion of a structure and its surrounding flowing fluid are coupled in a constructive manner, causing large amplitudes of vibration in the immersed solid. A cantilevered beam in axial flow within a nozzle-diffuser geometry exhibits interesting resonance behavior that presents good prospects for internal flow energy harvesting. Different modes can be excited as a function of throat velocity, nozzle geometry, fluid and cantilever material parameters. This work explores the relationship between the aeroelastic flutter instability boundaries and relevant non-dimensional parameters via experiments. Results suggest that for a linear expansion diffuser geometry, a non-dimensional stiffness, non-dimensional mass, and non-dimensional throat size are the critical parameters in mapping the instability. This map can serve as a guide to future work concerning possible electrical output and failure prediction in energy harvesters.

  2. Piezoelectric coupling in energy-harvesting fluttering flexible plates : linear stability analysis and conversion efficiency

    CERN Document Server

    Doare, Olivier

    2011-01-01

    This paper investigates the energy harvested from the flutter of a plate in an axial flow by making use of piezoelectric materials. The equations for fully-coupled linear dynamics of the fluid-solid and electrical systems are derived. The continuous limit is then considered, when the characteristic length of the plate's deformations is large compared to the piezoelectric patches' length. The linear stability analysis of the coupled system is addressed from both a local and global point of view. Piezoelectric energy harvesting adds rigidity and damping on the motion of the flexible plate, and destabilization by dissipation is observed for negative energy waves propagating in the medium. This result is confirmed in the global analysis of fluttering modes of a finite-length plate. It is finally observed that waves or modes destabilized by piezoelectric coupling maximize the energy conversion efficiency.

  3. Design for coupled-mode flutter and non-synchronous vibration in turbomachinery

    Science.gov (United States)

    Clark, Stephen Thomas

    This research presents the detailed investigation of coupled-mode flutter and non-synchronous vibration in turbomachinery. Coupled-mode flutter and non-synchronous vibration are two aeromechanical challenges in designing turbomachinery that, when present, can cause engine blade failure. Regarding flutter, current industry design practices calculate the aerodynamic loads on a blade due to a single mode. In response to these design standards, a quasi three-dimensional, reduced-order modeling tool was developed for identifying the aeroelastic conditions that cause multi-mode flutter. This tool predicts the onset of coupled-mode flutter reasonable well for four different configurations, though certain parameters were tuned to agree with experimentation. Additionally, the results of this research indicate that mass ratio, frequency separation, and solidity have an effect on critical rotor speed for flutter. Higher mass-ratio blades require larger rotational velocities before they experience coupled-mode flutter. Similarly, increasing the frequency separation between modes and raising the solidity increases the critical rotor speed. Finally, and most importantly, design guidelines were generated for defining when a multi-mode flutter analysis is required in practical turbomachinery design. Previous work has shown that industry computational fluid dynamics can approximately predict non-synchronous vibration (NSV), but no real understanding of frequency lock-in and blade limit-cycle amplitude exists. Therefore, to understand the causes of NSV, two different reduced-order modeling approaches were used. The first approach uses a van der Pol oscillator to model a non-linear fluid instability. The van der Pol model is then coupled to a structural degree of freedom. This coupled system exhibits the two chief properties seen in experimental and computational non-synchronous vibration. Under various conditions, the fluid instability and the natural structural frequency will lock

  4. Highly flexible flight vehicle aeroelastic and aero-viscoelastic flutter issues

    Science.gov (United States)

    Merrett, Craig G.; Hilton, Harry H.

    2012-11-01

    Aeroelastic and aero-viscoelastic phenomena arising from the high flexibility of modern flight vehicles are examined, and governing relations are formulated and solved. In particular, the time dependent flight velocities associated with maneuvers and with in-plane bending are considered, which necessitate new derivations of the Theodorsen function, unsteady aerodynamic relations and equations of motion. Under these conditions, simple harmonic motion (SHM) is no longer achievable and different flutter criteria based directly on motion stability are presented. The viscoelastic problem is formulated in terms of integral partial differential equations with variable nonlinear coefficients. Their solutions and evaluations are discussed in detail. One interesting departure from linear responses emerged, which indicates flutter in one bending while the other bending mode and the torsional are both stable. A detailed and extended treatment of these subjects may be found in [1].

  5. A method for obtaining practical flutter-suppression control laws using results of optimal control theory

    Science.gov (United States)

    Newson, J. R.

    1979-01-01

    The results of optimal control theory are used to synthesize a feedback filter. The feedback filter is used to force the output of the filtered frequency response to match that of a desired optimal frequency response over a finite frequency range. This matching is accomplished by employing a nonlinear programing algorithm to search for the coefficients of the feedback filter that minimize the error between the optimal frequency response and the filtered frequency response. The method is applied to the synthesis of an active flutter-suppression control law for an aeroelastic wind-tunnel model. It is shown that the resulting control law suppresses flutter over a wide range of subsonic Mach numbers. This is a promising method for synthesizing practical control laws using the results of optimal control theory.

