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Sample records for flow reserve ffr

  1. Determination of fractional flow reserve (FFR) based on scaling laws: a simulation study

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    Wong, Jerry T; Molloi, Sabee [Department of Radiological Sciences, University of California, Irvine-92697, CA (United States)], E-mail: symolloi@uci.edu

    2008-07-21

    Fractional flow reserve (FFR) provides an objective physiological evaluation of stenosis severity. A technique that can measure FFR using only angiographic images would be a valuable tool in the cardiac catheterization laboratory. To perform this, the diseased blood flow can be measured with a first pass distribution analysis and the theoretical normal blood flow can be estimated from the total coronary arterial volume based on scaling laws. A computer simulation of the coronary arterial network was used to gain a better understanding of how hemodynamic conditions and coronary artery disease can affect blood flow, arterial volume and FFR estimation. Changes in coronary arterial flow and volume due to coronary stenosis, aortic pressure and venous pressure were examined to evaluate the potential use of flow and volume for FFR determination. This study showed that FFR can be estimated using arterial volume and a scaling coefficient corrected for aortic pressure. However, variations in venous pressure were found to introduce some error in FFR estimation. A relative form of FFR was introduced and was found to cancel out the influence of pressure on coronary flow, arterial volume and FFR estimation. The use of coronary flow and arterial volume for FFR determination appears promising.

  2. Comparison of instantaneous wave-free ratio (iFR) and fractional flow reserve (FFR) - First real world experience

    NARCIS (Netherlands)

    Haerle, Tobias; Bojara, Waldemar; Meyer, Sven; Elsaesser, Albrecht

    2015-01-01

    Background: The instantaneous wave-free ratio (iFR) is a new adenosine-independent index of coronary stenosis severity. Most published data have been based on off-line analyses of pressure recordings in a core laboratory. We prospectively compared real-time iFR and fractional flow reserve (FFR) meas

  3. Myocardial FFR (Fractional Flow Reserve in patients with angiographically intermediate coronary artery stenosis - an initial institutional experience

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    Jagadish H. Ramaiah

    2013-02-01

    Full Text Available Background: The clinical significance of coronary artery stenosis of intermediate severity can be difficult to determine. The management of intermediate coronary lesions, defined by a diameter stenosis of ¡I40% to ¡U70%, continues to be a therapeutic dilemma for cardiologists. The 2-dimensional representation of the arterial lesion provided by angiography is limited in distinguishing intermediate lesions that require stenting from those that simply need appropriate medical therapy. In the era of drug-eluting stents, some might propose that stenting all intermediate coronary lesions is an appropriate solution. However, the possibility of procedural complications such as coronary dissection, no reflow phenomenon, in-stent restenosis, and stent thrombosis requires accurate stratification of patients with intermediate coronary lesions to appropriate therapy. Myocardial fractional flow reserve (FFR is an index of the functional severity of coronary stenosis that is calculated from pressure measurements made during coronary angiography. The objective of the study is to evaluate the usefulness of FFR in patients with angiographically intermediate coronary artery stenosis. Methods: 20 patients with intermediate coronary stenosis and chest pain of uncertain origin. The Exercise Electrocardiography (TMT, Myocardial Perfusion Imaging study (MPI, Quantitative Coronary Angiography (QCA were compared with the results of FFR measurements. Results: 20 patients were undergone FFR measurement during the study period. With the mean age of 57.25¡À11.2 and male patients were 16 (80%, female patients 4 (20%, in all 13 patients with an FFR of 0.75 tested negative for reversible myocardial ischemia on TMT and MPI study. No revascularization procedures were performed in 7 (35% patients, and no adverse cardiovascular events were noted in all these patients during 6 months of follow-up. Conclusions: In patients with coronary stenosis of intermediate severity, FFR

  4. Estimating the accuracy of a reduced-order model for the calculation of fractional flow reserve (FFR).

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    Boileau, Etienne; Pant, Sanjay; Roobottom, Carl; Sazonov, Igor; Deng, Jingjing; Xie, Xianghua; Nithiarasu, Perumal

    2017-06-09

    Image-based noninvasive fractional flow reserve (FFR) is an emergent approach to determine the functional relevance of coronary stenoses. The present work aimed to determine the feasibility of using a method based on coronary computed tomography angiography (CCTA) and reduced-order models (0D-1D) for the evaluation of coronary stenoses. The reduced-order methodology (cFFRRO ) was kept as simple as possible and did not include pressure drop or stenosis models. The geometry definition was incorporated into the physical model used to solve coronary flow and pressure. cFFRRO was assessed on a virtual cohort of 30 coronary artery stenoses in 25 vessels and compared with a standard approach based on 3D computational fluid dynamics (cFFR3D ). In this proof-of-concept study, we sought to investigate the influence of geometry and boundary conditions on the agreement between both methods. Performance on a per-vessel level showed a good correlation between both methods (Pearson's product-moment R=0.885, P<0.01), when using cFFR3D  as the reference standard. The 95% limits of agreement were -0.116 and 0.08, and the mean bias was -0.018 (SD =0.05). Our results suggest no appreciable difference between cFFRRO  and cFFR3D with respect to lesion length and/or aspect ratio. At a fixed aspect ratio, however, stenosis severity and shape appeared to be the most critical factors accounting for differences in both methods. Despite the assumptions inherent to the 1D formulation, asymmetry did not seem to affect the agreement. The choice of boundary conditions is critical in obtaining a functionally significant drop in pressure. Our initial data suggest that this approach may be part of a broader risk assessment strategy aimed at increasing the diagnostic yield of cardiac catheterisation for in-hospital evaluation of haemodynamically significant stenoses. Copyright © 2017 John Wiley & Sons, Ltd.

  5. Initial simulated FFR investigation using flow measurements in patient-specific 3D printed coronary phantoms

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    Shepard, Lauren; Sommer, Kelsey; Izzo, Richard; Podgorsak, Alexander; Wilson, Michael; Said, Zaid; Rybicki, Frank J.; Mitsouras, Dimitrios; Rudin, Stephen; Angel, Erin; Ionita, Ciprian N.

    2017-03-01

    Purpose: Accurate patient-specific phantoms for device testing or endovascular treatment planning can be 3D printed. We expand the applicability of this approach for cardiovascular disease, in particular, for CT-geometry derived benchtop measurements of Fractional Flow Reserve, the reference standard for determination of significant individual coronary artery atherosclerotic lesions. Materials and Methods: Coronary CT Angiography (CTA) images during a single heartbeat were acquired with a 320x0.5mm detector row scanner (Toshiba Aquilion ONE). These coronary CTA images were used to create 4 patientspecific cardiovascular models with various grades of stenosis: severe, stenosis using pressure transducers. Compliance chambers were used before and after the model to modulate the pressure wave. A flow sensor was used to ensure flow rates within physiological reported values. Results: 3D model based FFR measurements correlated well with stenosis severity. FFR measurements for each stenosis grade were: 0.8 severe, 0.7 moderate and 0.88 mild. Conclusions: 3D printed models of patient-specific coronary arteries allows for accurate benchtop diagnosis of FFR. This approach can be used as a future diagnostic tool or for testing CT image-based FFR methods.

  6. Correlation between coronary computed tomographic angiography and fractional flow reserve

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    Kristensen, Thomas Skaarup; Engstrøm, Thomas; Kelbæk, Henning

    2010-01-01

    Coronary CT angiography (CCTA) has become an important modality to evaluate the presence of coronary artery disease. Coronary artery stenosis of intermediate severity remains a therapeutic dilemma. Measurement of fractional flow reserve (FFR) during coronary angiography is the most established...... technique to determine the hemodynamic severity of a coronary artery lesion. The aim of this study was to compare CCTA with FFR....

  7. Image-based assessment of fractional flow reserve.

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    Tu, Shengxian; Bourantas, Christos V; Nørgaard, Bjarne L; Kassab, Ghassan S; Koo, Bon-Kwon; Reiber, Johan H C

    2015-01-01

    Pressure-derived fractional flow reserve (FFR) is an index of the haemodynamic significance of a coronary lesion. Numerous studies have provided robust evidence that FFR-guided percutaneous coronary intervention is associated with better clinical outcomes and reduces the need for repeat revascularisation. Although FFR is regarded as the gold standard for assessing lesion severity, it has limited clinical applications, mainly because it is a relatively expensive and time-consuming procedure. To overcome these limitations, several computational-based methodologies have been developed which enable estimation of the FFR in three-dimensional models derived from anatomic imaging data. Multislice computed tomographic coronary angiography and quantitative coronary angiography have been proposed for coronary reconstruction and computational evaluation of the FFR. In this review article, we describe the currently available methodologies for the computational estimation of FFR, present evidence derived from their clinical evaluations, stress their limitations, and discuss their potential value in clinical practice.

  8. Physiological basis and long-term clinical outcome of discordance between fractional flow reserve and coronary flow velocity reserve in coronary stenoses of intermediate severity.

    Science.gov (United States)

    van de Hoef, Tim P; van Lavieren, Martijn A; Damman, Peter; Delewi, Ronak; Piek, Martijn A; Chamuleau, Steven A J; Voskuil, Michiel; Henriques, José P S; Koch, Karel T; de Winter, Robbert J; Spaan, Jos A E; Siebes, Maria; Tijssen, Jan G P; Meuwissen, Martijn; Piek, Jan J

    2014-06-01

    Discordance between fractional flow reserve (FFR) and coronary flow velocity reserve (CFVR) may reflect important coronary pathophysiology but usually remains unnoticed in clinical practice. We evaluated the physiological basis and clinical outcome associated with FFR/CFVR discordance. We studied 157 intermediate coronary stenoses in 157 patients, evaluated by FFR and CFVR between April 1997 and September 2006 in which revascularization was deferred. Long-term follow-up was performed to document the occurrence of major adverse cardiac events: cardiac death, myocardial infarction, or target vessel revascularization. Discordance between FFR and CFVR occurred in 31% and 37% of stenoses at the 0.75, and 0.80 FFR cut-off value, respectively, and was characterized by microvascular resistances during basal and hyperemic conditions. Follow-up duration amounted to 11.7 years (Q1-Q3, 9.9-13.3 years). Compared with concordant normal results of FFR and CFVR, a normal FFR with an abnormal CFVR was associated with significantly increased major adverse cardiac events rate throughout 10 years of follow-up, regardless of the FFR cut-off applied. In contrast, an abnormal FFR with a normal CFVR was associated with equivalent clinical outcome compared with concordant normal results: ≤ 3 years when FFR requirement of intracoronary flow assessment in addition to coronary pressure for optimal risk stratification in stable coronary artery disease. © 2014 American Heart Association, Inc.

  9. Coronary CT angiography-derived fractional flow reserve correlated with invasive fractional flow reserve measurements - initial experience with a novel physician-driven algorithm

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    Baumann, Stefan [Medical University of South Carolina, Heart and Vascular Center, Charleston, SC (United States); University Medical Centre Mannheim (UMM), University of Heidelberg, First Department of Medicine, Faculty of Medicine Mannheim, Mannheim (Germany); Wang, Rui [Medical University of South Carolina, Heart and Vascular Center, Charleston, SC (United States); Beijing Anzhen Hospital, Capital Medical University, Department of Radiology, Beijing (China); Schoepf, U.J.; Steinberg, Daniel H.; Spearman, James V.; Bayer, Richard R. [Medical University of South Carolina, Heart and Vascular Center, Charleston, SC (United States); Hamm, Christian W. [Giessen University, Department of Internal Medicine I, Cardiology/Angiology, Giessen (Germany); Renker, Matthias [Medical University of South Carolina, Heart and Vascular Center, Charleston, SC (United States); Giessen University, Department of Internal Medicine I, Cardiology/Angiology, Giessen (Germany)

    2015-04-01

    The present study aimed to determine the feasibility of a novel fractional flow reserve (FFR) algorithm based on coronary CT angiography (cCTA) that permits point-of-care assessment, without data transfer to core laboratories, for the evaluation of potentially ischemia-causing stenoses. To obtain CT-based FFR, anatomical coronary information and ventricular mass extracted from cCTA datasets were integrated with haemodynamic parameters. CT-based FFR was assessed for 36 coronary artery stenoses in 28 patients in a blinded fashion and compared to catheter-based FFR. Haemodynamically relevant stenoses were defined by an invasive FFR ≤0.80. Time was measured for the processing of each cCTA dataset and CT-based FFR computation. Assessment of cCTA image quality was performed using a 5-point scale. Mean total time for CT-based FFR determination was 51.9 ± 9.0 min. Per-vessel analysis for the identification of lesion-specific myocardial ischemia demonstrated good correlation (Pearson's product-moment r = 0.74, p < 0.0001) between the prototype CT-based FFR algorithm and invasive FFR. Subjective image quality analysis resulted in a median score of 4 (interquartile ranges, 3-4). Our initial data suggest that the CT-based FFR method for the detection of haemodynamically significant stenoses evaluated in the selected population correlates well with invasive FFR and renders time-efficient point-of-care assessment possible. (orig.)

  10. Physiologic Assessment of Coronary Artery Disease: Focus on Fractional Flow Reserve

    OpenAIRE

    Hwang, Doyeon; Lee, Joo Myung; Koo, Bon-Kwon

    2016-01-01

    The presence of myocardial ischemia is the most important prognostic factor in patients with ischemic heart disease. Fractional flow reserve (FFR) is a gold standard invasive method used to detect the stenosis-specific myocardial ischemia. FFR-guided revascularization strategy is superior to angiography-guided strategy. The recently developed hyperemia-free index, instantaneous wave free ratio is being actively investigated. A non-invasive FFR derived from coronary CT angiography is now used ...

  11. Diagnostic Performance of a Lattice Boltzmann-Based Method for Fast CT-Fractional Flow Reserve.

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    Giannopoulos, Andreas; Tang, Anji; Ge, Yin; Cheezum, Michael; Steigner, Michael; Fujimoto, Shinichiro; Kumamaru, Kanako; Chiappino, Dante; Della Latta, Daniele; Berti, Sergio; Chiappino, Sara; Rybicki, Frank; Melchionna, Simone; Mitsouras, Dimitrios

    2017-06-27

    Fractional flow reserve (FFR) estimated from coronary computed tomography angiography (CT-FFR) offers non-invasive detection of lesion-specific ischemia. We developed and validated a fast CT-FFR algorithm utilizing the Lattice-Boltzmann Method for blood flow simulation (LBM CT-FFR). 64 patients from 3 institutions with clinically-indicated CTA and invasive FFR measurement were retrospectively analyzed. CT-FFR was performed using an on-site tool interfacing with a commercial Lattice-Boltzmann fluid dynamics cloud-based platform. Diagnostic accuracy of LBM CT-FFR≤0.8 and percent diameter stenosis >50% by CTA to detect invasive FFR≤0.8 were compared using area under the receiver operating characteristic curve (AUC). 60 patients successfully underwent LBM CT-FFR analysis; 29 of 73 lesions in 69 vessels had invasive FFR≤0.8. Total time to perform LBM CT-FFR was 40±10 min. Compared to invasive FFR, LBM CT-FFR had good correlation (r=0.64), small bias (0.009) and good limits of agreement (-0.223 to 0.206). The AUC of LBM CT-FFR (AUC=0.894, 95% confidence interval [CI]: 0.792- 0.996) was significantly higher than CTA (AUC=0.685, 95% CI: 0.576-0.794) to detect FFR≤0.8 (p=0.0021). Per-lesion specificity, sensitivity, accuracy of LBM CT-FFR were 97.7%, 79.3%, and 90.4%, respectively. LBM CT-FFR has very good diagnostic accuracy to detect lesion-specific ischemia (FFR≤0.8) and can be performed in less than 1 hour.

  12. Fractional Flow Reserve-Guided Deferred Versus Complete Revascularization in Patients With Diabetes Mellitus.

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    Kennedy, Mark W; Hermanides, Rik S; Kaplan, Emel; Hemradj, Veemal; Fabris, Enrico; Koopmans, Petra C; Dambrink, Jan-Henk E; Gosselink, A T Marcel; Van't Hof, Arnoud W J; Ottervanger, Jan Paul; Roolvink, Vincent; Remkes, Wouter S; van der Sluis, Aize; Suryapranata, Harry; Kedhi, Elvin

    2016-11-01

    To assess the safety and efficacy of deferred versus complete revascularization using a fractional flow reserve (FFR)-guided strategy in patients with diabetes mellitus (DM), we analyzed all DM patients who underwent FFR-guided revascularization from January 1, 2010, to December 12, 2013. Patients were divided into 2 groups: those with ≥1 remaining FFR-negative (>0.80) medically treated lesions [FFR(-)MT] and those with only FFR-positive lesions (≤0.80) who underwent complete revascularization [FFR(+)CR] and were followed until July 1, 2015. The primary end point was the incidence of major adverse cardiovascular events (MACE), a composite of death, myocardial infarction (MI), target lesion (FFR assessed) revascularization, and rehospitalization for acute coronary syndrome. A total of 294 patients, 205 (69.7%) versus 89 (30.3%) in FFR(-)MT and FFR(+)CR, respectively, were analyzed. At a mean follow-up of 32.6 ± 18.1 months, FFR(-)MT was associated with higher MACE rate 44.0% versus 26.6% (log-rank p = 0.02, Cox regression-adjusted hazard ratio [HR] 2.01, 95% confidence interval [CI] 1.21 to 3.33, p required to guide our treatment strategy in these patients with high-risk, fast-progressing atherosclerosis.