  6. The antiarrhythmic peptide analog ZP123 prevents atrial conduction slowing during metabolic stress

    DEFF Research Database (Denmark)

    Haugan, Ketil; Olsen, Kristine Boisen; Hartvig, Line;

    2005-01-01

    OBJECTIVE: As atrial conduction slowing is important in the pathogenesis of atrial reentry arrhythmias, a drug that increases atrial conduction or prevents atrial conduction slowing could serve to prevent atrial reentry arrhythmias. In this study, we investigated whether the novel stable antiarrh...

  7. Percutaneous Left Atrial Appendage Ligation for Stroke Prevention in Atrial Fibrillation.

    Science.gov (United States)

    Valderrábano, Miguel; Price, Matthew J

    2015-01-01

    Prevention of thromboembolic complications in atrial fibrillation remains a tremendous clinical challenge. Knowledge that the left atrial appendage (LAA) is the most common anatomical origin of cardioembolic strokes1 has been the main motivation to develop clinical and procedural strategies to exclude the LAA from the circulation, either surgically or percutaneously. This review discusses the rationale behind these strategies, their relative merits, and future prospects for LAA exclusion strategies. PMID:26306126

  8. Valsartan Reduced Atrial Fibrillation Susceptibility by Inhibiting Atrial Parasympathetic Remodeling through MAPKs/Neurturin Pathway

    Directory of Open Access Journals (Sweden)

    Lei Liu

    2015-07-01

    Full Text Available Background/Aims: Angiotensin II receptor blockers (ARBs have been proved to be effective in preventing atrial structural and electrical remodelinq in atrial fibrillation (AF. Previous studies have shown that parasympathetic remodeling plays an important role in AF. However, the effects of ARBs on atrial parasympathetic remodeling in AF and the underlying mechanisms are still unknown. Methods: Canines were divided into sham-operated, pacing and valsartan + pacing groups. Rats and HL-1 cardiomyocytes were divided into control, angiotensin II (Ang II and Ang II + valsartan groups, respectively. Atrial parasympathetic remodeling was quantified by immunocytochemical staining with anti-choline acetyltransferase (ChAT antibody. Western blot was used to analysis the protein expression of neurturin. Results: Both inducibility and duration were increased in chronic atrial rapid-pacing canine model, which was significantly inhibited by the treatment with valsartan. The density of ChAT-positive nerves and the protein level of neurturin in the atria of pacing canines were both increased than those in sham-operated canines. Ang II treatment not only induced atrial parasympathetic remodeling in rats, but also up-regulated the protein expression of neurturin. Valsartan significantly prevented atrial parasympathetic remodeling, and suppressed the protein expression of neurturin. Meanwhile, valsartan inhibited Ang II -induced up-regulation of neurturin and MAPKs in cultured cardiac myocytes. Inhibition of MAPKs dramatically attenuated neurturin up-regulation induced by Ang II. Conclusion: Parasympathetic remodeling was present in animals subjected to rapid pacing or Ang II infusion, which was mediated by MAPKs/neurturin pathway. Valsartan is able to prevent atrial parasympathetic remodeling and the occurrence of AF via inhibiting MAPKs/neurturin pathway.

  9. Left Atrial Decompression by Percutaneous Left Atrial Venting Cannula Insertion during Venoarterial Extracorporeal Membrane Oxygenation Support

    Science.gov (United States)

    Kim, Ha Eun; Jung, Jo Won; Shin, Yu Rim; Park, Han Ki; Park, Young Hwan; Shin, Hong Ju

    2016-01-01

    Patients with venoarterial extracorporeal membrane oxygenation (ECMO) frequently suffer from pulmonary edema due to left ventricular dysfunction that accompanies left heart dilatation, which is caused by left atrial hypertension. The problem can be resolved by left atrium (LA) decompression. We performed a successful percutaneous LA decompression with an atrial septostomy and placement of an LA venting cannula in a 38-month-old child treated with venoarterial ECMO for acute myocarditis. PMID:27298800

  10. Left Atrial Appendage Closure for Stroke Prevention in Patients with Atrial Fibrillation and Hereditary Hemorrhagic Telangiectasia

    OpenAIRE

    Sebastiaan Velthuis; Swaans, Martin J.; Mager, Johannes J.; Rensing, Benno J. W. M.; Lucas V. A. Boersma; Post, Martijn C.

    2012-01-01

    Atrial fibrillation (AF) is the most common cardiac arrhythmia, affecting millions of individuals worldwide, and a major risk factor for disabling cerebral embolic stroke. Hereditary hemorrhagic telangiectasia (HHT) is an autosomal dominant inherited disorder, characterized by vascular abnormalities with high-bleeding tendency and therefore intolerance for oral anticoagulation. We report a case of percutaneous closure of the left atrial appendage, which might be a good alternative strategy in...

  11. Percutaneous Left Atrial Appendage Ligation for Stroke Prevention in Atrial Fibrillation

    OpenAIRE

    Valderrábano, Miguel; Price, Matthew J.

    2015-01-01

    Prevention of thromboembolic complications in atrial fibrillation remains a tremendous clinical challenge. Knowledge that the left atrial appendage (LAA) is the most common anatomical origin of cardioembolic strokes1 has been the main motivation to develop clinical and procedural strategies to exclude the LAA from the circulation, either surgically or percutaneously. This review discusses the rationale behind these strategies, their relative merits, and future prospects for LAA exclusion stra...

  12. ANTIARRHYTMIC EFFICACY OF SOTALOL IN PATIENTS WITH TACHY-BRADY SYNDROME HAVING ATRIAL PACEMAKER WITH DIFFERENT ATRIAL ELECTRODE POSITION

    Directory of Open Access Journals (Sweden)

    T. N. Novikova

    2016-01-01

    Full Text Available Aim. To evaluate efficacy of the combined therapy (sotalol and constant electric cardiostimulation in AAI regimen at two atrial electrode position: in low back part of interatrial septum (IAS and in right atrial auricle (RAA.Material and methods. 20 patients with tachy-brady syndrome were examined. They were randomized in 2 groups depending on atrial electrode position. Sotalol (160 mg daily was prescribed to all patients in a month after implantation of constant atrial pacemaker (CAP. A number of atrial fibrillation paroxysms (AFP was evaluated initially, in a month after CAP implantation and in a month after start of sotalol therapy.Results. Significant AFP reduction was observed in IAS stimulation, unlike RAA stimulation. Sotalol addition had essential significance in the termination or reduction of AFP. Sotalol effect did not depend on atrial electrode position.Conclusion. Sotalol usage together with constant electric cardiostimulation significantly reduces AFP irrespectively of atrial electrode position. 

  13. Numerical investigation of blade flutter at or near stall in axial turbomachines

    OpenAIRE

    Höhn, Wolfgang

    2000-01-01

    During the design of the compressor and turbine stages oftoday's aeroengines aerodynamically induced vibrations becomeincreasingly important since higher blade load and betterefficiency are desired. Aerodynamically induced vibrations inturbomachines can be classified into two general categories,i.e. selfexcited vibrations, usually denoted as flutter, andforced response. In the first case the aerodynamic forcesacting on the structure are dependent on the motion of thestructure. In the latter c...

  14. The flow field acting on the fluttering profile, measurements and evaluation

    Czech Academy of Sciences Publication Activity Database

    Kozánek, Jan; Vlček, Václav; Zolotarev, Igor

    Lodž: Department of Automation and Biomechanics, 2011 - (Awrejcewicz, J.; Kazmierczak, P.; Olejnik, P.; Mrozowski, J.), s. 283-288 ISBN 978-83-7283-447-8. [Conference on Dynamical System /11./. Lodž (PL), 05.12.2011-08.12.2011] R&D Projects: GA ČR GA101/09/1522 Institutional research plan: CEZ:AV0Z20760514 Keywords : fluttering profile * interferograms * kinematics * aerodynamic forces and moments Subject RIV: BI - Acoustics

  15. Smolyak-Grid-Based Flutter Analysis with the Stochastic Aerodynamic Uncertainty

    OpenAIRE

    Yuting Dai; Chao Yang

    2014-01-01

    How to estimate the stochastic aerodynamic parametric uncertainty on aeroelastic stability is studied in this current work. The aerodynamic uncertainty is more complicated than the structural one, and it takes more significant effect on the flutter boundary. First, the nominal unsteady aerodynamic influence coefficients were calculated with the doublet lattice method. Based on this nominal model, the stochastic uncertainty model for unsteady aerodynamic pressure coefficients was constructed w...

  16. Computer modeling of flutter of viscoelastic orthotropic plates in supersonic flow

    OpenAIRE

    ВЕРЛАНЬ, А.Ф.; ХУДАЯРОВ, Б.А.; Файзибоев, Э. Ф.; ЮЛДАШЕВ, З.У.

    2012-01-01

    This paper considers the nonlinear flutter of viscoelastic orthotropic plates in supersonic flow. The equations of motion derived from the most general theory of plates Foppl-Karman in displacements, which satisfy the Kirchhoff hypothesis. Aerodynamic pressure is accounted for under the piston theory A.A. Ilyushin. Using the Bubnov - Galerkin method based on polynomial approximation of displacements, the problem is reduced to the study of a system of ordinary integro-differential equations (I...