  13. Clinical Relevance of Coronary Fractional Flow Reserve: Art-of-state

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    Yohanes Adiputra; Shao-Liang Chen

    2015-01-01

    Objective:The objective was to delineate the current knowledge of fractional flow reserve (FFR) in terms of definition,features,clinical applications,and pitfalls of measurement of FFR.Data Sources:We searched database for primary studies published in English.The database of National Library of Medicine (NLM),MEDLINE,and PubMed up to July 2014 was used to conduct a search using the keyword term "FFR".Study Selection:The articles about the definition,features,clinical application,and pitfalls of measurement of FFR were identified,retrieved,and reviewed.Results:Coronary pressure-derived FFR rapidly assesses the hemodynamic significance of individual coronary artery lesions and can readily be performed in the catheterization laboratory.The use of FFR has been shown to effectively guide coronary revascularization procedures leading to improved patient outcomes.Conclusions:FFR is a valuable tool to determine the functional significance of coronary stenosis.It combines physiological and anatomical information,and can be followed immediately by percutaneous coronary intervention (PCI) if necessary.The technique of FFR measurement can be performed easily,rapidly,and safely in the catheterization laboratory.By systematic use of FFR in dubious stenosis and multi-vessel disease,PCI can be made an even more effective and better treatment than it is currently.The current clinical evidence for FFR should encourage cardiologists to use this tool in the catheterization laboratory.

  14. Clinical Relevance of Coronary Fractional Flow Reserve: Art-of-state.

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    Adiputra, Yohanes; Chen, Shao-Liang

    2015-05-20

    The objective was to delineate the current knowledge of fractional flow reserve (FFR) in terms of definition, features, clinical applications, and pitfalls of measurement of FFR. We searched database for primary studies published in English. The database of National Library of Medicine (NLM), MEDLINE, and PubMed up to July 2014 was used to conduct a search using the keyword term "FFR". The articles about the definition, features, clinical application, and pitfalls of measurement of FFR were identified, retrieved, and reviewed. Coronary pressure-derived FFR rapidly assesses the hemodynamic significance of individual coronary artery lesions and can readily be performed in the catheterization laboratory. The use of FFR has been shown to effectively guide coronary revascularization procedures leading to improved patient outcomes. FFR is a valuable tool to determine the functional significance of coronary stenosis. It combines physiological and anatomical information, and can be followed immediately by percutaneous coronary intervention (PCI) if necessary. The technique of FFR measurement can be performed easily, rapidly, and safely in the catheterization laboratory. By systematic use of FFR in dubious stenosis and multi-vessel disease, PCI can be made an even more effective and better treatment than it is currently. The current clinical evidence for FFR should encourage cardiologists to use this tool in the catheterization laboratory.

  15. Fractional flow reserve and instantaneous wave free ratio in 2015.

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    Kondareddy, S R; Singh, M; Stapleton, D; Rudzinski, W; Kaluski, E

    2015-06-01

    In the recent years it has become apparent that angiography-based assessment of coronary artery stenosis suffers from considerable inaccuracy and pitfalls. Besides interobserver variability in assessing stenosis severity, the correlation between angiographic severity and ischemia is suboptimal. Percutaneous coronary intervention (PCI) guided by the physiologic lesion assessment employing fractional flow reserve (FFR) is rendered superior to angiographic lesion assessment and proven to improve cardiovascular outcomes and reduce cost. In this manuscript we discuss the accepted and emerging clinical indications for FFR use. The correlation between FFR and symptoms, stress imaging and intravascular ultrasound are reviewed along with the inherent limitations and pitfalls of these diagnostic technologies. The data regarding the correlation between Instantaneous (vasodilator free) wave-free ratio (iFR) and conventional FFR is summarized.

  16. Outcomes of coronary stenoses deferred revascularization for borderline versus nonborderline fractional flow reserve values.

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    Depta, Jeremiah P; Patel, Jayendrakumar S; Novak, Eric; Masrani, Shriti K; Raymer, David; Facey, Gabrielle; Patel, Yogesh; Zajarias, Alan; Lasala, John M; Singh, Jasvindar; Bach, Richard G; Kurz, Howard I

    2014-06-01

    Current evidence supports deferral of revascularization for lesions with fractional flow reserve (FFR) values >0.80. The natural history after deferral of revascularization of lesions with borderline FFR values is unknown. This study evaluated the outcomes of patients after deferred revascularization of coronary stenoses based on a borderline FFR value. We retrospectively studied 720 patients with 881 intermediate-severity coronary stenoses who underwent FFR assessment from October 2002 to July 2010 and were deferred revascularization. Patients were divided into gray zone (0.75 to 0.80), borderline (0.81 to 0.85), and nonborderline (>0.85) FFR groups. Any subsequent percutaneous coronary intervention or coronary artery bypass grafting of a deferred stenosis during follow-up was classified as a deferred lesion intervention (DLI). Patient and/or lesion characteristics and clinical outcomes were compared between the FFR groups using univariate and propensity score-adjusted inverse probability of weighting Cox proportional hazards analyses. During a mean follow-up of 4.5 ± 2.1 years, 157 deferred lesions (18%) underwent DLI by percutaneous coronary intervention (n = 117) or coronary artery bypass grafting (n = 40). No statistically significant differences were observed in clinical outcomes between the gray zone and borderline FFR groups. Lesions with a borderline FFR were associated with a significantly higher risk of DLI compared with lesions with nonborderline FFR values (hazard ratio 1.63, 95% confidence interval 1.14 to 2.33, p = 0.007). Lesions deferred revascularization because of a borderline FFR (0.81 to 0.85) were associated with a higher risk of DLI compared with lesions with a nonborderline FFR (>0.85). Further study is needed to determine the optimal management of coronary stenoses with a borderline FFR value. Copyright © 2014 Elsevier Inc. All rights reserved.

  17. Coronary plaque quantification and fractional flow reserve by coronary computed tomography angiography identify ischaemia-causing lesions

    DEFF Research Database (Denmark)

    Gaur, Sara; Øvrehus, Kristian Altern; Dey, Damini

    2016-01-01

    tomography angiography (CTA)-derived fractional flow reserve (FFRCT), and lesion-specific ischaemia identified by FFR in a substudy of the NXT trial (Analysis of Coronary Blood Flow Using CT Angiography: Next Steps). METHODS AND RESULTS: Coronary CTA stenosis, plaque volumes, FFRCT, and FFR were assessed...... the receiver-operating characteristics curve (AUC) analysis. Ischaemia was defined by FFR or FFRCT ≤0.80. Plaque volumes were inversely related to FFR irrespective of stenosis severity. Relative risk (95% confidence interval) for prediction of ischaemia for stenosis >50%, NCP ≥185 mm(3), LD-NCP ≥30 mm(3), CP...

  18. Coronary Computed Tomography Angiography Derived Fractional Flow Reserve and Plaque Stress

    DEFF Research Database (Denmark)

    Nørgaard, Bjarne Linde; Leipsic, Jonathon; Koo, Bon-Kwon;

    2016-01-01

    Fractional flow reserve (FFR) measured during invasive coronary angiography is an independent prognosticator in patients with coronary artery disease and the gold standard for decision making in coronary revascularization. The integration of computational fluid dynamics and quantitative anatomic...

  19. The effect of blood pressure on non-invasive fractional flow reserve derived from coronary computed tomography angiography

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    Kurata, Akira [Ehime University Graduate School of Medicine, Department of Radiology, Toon, Ehime (Japan); Erasmus University Medical Center, Department of Radiology, Rotterdam (Netherlands); Coenen, Adriaan; Lubbers, Marisa M.; Nieman, Koen [Erasmus University Medical Center, Department of Radiology, Rotterdam (Netherlands); Erasmus University Medical Center, Departmenet of Cardiology, Rotterdam (Netherlands); Kido, Teruhito; Mochizuki, Teruhito [Ehime University Graduate School of Medicine, Department of Radiology, Toon, Ehime (Japan); Kido, Tomoyuki [Matsuyama Saiseikai Hospital, Department of Radiology, Matsuyama, Ehime (Japan); Yamashita, Natsumi [Clinical Research Center, National Hospital Organization Shikoku Cancer Center, Division of Clinical Biostatistics, Section of Cancer Prevention and Epidemiology, Matsuyama, Ehime (Japan); Watanabe, Kouki [Matsuyama Saiseikai Hospital, Department of Cardiology, Matsuyama, Ehime (Japan); Krestin, Gabriel P. [Erasmus University Medical Center, Department of Radiology, Rotterdam (Netherlands)

    2017-04-15

    The aim of this study is to assess the effect of blood pressure (BP) on coronary computed tomography angiography (CTA) derived computational fractional flow reserve (CTA-FFR). Twenty-one patients who underwent coronary CTA and invasive FFR were retrospectively identified. Ischemia was defined as invasive FFR ≤0.80. Using a work-in-progress computational fluid dynamics algorithm, CTA-FFR was computed with BP measured before CTA, and simulated BPs of 60/50, 90/60, 110/70, 130/80, 150/90, and 180/100 mmHg respectively. Correlation between CTA-FFR and invasive FFR was assessed using Pearson test. The repeated measuring test was used for multiple comparisons of CTA-FFR values by simulated BP inputs. Twenty-nine vessels (14 with invasive FFR ≤0.80) were assessed. The average CTA-FFR for measured BP (134 ± 20/73 ± 12 mmHg) was 0.77 ± 0.12. Correlation between CTA-FFR by measured BP and invasive FFR was good (r = 0.735, P < 0.001). For simulated BPs of 60/50, 90/60, 110/70, 130/80, 150/90, and 180/100 mmHg, the CTA-FFR increased: 0.69 ± 0.13, 0.73 ± 0.12, 0.75 ± 0.12, 0.77 ± 0.11, 0.79 ± 0.11, and 0.81 ± 0.10 respectively (P < 0.05). Measurement of the BP just before CTA is preferred for accurate CTA-FFR simulation. BP variations in the common range slightly affect CTA-FFR. However, inaccurate BP assumptions differing from the patient-specific BP could cause misinterpretation of borderline significant lesions. (orig.)

  20. Fractional flow reserve as a surrogate for inducible myocardial ischaemia.

    Science.gov (United States)

    van de Hoef, Tim P; Meuwissen, Martijn; Escaned, Javier; Davies, Justin E; Siebes, Maria; Spaan, Jos A E; Piek, Jan J

    2013-08-01

    Documentation of inducible myocardial ischaemia, related to the coronary stenosis of interest, is of increasing importance in lesion selection for percutaneous coronary intervention (PCI). Fractional flow reserve (FFR) is an easily understood, routine diagnostic modality that has become part of daily clinical practice, and is used as a surrogate technique for noninvasive assessment of myocardial ischaemia. However, the application of a single, discrete, cut-off value for FFR-guided lesion selection for PCI, and its adoption in contemporary revascularization guidelines, has limited the requirement for a thorough understanding of the physiological basis of FFR. This limitation constitutes an obstacle for the adequate use and interpretation of this technique, and also for the understanding of new and future modalities of physiological functional intracoronary testing. In this Review, we revisit the fundamental elements of coronary physiology in the absence or presence of coronary artery disease. We provide insight into three essential characteristics of FFR as a diagnostic tool in contemporary clinical practice--the theoretical framework of FFR and its associated limitations; the characteristics and role of FFR as a surrogate for noninvasively assessed myocardial ischaemia; and the requirement and associated caveats of potent vasodilatory drugs to induce maximal vasodilatation of the coronary vascular bed.

  1. Fractional flow reserve derived from coronary computed tomography angiography

    DEFF Research Database (Denmark)

    Eftekhari, Ashkan; Min, James; Achenbach, Stephan

    2016-01-01

    AIMS: Fractional flow reserve (FFR) derived from coronary computed tomography (FFRCT) has high diagnostic performance in stable coronary artery disease (CAD). The diagnostic performance of FFRCT in patients with hypertension (HTN) and diabetes (DM), who are at risk of microvascular impairment, is...

  2. Association of Coronary Stenosis and Plaque Morphology With Fractional Flow Reserve and Outcomes

    DEFF Research Database (Denmark)

    Ahmadi, Amir; Stone, Gregg W; Leipsic, Jonathon

    2016-01-01

    IMPORTANCE: Obstructive coronary lesions with reduced luminal dimensions may result in abnormal regional myocardial blood flow as assessed by stress-induced myocardial perfusion imaging or a significant fall in distal perfusion pressure with hyperemia-induced vasodilatation (fractional flow reserve......: Having a normal FFR requires unimpaired vasoregulatory ability and significant luminal stenosis. Therefore, FFR should identify lesions that are unlikely to possess large necrotic core, rendering them safe for treatment with medical therapy alone. Further studies are warranted to determine whether...

  3. The effect of CTO recanalization on FFR of the donor artery.

    Science.gov (United States)

    Sachdeva, Rajesh; Uretsky, Barry F

    2011-02-15

    This case illustrates that fractional flow reserve (FFR) in addition to the severity and length of the coronary stenosis is critically dependent on the extent of viable myocardium perfused. In the presented case, the left anterior descending artery (LAD) that had modest angiographic stenosis supplied collaterals to the entire left ventricle. After recanalization of chronic total occlusions (CTO) of the right and circumflex arteries, FFR in the LAD had normalized.

  4. Fractional flow reserve versus angiography for guiding percutaneous coronary intervention

    DEFF Research Database (Denmark)

    Tonino, Pim A L; De Bruyne, Bernard; Pijls, Nico H J

    2009-01-01

    BACKGROUND: In patients with multivessel coronary artery disease who are undergoing percutaneous coronary intervention (PCI), coronary angiography is the standard method for guiding the placement of the stent. It is unclear whether routine measurement of fractional flow reserve (FFR; the ratio......-eluting stents guided by angiography alone or guided by FFR measurements in addition to angiography. Before randomization, lesions requiring PCI were identified on the basis of their angiographic appearance. Patients assigned to angiography-guided PCI underwent stenting of all indicated lesions, whereas those...

  5. Fractional flow reserve and resting indices for coronary physiologic assessment: Practical guide, tips, and tricks.

    Science.gov (United States)

    Picard, Fabien; Pighi, Michele; Ly, Hung Q

    2017-02-04

    Physiologic assessment using fractional flow reserve (FFR) to guide percutaneous coronary interventions (PCI) has been demonstrated to improve clinical outcomes, compared to angiography-guided PCI. Recently, resting indices such as resting Pd/Pa, "instantaneous wave-free ratio", and contrast medium induced FFR have been evaluated for the assessment of the functional consequences of coronary lesions. Herein, we review and discuss the use of FFR and other indices for the functional assessment of coronary lesions. This review will cover theoretical aspects, as well as practical points and common pitfalls related to coronary physiological assessment. © 2017 Wiley Periodicals, Inc.

  6. Myocardial perfusion imaging with a cadmium zinc telluride-based gamma camera versus invasive fractional flow reserve

    Energy Technology Data Exchange (ETDEWEB)

    Mouden, Mohamed [Isala klinieken, Department of Cardiology, Zwolle (Netherlands); Isala klinieken, Department of Nuclear Medicine, Zwolle (Netherlands); Ottervanger, Jan Paul; Timmer, Jorik R. [Isala klinieken, Department of Cardiology, Zwolle (Netherlands); Knollema, Siert; Reiffers, Stoffer; Oostdijk, Ad H.J.; Jager, Pieter L. [Isala klinieken, Department of Nuclear Medicine, Zwolle (Netherlands); Boer, Menko-Jan de [University Medical Centre Nijmegen, Department of Cardiology, Nijmegen (Netherlands)

    2014-05-15

    Recently introduced ultrafast cardiac SPECT cameras with cadmium zinc telluride-based (CZT) detectors may provide superior image quality allowing faster acquisition with reduced radiation doses. Although the level of concordance between conventional SPECT and invasive fractional flow reserve (FFR) measurement has been studied, that between FFR and CZT-based SPECT is not yet known. Therefore, we aimed to assess the level of concordance between CZT SPECT and FFR in a large patient group with stable coronary artery disease. Both invasive FFR and myocardial perfusion imaging with a CZT-based SPECT camera, using Tc-tetrofosmin as tracer, were performed in 100 patients with stable angina and intermediate grade stenosis on invasive coronary angiography. A cut-off value of <0.75 was used to define abnormal FFR. The mean age of the patients was 64 ± 11 years, and 64 % were men. SPECT demonstrated ischaemia in 31 % of the patients, and 20 % had FFR <0.75. The concordance between CZT SPECT and FFR was 73 % on a per-patient basis and 79 % on a per-vessel basis. Discordant findings were more often seen in older patients and were mainly (19 %) the result of ischaemic SPECT findings in patients with FFR ≥0.75, whereas only 8 % had an abnormal FFR without ischaemia as demonstrated by CZT SPECT. Only 20 - 30 % of patients with intermediate coronary stenoses had significant ischaemia as assessed by CZT SPECT or invasive FFR. CZT SPECT showed a modest degree of concordance with FFR, which is comparable with previous results with conventional SPECT. Further investigations are particularly necessary in patients with normal SPECT and abnormal FFR, especially to determine whether these patients should undergo revascularization. (orig.)

  7. Fractional flow reserve versus angiography for guidance of PCI in patients with multivessel coronary artery disease (FAME)

    DEFF Research Database (Denmark)

    van Nunen, Lokien X; Zimmermann, Frederik M; Tonino, Pim A L

    2015-01-01

    BACKGROUND: In the Fractional Flow Reserve Versus Angiography for Multivessel Evaluation (FAME) study, fractional flow reserve (FFR)-guided percutaneous coronary intervention (PCI) improved outcome compared with angiography-guided PCI for up to 2 years of follow-up. The aim in this study...... artery disease were randomly assigned to undergo angiography-guided PCI or FFR-guided PCI. Before randomisation, stenoses requiring PCI were identified on the angiogram. Patients allocated to angiography-guided PCI had revascularisation of all identified stenoses. Patients allocated to FFR-guided PCI had...