  17. A Study on Fluid Self-Excited Flutter and Forced Response of Turbomachinery Rotor Blade

    OpenAIRE

    Chih-Neng Hsu

    2014-01-01

    Complex mode and single mode approach analyses are individually developed to predict blade flutter and forced response. These analyses provide a system approach for predicting potential aeroelastic problems of blades. The flow field properties of a blade are analyzed as aero input and combined with a finite element model to calculate the unsteady aero damping of the blade surface. Forcing function generators, including inlet and distortions, are provided to calculate the forced response of tu...

  18. The effect of non-uniform damping on flutter in axial flow and energy harvesting strategies

    OpenAIRE

    Singh, Kiran; Michelin, Sebastien; de Langre, Emmanuel

    2012-01-01

    The problem of energy harvesting from flutter instabilities in flexible slender structures in axial flows is considered. In a recent study, we used a reduced order theoretical model of such a system to demonstrate the feasibility for harvesting energy from these structures. Following this preliminary study, we now consider a continuous fluid-structure system. Energy harvesting is modelled as strain-based damping and the slender structure under investigation lies in a moderate fluid loading ra...

  19. Flutter and vibration control of an aluminum plate wing by piezoceramic actuators

    Science.gov (United States)

    Sanda, Tomio; Takahashi, Kosaku

    1998-07-01

    We carried out tests and analysis of flutter and vibration control of rectangular aluminum plate wing. The dimensions of the plate wing (420.0 X 140.0 X 1.0 mmt) were determined based on the wind tunnel size and blowing air velocity. The plate wing was driven by eight piezoceramic actuators bonded on the surfaces at the wing root part. Acceleration sensor was located at the wing tip and the signal was sent to digital signal processor through filters and control signal was sent to power amplifier. Amplified signal drove the piezoceramic actuator and suppressed vibration of the plate wing. System consist of structure, piezoceramic actuator and unsteady aerodynamic force was modeled into the standard form of modern control theory. Piezoceramic actuator's force was modeled using analogy of thermal analysis. Unsteady aerodynamic force in case of flutter control was calculated by DLM (frequency domain), then transformed to Roger's approximation for the purpose of time domain analysis. Full order control law consist of optimum regulator and Kalman's filter was reduced to low order law for practical use. First, we carried out the test for vibration control. In this case, structural damping ratio of the system increased remarkably in both case of gain control and reduced LQG control. Using gain control, that of the system increased up to 0.3. Second, we carried out the wind tunnel test of flutter control. Flutter speed at test increased about 2.9 m/s (10.8%, in calculation 12.2%) using reduced LQG controller.

  20. The dynamic and flutter properties of the new airfoil model NACA0015

    Czech Academy of Sciences Publication Activity Database

    Kozánek, Jan; Vlček, Václav; Zolotarev, Igor; Štěpán, M.

    Lodž: Department of Automation, Biomechanics and Mechatronics, 2015 - (Awrejcewicz, J.; Kazmierczak, M.), s. 341-350 ISBN 978-83-7283-708-0. [Dynamical systems – theory and applications /13./. Lodž (PL), 07.12.2015-10.12.2015] R&D Projects: GA ČR GA13-10527S Institutional support: RVO:61388998 Keywords : airfoil model * flutter * aerodynamic tunnel Subject RIV: BI - Acoustics

  1. Percutaneous closure of atrial septal defects leads to normalisation of atrial and ventricular volumes

    Directory of Open Access Journals (Sweden)

    Worthley Matthew I

    2008-12-01

    Full Text Available Abstract Background Percutaneous closure of atrial septal defects (ASDs should potentially reduce right heart volumes by removing left-to-right shunting. Due to ventricular interdependence, this may be associated with impaired left ventricular filling and potentially function. Furthermore, atrial changes post-ASD closure have been poorly understood and may be important for understanding risk of atrial arrhythmia post-ASD closure. Cardiovascular magnetic resonance (CMR is an accurate and reproducible imaging modality for the assessment of cardiac function and volumes. We assessed cardiac volumes pre- and post-percutaneous ASD closure using CMR. Methods Consecutive patients (n = 23 underwent CMR pre- and 6 months post-ASD closure. Steady state free precession cine CMR was performed using contiguous slices in both short and long axis views through the ASD. Data was collected for assessment of left and right atrial, ventricular end diastolic volumes (EDV and end systolic volumes (ESV. Data is presented as mean ± SD, volumes as mL, and paired t-testing performed between groups. Statistical significance was taken as p Results There was a significant reduction in right ventricular volumes at 6 months post-ASD closure (RVEDV: 208.7 ± 76.7 vs. 140.6 ± 60.4 mL, p Conclusion ASD closure leads to normalisation of ventricular volumes and also a reduction in right atrial volume. Further follow-up is required to assess how this predicts outcomes such as risk of atrial arrhythmias after such procedures.