  8. Fractional flow reserve: physiological basis, advantages and limitations, and potential gender differences.

    Science.gov (United States)

    Crystal, George J; Klein, Lloyd W

    2015-01-01

    Fractional flow reserve (FFR) is a physiological index of the severity of a stenosis in an epicardial coronary artery, based on the pressure differential across the stenosis. Clinicians are increasingly relying on this method because it is independent of baseline flow, relatively simple, and cost effective. The accurate measurement of FFR is predicated on maximal hyperemia being achieved by pharmacological dilation of the downstream resistance vessels (arterioles). When the stenosis causes FFR to be impaired by > 20%, it is considered to be significant and to justify revascularization. A diminished hyperemic response due to microvascular dysfunction can lead to a false normal FFR value, and a misguided clinical decision. The blunted vasodilation could be the result of defects in the signaling pathways modulated (activated or inhibited) by the drug. This might involve a downregulation or reduced number of vascular receptors, endothelial impairment, or an increased activity of an opposing vasoconstricting mechanism, such as the coronary sympathetic nerves or endothelin. There are data to suggest that microvascular dysfunction is more prevalent in post-menopausal women, perhaps due to reduced estrogen levels. The current review discusses the historical background and physiological basis for FFR, its advantages and limitations, and the phenomenon of microvascular dysfunction and its impact on FFR measurements. The question of whether it is warranted to apply gender-specific guidelines in interpreting FFR measurements is addressed.

  9. Safety and Efficacy of a Novel Technique in the Use of Fractional Flow Reserve in Complex Coronary Artery Lesions

    Directory of Open Access Journals (Sweden)

    Wen-Ming He

    2015-01-01

    Full Text Available Background: Fractional flow reserve (FFR has become an increasingly important index when making decisions with respect to revascularization of coronary artery stenosis. However, the pressure guidewire used in obtaining FFR measurements is difficult to control and manipulate in certain complex coronary artery lesions, resulting in increased fluoroscopy time and contrast dye usage. This study examined a novel (NOV technique for obtaining FFR measurements in hope of easing the difficulties associated with evaluating and treating complex coronary artery lesions. Methods: Fifty-six patients with complex coronary artery lesions were assigned to a conventional (CON FFR technique group or a NOV FFR technique group. The NOV technique involved the use of a balloon and wire exchange within the coronary artery. The fluoroscopy time, contrast dye usage, and FFR-related complications were assessed after completing the FFR measurement procedure for each patient. Results: The median time required for fluoroscopy in the NOV technique group was significantly less than that in the CON technique group; additionally, lesser amounts of contrast dye were used in the NOV technique group (both P 0.05. Conclusions: Compared to the CON technique used for measuring FFR, the new technique reduced the fluoroscopy time and amount of contrast dye used when evaluating complex coronary artery lesions. The new technique did not increase the risk of operation or decrease the success rate.

  10. Applicability of 3-Dimensional Quantitative Coronary Angiography-Derived Computed Fractional Flow Reserve for Intermediate Coronary Stenosis.

    Science.gov (United States)

    Yazaki, Kyoichiro; Otsuka, Masato; Kataoka, Shohei; Kahata, Mitsuru; Kumagai, Asako; Inoue, Koji; Koganei, Hiroshi; Enta, Kenji; Ishii, Yasuhiro

    2017-06-23

    Quantitative flow ratio (QFR) is a newly developed image-based index for estimating fractional flow reserve (FFR).Methods and Results:We analyzed 151 coronary arteries with intermediate stenosis in 142 patients undergoing wire-based FFR measurement using dedicated software. Predefined contrast flow QFR, which was derived from 3-dimensional quantitative coronary angiography (3-D QCA) withThrombolysis in Myocardial Infarction (TIMI) frame counts, was compared with FFR as a reference. QFR had good correlation (r=0.80, P<0.0001) and agreement (mean difference: 0.01±0.05) with FFR. After applying the FFR cut-off ≤0.8, the overall accuracy rate of QFR ≤0.8 was 88.0%. On receiver operating characteristics analysis, the area under the curve was 0.93 for QFR. In contrast, 3-D QCA-derived anatomical indices had insufficient correlation with FFR and diagnostic performance compared with QFR. QFR had good correlation and agreement with FFR and high diagnostic performance in the evaluation of intermediate coronary stenosis, suggesting that QFR may be an alternative tool for estimating myocardial ischemia.

  11. Pooled comparison of regadenoson versus adenosine for measuring fractional flow reserve and coronary flow in the catheterization laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Stolker, Joshua M., E-mail: jstolker@yahoo.com [Mercy Heart and Vascular, 901 Patients First Drive, Washington, MO 63090 (United States); Saint Louis University, 3635 Vista Ave, St. Louis, MO 63110 (United States); Lim, Michael J., E-mail: limmj@slu.edu [Saint Louis University, 3635 Vista Ave, St. Louis, MO 63110 (United States); Shavelle, David M., E-mail: david.shavelle@med.usc.edu [University of Southern California, 1510 San Pablo St, Suite 322, Los Angeles, CA 90033 (United States); Morris, D. Lynn, E-mail: morrisdl@einstein.edu [Albert Einstein Medical Center, 5501 Old York Rd, Philadelphia, PA 19141 (United States); Angiolillo, Dominick J., E-mail: dominick.angiolillo@jax.ufl.edu [University of Florida Health-Jacksonville, 655 West 8th St, Jacksonville, FL 32209 (United States); Guzman, Luis A., E-mail: luis.guzman@jax.ufl.edu [University of Florida Health-Jacksonville, 655 West 8th St, Jacksonville, FL 32209 (United States); Kennedy, Kevin F., E-mail: kfkennedy@saint-lukes.org [Saint Luke' s Mid America Heart Institute, 4401 Wornall Road, Kansas City, MO 64111 (United States); Weber, Elizabeth, E-mail: eweber1@slu.edu [Saint Louis University, 3635 Vista Ave, St. Louis, MO 63110 (United States); Zareh, Meena, E-mail: meena.zareh@med.usc.edu [University of Southern California, 1510 San Pablo St, Suite 322, Los Angeles, CA 90033 (United States); Neumayr, Robert H., E-mail: robneumayr@gmail.com [Mercy Heart and Vascular, 901 Patients First Drive, Washington, MO 63090 (United States); Saint Louis University, 3635 Vista Ave, St. Louis, MO 63110 (United States); Zenni, Martin M., E-mail: martin.zenni@jax.ufl.edu [University of Florida Health-Jacksonville, 655 West 8th St, Jacksonville, FL 32209 (United States)

    2015-07-15

    Background: Adenosine is the gold standard for augmenting coronary flow during fractional flow reserve (FFR) testing of intermediate coronary stenoses. However, intravenous infusion is time-consuming and intracoronary injection is subject to variability. Regadenoson is a newer adenosine alternative administered as a single intravenous bolus during nuclear stress testing, but its efficacy and safety during FFR testing have been evaluated only in small, single-center studies. Methods: We pooled data from 5 academic hospitals, in which patients undergoing clinically-indicated FFR prospectively underwent comparison of intravenous adenosine infusion (140–175 mcg/kg/min) versus regadenoson bolus (400 mcg). Hemodynamics and symptoms with adenosine were recorded until maximal hyperemia occurred, and after returning to baseline hemodynamics, regadenoson was administered and monitoring was repeated. In a subset of patients with coronary flow data, average peak velocity (APV) at the distal flow sensor was recorded. Results: Of 149 patients enrolled, mean age was 59 ± 9 years, 76% were male, and 54% underwent testing of the left anterior descending artery. Mean adenosine-FFR and regadenoson-FFR were identical (0.82 ± 0.10) with excellent correlation of individual values (r = 0.96, p < 0.001) and no difference in patient-reported symptoms. Four patients (2.6%) had discrepancies between the 2 drugs for the clinical decision-making cutoff of FFR ≤ 0.80. Coronary flow responses to adenosine and regadenoson were similar (APV at maximal hyperemia 36 cm/s for both, p = 0.81). Conclusions: Regadenoson single-bolus administration has comparable FFR, symptoms, and coronary flow augmentation when compared with standard intravenous adenosine infusion. With its greater ease of administration, regadenoson may be a more “user-friendly” option for invasive ischemic testing.

  12. The relationship between fractional flow reserve, platelet reactivity and platelet leukocyte complexes in stable coronary artery disease.

    Directory of Open Access Journals (Sweden)

    Jan-Willem E M Sels

    Full Text Available BACKGROUND: The presence of stenoses that significantly impair blood flow and cause myocardial ischemia negatively affects prognosis of patients with stable coronary artery disease. Altered platelet reactivity has been associated with impaired prognosis of stable coronary artery disease. Platelets are activated and form complexes with leukocytes in response to microshear gradients caused by friction forces on the arterial wall or flow separation. We hypothesized that the presence of significantly flow-limiting stenoses is associated with altered platelet reactivity and formation of platelet-leukocyte complexes. METHODS: One hundred patients with stable angina were studied. Hemodynamic significance of all coronary stenoses was assessed with Fractional Flow Reserve (FFR. Patients were classified FFR-positive (at least one lesion with FFR≤0.75 or FFR-negative (all lesions FFR>0.80. Whole blood samples were stimulated with increasing concentrations of ADP, TRAP, CRP and Iloprost with substimulatory ADP. Expression of P-selectin as platelet activation marker and platelet-leukocyte complexes were measured by flowcytometry. Patients were stratified on clopidogrel use. FFR positive and negative patient groups were compared on platelet reactivity and platelet-leukocyte complexes. RESULTS: Platelet reactivity between FFR-positive patients and FFR-negative patients did not differ. A significantly lower percentage of circulating platelet-neutrophil complexes in FFR-positive patients and a similar non-significant decrease in percentage of circulating platelet-monocyte complexes in FFR-positive patients was observed. CONCLUSION: The presence of hemodynamically significant coronary stenoses does not alter platelet reactivity but is associated with reduced platelet-neutrophil complexes in peripheral blood of patients with stable coronary artery disease.

  13. Long-term prognostic value of CFVR and FFR versus perfusion scintigraphy in patients with multivessel disease

    Science.gov (United States)

    Chamuleau, S.A.J.; van Eck-Smit, B.L.F.; Meuwissen, M.; Koch, K.T.; Dijkgraaf, M.G.W.; Verberne, H.J.; Tijssen, J.G.P.; Piek, J.J.

    2007-01-01

    Objective In this multicentre study, we investigated the long-term prognostic value of intracoronary derived haemodynamic parameters compared with the results of myocardial perfusion scintigraphy (MPS). Methods Patients (n=191) who were referred for angioplasty of a severe lesion in the presence of an intermediate lesion in another coronary artery were included. MPS was performed to determine the presence of reversible perfusion defects in the area of the intermediate lesion. Coronary flow velocity reserve (CFVR), and additionally fractional flow reserve (FFR; n=129), were determined distal to the intermediate lesion; CFVR ≥2.0 and FFR ≥0.75 were considered negative. Results In total 67 events occurred in 49 patients (3 deaths, 9 MI, 9 CABG, 46 PTCA) during a mean of 793 days follow-up. Event-free survival was 63% for MPS, 79% for CFVR, and 79% for FFR if a negative test result was obtained. The relative risk was 1.2 (not significant) for MPS, 2.2 (p=0.001) for CFVR, and 2.4 (p=0.004) for FFR. Conclusion Selective evaluation of an intermediate lesion using CFVR or FFR allows more adequate risk stratification in patients with multivessel disease than MPS. A CFVR <2.0 or a FFR <0.75 was associated with a significant increase of the occurrence of cardiac events during long-term follow-up, predominantly associated with revascularisation. (Neth Heart J 2007;15:369-74.18176638) PMID:18176638

  14. Risk model for estimating the 1-year risk of deferred lesion intervention following deferred revascularization after fractional flow reserve assessment.

    Science.gov (United States)

    Depta, Jeremiah P; Patel, Jayendrakumar S; Novak, Eric; Gage, Brian F; Masrani, Shriti K; Raymer, David; Facey, Gabrielle; Patel, Yogesh; Zajarias, Alan; Lasala, John M; Amin, Amit P; Kurz, Howard I; Singh, Jasvindar; Bach, Richard G

    2015-02-21

    Although lesions deferred revascularization following fractional flow reserve (FFR) assessment have a low risk of adverse cardiac events, variability in risk for deferred lesion intervention (DLI) has not been previously evaluated. The aim of this study was to develop a prediction model to estimate 1-year risk of DLI for coronary lesions where revascularization was not performed following FFR assessment. A prediction model for DLI was developed from a cohort of 721 patients with 882 coronary lesions where revascularization was deferred based on FFR between 10/2002 and 7/2010. Deferred lesion intervention was defined as any revascularization of a lesion previously deferred following FFR. The final DLI model was developed using stepwise Cox regression and validated using bootstrapping techniques. An algorithm was constructed to predict the 1-year risk of DLI. During a mean (±SD) follow-up period of 4.0 ± 2.3 years, 18% of lesions deferred after FFR underwent DLI; the 1-year incidence of DLI was 5.3%, while the predicted risk of DLI varied from 1 to 40%. The final Cox model included the FFR value, age, current or former smoking, history of coronary artery disease (CAD) or prior percutaneous coronary intervention, multi-vessel CAD, and serum creatinine. The c statistic for the DLI prediction model was 0.66 (95% confidence interval, CI: 0.61-0.70). Patients deferred revascularization based on FFR have variation in their risk for DLI. A clinical prediction model consisting of five clinical variables and the FFR value can help predict the risk of DLI in the first year following FFR assessment. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2014. For permissions please email: journals.permissions@oup.com.

  15. Effect of Fractional Flow Reserve (≤0.90 vs >0.90) on Long-Term Outcome (>10 Years) in Patients With Nonsignificant Coronary Arterial Narrowings.

    Science.gov (United States)

    Badoz, Marc; Chatot, Marion; Hechema, Rémy; Chopard, Romain; Meneveau, Nicolas; Schiele, François

    2016-08-15

    We assessed the long-term (>10 years) clinical course of patients with documented coronary lesions deemed nonsignificant according to fractional flow reserve (FFR) assessment and investigated whether the initial FFR value impacted on prognosis. From January 2000 to October 2003, all patients submitted to coronary angiography with FFR measurement were included in a single-center, prospective registry. Patients with an FFR value >0.80 were treated medically without revascularization. Major adverse cardiac events (MACE) (death, acute coronary syndrome (ACS), or coronary revascularization) were compared according to initial FFR value (absolute value and by category, ≤0.90 vs >0.90). Analyses were performed using a multivariable Cox model and propensity score matching. Among 257 patients (332 lesions) treated medically initially, 131 (51%, 143 lesions) had FFR ≤0.90 and 126 (49%, 189 lesions) >0.90. During follow-up (median duration, 11.6 years), 82 (31.9%) had a MACE, 38 (14.8%) died, 17 (6.6%) had ACS, 93 (36.2%) had repeat coronary angiography, and 27 (10.5%) had revascularization. There was no clinical, biologic or angiographic difference between patients with initial FFR value ≤0.90 versus >0.90. Adjusted Cox model showed no difference in relative risk of MACE, death, ACS, or revascularization. Coronary angiographies were numerically more frequent in patients with FFR ≤0.90, versus FFR >0.90. These findings were confirmed by propensity score-matched comparison. In patients with coronary narrowings left unrevascularized based on FFR, an FFR value between 0.80 and 0.90 has no impact on long-term outcome compared with those with FFR >0.90. In conclusion, patients with high FFR values should not be considered as having a lower risk of coronary event.

  16. Assessment of left anterior descending artery stenosis of intermediate severity by fractional flow reserve, instantaneous wave-free ratio, and non-invasive coronary flow reserve.

    Science.gov (United States)

    Meimoun, P; Clerc, J; Ardourel, D; Djou, U; Martis, S; Botoro, T; Elmkies, F; Zemir, H; Luycx-Bore, A; Boulanger, J

    2016-10-17

    To test the usefulness of non-invasive coronary flow reserve (CFR) by transthoracic Doppler echocardiography by comparison to invasive fractional flow reserve (FFR) and instantaneous wave-free ratio (IFR), a new vasodilator-free index of coronary stenosis severity, in patients with left anterior descending artery (LAD) stenosis of intermediate severity (IS) and stable coronary artery disease. 94 consecutive patients (mean age 68 ± 10 years) with angiographic LAD stenosis of IS (50-70 % diameter stenosis), were prospectively studied. IFR was calculated as a trans-lesion pressure ratio during the wave-free period in diastole; FFR as distal pressure divided by mean aortic pressure during maximal hyperemia (using 180 μg intracoronary adenosine); and CFR as hyperemic peak LAD flow velocity divided by baseline flow velocity using intravenous adenosine (140 μg/kg/min over 2 min). The mean values of IFR, FFR, and CFR were 0.88 ± 0.07, 0.81 ± 0.09, and 2.4 ± 0.6 respectively. A significant correlation was found between CFR and FFR (r = 0. 68), FFR and IFR (r = 0.6), and between CFR and IFR (r = 0.5) (all, p < 0.01). Using a ROC curve analysis, the best cut-off to detect a significant lesion based on FFR assessment (FFR ≤ 0.8, n = 31) was IFR ≤ 0.88 with a sensitivity (Se) of 74 %, specificity (Sp) of 73 %, AUC 0.81 ± 0.04, accuracy 72 %; and CFR ≤ 2 with a Se = 77 %, Sp = 89 %, AUC 0.88 ± 0.04, accuracy 85 % (all, p < 0.001). In stable patients with LAD stenosis of IS, non-invasive CFR is a useful tool to detect a significant lesion based on FFR. Furthermore, there was a better correlation between CFR and FFR than between CFR and IFR, and a trend to a better diagnostic performance for CFR versus IFR.

  17. Fractional flow reserve derived from coronary CT angiography in stable coronary disease: a new standard in non-invasive testing?

    Energy Technology Data Exchange (ETDEWEB)

    Noergaard, B.L.; Jensen, J.M. [Aarhus University Hospital Skejby, Department of Cardiology B, Aarhus N (Denmark); Leipsic, J. [St. Paul' s Hospital, Department Radiology, Vancouver, British Columbia (Canada)

    2015-08-15

    Fractional flow reserve (FFR) measured during invasive coronary angiography is the gold standard for lesion-specific decisions on coronary revascularization in patients with stable coronary artery disease (CAD). Current guidelines recommend non-invasive functional or anatomic testing as a gatekeeper to the catheterization laboratory. However, the ''holy grail'' in non-invasive testing of CAD is to establish a single test that quantifies both coronary lesion severity and the associated ischemia. Most evidence to date of such a test is based on the addition of computational analysis of FFR to the anatomic information obtained from standard-acquired coronary CTA data sets at rest (FFR{sub CT}). This review summarizes the clinical evidence for the use of FFR{sub CT} in stable CAD in context to the diagnostic performance of other non-invasive testing modalities. (orig.)

  18. Safety and Efficacy of a Novel Technique in the Use of Fractional Flow Reserve in Complex Coronary Artery Lesions

    Institute of Scientific and Technical Information of China (English)

    Wen-Ming He; Chang-Ling Li; Yong Sun; Zhong Zhou; Yi-Feng Mai

    2015-01-01

    Background:Fractional flow reserve (FFR) has become an increasingly important index when making decisions with respect to revascularization of coronary artery stenosis.However,the pressure guidewire used in obtaining FFR measurements is difficult to control and manipulate in certain complex coronary artery lesions,resulting in increased fluoroscopy time and contrast dye usage.This study examined a novel (NOV) technique for obtaining FFR measurements in hope of easing the difficulties associated with evaluating and treating complex coronary artery lesions.Methods:Fifty-six patients with complex coronary artery lesions were assigned to a conventional (CON) FFR technique group or a NOV FFR technique group.The NOV technique involved the use of a balloon and wire exchange within the coronary artery.The fluoroscopy time,contrast dye usage,and FFR-related complications were assessed after completing the FFR measurement procedure for each patient.Results:The median time required for fluoroscopy in the NOV technique group was significantly less than that in the CON technique group; additionally,lesser amounts of contrast dye were used in the NOV technique group (both P < 0.05).The NOV technique was successfully performed in thirty patients,without any FFR-related complications.However,the CON technique failed in three patients,including two who experienced coronary artery spasms (P > 0.05).Conclusions:Compared to the CON technique used for measuring FFR,the new technique reduced the fluoroscopy time and amount of contrast dye used when evaluating complex coronary artery lesions.The new technique did not increase the risk of operation or decrease the success rate.

  19. Comparative Study between Perfusion Changes and Positive Findings on Coronary Flow Reserve

    Directory of Open Access Journals (Sweden)

    Costantino Roberto Frack Costantini

    Full Text Available Abstract Background: Functional assessment of coronary artery obstruction is used in cardiology practice to correlate anatomic obstructions with flow decrease. Among such assessments, the study of the coronary fractional flow reserve (FFR has become the most widely used. Objective: To evaluate the correlation between FFR and findings of ischemia obtained by noninvasive methods including stress echocardiography and nuclear medicine and the presence of critical coronary artery obstruction. Methods: Retrospective study of cases treated with systematized and standardized procedures for coronary disease between March 2011 and August 2014. We included 96 patients with 107 critical coronary obstructions (> 50% in the coronary trunk and/or ≥ 70% in other segments estimated by quantitative coronary angiography (QCA and intracoronary ultrasound (ICUS. All cases presented ischemia in one of the noninvasive studies. Results: All 96 patients presented ischemia (100% in one of the functional tests. On FFR study with adenosine 140 g/kg/min, 52% of the cases had values ≤ 0.80. On correlation analysis for FFR ≤ 0.80, the evaluation of sensitivity, specificity, positive and negative predictive values, accuracy, and ROC curve in relation to the stenosis degree and length, and presence of ischemia, no significant values or strong correlation were observed. Conclusion: Coronary FFR using a cut-off value of 0.80 showed no correlation with noninvasive ischemia tests in patients with severe coronary artery obstructions on QCA and ICUS.

  20. Comparative Study between Perfusion Changes and Positive Findings on Coronary Flow Reserve

    Science.gov (United States)

    Costantini, Costantino Roberto Frack; Ramires, Jose Antonio; Costantini, Costantino Ortiz; Denk, Marcos Antonio; Tarbine, Sergio Gustavo; Santos, Marcelo de Freitas; Zanuttini, Daniel Aníbal; Silveira, Carmen Weigert; de Souza, Admar Moraes; de Macedo, Rafael Michel

    2017-01-01

    Background Functional assessment of coronary artery obstruction is used in cardiology practice to correlate anatomic obstructions with flow decrease. Among such assessments, the study of the coronary fractional flow reserve (FFR) has become the most widely used. Objective To evaluate the correlation between FFR and findings of ischemia obtained by noninvasive methods including stress echocardiography and nuclear medicine and the presence of critical coronary artery obstruction. Methods Retrospective study of cases treated with systematized and standardized procedures for coronary disease between March 2011 and August 2014. We included 96 patients with 107 critical coronary obstructions (> 50% in the coronary trunk and/or ≥ 70% in other segments) estimated by quantitative coronary angiography (QCA) and intracoronary ultrasound (ICUS). All cases presented ischemia in one of the noninvasive studies. Results All 96 patients presented ischemia (100%) in one of the functional tests. On FFR study with adenosine 140 g/kg/min, 52% of the cases had values ≤ 0.80. On correlation analysis for FFR ≤ 0.80, the evaluation of sensitivity, specificity, positive and negative predictive values, accuracy, and ROC curve in relation to the stenosis degree and length, and presence of ischemia, no significant values or strong correlation were observed. Conclusion Coronary FFR using a cut-off value of 0.80 showed no correlation with noninvasive ischemia tests in patients with severe coronary artery obstructions on QCA and ICUS. PMID:27982159

  1. Advanced computed tomographic anatomical and morphometric plaque analysis for prediction of fractional flow reserve in intermediate coronary lesions

    Energy Technology Data Exchange (ETDEWEB)

    Opolski, Maksymilian P., E-mail: opolski.mp@gmail.com [Department of Interventional Cardiology and Angiology, Institute of Cardiology, Warsaw (Poland); Kepka, Cezary, E-mail: c.kepka@ikard.pl [Department of Coronary and Structural Heart Diseases, Institute of Cardiology, Warsaw (Poland); Achenbach, Stephan, E-mail: stephan.achenbach@uk-erlangen.de [Department of Internal Medicine 2 (Cardiology), University of Erlangen, Erlangen (Germany); Pregowski, Jerzy, E-mail: jerzypregowski74@gmail.com [Department of Interventional Cardiology and Angiology, Institute of Cardiology, Warsaw (Poland); Kruk, Mariusz, E-mail: mariuszkruk2000@yahoo.com [Department of Coronary and Structural Heart Diseases, Institute of Cardiology, Warsaw (Poland); Staruch, Adam D., E-mail: adstarman@gmail.com [Medical University of Warsaw, Warsaw (Poland); Kadziela, Jacek, E-mail: j.kadziela@ikard.pl [Department of Interventional Cardiology and Angiology, Institute of Cardiology, Warsaw (Poland); Ruzyllo, Witold, E-mail: w.ruzyllo@ikard.pl [Department of Coronary and Structural Heart Diseases, Institute of Cardiology, Warsaw (Poland); Witkowski, Adam, E-mail: witkowski@hbz.pl [Department of Interventional Cardiology and Angiology, Institute of Cardiology, Warsaw (Poland)

    2014-01-15

    Objective: To determine the application of advanced coronary computed tomography angiography (CCTA) plaque analysis for predicting invasive fractional flow reserve (FFR) in intermediate coronary lesions. Methods: Sixty-one patients with 71 single intermediate coronary lesions (≥50–80% stenosis) on CCTA prospectively underwent coronary angiography and FFR. Advanced anatomical and morphometric plaque analysis was performed based on CCTA data set to determine optimal criteria for significant flow impairment. A significant stenosis was defined as FFR ≤ 0.80. Results: FFR averaged 0.85 ± 0.09, and 19 lesions (27%) were functionally significant. FFR correlated with minimum lumen area (MLA) (r = 0.456, p < 0.001), minimum lumen diameter (MLD) (r = 0.326, p = 0.006), reference lumen diameter (RLD) (r = 0.245, p = 0.039), plaque burden (r = −0.313, p = 0.008), lumen area stenosis (r = −0.305, p = 0.01), lesion length (r = −0.692, p < 0.001), and plaque volume (r = −0.668, p < 0.001). There was no relationship between FFR and CCTA morphometric plaque parameters. By multivariate analysis the independent predictors of FFR were lesion length (beta = −0.581, p < 0.001), MLA (beta = 0.360, p = 0.041), and RLD (beta = −0.255, p = 0.036). The optimal cutoffs for lesion length, MLA, MLD, RLD, and lumen area stenosis were >18.5 mm, ≤3.0 mm{sup 2}, ≤2.1 mm, ≤3.2 mm, and >69%, respectively (max. sensitivity: 100% for MLA, max. specificity: 79% for lumen area stenosis). Conclusions: CCTA predictors for FFR support the mathematical relationship between stenosis pressure drop and coronary flow. CCTA could prove to be a useful rule-out test for significant hemodynamic effects of intermediate coronary stenoses.

  2. Prediction of the true fractional flow reserve of left main coronary artery stenosis with concomitant downstream stenoses: in vitro and in vivo experiments.

    Science.gov (United States)

    Yamamoto, Erika; Saito, Naritatsu; Matsuo, Hitoshi; Kawase, Yoshiaki; Watanabe, Shin; Bao, Bingyuan; Watanabe, Hiroki; Higami, Hirooki; Nakatsuma, Kenji; Kimura, Takeshi

    2016-02-01

    The functional impact of downstream coronary stenoses on left main coronary artery (LMCA) stenosis has not been fully elucidated. This study therefore aimed to use in vitro and in vivo experiments to assess two novel equations that predict the true fractional flow reserve (FFR) of a left main coronary artery (LMCA) stenosis with concomitant downstream stenoses. Two novel equations were derived. One equation predicts the true fractional flow reserve (FFR) of an LMCA stenosis with a downstream stenosis (Equation A), and the other predicts the true FFR of an LMCA stenosis with downstream stenoses in both the left anterior descending and left circumflex arteries (Equation B). The equations were validated in both in vitro and in vivo models of the coronary circulation. The agreements between the apparent FFR (FFRapp), the predicted FFR (FFRpred) and the true FFR (FFRtrue) were assessed by Passing-Bablok regression analysis. Passing-Bablok regression analysis revealed that there were fixed proportional errors between FFRapp-m and FFRtrue-m, though a very small fixed error and no proportional errors between FFRpred-m and FFRtrue-m. The absolute differences between FFRpred and FFRtrue were significantly lower as compared to those between FFRapp and FFRtrue in all experiments. Two novel equations which predict the true FFR of LMCA stenosis were demonstrated to be correct. The study also revealed that the functional impact of downstream stenoses on the LMCA stenosis became stronger when the downstream stenoses became more severe.

  3. Physiologic Assessment of Coronary Artery Disease: Focus on Fractional Flow Reserve.

    Science.gov (United States)

    Hwang, Doyeon; Lee, Joo Myung; Koo, Bon-Kwon

    2016-01-01

    The presence of myocardial ischemia is the most important prognostic factor in patients with ischemic heart disease. Fractional flow reserve (FFR) is a gold standard invasive method used to detect the stenosis-specific myocardial ischemia. FFR-guided revascularization strategy is superior to angiography-guided strategy. The recently developed hyperemia-free index, instantaneous wave free ratio is being actively investigated. A non-invasive FFR derived from coronary CT angiography is now used in clinical practice. Due to rapid expansion of invasive and non-invasive physiologic assessment, comprehensive understanding of the role and potential pitfalls of each modality are required for its application. In this review, we focus on the basic and clinical aspects of physiologic assessment in ischemic heart disease.

  4. Physiologic assessment of coronary artery disease: Focus on fractional flow reserve

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, Do Yeon; Koo, Bon Kwon [Dept. of Radiology, Internal Medicine and Cardiovascular Center, Seoul National University Hospital, Seoul (Korea, Republic of); Lee, Joo Myung [Dept. of Internal Medicine and Cardiovascular Center, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul (Korea, Republic of)

    2016-06-15

    The presence of myocardial ischemia is the most important prognostic factor in patients with ischemic heart disease. Fractional flow reserve (FFR) is a gold standard invasive method used to detect the stenosis-specific myocardial ischemia. FFR-guided revascularization strategy is superior to angiography-guided strategy. The recently developed hyperemia-free index, instantaneous wave free ratio is being actively investigated. A non-invasive FFR derived from coronary CT angiography is now used in clinical practice. Due to rapid expansion of invasive and non-invasive physiologic assessment, comprehensive understanding of the role and potential pitfalls of each modality are required for its application. In this review, we focus on the basic and clinical aspects of physiologic assessment in ischemic heart disease.

  5. Clinical use of optical coherence tomography and fractional flow reserve

    Directory of Open Access Journals (Sweden)

    Ivanović Vladimir

    2016-01-01

    Full Text Available Introduction. The aim of each diagnostic method is to serve as a guide in deciding about the right patient treatment. During myocardial revascularization the decision to perform revascularization is usually not easy to make, especially in case of borderline stenosis. It has been proven that it is not enough to base morphological evaluation of coronary artery vessel stenosis solely on angiography. It is necessary to include additional modern diagnostic methods for functional analysis and detailed morphological analysis using fractional flow reserve (FFR and optical coherence tomography (OCT, respectively. Case reports. In the first case report we showed the significance of morphological analysis using OCT and proved that it was not lumen stenosis. The second and the third case reports showed the complementarity between functional analysis (FFR and morphological analysis (OCT of stenosis in solving a complex coronary disease. The fourth case report showed the significance of OCT in dealing with the recurrent stent restenosis. Conclusion. By these short case reports we confirmed that percutaneous coronary intervention (PCI guided by angiography is definitely not enough in deciding about myocardial revascularization especially in patients with a complex coronary disease. In certain cases FFR and OCT procedures can be complementary methods and improve quality of revascularization, particularly in the case of recurrent in-stent restenosis.

  6. A machine-learning approach for computation of fractional flow reserve from coronary computed tomography.

    Science.gov (United States)

    Itu, Lucian; Rapaka, Saikiran; Passerini, Tiziano; Georgescu, Bogdan; Schwemmer, Chris; Schoebinger, Max; Flohr, Thomas; Sharma, Puneet; Comaniciu, Dorin

    2016-07-01

    Fractional flow reserve (FFR) is a functional index quantifying the severity of coronary artery lesions and is clinically obtained using an invasive, catheter-based measurement. Recently, physics-based models have shown great promise in being able to noninvasively estimate FFR from patient-specific anatomical information, e.g., obtained from computed tomography scans of the heart and the coronary arteries. However, these models have high computational demand, limiting their clinical adoption. In this paper, we present a machine-learning-based model for predicting FFR as an alternative to physics-based approaches. The model is trained on a large database of synthetically generated coronary anatomies, where the target values are computed using the physics-based model. The trained model predicts FFR at each point along the centerline of the coronary tree, and its performance was assessed by comparing the predictions against physics-based computations and against invasively measured FFR for 87 patients and 125 lesions in total. Correlation between machine-learning and physics-based predictions was excellent (0.9994, P machine-learning algorithm with a sensitivity of 81.6%, a specificity of 83.9%, and an accuracy of 83.2%. The correlation was 0.729 (P machine-learning model on a workstation with 3.4-GHz Intel i7 8-core processor. Copyright © 2016 the American Physiological Society.

  7. Fractional Flow Reserve-Guided Multivessel Angioplasty in Myocardial Infarction.

    Science.gov (United States)

    Smits, Pieter C; Abdel-Wahab, Mohamed; Neumann, Franz-Josef; Boxma-de Klerk, Bianca M; Lunde, Ketil; Schotborgh, Carl E; Piroth, Zsolt; Horak, David; Wlodarczak, Adrian; Ong, Paul J; Hambrecht, Rainer; Angerås, Oskar; Richardt, Gert; Omerovic, Elmir

    2017-03-30

    Background In patients with ST-segment elevation myocardial infarction (STEMI), the use of percutaneous coronary intervention (PCI) to restore blood flow in an infarct-related coronary artery improves outcomes. The use of PCI in non-infarct-related coronary arteries remains controversial. Methods We randomly assigned 885 patients with STEMI and multivessel disease who had undergone primary PCI of an infarct-related coronary artery in a 1:2 ratio to undergo complete revascularization of non-infarct-related coronary arteries guided by fractional flow reserve (FFR) (295 patients) or to undergo no revascularization of non-infarct-related coronary arteries (590 patients). The FFR procedure was performed in both groups, but in the latter group, both the patients and their cardiologist were unaware of the findings on FFR. The primary end point was a composite of death from any cause, nonfatal myocardial infarction, revascularization, and cerebrovascular events at 12 months. Clinically indicated elective revascularizations performed within 45 days after primary PCI were not counted as events in the group receiving PCI for an infarct-related coronary artery only. Results The primary outcome occurred in 23 patients in the complete-revascularization group and in 121 patients in the infarct-artery-only group that did not receive complete revascularization, a finding that translates to 8 and 21 events per 100 patients, respectively (hazard ratio, 0.35; 95% confidence interval [CI], 0.22 to 0.55; Pratio, 0.80; 95% CI, 0.25 to 2.56), myocardial infarction in 7 and 28 patients, respectively (2.4% vs. 4.7%) (hazard ratio, 0.50; 95% CI, 0.22 to 1.13), revascularization in 18 and 103 patients (6.1% vs. 17.5%) (hazard ratio, 0.32; 95% CI, 0.20 to 0.54), and cerebrovascular events in 0 and 4 patients (0 vs. 0.7%). An FFR-related serious adverse event occurred in 2 patients (both in the group receiving infarct-related treatment only). Conclusions In patients with STEMI and multivessel

  8. Virtual Resting Pd/Pa From Coronary Angiography and Blood Flow Modelling: Diagnostic Performance Against Fractional Flow Reserve.