  2. Assessment of atrial fibrosis for the rhythm control of atrial fibrillation.

    Science.gov (United States)

    Begg, Gordon A; Holden, Arun V; Lip, Gregory Y H; Plein, Sven; Tayebjee, Muzahir H

    2016-10-01

    Rhythm control of atrial fibrillation (AF) remains challenging, with modest long-term success rates. Atrial fibrosis has been associated with AF, but the clinical utility of assessment of this fibrosis has yet to be fully elucidated. In this paper we review the current state of understanding of the pathophysiology of atrial fibrosis in AF, and its impact upon the instigation and propagation of the arrhythmia. Fibrosis causes an increase in volume of dysfunctional extracellular matrix, and is associated with cellular alterations such as hypertrophy, apoptosis and membrane dysfunction within the atrial myocardium. In turn, these cause pathological alterations to atrial conduction, such as increased anisotropy, conduction block and re-entry, which can lead to AF. We review current methods of assessing atrial fibrosis and their impact upon the prediction of success of interventional rhythm control strategies such as ablation and cardioversion. We focus particularly on circulating biomarkers of fibrosis and scar formation; their role in the fibrotic process, and their value in the prediction of rhythm control success. We also review imaging and invasive electrocardiographic mapping techniques that may identify fibrosis, and again assess their potential predictive value. In this area there exist many unanswered questions, but further work will help to refine techniques to reliably identify and treat those patients who are most likely to benefit from rhythm control treatment strategies. PMID:27389440

  3. Left atrial appendage closure devices for cardiovascular risk reduction in atrial fibrillation patients

    Directory of Open Access Journals (Sweden)

    Cruz-Gonzalez I

    2015-05-01

    Full Text Available Ignacio Cruz-Gonzalez,* Juan Carlos Rama-Merchan,* Javier Rodriguez-Collado, Javier Martin-Moreiras, Alejandro Diego-Nieto, Antonio Arribas-Jimenez, Pedro Luís SanchezDepartment of Cardiology, University Hospital of Cardiology and IBSAL, Salamanca, Spain *Ignacio Cruz-Gonzalez and Juan Carlos Rama-Merchan have contributed equally to this work and should be considered co-first authors Abstract: Atrial fibrillation (AF is the most common sustained arrhythmia in clinical practice. AF is associated with a 4–5-fold increased risk of stroke and systemic embolism. Oral anticoagulant is the first-line therapy for this purpose, but it has various limitations and is often contraindicated or underutilized. Autopsy and surgical data have suggested that 90% of atrial thrombi in nonvalvular AF patients originate from the left atrial appendage, leading to the development of percutaneous closure for thromboembolic prevention. This paper examines the current evidence on left atrial appendage closure devices for cardiovascular risk reduction in AF patients. Keywords: atrial fibrillation, left atrial appendage, stroke, oral anticoagulant, percutaneous closure, thromboembolic prevention

  4. Aeroelastic flutter energy harvester design: the sensitivity of the driving instability to system parameters

    International Nuclear Information System (INIS)

    This study examines the design parameters affecting the stability characteristics of a novel fluid flow energy harvesting device powered by aeroelastic flutter vibrations. The energy harvester makes use of a modal convergence flutter instability to generate limit cycle bending oscillations of a cantilevered piezoelectric beam with a small flap connected to its free end by a revolute joint. The critical flow speed at which destabilizing aerodynamic effects cause self-excited vibrations of the structure to emerge is essential to the design of the energy harvester because it sets the lower bound on the operating wind speed and frequency range of the system. A linearized analytic model of the device that accounts for the three-way coupling between the structural, unsteady aerodynamic, and electrical aspects of the system is used to examine tuning several design parameters while the size of the system is held fixed. The effects on the aeroelastic system dynamics and relative sensitivity of the flutter stability boundary are presented and discussed. A wind tunnel experiment is performed to validate the model predictions for the most significant system parameters

  5. Flutter Analysis of a Morphing Wing Technology Demonstrator: Numerical Simulation and Wind Tunnel Testing

    Directory of Open Access Journals (Sweden)

    Andreea KOREANSCHI

    2016-03-01

    Full Text Available As part of a morphing wing technology project, the flutter analysis of two finite element models and the experimental results of a morphing wing demonstrator equipped with aileron are presented. The finite element models are representing a wing section situated at the tip of the wing; the first model corresponds to a traditional aluminium upper surface skin of constant thickness and the second model corresponds to a composite optimized upper surface skin for morphing capabilities. The two models were analyzed for flutter occurrence and effects on the aeroelastic behaviour of the wing were studied by replacing the aluminium upper surface skin of the wing with a specially developed composite version. The morphing wing model with composite upper surface was manufactured and fitted with three accelerometers to record the amplitudes and frequencies during tests at the subsonic wind tunnel facility at the National Research Council. The results presented showed that no aeroelastic phenomenon occurred at the speeds, angles of attack and aileron deflections studied in the wind tunnel and confirmed the prediction of the flutter analysis on the frequencies and modal displacements.