    Science.gov (United States)

    Papafaklis, Michail I; Muramatsu, Takashi; Ishibashi, Yuki; Bourantas, Christos V; Fotiadis, Dimitrios I; Brilakis, Emmanouil S; Garcia-Garcia, Héctor M; Escaned, Javier; Serruys, Patrick W; Michalis, Lampros K

    2017-05-03

    Fractional flow reserve (FFR) has been established as a useful diagnostic tool. The distal coronary pressure to aortic pressure (Pd/Pa) ratio at rest is a simpler physiologic index but also requires the use of the pressure wire, whereas recently proposed virtual functional indices derived from coronary imaging require complex blood flow modelling and/or are time-consuming. Our aim was to test the diagnostic performance of virtual resting Pd/Pa using routine angiographic images and a simple flow model. Three-dimensional quantitative coronary angiography (3D-QCA) was performed in 139 vessels (120 patients) with intermediate lesions assessed by FFR. The resting Pd/Pa for each lesion was assessed by computational fluid dynamics. The discriminatory power of virtual resting Pd/Pa against FFR (reference: ≤0.80) was high (area under the receiver operator characteristic curve [AUC]: 90.5% [95% CI: 85.4-95.6%]). Diagnostic accuracy, sensitivity and specificity for the optimal virtual resting Pd/Pa cut-off (≤0.94) were 84.9%, 90.4% and 81.6%, respectively. Virtual resting Pd/Pa demonstrated superior performance (pvirtual resting Pd/Pa and FFR (r=0.69, pVirtual resting Pd/Pa using routine angiographic data and a simple flow model provides fast functional assessment of coronary lesions without requiring the pressure-wire and hyperaemia induction. The high diagnostic performance of virtual resting Pd/Pa for predicting FFR shows promise for using this simple/fast virtual index in clinical practice. Copyright © 2017 Australian and New Zealand Society of Cardiac and Thoracic Surgeons (ANZSCTS) and the Cardiac Society of Australia and New Zealand (CSANZ). Published by Elsevier B.V. All rights reserved.

  9. Influence of routine assessment of fractional flow reserve on decision making during coronary interventions.

    Science.gov (United States)

    Sant'Anna, Fernando M; Silva, Expedito E R; Batista, Leonardo Alves; Ventura, Fábio Machado; Barrozo, Carlos Alberto Mussel; Pijls, Nico H J

    2007-02-15

    In complex coronary artery disease, it is sometimes difficult to determine which lesions are associated with reversible ischemia and should be stented. Fractional flow reserve (FFR) is an established objective methodology to indicate which lesions produce ischemia. Despite this, the selection of lesions to be stented is often based on the subjectively interpreted angiogram alone. The aim of this study in patients admitted for elective percutaneous intervention (PCI) was to evaluate the change in strategy if the decision to intervene was based on FFR measurement rather than on angiographic assessment. Two hundred fifty consecutive patients (471 arteries) scheduled for PCI were included in this study. All stenoses >or=50% by visual estimation and initially selected to be stented by 3 independent reviewers were assessed by FFR measurements. If FFR was or=0.75, no interventional treatment was given. Optimal pressure measurements were obtained in 452 lesions (96%). Diameter stenosis was 62 +/- 12%, and FFR was 0.67 +/- 0.17 for the entire group. In 68% of the stenoses, initial strategy as assessed from the angiogram was followed, and in 32%, there was a change in the planned approach based on FFR. In 48% of the patients, there was >or=1 lesion in which the treatment decision was changed after physiologic measurements. In conclusion, in this prospective, nonselective, but complete study representing the real world of PCI, 32% of the coronary stenoses and 48% of patients would have received a different treatment if the decision had been based on angiography only, stressing the utility of physiologic assessment in refining decision making during PCI.

  10. Long-term outcome of FFR-guided PCI for stable coronary artery disease in daily clinical practice

    DEFF Research Database (Denmark)

    De Backer, Ole; Biasco, Luigi; Lønborg, Jacob

    2016-01-01

    AIMS: Our aim was to investigate the strength of fractional flow reserve (FFR)-guided percutaneous coronary intervention (PCI) for stable coronary artery disease (CAD) in daily practice. METHODS AND RESULTS: For this study, 3,512 patients with stable CAD and at least one 50-89% coronary stenosis...... were identified; those patients thought to require PCI (n=1,716) were selected. Of these, 962 (56%) were treated based on angiography (XA) alone, whereas 754 patients (44%) had an FFR-guided treatment. In the latter group, 321 patients (43%) were reallocated to another treatment, predominantly medical...

  11. Use of the Instantaneous Wave-free Ratio or Fractional Flow Reserve in PCI.

    Science.gov (United States)

    Davies, Justin E; Sen, Sayan; Dehbi, Hakim-Moulay; Al-Lamee, Rasha; Petraco, Ricardo; Nijjer, Sukhjinder S; Bhindi, Ravinay; Lehman, Sam J; Walters, Darren; Sapontis, James; Janssens, Luc; Vrints, Christiaan J; Khashaba, Ahmed; Laine, Mika; Van Belle, Eric; Krackhardt, Florian; Bojara, Waldemar; Going, Olaf; Härle, Tobias; Indolfi, Ciro; Niccoli, Giampaolo; Ribichini, Flavo; Tanaka, Nobuhiro; Yokoi, Hiroyoshi; Takashima, Hiroaki; Kikuta, Yuetsu; Erglis, Andrejs; Vinhas, Hugo; Canas Silva, Pedro; Baptista, Sérgio B; Alghamdi, Ali; Hellig, Farrel; Koo, Bon-Kwon; Nam, Chang-Wook; Shin, Eun-Seok; Doh, Joon-Hyung; Brugaletta, Salvatore; Alegria-Barrero, Eduardo; Meuwissen, Martijin; Piek, Jan J; van Royen, Niels; Sezer, Murat; Di Mario, Carlo; Gerber, Robert T; Malik, Iqbal S; Sharp, Andrew S P; Talwar, Suneel; Tang, Kare; Samady, Habib; Altman, John; Seto, Arnold H; Singh, Jasvindar; Jeremias, Allen; Matsuo, Hitoshi; Kharbanda, Rajesh K; Patel, Manesh R; Serruys, Patrick; Escaned, Javier

    2017-03-18

    Background Coronary revascularization guided by fractional flow reserve (FFR) is associated with better patient outcomes after the procedure than revascularization guided by angiography alone. It is unknown whether the instantaneous wave-free ratio (iFR), an alternative measure that does not require the administration of adenosine, will offer benefits similar to those of FFR. Methods We randomly assigned 2492 patients with coronary artery disease, in a 1:1 ratio, to undergo either iFR-guided or FFR-guided coronary revascularization. The primary end point was the 1-year risk of major adverse cardiac events, which were a composite of death from any cause, nonfatal myocardial infarction, or unplanned revascularization. The trial was designed to show the noninferiority of iFR to FFR, with a margin of 3.4 percentage points for the difference in risk. Results At 1 year, the primary end point had occurred in 78 of 1148 patients (6.8%) in the iFR group and in 83 of 1182 patients (7.0%) in the FFR group (difference in risk, -0.2 percentage points; 95% confidence interval [CI], -2.3 to 1.8; Pratio, 0.95; 95% CI, 0.68 to 1.33; P=0.78). The risk of each component of the primary end point and of death from cardiovascular or noncardiovascular causes did not differ significantly between the groups. The number of patients who had adverse procedural symptoms and clinical signs was significantly lower in the iFR group than in the FFR group (39 patients [3.1%] vs. 385 patients [30.8%], P<0.001), and the median procedural time was significantly shorter (40.5 minutes vs. 45.0 minutes, P=0.001). Conclusions Coronary revascularization guided by iFR was noninferior to revascularization guided by FFR with respect to the risk of major adverse cardiac events at 1 year. The rate of adverse procedural signs and symptoms was lower and the procedural time was shorter with iFR than with FFR. (Funded by Philips Volcano; DEFINE-FLAIR ClinicalTrials.gov number, NCT02053038 .).

  12. Meta-Analysis of Diagnostic Performance of Coronary Computed Tomography Angiography, Computed Tomography Perfusion, and Computed Tomography-Fractional Flow Reserve in Functional Myocardial Ischemia Assessment Versus Invasive Fractional Flow Reserve.

    Science.gov (United States)

    Gonzalez, Jorge A; Lipinski, Michael J; Flors, Lucia; Shaw, Peter W; Kramer, Christopher M; Salerno, Michael

    2015-11-01

    We sought to compare the diagnostic performance of coronary computed tomography angiography (CCTA), computed tomography perfusion (CTP), and computed tomography (CT)-fractional flow reserve (FFR) for assessing the functional significance of coronary stenosis as defined by invasive FFR in patients with known or suspected coronary artery disease (CAD). CCTA has proved clinically useful for excluding obstructive CAD because of its high sensitivity and negative predictive value (NPV); however, the ability of CTA to identify functionally significant CAD has remained challenging. We searched PubMed/Medline for studies evaluating CCTA, CTP, or CT-FFR for the noninvasive detection of obstructive CAD compared with catheter-derived FFR as the reference standard. Pooled sensitivity, specificity, PPV, NPV, likelihood ratios, and odds ratio of all diagnostic tests were assessed. Eighteen studies involving a total of 1,535 patients were included. CTA demonstrated a pooled sensitivity of 0.92, specificity 0.43, PPV of 0.56, and NPV of 0.87 on a per-patient level. CT-FFR and CTP increased the specificity to 0.72 and 0.77, respectively (p = 0.004 and p = 0.0009) resulting in higher point estimates for PPV 0.70 and 0.83, respectively. There was no improvement in the sensitivity. The CTP protocol involved more radiation (3.5 mSv CCTA vs 9.6 mSv CTP) and a higher volume of iodinated contrast (145 ml). In conclusion, CTP and CT-FFR improve the specificity of CCTA for detecting functionally significant stenosis as defined by invasive FFR on a per-patient level; both techniques could advance the ability to noninvasively detect the functional significance of coronary lesions.

  13. Clinical Outcomes in Patients with Deferred Coronary Lesions according to Disease Severity Assessed by Fractional Flow Reserve.

    Science.gov (United States)

    Won, Ki Bum; Nam, Chang Wook; Cho, Yun Kyeong; Yoon, Hyuck Jun; Park, Hyoung Seob; Kim, Hyungseop; Han, Seongwook; Hur, Seung Ho; Kim, Yoon Nyun; Park, Sang Hyun; Han, Jung Kyu; Koo, Bon Kwon; Kim, Hyo Soo; Doh, Joon Hyung; Lee, Sung Yun; Yang, Hyoung Mo; Lim, Hong Seok; Yoon, Myeong Ho; Tahk, Seung Jea; Kim, Kwon Bae

    2016-12-01

    Data on the clinical outcomes in deferred coronary lesions according to functional severity have been limited. This study evaluated the clinical outcomes of deferred lesions according to fractional flow reserve (FFR) grade using Korean FFR registry data. Among 1,294 patients and 1,628 lesions in Korean FFR registry, 665 patients with 781 deferred lesions were included in this study. All participants were consecutively categorized into 4 groups according to FFR; group 1: ≥ 0.96 (n = 56), group 2: 0.86-0.95 (n = 330), group 3: 0.81-0.85 (n = 170), and group 4: ≤ 0.80 (n = 99). Primary endpoint was major adverse cardiac events (MACE), a composite of all-cause death, myocardial infarction, and target vessel revascularization. The median follow-up period was 2.1 years. During follow-up, the incidence of MACE in groups 1-4 was 1.8%, 7.6%, 8.8%, and 13.1%, respectively. Compared to group 1, the cumulative rate by Kaplan-Meier analysis of MACE was not different for groups 2 and 3. However, group 4 had higher cumulative rate of MACE compared to group 1 (log-rank P = 0.013). In the multivariate Cox hazard models, only FFR (hazard ratio [HR], 0.95; P = 0.005) was independently associated with MACE among all participants. In contrast, previous history of percutaneous coronary intervention (HR, 2.37; P = 0.023) and diagnosis of acute coronary syndrome (ACS) (HR, 2.35; P = 0.015), but not FFR, were independent predictors for MACE in subjects with non-ischemic (FFR ≥ 0.81) deferred coronary lesions. Compared to subjects with ischemic deferred lesions, clinical outcomes in subjects with non-ischemic deferred lesions according to functional severity are favorable. However, longer-term follow-up may be necessary.

  14. Fractional flow reserve-guided PCI for stable coronary artery disease

    DEFF Research Database (Denmark)

    De Bruyne, Bernard; Fearon, William F; Pijls, Nico H J

    2014-01-01

    BACKGROUND: We hypothesized that in patients with stable coronary artery disease and stenosis, percutaneous coronary intervention (PCI) performed on the basis of the fractional flow reserve (FFR) would be superior to medical therapy. METHODS: In 1220 patients with stable coronary artery disease, we......-therapy group (8.1% vs. 19.5%; hazard ratio, 0.39; 95% confidence interval [CI], 0.26 to 0.57; Pratio, 0.23; 95% CI, 0.14 to 0.38; P

  15. Metoprolol does not effect myocardial fractional flow reserve in patients with intermediate coronary stenoses.

    Science.gov (United States)

    Ozdemir, Murat; Yazici, Guliz Erdem; Turkoglu, Sedat; Timurkaynak, Timur; Cengel, Atiye

    2007-07-01

    Myocardial fractional flow reserve (FFR) is utilized to determine the hemodynamic significance of coronary stenoses. We sought to determine the effect, if any, of metoprolol on FFR in patients with coronary stenoses of intermediate severity. Eighteen patients (10 males, mean age, 59.4 +/- 7.7 years) with isolated, intermediate (30% to 70% narrowing on coronary angiogram) lesions on the proximal LAD and a preserved ejection fraction, underwent FFR measurement using a 0.014 inch pressurewire and intracoronary adenosine injection before and after intravenous metoprolol at a dose that achieved at least a 10% decrease in the heart rate. Heart rate dropped significantly with metoprolol. At the premetoprolol measurement, aortic pressure (Pa) remained essentially the same (105.7 +/- 11.5 versus 105.6 +/- 11.6 mmHg, P > 0.05) and distal coronary pressure (Pd) dropped significantly by 9% from 96.3 +/- 12.7 to 87.4 +/- 13.4 mmHg (P 0.05). In this study, FFR was found not to be influenced by metoprolol treatment in patients with intermediate coronary stenoses and a preserved ejection fraction.

  16. How good are experienced cardiologists at predicting the hemodynamic severity of coronary stenoses when taking fractional flow reserve as the gold standard.

    Science.gov (United States)

    Brueren, B R G; ten Berg, J M; Suttorp, M J; Bal, E T; Ernst, J M P G; Mast, E G; Plokker, H W M

    2002-04-01

    Coronary angioplasty should be based on documented ischemia. However, in daily clinical practice the indication for angioplasty is often based on eyeball assessment of the severity of the stenosis. This study was performed to assess the accuracy of eyeball estimation of coronary stenosis when taking functional flow reserve (FFR) as gold standard. Study lesions were where no mutual agreement on the severity of the stenosis was obtained. The procedure consisted of a repeat control angiogram, FFR measurement and in case of FFR<75% percutaneous coronary intervention. The eyeball assessment of the stenosis was written down before further execution of the procedure. FFR was measured with a pressure monitoring guide. Maximal myocardial hyperemia was induced by intravenous adenosine infusion. Fifty-two patients were studied. Agreement between eyeball assessment and FFR existed in a total of 36 cases (69.2%). Over estimation of hemodynamic severity occurred in six cases (11.5%) and under estimation in 10 cases (19.2%). Consequently, the positive predictive value of eyeball assessment for pressure-derived FFR was 63% and the negative predictive value 76%. The assessment of the hemodynamic severity of intermediate coronary stenosis should not be based on eyeball assessment even by experienced interventional cardiologists.

  17. Noninvasive Fractional Flow Reserve for the Diagnosis of Lesion-specific Ischemia: A Case Example

    Directory of Open Access Journals (Sweden)

    Jesper Møller Jensen

    2015-01-01

    Full Text Available A physically active 52-year-old male with atypical chest pain was referred to our department. A coronary computed tomography angiography (CCTA showed a stenotic plaque in the mid left anterior descending coronary artery (LAD. A rest-stress Rubidium-82 myocardial perfusion was normal. One year later the patient sustained a cardiac arrest and percutaneous coronary intervention of the mid-LAD was successfully performed. The original CCTA data were submitted for noninvasive determination of fractional flow reserve (FFR CT revealing an ischemia-producing lesion in the mid-LAD. This case demonstrates the inherent limitations of assessing lesion-specific ischemia. FFR CT shows promise as a new method for future selection of patients for coronary angiography.

  18. Instantaneous wave-free ratio to guide coronary revascularization: physiological framework, validation and differences with fractional flow reserve.