  6. Energy Harvesting for Micropower Applications by Flow-Induced Flutter of an Inverted Piezoelectric Flag

    Science.gov (United States)

    Shoele, Kourosh; Mittal, Rajat

    2015-11-01

    Piezoelectric flexible flags can be used to continuously generate energy for small-scale sensor used in a wide variety of applications ranging from measurement/monitoring of environmental conditions (outdoors or indoors) to in-situ tracking of wild animals. Here, we study the energy harvesting performance as well as the flow-structure interaction of an inverted piezoelectric flag. We use a coupled fluid-structure-electric solver to examine the dynamic response of the inverted flag as well as the associated vortical characteristics with different inertia and bending stiffness. Simulations indicate that large amplitude vibrations can be achieved over a large range of parameters over which lock-on between the flag flutter and the intrinsic wake shedding occurs. The effects of initial inclination of the flag to the prevailing flow as well as Reynolds number of the flow are explored, and the effect of piezoelectric material parameters on the energy harvesting performance of this flutter state is examined in detail. The maximum energy efficiency occurs when there is a match between the intrinsic timescales of flutter and the piezoelectric circuit. The simulations are used to formulate a scaling law that could be used to predict the energy harvesting performance of such devices. The support for this study comes from AFSOR, NSF, EPRI and Johns Hopkins E2SHI Seed Grant.

  7. Influence of upstream stator on rotor flutter stability in a low pressure steam turbine stage

    Energy Technology Data Exchange (ETDEWEB)

    Huang, X.; He, L. [University of Durham (United Kingdom). School of Engineering; Bell, D. [ALSTOM Power Ltd., Rugby (United Kingdom)

    2006-07-01

    Conventional blade flutter prediction is normally based on an isolated blade row model, however, little is known about the influence of adjacent blade rows. In this article, an investigation is presented into the influence of the upstream stator row on the aero-elastic stability of rotor blades in the last stage of a low pressure (LP) steam turbine. The influence of the upstream blade row is computed directly by a time-marching, unsteady, Navier-Stokes flow solver in a stator-rotor coupled computational domain. The three-dimensional flutter solution is obtained, with adequate mesh resolution, in a single passage domain through application of the Fourier-Transform based Shape-Correction method. The capability of this single-passage method is examined through comparison with predictions obtained from a complete annulus model, and the results demonstrate a good level of accuracy, while achieving a speed up factor of 25. The present work shows that the upstream stator blade row can significantly change the aero-elastic behaviour of an LP steam turbine rotor. Caution is, therefore, advised when using an isolated blade row model for blade flutter prediction. The results presented also indicated that the intra-row interaction is of a strong three-dimensional nature. (author)

  8. Swallowing‐induced atrial tachycardia: case report

    OpenAIRE

    Xu, Ye; Cheng, Kuan; Zhu, Wenqing

    2015-01-01

    Key Clinical Message A 53‐year‐old man presented with heart palpitations while swallowing. Electrophysiologic study (EPS) and immunohistochemical results of his esophageal leiomyoma suggested that swallowing‐induced atrial tachycardia is related with neural reflex. S100‐immunopositive nerve fibers are demonstrated sympathetic nerves which possibly explain the mechanism. Metoprolol tartrate tablets are effective in our patient.

  9. An "account" of digitalis and atrial fibrillation

    NARCIS (Netherlands)

    Meijler, F.L.

    1985-01-01

    This review deals with the mechanisms by which digitalis exerts its "opium-Iike" action on the ventricular rate in patients with atrial fibrillation. To understand the effect of digitalis on ventricular rate and rhythm, it is essential to learn more about the basic electrophysiologic principles resp

  10. Epicardial adipose tissue and atrial fibrillation.

    Science.gov (United States)

    Hatem, Stéphane N; Sanders, Prashanthan

    2014-05-01

    Atrial fibrillation (AF) is the most frequent cardiac arrhythmia in clinical practice. AF is often associated with profound functional and structural alterations of the atrial myocardium that compose its substrate. Recently, a relationship between the thickness of epicardial adipose tissue (EAT) and the incidence and severity of AF has been reported. Adipose tissue is a biologically active organ regulating the metabolism of neighbouring organs. It is also a major source of cytokines. In the heart, EAT is contiguous with the myocardium without fascia boundaries resulting in paracrine effects through the release of adipokines. Indeed, Activin A, which is produced in abundance by EAT during heart failure or diabetes, shows a marked fibrotic effect on the atrial myocardium. The infiltration of adipocytes into the atrial myocardium could also disorganize the depolarization wave front favouring micro re-entry circuits and local conduction block. Finally, EAT contains progenitor cells in abundance and therefore could be a source of myofibroblasts producing extracellular matrix. The study on the role played by adipose tissue in the pathogenesis of AF is just starting and is highly likely to uncover new biomarkers and therapeutic targets for AF. PMID:24648445

  11. Attitudes Towards Catheter Ablation for Atrial Fibrillation

    DEFF Research Database (Denmark)

    Vadmann, Henrik; Pedersen, Susanne S; Nielsen, Jens Cosedis;

    2015-01-01

    BACKGROUND: Catheter ablation for atrial fibrillation (AF) is an important but expensive procedure that is the subject of some debate. Physicians´ attitudes towards catheter ablation may influence promotion and patient acceptance. This is the first study to examine the attitudes of Danish...

  12. Spontaneous conversion of first onset atrial fibrillation

    DEFF Research Database (Denmark)

    Lindberg, Søren Østergaard; Hansen, Sidsel; Nielsen, Tonny

    2011-01-01

    Background  We studied all patients admitted to hospital with first onset atrial fibrillation (AF) to determine the probability of spontaneous conversion to sinus rhythm and to identify factors predictive of such a conversion. Methods and Results  We retrospectively reviewed charts of 438...

  13. Genetic aspects of lone atrial fibrillation

    DEFF Research Database (Denmark)

    Andreasen, Laura; Nielsen, Jonas B; Olesen, Morten S

    2015-01-01

    Atrial fibrillation (AF) is the most common cardiac arrhythmia. A subgroup of patients presents with AF without traditional risk factors and is diagnosed before the age of 60 years. Such patients are commonly referred as having "lone AF" and comprise 10-20% of all cases. A number of studies have...

  14. A population screening programme for atrial fibrillation

    DEFF Research Database (Denmark)

    Proietti, Marco; Mairesse, Georges H; Goethals, Peter;

    2016-01-01

    AIMS: Despite the increased prevalence of atrial fibrillation (AF), data for the implementation of nationwide screening programmes are limited. The aim of this national screening study was to increase nationwide awareness about AF and stroke risk, to determine the prevalence of AF in Belgian...

  15. Bleeding Risk Assessment in Atrial Fibrillation

    DEFF Research Database (Denmark)

    Lip, Gregory Y H; Lane, Deirdre A

    2016-01-01

    Stroke prevention is central to the management of atrial fibrillation (AF), and effective thromboprophylaxis requires oral anticoagulation (OAC). Even a single stroke risk factor confers excess risk, and the net clinical benefit of treatment is positive for OAC compared to no treatment or aspirin...

  16. Idiopathic Aortic Root to Right Atrial Fistula.

    Science.gov (United States)

    Campisi, Salvatore; Cluzel, Armand; Vola, Marco; Fuzellier, Jean Francois

    2016-06-01

    An aorta to right atrium fistula is rare. We report a case of idiopathic aortic root to right atrial fistula with right heart failure and review the literature. doi: 10.1111/jocs.12751 (J Card Surg 2016;31:373-375). PMID:27109166

  17. COMPARISON OF TEMPORAL PARAMETERS OF SWIMMING RESCUE ELEMENTS WHEN PERFORMED USING DOLPHIN AND FLUTTER KICK WITH FINS - DIDACTICAL APPROACH

    Directory of Open Access Journals (Sweden)

    Marek Rejman

    2012-12-01

    Full Text Available The aim of this study was an analysis of the time required to swim to a victim and tow them back to shore, while perfoming the flutter-kick and the dolphin-kick using fins. It has been hypothesized that using fins while using the dolphin-kick when swimming leads to reduced rescue time. Sixteen lifeguards took part in the study. The main tasks performed by them, were to approach and tow (double armpit a dummy a distance of 50m while applying either the flutter-kick, or the dolphin-kick with fins. The analysis of the temporal parameters of both techniques of kicking demonstrates that, during the approach to the victim, neither the dolphin (tmean = 32.9s or the flutter kick (tmean = 33.0s were significantly faster than the other. However, when used for towing a victim the flutter kick (tmean = 47.1s was significantly faster when compared to the dolphin-kick (tmean = 52.8s. An assessment of the level of technical skills in competitive swimming, and in approaching and towing the victim, were also conducted. Towing time was significantly correlated with the parameter that linked the temporal and technical dimensions of towing and swimming (difference between flutter kick towing time and dolphin-kick towing time, 100m medley time and the four swimming strokes evaluation. No similar interdependency has been discovered in flutter kick towing time. These findings suggest that the dolphin-kick is a more difficult skill to perform when towing the victim than the flutter-kick. Since the hypothesis stated was not confirmed, postulates were formulated on how to improve dolphin-kick technique with fins, in order to reduce swimming rescue time

  18. 78 FR 11207 - Clinical Study Designs for Surgical Ablation Devices for Treatment of Atrial Fibrillation...