    Science.gov (United States)

    de Waard, Guus A; Di Mario, Carlo; Lerman, Amir; Serruys, Patrick W; van Royen, Niels

    2017-02-14

    Determining the optimal treatment strategy for revascularization of coronary artery stenosis involves the use of fractional flow reserve (FFR). To improve the low clinical uptake of physiological lesion assessment to guide revascularization, the instantaneous wave-free period (iFR) was proposed as a simpler alternative to FFR that does not require adenosine administration. iFR is calculated as the ratio of blood pressure distal and proximal to a coronary artery stenosis during the diastolic wave- free period. The wave-free period is a part of the cardiac cycle where generation of new pressure wavefronts does not occur and resting microvascular resistance is relatively minimized. iFR indicates the hemodynamic severity of a stenosis, by assessing the extent to which the epicardial stenosis depletes the microcirculatory, autoregulatory reserve. The introduction of iFR and the potential to assess hemodynamic stenosis severity without the need for administration of potent vasodilators such as adenosine, sparked an interesting debate about the fundamentals of human coronary physiology. Outcomes of two randomized clinical trials investigating iFR are pending. These studies are designed to evaluate whether iFR guided revascularisation is non-inferior to an FFR guided approach. The purpose of this review article is to discuss the physiological concepts underlying iFR, examine the existing validation studies and discuss the advantages and disadvantages of iFR as compared to FFR.

  19. Instantaneous Wave-free Ratio versus Fractional Flow Reserve to Guide PCI.

    Science.gov (United States)

    Götberg, Matthias; Christiansen, Evald H; Gudmundsdottir, Ingibjörg J; Sandhall, Lennart; Danielewicz, Mikael; Jakobsen, Lars; Olsson, Sven-Erik; Öhagen, Patrik; Olsson, Hans; Omerovic, Elmir; Calais, Fredrik; Lindroos, Pontus; Maeng, Michael; Tödt, Tim; Venetsanos, Dimitrios; James, Stefan K; Kåregren, Amra; Nilsson, Margareta; Carlsson, Jörg; Hauer, Dario; Jensen, Jens; Karlsson, Ann-Charlotte; Panayi, Georgios; Erlinge, David; Fröbert, Ole

    2017-03-18

    Background The instantaneous wave-free ratio (iFR) is an index used to assess the severity of coronary-artery stenosis. The index has been tested against fractional flow reserve (FFR) in small trials, and the two measures have been found to have similar diagnostic accuracy. However, studies of clinical outcomes associated with the use of iFR are lacking. We aimed to evaluate whether iFR is noninferior to FFR with respect to the rate of subsequent major adverse cardiac events. Methods We conducted a multicenter, randomized, controlled, open-label clinical trial using the Swedish Coronary Angiography and Angioplasty Registry for enrollment. A total of 2037 participants with stable angina or an acute coronary syndrome who had an indication for physiologically guided assessment of coronary-artery stenosis were randomly assigned to undergo revascularization guided by either iFR or FFR. The primary end point was the rate of a composite of death from any cause, nonfatal myocardial infarction, or unplanned revascularization within 12 months after the procedure. Results A primary end-point event occurred in 68 of 1012 patients (6.7%) in the iFR group and in 61 of 1007 (6.1%) in the FFR group (difference in event rates, 0.7 percentage points; 95% confidence interval [CI], -1.5 to 2.8%; P=0.007 for noninferiority; hazard ratio, 1.12; 95% CI, 0.79 to 1.58; P=0.53); the upper limit of the 95% confidence interval for the difference in event rates fell within the prespecified noninferiority margin of 3.2 percentage points. The results were similar among major subgroups. The rates of myocardial infarction, target-lesion revascularization, restenosis, and stent thrombosis did not differ significantly between the two groups. A significantly higher proportion of patients in the FFR group than in the iFR group reported chest discomfort during the procedure. Conclusions Among patients with stable angina or an acute coronary syndrome, an iFR-guided revascularization strategy was

  20. Diagnostic performance of cardiac imaging methods to diagnose ischaemia-causing coronary artery disease when directly compared with fractional flow reserve as a reference standard

    DEFF Research Database (Denmark)

    Danad, Ibrahim; Szymonifka, Jackie; Twisk, Jos W R

    2016-01-01

    ), and cardiac magnetic resonance (MRI) imaging when directly compared with an FFR reference standard. METHOD AND RESULTS: PubMed and Web of Knowledge were searched for investigations published between 1 January 2002 and 28 February 2015. Studies performing FFR in at least 75% of coronary vessels......AIMS: The aim of this study was to determine the diagnostic performance of single-photon emission computed tomography (SPECT), stress echocardiography (SE), invasive coronary angiography (ICA), coronary computed tomography angiography (CCTA), fractional flow reserve (FFR) derived from CCTA (FFRCT...... for the diagnosis of ischaemic coronary artery disease (CAD) were included. Twenty-three articles reporting on 3788 patients and 5323 vessels were identified. Meta-analysis was performed for pooled sensitivity, specificity, likelihood ratios (LR), diagnostic odds ratio, and summary receiver operating characteristic...

  1. Physiological assessment of coronary lesion severity: fractional flow reserve versus nonhyperaemic indices.

    Science.gov (United States)

    Robertson, Keith E; Hennigan, Barry; Berry, Colin; Oldroyd, Keith G

    2015-08-01

    Coronary angiography alone cannot accurately identify the haemodynamic impact of a coronary artery stenosis. Current international guidelines for myocardial revascularization recommend that inducible ischaemia should be demonstrated before the consideration of percutaneous coronary intervention. Invasive physiological assessment of coronary stenosis severity has increasingly been utilized for this purpose and use of the best validated technique, fractional flow reserve (FFR), has been shown to improve clinical outcomes in patients with stable and unstable coronary artery disease. This has led to the use of FFR being recommended in international revascularization guidelines, despite which, clinical uptake has been limited. One potential reason for slow adoption has been the requirement for maximal hyperaemia at the time of FFR measurement, usually achieved by the administration of pharmacological vasodilators such as adenosine. In some healthcare systems, adenosine is expensive and, in addition, its use can be associated with significant, albeit transient, adverse effects that patients (and some operators) find uncomfortable. Consequently, several methods of nonhyperaemic lesion assessment and their potential role in decision making have been reported. In this review we will review and discuss the current evidence for hyperaemic and nonhyperaemic methods of lesion assessment. We will also look at hybrid strategies that utilize both hyperaemic and nonhyperaemic methods as a means of potentially maintaining diagnostic accuracy while minimizing the requirement for adenosine administration and discuss whether or not they represent viable clinical alternatives.

  2. SPECT myocardial perfusion versus fractional flow reserve for evaluation of functional ischemia: A meta analysis

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Tao; Yang, Lin-feng [Department of Medical Imaging, Jinan Military General Hospital, No, 25, Shifan Road, Jinan, Shandong Province, China. 250031 (China); Zhai, Ji-liang [Department of Medical Imaging, The Branch of TaiAn Central Hospital, Middle of Changcheng Road, Shandong Province, China. 271000 (China); Li, Jiang [Department of Medical Imaging, Affiliated Hospital of Taishan Medical University, No, 706, Taishan Road, Shandong Province, China. 271000 (China); Wang, Qi-meng [Department of Medical Imaging, Taishan Hospital of Traditional Chinese Medicine, No, 216, Yingxuan Street, Shandong Province, China. 271000. (China); Zhang, Rui-jie; Wang, Sen; Peng, Zhao-hui [Department of Medical Imaging, Jinan Military General Hospital, No, 25, Shifan Road, Jinan, Shandong Province, China. 250031 (China); Li, Min, E-mail: liminyingxiang@163.com [Department of Medical Imaging, Jinan Military General Hospital, No, 25, Shifan Road, Jinan, Shandong Province, China. 250031 (China); Sun, Gang, E-mail: cjr.sungang@vip.163.com [Department of Medical Imaging, Jinan Military General Hospital, No, 25, Shifan Road, Jinan, Shandong Province, China. 250031 (China)

    2014-06-15

    Purpose: The present meta-analysis illustrates the accuracy of myocardial perfusion SPECT (MPS) to diagnose functional stenotic coronary artery disease (CAD) with fractional flow reserve (FFR) as standard reference. Methods: All investigators screened and selected studies that compared MPS with FFR in symptomatic patients with suspected CAD. Patients and study characteristics were independently extracted by two investigators; differences were resolved by consensus. Results: 13 articles, including 1,017 patients, 699 vessels were included in the study. No significant publication bias was detected (P = 0.65). At the patient level, the summary sensitivity and specificity were 77% (95% confidence interval [CI], 70–83%) and 77% (95%CI, 67–84%) for MPS. Vessel-level pooled sensitivity was 66% (95%CI, 57–74%) and specificity was 81% (95%CI, 70–89%). The overall diagnostic performance of MPS was moderate. [The area under the summary receiver operating characteristic (sROC) curve was 0.83]. No study influenced the pooled results larger than 0.03. Conclusions: The accuracy between FFR and MPS SPECT was moderate.

  3. Computed tomography myocardial perfusion vs {sup 15}O-water positron emission tomography and fractional flow reserve

    Energy Technology Data Exchange (ETDEWEB)

    Williams, Michelle C.; Dweck, Marc R.; Golay, Saroj K. [University of Edinburgh/British Heart Foundation Centre for Cardiovascular Science, Edinburgh (United Kingdom); Mirsadraee, Saeed; Weir, Nicholas W.; Fletcher, Alison; Lucatelli, Christophe; Reid, John H. [University of Edinburgh, Clinical Research Imaging Centre, Edinburgh (United Kingdom); MacGillivray, Tom; Van Beek, Edwin J.R.; Newby, David E. [University of Edinburgh/British Heart Foundation Centre for Cardiovascular Science, Edinburgh (United Kingdom); University of Edinburgh, Clinical Research Imaging Centre, Edinburgh (United Kingdom); Cruden, Nicholas L.; Henriksen, Peter A.; Uren, Neal [Edinburgh Heart Centre, Royal Infirmary of Edinburgh, Edinburgh (United Kingdom); McKillop, Graham; Patel, Dilip [Department of Radiology, Royal Infirmary of Edinburgh, Edinburgh (United Kingdom); Lima, Joao A.C. [Johns Hopkins Hospital, Departments of Medicine and Radiology, Baltimore, MD (United States)

    2017-03-15

    Computed tomography (CT) can perform comprehensive cardiac imaging. We compared CT coronary angiography (CTCA) and CT myocardial perfusion (CTP) with {sup 15}O-water positron emission tomography (PET) and invasive coronary angiography (ICA) with fractional flow reserve (FFR). 51 patients (63 (61-65) years, 80 % male) with known/suspected coronary artery disease (CAD) underwent 320-multidetector CTCA followed by ''snapshot'' adenosine stress CTP. Of these 22 underwent PET and 47 ICA/FFR. Obstructive CAD was defined as CTCA stenosis >50 % and CTP hypoperfusion, ICA stenosis >70 % or FFR <0.80. PET hyperaemic myocardial blood flow (MBF) was lower in obstructive than non-obstructive territories defined by ICA/FFR (1.76 (1.32-2.20) vs 3.11 (2.44-3.79) mL/(g/min), P < 0.001) and CTCA/CTP (1.76 (1.32-2.20) vs 3.12 (2.44-3.79) mL/(g/min), P < 0.001). Baseline and hyperaemic CT attenuation density was lower in obstructive than non-obstructive territories (73 (71-76) vs 86 (84-88) HU, P < 0.001 and 101 (96-106) vs 111 (107-114) HU, P 0.001). PET hyperaemic MBF corrected for rate pressure product correlated with CT attenuation density (r = 0.579, P < 0.001). There was excellent per-patient sensitivity (96 %), specificity (85 %), negative predictive value (90 %) and positive predictive value (94 %) for CTCA/CTP vs ICA/FFR. CT myocardial attenuation density correlates with {sup 15}O-water PET MBF. CTCA and CTP can accurately identify obstructive CAD. (orig.)

  4. Assessment of renal artery stenosis using both resting pressures ratio and fractional flow reserve: relationship to angiography and ultrasonography.

    Science.gov (United States)

    Kadziela, Jacek; Witkowski, Adam; Januszewicz, Andrzej; Cedro, Krzysztof; Michałowska, Ilona; Januszewicz, Magdalena; Kabat, Marek; Prejbisz, Aleksander; Kalińczuk, Lukasz; Zieleń, Piotr; Michel-Rowicka, Katarzyna; Warchoł, Ewa; Rużyłło, Witold

    2011-08-01

    BACKGROUND. Clinical benefit from renal artery revascularization remains controversial, probably because of inaccurate stenosis severity assessment. Objective. The aim of the study was to evaluate resting translesional pressures ratio and renal fractional flow reserve (rFFR) in relation to angiography and Doppler duplex ultrasonography in patients with at least moderate renal artery stenosis (RAS). METHODS. 44 hypertensive patients (48% of males, mean age 65 years) with at least moderate RAS were investigated. Translesional systolic pressure gradient (TSPG), resting Pd/Pa ratio (the ratio of mean distal to lesion and mean proximal pressures) and hyperemic rFFR - after intrarenal administration of papaverine - were evaluated. Quantitative angiographic analysis of stenosis severity was performed including minimal lumen diameter (MLD) and percent diameter stenosis (DS) assessment. Renal/aortic ratio (RAR), resistive index (RI) and deltaRI (side-to side difference) were obtained in Doppler-duplex ultrasonography. The predictive value of selected variables was calculated using receiver-operating characteristics curves. RESULTS. Mean Pd/Pa ratio was 0.86 ± 0.12 and decreased to 0.79 ± 0.13 after papaverine administration. Both Pd/Pa ratio and rFFR strongly correlated with TSPG (r = -0.92, p ratio and 0.80 for rFFR. CONCLUSIONS. Mean Pd/Pa ratio and rFFR strongly correlated with angiographic data and in less pronounced manner with ultrasound parameters reflecting intrarenal blood flow. The best accuracy cut-off points for severe RAS predicting were 0.93 and 0.80, respectively.

  5. Intracoronary Electrocardiogram to guide Percutaneous Interventions in Coronary Bifurcations: A proof of Concept: The FIESTA (Ffr vs. IcEcgSTA) study.

    Science.gov (United States)

    Vassilev, Dobrin; Dosev, Liubomir; Collet, Carlos; Karamfiloff, Kiril; Stoikova, Jivka; Pancheva, Ralica; Shumkova, Monika; Zlatancheva, Galina; Naunov, Vladimir; Rigatelli, Gianluca; Kassab, Ghassan S; Gil, Robert J; Serruys, Patrick W

    2017-08-22

    The aim of this study was to determine the accuracy of the intracoronary electrocardiogram (icECG) to detect ischemia during bifurcation lesions percutaneous coronary intervention (PCI) with fractional flow reserve (FFR) as a reference. Patients with significant bifurcation lesions defined as FFR≤0.80 were included. FFR and icECG were performed in the main vessel (MV) and side branch (SB) before and after provisional stenting. icECG was recorded with a uninsulated proximal wire end connected to a unipolar lead. The diagnostic accuracy of icECG for the detection of ischemia in the SB after MV stenting was determined with FFR as a reference. Overall, 37 patients were included. Seventeen bifurcations had SB FFR ≤0.80 after MV stenting and 20 patients had ST-segment elevation on the icECG. There was significant correlation between SB FFR and ST-segment elevation on icECG (r=-0.533, p<0.001). The diagnostic accuracy of icECG ST-Elevation to detect functionally significant SB stenosis revealed an AUC of 0.71 (95%CI 0.64- 0.80) with a sensitivity of 88% and specificity of 75% with a positive predictive value of 75% and negative predictive value of 88%. Neither SB FFR nor icECG correlated with SB percent diameter stenosis after MV stenting. Intracoronary ECG has a good ability to predict functionally significant stenosis at the SB after MV stenting during bifurcation PCI. This method provides a novel strategy to assess the significance of a SB lesion without the need of a pressure wire.

  6. The influence of artery wall curvature on the anatomical assessment of stenosis severity derived from fractional flow reserve: a computational fluid dynamics study.

    Science.gov (United States)

    Govindaraju, Kalimuthu; Viswanathan, Girish N; Badruddin, Irfan Anjum; Kamangar, Sarfaraz; Salman Ahmed, N J; Al-Rashed, Abdullah A A A

    2016-11-01

    This study aims to investigate the influence of artery wall curvature on the anatomical assessment of stenosis severity and to identify a region of misinterpretation in the assessment of per cent area stenosis (AS) for functionally significant stenosis using fractional flow reserve (FFR) as standard. Five artery models of different per cent AS severity (70, 75, 80, 85 and 90%) were considered. For each per cent AS severity, the angle of curvature of the arterial wall varied from straight to an increasingly curved model (0°, 30°, 60°, 90° and 120°). Computational fluid dynamics was performed under transient physiologic hyperemic flow conditions to investigate the influence of artery wall curvature on the pressure drop and the FFR. The findings in this study may be useful in in vitro anatomical assessment of functionally significant stenosis. The FFR decreased with increasing stenosis severity for a given curvature of the artery wall. Moreover, a significant decrease in FFR was found between straight and curved models discussed for a given severity condition. These findings indicate that the curvature effect was included in the FFR assessment in contrast to minimum lumen area (MLA) or per cent AS assessment. The MLA or per cent AS assessment may lead to underestimation of stenosis severity. From this numerical study, an uncertainty region could be evaluated using the clinical FFR cutoff value of 0.8. This value was observed at 81.98 and 79.10% AS for arteries with curvature angles of 0° and 120° respectively. In conclusion, the curvature of the artery should not be neglected in in vitro anatomical assessment.

  7. Use of fractional flow reserve in patients with coronary artery disease: The right choice for the right outcome.

    Science.gov (United States)

    Park, Jae Yoon; Lerman, Amir; Herrmann, Joerg

    2017-02-01

    Despite advances in therapy, coronary artery disease (CAD) remains the leading cause of morbidity and mortality worldwide. Over the past years, the utilization of revascularization procedures has been refined, and in the best interest of the patient and to reduce the healthcare burden of CAD, it is paramount that patients are appropriately selected for therapies aiming at improving their symptoms and prognosis. Fractional flow reserve (FFR) is the current invasive standard test to identify hemodynamically significant coronary artery stenoses with resultant implications for revascularization and clinical outcomes. In this review, we discuss the current evidence behind the use of FFR as well as new trends in the application of this technique to help guide clinicians in making the best management decisions for patients with CAD.

  8. Contrast-induced Hyperemia as an Alternative to Drug-induced Hyperemia in the Evaluation of the Fractional Flow Reserve in Coronary Lesions

    Science.gov (United States)

    Shiode, Nobuo; Okimoto, Tomokazu; Tamekiyo, Hiromichi; Kawase, Tomoharu; Yamane, Kenichi; Kagawa, Yuzo; Fujii, Yuto; Ueda, Yusuke; Hironobe, Naoya; Kato, Yasuko; Hayashi, Yasuhiko

    2017-01-01

    Objective Measuring the fractional flow reserve (FFR) requires the induction of coronary hyperemia, usually with adenosine, adenosine triphosphate (ATP), or papaverine. However, adenosine can induce rhythmic complications, and intracoronary boluses of papaverine that prolong the QT interval can cause ventricular tachycardia. Injection of contrast media, which is routinely performed to validate the FFR guidewire placement, also induces hyperemia and may be an alternative method of measuring the FFR. We evaluated the diagnostic accuracy of the FFR after contrast hyperemia (FFRcont) compared to FFR evaluated after intracoronary papaverine (FFRpp). Methods This study included 109 lesions in 93 patients (mean age 70.4±8.7 years) with stable coronary disease. The FFR was measured as follows: 1) baseline pressure value; 2) FFRcont after intracoronary contrast injection (iopamidol, 8 mL for left coronary artery [LCA] or 6 mL for right coronary artery [RCA]); 3) FFRpp after intracoronary injection of papaverine (12 mg for LCA or 8 mg for RCA). Results FFRcont values were strongly correlated with FFRpp (R=0.940, p<0.0001; FFRpp = FFRcont ×1.007-0.032). The best cut-off point in the receiver operator curve analysis for predicting a FFRpp <0.80 was 0.82 (area under the curve =0.980; sensitivity 95.1%, specificity 91.2%, positive predictive value 86.7%, negative predictive value 96.9%). Conclusion FFRcont is highly accurate for predicting FFRpp. An FFRcont threshold value of 0.82 provides excellent sensitivity and a negative predictive value. FFRcont is an alternative method of inducing hyperemia. PMID:28154267

  9. TU-G-204-01: BEST IN PHYSICS (IMAGING): Dynamic CT Myocardial Perfusion Measurement and Its Comparison to Fractional Flow Reserve

    Energy Technology Data Exchange (ETDEWEB)

    Ziemer, B; Hubbard, L; Groves, E; Sadeghi, B; Javan, H; Lipinski, J; Molloi, S [University of California, Irvine, CA (United States)

    2015-06-15

    Purpose: To evaluate a first pass analysis (FPA) technique for CT perfusion measurement in a swine animal and its validation using fractional flow reserve (FFR) as a reference standard. Methods: Swine were placed under anesthesia and relevant physiologic parameters were continuously recorded. Intra-coronary adenosine was administered to induce maximum hyperemia. A pressure wire was advanced distal to the first diagonal branch of the left anterior descending (LAD) artery for FFR measurements and a balloon dilation catheter was inserted over the pressure wire into the proximal LAD to create varying levels of stenosis. Images were acquired with a 320-row wide volume CT scanner. Three main coronary perfusion beds were delineated in the myocardium using arteries extracted from CT angiography images using a minimum energy hypothesis. The integrated density in the perfusion bed was used to calculate perfusion using the FPA technique. The perfusion in the LAD bed over a range of stenosis severity was measured. The measured fractional perfusion was compared to FFR and linear regression was performed. Results: The measured fractional perfusion using the FPA technique (P-FPA) and FFR were related as P-FPA = 1.06FFR – 0.06 (r{sup 2} = 0.86). The perfusion measurements were calculated with only three to five total CT volume scans, which drastically reduces the radiation dose as compared with the existing techniques requiring 15–20 volume scans. Conclusion: The measured perfusion using the first pass analysis technique showed good correlation with FFR measurements as a reference standard. The technique for perfusion measurement can potentially make a substantial reduction in radiation dose as compared with the existing techniques.

  10. Transient integral boundary layer method to calculate the translesional pressure drop and the fractional flow reserve in myocardial bridges

    Directory of Open Access Journals (Sweden)

    Möhlenkamp Stefan

    2006-06-01

    Full Text Available Abstract Background The pressure drop – flow relations in myocardial bridges and the assessment of vascular heart disease via fractional flow reserve (FFR have motivated many researchers the last decades. The aim of this study is to simulate several clinical conditions present in myocardial bridges to determine the flow reserve and consequently the clinical relevance of the disease. From a fluid mechanical point of view the pathophysiological situation in myocardial bridges involves fluid flow in a time dependent flow geometry, caused by contracting cardiac muscles overlying an intramural segment of the coronary artery. These flows mostly involve flow separation and secondary motions, which are difficult to calculate and analyse. Methods Because a three dimensional simulation of the haemodynamic conditions in myocardial bridges in a network of coronary arteries is time-consuming, we present a boundary layer model for the calculation of the pressure drop and flow separation. The approach is based on the assumption that the flow can be sufficiently well described by the interaction of an inviscid core and a viscous boundary layer. Under the assumption that the idealised flow through a constriction is given by near-equilibrium velocity profiles of the Falkner-Skan-Cooke (FSC family, the evolution of the boundary layer is obtained by the simultaneous solution of the Falkner-Skan equation and the transient von-Kármán integral momentum equation. Results The model was used to investigate the relative importance of several physical parameters present in myocardial bridges. Results have been obtained for steady and unsteady flow through vessels with 0 – 85% diameter stenosis. We compare two clinical relevant cases of a myocardial bridge in the middle segment of the left anterior descending coronary artery (LAD. The pressure derived FFR of fixed and dynamic lesions has shown that the flow is less affected in the dynamic case, because the distal

  11. Angiographic characteristics of intermediate stenosis of the left anterior descending artery for determination of lesion significance as identified by fractional flow reserve

    DEFF Research Database (Denmark)

    Biasco, Luigi; Pedersen, Frants; Lønborg, Jacob

    2015-01-01

    Previous studies have shown a poor correlation between angiographic assessment of stenosis grade (%) and its functional assessment by fractional flow reserve (FFR). This study aimed to investigate whether a more comprehensive evaluation of the coronary angiogram may contribute to a better...... identification of flow-limiting stenoses. Coronary angiograms of 1,350 patients (1,883 lesions) were retrospectively analyzed for stenosis grade (eyeballing, %) and matched with FFR values. Angiography-derived optimal cut-off values and intervals delineating the [90% sensitivity-90% specificity] range were 50...... wrap" of LAD, and (5) collaterals to an occluded LCX/RCA. Based on these results, a risk score (P20-DAC2) for prediction of flow limitation in intermediate LAD lesions was derived. In conclusion, a comprehensive evaluation of the coronary angiogram-in which besides stenosis grade also other lesion...

  12. 320-row CT coronary angiography predicts freedom from revascularisation and acts as a gatekeeper to defer invasive angiography in stable coronary artery disease: a fractional flow reserve-correlated study

    Energy Technology Data Exchange (ETDEWEB)

    Ko, Brian S.; Wong, Dennis T.L.; Cameron, James D.; Leung, Michael; Meredith, Ian T.; Nerlekar, Nitesh; Antonis, Paul; Harper, Richard; Malaiapan, Yuvaraj; Seneviratne, Sujith K. [Southern Health and Monash University, Monash Cardiovascular Research Centre, MonashHEART, Department of Medicine Monash Medical Centre (MMC), Melbourne (Australia); Leong, Darryl P. [University of Adelaide, Discipline of Medicine, Adelaide (Australia); Flinders University, Adelaide (Australia); Crossett, Marcus; Troupis, John [Southern Health and Monash University, Monash Cardiovascular Research Centre, MonashHEART, Department of Medicine Monash Medical Centre (MMC), Melbourne (Australia); Southern Health and Monash University, Department of Diagnostic Imaging, MMC, Melbourne (Australia)

    2014-03-15

    To determine the accuracy of 320-row multidetector coronary computed tomography angiography (M320-CCTA) to detect functional stenoses using fractional flow reserve (FFR) as the reference standard and to predict revascularisation in stable coronary artery disease. One hundred and fifteen patients (230 vessels) underwent M320-CCTA and FFR assessment and were followed for 18 months. Diameter stenosis on invasive angiography (ICA) and M320-CCTA were assessed by consensus by two observers and significant stenosis was defined as ≥50 %. FFR ≤0.8 indicated functionally significant stenoses. M320-CCTA had 94 % sensitivity and 94 % negative predictive value (NPV) for FFR ≤0.8. Overall accuracy was 70 %, specificity 54 % and positive predictive value 65 %. On receiver operating characteristic (ROC) curve analysis, the area under the curve (AUC) for CCTA to predict FFR ≤0.8 was 0.74 which was comparable with ICA. The absence of a significant stenosis on M320-CCTA was associated with a 6 % revascularisation rate. M320-CCTA predicted revascularisation with an AUC of 0.71 which was comparable with ICA. M320-CCTA has excellent sensitivity and NPV for functional stenoses and therefore may act as an effective gatekeeper to defer ICA and revascularisation. Like ICA, M320-CCTA lacks specificity for functional stenoses and only has moderate accuracy to predict the need for revascularisation. (orig.)

  13. Validation of pressure gradient and peripheral fractional flow reserve measured by a pressure wire for diagnosis of iliofemoral artery disease with intermediate stenosis

    Directory of Open Access Journals (Sweden)

    Murata N

    2015-11-01

    Full Text Available Naotaka Murata,1 Hideaki Aihara,2 Yoshimitsu Soga,1 Yusuke Tomoi,1 Seiichi Hiramori,1 Yohei Kobayashi,1 Kei Ichihashi,1 Nobuhiro Tanaka3 1Department of Cardiology, Kokura Memorial Hospital, Kitakyushu, 2Department of Cardiology, Tsukuba Medical Center Hospital, Ibaraki, 3Department of Cardiology, Tokyo Medical University, Tokyo, Japan Objective: To examine the pressure gradient and peripheral fractional flow reserve (pFFR measured by a pressure wire as indicators of hemodynamic significance in iliofemoral angiographic intermediate stenosis. Background: The utility of pressure measurements using a pressure wire with vasodilators is unclear in cases with intermediate iliofemoral stenosis. Methods: The mean pressure gradient (MPG and mean pressure ratio (MPR were measured at baseline and after injection of isosorbide dinitrate in 23 lesions with angiographically intermediate iliofemoral stenosis. Patients with complex lesions, infrapopliteal artery lesions, chronic total occlusion, and surgical bypass grafts were excluded. Hyperemic MPR was considered equivalent to pFFR. Changes in parameters in response to vasodilators were assessed and correlations of peak systolic velocity ratio (PSVR with hyperemic MPG and pFFR were examined using duplex ultrasound. Results: After injection of isosorbide dinitrate, hyperemic MPG increased significantly (from 9.0±5.7 to 16.3±6.2 mmHg; P<0.05 and hyperemic MPR (pFFR decreased significantly (from 0.92±0.06 to 0.81±0.07; P<0.05. PSVR was significantly correlated with hyperemic MPG (R=0.52; P<0.05 and pFFR (R=–0.50; P<0.05. The optimal cut-off value of pFFR as an indicator of significant hemodynamic stenosis (PSVR >2.5 was 0.85 (area under the curve 0.72; sensitivity 94%; specificity 50%, P<0.05. Conclusion: pFFR measured using a pressure wire is reliable for prediction of hemodynamic significance in iliofemoral intermediate stenosis. Keywords: endovascular therapy, peripheral artery disease, pressure

  14. Prognostic value of fractional flow reserve

    DEFF Research Database (Denmark)

    Johnson, Nils P; Tóth, Gábor G; Lai, Dejian

    2014-01-01

    anatomy-based strategy, but with 20% fewer adverse events and 10% better angina relief. CONCLUSIONS: FFR demonstrates a continuous and independent relationship with subsequent outcomes, modulated by medical therapy...... events and increases freedom from angina with fewer procedures than an anatomy-based strategy....

  15. [Fractional flow reserve and instantaneous wave-free ratio for the physiological assessment of coronary artery stenosis in the catheterization laboratory: Practical tips].

    Science.gov (United States)

    Picard, F; Tadros, V X; Pighi, M; Spagnoli, V; De Hemptinne, Q; Ly, H Q

    2017-02-01

    In recent years, a large body of evidence has revealed the limitations of angiographic evaluation in determining the physiological significance of coronary stenosis, particularly when these are intermediate lesions. Percutaneous coronary interventions (PCI) guided by physiological assessment using fractional flow reserve (FFR) have been shown to reduce cardiovascular events when compared to angiography alone. Recently, another coronary physiologic parameter has been introduced: the "instantaneous wave-free ratio" (iFR). In this review, we will discuss the FFR, the iFR, and their use in the functional assessment of coronary stenosis in the cardiac catheterization laboratory. This review will cover theoretical aspects for non-interventional cardiologists, as well as practice points and common pitfalls related to coronary physiological assessment for interventional cardiologists.

  16. Usefulness of fractional flow reserve measurements to defer revascularization in patients with stable or unstable angina pectoris, non-ST-elevation and ST-elevation acute myocardial infarction, or atypical chest pain.

    Science.gov (United States)

    Potvin, Jean-Michel; Rodés-Cabau, Josep; Bertrand, Olivier F; Gleeton, Onil; Nguyen, Can Nanh; Barbeau, Gerald; Proulx, Guy; De Larochellière, Robert; Déry, Jean-Pierre; Batalla, Nuria; Dana, Ali; Facta, Alvaro; Roy, Louis

    2006-08-01

    This study determined the safety of deferring coronary revascularization based on a fractional flow reserve (FFR) value > or = 0.75 in a series of consecutive unselected coronary patients with moderate coronary lesions, including patients with unstable angina, myocardial infarction (MI), and/or positive noninvasive test findings. The study included 201 consecutive coronary patients (mean age 62 +/- 10 years; 65% men) with 231 lesions evaluated by FFR measurement for which revascularization was deferred based on a FFR value > or = 0.75. Lesions associated with a positive noninvasive test result were those located in an artery supplying a myocardial territory in which myocardial ischemia was demonstrated by a noninvasive test. Cardiac events (cardiac death, MI, revascularization) and Canadian Cardiovascular Society angina class were evaluated at follow-up. Indications for coronary angiography included unstable angina or MI (62%), stable angina (30%), or atypical chest pain (8%). Forty-four patients (22%) had > or = 1 coronary lesion associated with a positive noninvasive test result in which FFR was evaluated. Mean FFR value was 0.87 +/- 0.06 and mean lesion percent diameter stenosis was 41 +/- 8%. At 11 +/- 6 months of follow-up, cardiac events occurred in 20 patients (10%), and no significant differences were observed between patients with unstable angina or MI and those with stable angina (9% vs 13%, p = 0.44) or between patients with and without lesions associated with positive noninvasive test results (9% vs 10%, p = 1.00). At the end of follow-up, 88% of patients were asymptomatic in angina class 0 or I, with no differences across various groups. In conclusion, these results suggest that patients with moderate coronary lesions can be safely managed without revascularization on the basis of FFR measurements, irrespective of clinical presentation and/or presence of positive noninvasive test results.

  17. Diagnostic Performance of First-Pass Myocardial Perfusion Imaging without Stress with Computed Tomography (CT) Compared with Coronary CT Angiography Alone, with Fractional Flow Reserve as the Reference Standard.

    Science.gov (United States)

    Osawa, Kazuhiro; Miyoshi, Toru; Miki, Takashi; Koyama, Yasushi; Sato, Shuhei; Kanazawa, Susumu; Ito, Hiroshi

    2016-01-01

    Coronary computed tomography angiography (CCTA) in combination with first-pass CT myocardial perfusion imaging (MPI) has a better diagnostic performance than CCTA alone, compared with invasive coronary angiography as the reference standard. The aim of this study was to investigate the additional diagnostic value of first-pass CT-MPI without stress for detecting hemodynamic significance of coronary stenosis, compared with invasive fractional flow reserve (FFR). We recruited 53 patients with suspected coronary artery disease undergoing both CCTA and first-pass CT-MPI without stress and invasive FFR, and 75 vessels were analyzed. We used the same raw data for CCTA and CT-MPI. First-pass CT-MPI was reconstructed by examining the diastolic signal densities as a bull's eye map. Invasive FFR CT-MPI and CCTA alone was 0.81 (0.73-0.90) and 0.70 (0.61-0.81), respectively (P = 0.036). CCTA plus first-pass CT-MPI without stress showed 0.73 sensitivity, 0.74 specificity, 0.53 positive predictive value, and 0.87 negative predictive value for detecting hemodynamically significant coronary stenosis. First-pass CT-MPI without stress correctly reclassified 38% of CCTA false-positive vessels as true negative. First-pass CT-MPI without stress combined with CCTA demonstrated excellent diagnostic accuracy, compared with invasive FFR as the reference standard. This technique could complement CCTA for diagnosis of coronary artery disease.

  18. Reserve, flowing electrolyte, high rate lithium battery

    Science.gov (United States)

    Puskar, M.; Harris, P.