    Science.gov (United States)

    2013-02-15

    ... Treatment of Atrial Fibrillation; Guidance for Industry and Food and Drug Administration Staff; Availability... Ablation Devices for Treatment of Atrial Fibrillation.'' This guidance provides FDA's recommendations on clinical trial designs for surgical ablation devices intended for the treatment of atrial...

  19. Assessment of the dynamics of atrial signals and local atrial period series during atrial fibrillation: effects of isoproterenol administration

    Directory of Open Access Journals (Sweden)

    Mantica Massimo

    2004-10-01

    Full Text Available Abstract Background The autonomic nervous system (ANS plays an important role in the genesis and maintenance of atrial fibrillation (AF, but quantification of its electrophysiologic effects is extremely complex and difficult. Aim of the study was to evaluate the capability of linear and non-linear indexes to capture the fine changing dynamics of atrial signals and local atrial period (LAP series during adrenergic activation induced by isoproterenol (a sympathomimetic drug infusion. Methods Nine patients with paroxysmal or persistent AF (aged 60 ± 6 underwent electrophysiological study in which isoproterenol was administered to patients. Atrial electrograms were acquired during i sinus rhythm (SR; ii sinus rhythm during isoproterenol (SRISO administration; iii atrial fibrillation (AF and iv atrial fibrillation during isoproterenol (AFISO administration. The level of organization between two electrograms was assessed by the synchronization index (S, whereas the degree of recurrence of a pattern in a signal was defined by the regularity index (R. In addition, the level of predictability (LP and regularity of LAP series were computed. Results LAP series analysis shows a reduction of both LP and R index during isoproterenol infusion in SR and AF (RSR = 0.75 ± 0.07 RSRISO = 0.69 ± 0.10, p AF = 0.31 ± 0.08 RAFISO = 0.26 ± 0.09, p SR = 99.99 ± 0.001 LPSRISO = 99.97 ± 0.03, p AF = 69.46 ± 21.55 LPAFISO = 55 ± 24.75; p SR = 0.49 ± 0.08 RSRISO = 0.46 ± 0.09 p AF = 0.29 ± 0.09 RAFISO = 0.28 ± 0.08 n.s.. Conclusions The proposed parameters succeeded in discriminating the subtle changes due to isoproterenol infusion during both the rhythms especially when considering LAP series analysis. The reduced value of analyzed parameters after isoproterenol administration could reflect an important pro-arrhythmic influence of adrenergic activation on favoring maintenance of AF.

  20. Cytochrome 450-2D6 Genotype Definition May Improve Therapy for Paroxysmal Atrial Fibrillation. A Case of Syncope Following

    Directory of Open Access Journals (Sweden)

    Harry W. Daniell, MD

    2014-02-01

    Full Text Available An 81-year-old marathon runner-internist developed syncope followed by myocardial stunning two hours after conversion to normal sinus rhythm and 4 hours after adding a single 150mg dose of propafenone to 650mg of quinidine gluconate which he had ingested 3 hours earlier. Cardiac isoenzyme, electrolyte, CBC, TSH and EKG were normal. Echocardiogram one week later revealed left ventricular hypertrophy with an enlarged left atrium typical of men with habitual endurance-associated atrial fibrillation. Over the previous 24 years he had successfully converted more than 100 episodes of PAF with PIP oral quinidine sulfate (200mg-600mg or quinidine gluconate (650-975mg without utilizing other cardiac, anti-arrhythmic, or anti-coagulation therapy. Several months after we published his adverse event (37 CYP2D6 analysis demonstrated alleles 4 and 41, identifying him as an IM/PM 2D6-deficient subject. Within the next year, he successfully converted episodes of PAF on 2 occasions with 100mg of oral flecainide, but both were accompanied by mildly symptomatic EKG-documented atrial flutter with 2/1 AV block and a ventricular rate of 120-140 beats per minute, resulting in a return to PIP quinidine and successful conversion of over 60 additional mildly symptomatic but increasingly frequent episodes of PAF over the next 3 years by utilizing 200-600mg of oral quinidine sulfate each resolving within 4-8 hours, during which he was able to continue his daily exercise and other daily activities without interruption.