    Flowing electrolyte Li/SOCl2 tests in single cell and multicell bipolar fixtures have been conducted, and measurements are presented for electrolyte flow rates, inlet and outlet temperatures, fixture temperatures at several points, and the pressure drop across the fixture. Reserve lithium batteries with flowing thionyl-chloride electrolytes are found to be capable of very high energy densities with usable voltages and capacities at current densities as high as 500 mA/sq cm. At this current density, a battery stack 10 inches in diameter is shown to produce over 60 kW of power while maintaining a safe operating temperature.

  19. Invasive and non-invasive fractional flow reserve index in validation of hemodynamic severity of intracoronary lesions.

    Science.gov (United States)

    Wasilewski, Jarosław; Mirota, Kryspin; Hawranek, Michał; Poloński, Lech

    2013-01-01

    This review discusses visual and functional evaluation of the hemodynamic significance of the degree of stenosis in coronary angiography, with respect to the indications for revascularization. The concept of the coronary flow reserve is defined, and the theoretical assumptions of the invasive measurement of the fractional flow reserve (FFR) are presented. In the following part, the publication describes the basic steps of numerical stimulations in terms of computational fluid dynamics (CFD) in calculating the fractional flow reserve based on computed tomography (CT) coronary angiography (FFRCT). The numerical FFRCT estimation in correlation with invasive measurements, as well as benefits deriving from FFRCT in the diagnosis of coronary artery disease, is presented in the example of the multicentre prospective DISCOVER-FLOW trial and the DeFACTO project. The CDF method enables to obtain hemodynamic significance of stenosis solely from the coronary anatomy vizualized by CT angiography. The calculation of FFRCT increases the diagnostic reliability of coronary flow reserve estimations. It contributes to the improvement in patients' qualification for contrast coronarography. If the accuracy of FFRCT is confirmed in clinical practice, and the time required for computational processing is shortened, it may turn out that the algorithms of coronary heart disease diagnosis will be verified and it will be to a greater extent based on the CT results.

  20. Recruitable collateral blood flow index predicts coronary instent restenosis after percutaneous coronary intervention

    DEFF Research Database (Denmark)

    Jensen, Lisette Okkels; Thayssen, Per; Lassen, Jens Flensted

    2007-01-01

    in patients undergoing PCI with bare metal stents and using optimal antithrombotic treatment. METHODS AND RESULTS: In 95 patients, 95 de novo lesions were treated with PCI and a bare metal stent. Fractional flow reserve (FFR) at maximum hyperaemia induced by intravenous adenosine was determined. The pressure.......25) had a lower pre-interventional FFR (0.50 +/- 0.14 vs. 0.72 +/- 0.18, P ratio 1.07, 95% CI 1...

  1. Anatomical and Physiological Changes after Paclitaxel-Coated Balloon for Atherosclerotic De Novo Coronary Lesions: Serial IVUS-VH and FFR Study.

    Directory of Open Access Journals (Sweden)

    Soe Hee Ann

    Full Text Available To assess the serial changes of de novo coronary lesions treated with paclitaxel-coated balloon (PCB using intravascular ultrasound virtual histology (IVUS-VH and fractional flow reserve (FFR.This prospective observational study enrolled 27 patients with coronary artery disease treated with PCB who underwent coronary angiography, IVUS-VH and FFR before, immediately after intervention and at 9 months. 28 de novo lesions were successfully treated with PCB. Angiographic late luminal loss was 0.02 ± 0.27 mm. Mean vessel and lumen areas showed increase at 9 months (12.0 ± 3.5 mm(2 to 13.2 ± 3.9 mm(2, p <0.001; and 5.4 ± 1.2 mm(2 to 6.5 ± 1.8 mm(2, p <0.001, respectively. Although mean plaque area was unchanged (6.6 ± 2.6 mm2 to 6.6 ± 2.4 mm(2, p = 0.269, percent atheroma volume decreased significantly (53.4 ± 7.9% to 49.5 ± 6.4%, p = 0.002. The proportion of plaque compositions including fibrous, fibrofatty, dense calcium and necrotic core by IVUS-VH was unchanged at 9 months. The FFR of the treated lesion was 0.71 ± 0.13 pre-procedure, 0.87 ± 0.06 post-procedure and 0.84 ± 0.06 at follow-up.De novo coronary lesions treated with PCB showed persistent anatomical and physiological patency with plaque redistribution and vessel remodeling without chronic elastic recoil or plaque compositional change during follow-up.

  2. Integration of a capacitive pressure sensing system into the outer catheter wall for coronary artery FFR measurements

    Science.gov (United States)

    Stam, Frank; Kuisma, Heikki; Gao, Feng; Saarilahti, Jaakko; Gomes Martins, David; Kärkkäinen, Anu; Marrinan, Brendan; Pintal, Sebastian

    2017-05-01

    The deadliest disease in the world is coronary artery disease (CAD), which is related to a narrowing (stenosis) of blood vessels due to fatty deposits, plaque, on the arterial walls. The level of stenosis in the coronary arteries can be assessed by Fractional Flow Reserve (FFR) measurements. This involves determining the ratio between the maximum achievable blood flow in a diseased coronary artery and the theoretical maximum flow in a normal coronary artery. The blood flow is represented by a pressure drop, thus a pressure wire or pressure sensor integrated in a catheter can be used to calculate the ratio between the coronary pressure distal to the stenosis and the normal coronary pressure. A 2 Fr (0.67mm) outer diameter catheter was used, which required a high level of microelectronics miniaturisation to fit a pressure sensing system into the outer wall. The catheter has an eccentric guidewire lumen with a diameter of 0.43mm, which implies that the thickest catheter wall section provides less than 210 microns height for flex assembly integration consisting of two dies, a capacitive MEMS pressure sensor and an ASIC. In order to achieve this a very thin circuit flex was used, and the two chips were thinned down to 75 microns and flip chip mounted face down on the flex. Many challenges were involved in obtaining a flex layout that could wrap into a small tube without getting the dies damaged, while still maintaining enough flexibility for the catheter to navigate the arterial system.

  3. Clinical outcomes of combined flow-pressure drop measurements using newly developed diagnostic endpoint:Pressure drop coefficient in patients with coronary artery dysfunction

    Institute of Scientific and Technical Information of China (English)

    Mohamed A Effat; Srikara Viswanath Peelukhana; Rupak K Banerjee

    2016-01-01

    AIM:To combine pressure and flow parameter, pressure drop coefficient(CDP) will result in better clinical outcomes in comparison to the fractional flow reserve(FFR) group. METHODS:To test this hypothesis, a comparison was made between the FFR 27.9 groups in this study, for the major adverse cardiac events [major adverse cardiac events(MACE): Primary outcome] and patients’ quality of life(secondary outcome). Further, a comparison was also made between the survival curves for the FFR 27.9 groups. Two-tailed χ~2 test proportions were performed for the comparison of primary and secondary outcomes. Kaplan-Meier survival analysis was performed to compare the survival curves of FFR 27.9 groups(MedcalcV10.2, Mariakerke, Belgium). Results were considered statistically significant for P 27.9 group(8.57%, 2 out of 35). Noteworthy is the reduction in the %MACE in the CDP > 27.9 group, in comparison to the FFR 27.9 groups. Survival analysis results suggest that the survival time for the CDP > 27.9 group(n = 35) is significantly higher(P = 0.048) in comparison to the survival time for the FFR < 0.75 group(n = 20). The results remained similar for a FFR = 0.80 cut-off. CONCLUSION: Based on the above, CDP could prove to be a better diagnostic end-point for clinical revascularization decision-making in the cardiac catheterization laboratories.

  4. Dynamic CT myocardial perfusion imaging: detection of ischemia in a porcine model with FFR verification

    Science.gov (United States)

    Fahmi, Rachid; Eck, Brendan L.; Vembar, Mani; Bezerra, Hiram G.; Wilson, David L.

    2014-03-01

    Dynamic cardiac CT perfusion (CTP) is a high resolution, non-invasive technique for assessing myocardial blood ow (MBF), which in concert with coronary CT angiography enable CT to provide a unique, comprehensive, fast analysis of both coronary anatomy and functional ow. We assessed perfusion in a porcine model with and without coronary occlusion. To induce occlusion, each animal underwent left anterior descending (LAD) stent implantation and angioplasty balloon insertion. Normal ow condition was obtained with balloon completely de ated. Partial occlusion was induced by balloon in ation against the stent with FFR used to assess the extent of occlusion. Prospective ECG-triggered partial scan images were acquired at end systole (45% R-R) using a multi-detector CT (MDCT) scanner. Images were reconstructed using FBP and a hybrid iterative reconstruction (iDose4, Philips Healthcare). Processing included: beam hardening (BH) correction, registration of image volumes using 3D cubic B-spline normalized mutual-information, and spatio-temporal bilateral ltering to reduce partial scan artifacts and noise variation. Absolute blood ow was calculated with a deconvolutionbased approach using singular value decomposition (SVD). Arterial input function was estimated from the left ventricle (LV) cavity. Regions of interest (ROIs) were identi ed in healthy and ischemic myocardium and compared in normal and occluded conditions. Under-perfusion was detected in the correct LAD territory and ow reduction agreed well with FFR measurements. Flow was reduced, on average, in LAD territories by 54%.

  5. Coronary flow velocity reserve by echocardiography

    DEFF Research Database (Denmark)

    Olsen, Rasmus Huan; Pedersen, Lene Rørholm; Snoer, Martin

    2016-01-01

    reserve (MFR) measured by PET in overweight and obese patients. METHODS: Participants with revascularized coronary artery disease were examined by CFVR. Subgroups were examined by repeated CFVR (reproducibility) or Rubidium-82-PET (agreement). To account for time variation, results were computed for scans...... %, and reliability 0.97. Agreement with MFR of the LAD territory (n = 35) was without significant bias and overall LOA were (-1.40;1.46). Agreement was best for examinations performed within 1-week of participants without MI of the LAD-territory (n = 12); LOA = (-0.68;0.88). CONCLUSIONS: CFVR was highly feasible...... with a good reproducibility on par with other contemporary measures applied in cardiology. Agreement with MFR was acceptable, though discrepancy related to prior MI has to be considered. CFVR of LAD is a valid tool in overweight and obese patients....

  6. Functional Relevance of Coronary Artery Disease by Cardiac Magnetic Resonance and Cardiac Computed Tomography: Myocardial Perfusion and Fractional Flow Reserve

    Directory of Open Access Journals (Sweden)

    Gianluca Pontone

    2015-01-01

    Full Text Available Coronary artery disease (CAD is one of the leading causes of morbidity and mortality and it is responsible for an increasing resource burden. The identification of patients at high risk for adverse events is crucial to select those who will receive the greatest benefit from revascularization. To this aim, several non-invasive functional imaging modalities are usually used as gatekeeper to invasive coronary angiography, but the diagnostic yield of elective invasive coronary angiography remains unfortunately low. Stress myocardial perfusion imaging by cardiac magnetic resonance (stress-CMR has emerged as an accurate technique for diagnosis and prognostic stratification of the patients with known or suspected CAD thanks to high spatial and temporal resolution, absence of ionizing radiation, and the multiparametric value including the assessment of cardiac anatomy, function, and viability. On the other side, cardiac computed tomography (CCT has emerged as unique technique providing coronary arteries anatomy and more recently, due to the introduction of stress-CCT and noninvasive fractional flow reserve (FFR-CT, functional relevance of CAD in a single shot scan. The current review evaluates the technical aspects and clinical experience of stress-CMR and CCT in the evaluation of functional relevance of CAD discussing the strength and weakness of each approach.

  7. Functional Relevance of Coronary Artery Disease by Cardiac Magnetic Resonance and Cardiac Computed Tomography: Myocardial Perfusion and Fractional Flow Reserve

    Science.gov (United States)

    Andreini, Daniele; Bertella, Erika; Mushtaq, Saima; Guaricci, Andrea Igoren; Pepi, Mauro

    2015-01-01

    Coronary artery disease (CAD) is one of the leading causes of morbidity and mortality and it is responsible for an increasing resource burden. The identification of patients at high risk for adverse events is crucial to select those who will receive the greatest benefit from revascularization. To this aim, several non-invasive functional imaging modalities are usually used as gatekeeper to invasive coronary angiography, but the diagnostic yield of elective invasive coronary angiography remains unfortunately low. Stress myocardial perfusion imaging by cardiac magnetic resonance (stress-CMR) has emerged as an accurate technique for diagnosis and prognostic stratification of the patients with known or suspected CAD thanks to high spatial and temporal resolution, absence of ionizing radiation, and the multiparametric value including the assessment of cardiac anatomy, function, and viability. On the other side, cardiac computed tomography (CCT) has emerged as unique technique providing coronary arteries anatomy and more recently, due to the introduction of stress-CCT and noninvasive fractional flow reserve (FFR-CT), functional relevance of CAD in a single shot scan. The current review evaluates the technical aspects and clinical experience of stress-CMR and CCT in the evaluation of functional relevance of CAD discussing the strength and weakness of each approach. PMID:25692133

  8. Positron Emission Tomography-Determined Hyperemic Flow, Myocardial Flow Reserve, and Flow Gradient—Quo Vadis?

    Science.gov (United States)

    Leucker, Thorsten M.; Valenta, Ines; Schindler, Thomas Hellmut

    2017-01-01

    Positron emission tomography/computed tomography (PET/CT) applied with positron-emitting flow tracers such as 13N-ammonia and 82Rubidium enables the quantification of both myocardial perfusion and myocardial blood flow (MBF) in milliliters per gram per minute for coronary artery disease (CAD) detection and characterization. The detection of a regional myocardial perfusion defect during vasomotor stress commonly identifies the culprit lesion or most severe epicardial narrowing, whereas adding regional hyperemic MBFs, myocardial flow reserve (MFR), and/or longitudinal flow decrease may also signify less severe but flow-limiting stenosis in multivessel CAD. The addition of regional hyperemic flow parameters, therefore, may afford a comprehensive identification and characterization of flow-limiting effects of multivessel CAD. The non-specific origin of decreases in hyperemic MBFs and MFR, however, prompts an evaluation and interpretation of regional flow in the appropriate context with the presence of obstructive CAD. Conversely, initial results of the assessment of a longitudinal hyperemic flow gradient suggest this novel flow parameter to be specifically related to increases in CAD caused epicardial resistance. The concurrent assessment of myocardial perfusion and several hyperemic flow parameters with PET/CT may indeed open novel avenues of precision medicine to guide coronary revascularization procedures that may potentially lead to a further improvement in cardiovascular outcomes in CAD patients. PMID:28770213

  9. Diagnostic performance of cardiac imaging methods to diagnose ischaemia-causing coronary artery disease when directly compared with fractional flow reserve as a reference standard: a meta-analysis

    Science.gov (United States)

    Danad, Ibrahim; Szymonifka, Jackie; Twisk, Jos W.R.; Norgaard, Bjarne L.; Zarins, Christopher K.; Knaapen, Paul

    2017-01-01

    Aims The aim of this study was to determine the diagnostic performance of single-photon emission computed tomography (SPECT), stress echocardiography (SE), invasive coronary angiography (ICA), coronary computed tomography angiography (CCTA), fractional flow reserve (FFR) derived from CCTA (FFRCT), and cardiac magnetic resonance (MRI) imaging when directly compared with an FFR reference standard. Method and results PubMed and Web of Knowledge were searched for investigations published between 1 January 2002 and 28 February 2015. Studies performing FFR in at least 75% of coronary vessels for the diagnosis of ischaemic coronary artery disease (CAD) were included. Twenty-three articles reporting on 3788 patients and 5323 vessels were identified. Meta-analysis was performed for pooled sensitivity, specificity, likelihood ratios (LR), diagnostic odds ratio, and summary receiver operating characteristic curves. In contrast to ICA, CCTA, and FFRCT reports, studies evaluating SPECT, SE, and MRI were largely retrospective, single-centre and with generally smaller study samples. On a per-patient basis, the sensitivity of CCTA (90%, 95% CI: 86–93), FFRCT (90%, 95% CI: 85–93), and MRI (90%, 95% CI: 75–97) were higher than for SPECT (70%, 95% CI: 59–80), SE (77%, 95% CI: 61–88), and ICA (69%, 95% CI: 65–75). The highest and lowest per-patient specificity was observed for MRI (94%, 95% CI: 79–99) and for CCTA (39%, 95% CI: 34–44), respectively. Similar specificities were noted for SPECT (78%, 95% CI: 68–87), SE (75%, 95% CI: 63–85), FFRCT (71%, 95% CI: 65–75%), and ICA (67%, 95% CI: 63–71). On a per-vessel basis, the highest sensitivity was for CCTA (pooled sensitivity, 91%: 88–93), MRI (91%: 84–95), and FFRCT (83%, 78–87), with lower sensitivities for ICA (71%, 69–74), and SPECT (57%: 49–64). Per-vessel specificity was highest for MRI (85%, 79–89), FFRCT (78%: 78–81), and SPECT (75%: 69–80), whereas ICA (66%: 64–68) and CCTA (58%: 55

  10. Diagnostic value of quantitative stenosis predictors with coronary CT angiography compared to invasive fractional flow reserve

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Rui [Heart & Vascular Center, Medical University of South Carolina, Ashley River Tower, 25 Courtenay Drive Charleston, SC 29425-2260 (United States); Department of Radiology, Beijing Anzhen Hospital, Capital Medical University, 100029 Beijing (China); Renker, Matthias [Heart & Vascular Center, Medical University of South Carolina, Ashley River Tower, 25 Courtenay Drive Charleston, SC 29425-2260 (United States); Kerckhoff Heart and Thorax Center, Benekestrasse 2-8, 61231 Bad Nauheim (Germany); Schoepf, U. Joseph, E-mail: schoepf@musc.edu [Heart & Vascular Center, Medical University of South Carolina, Ashley River Tower, 25 Courtenay Drive Charleston, SC 29425-2260 (United States); Wichmann, Julian L. [Heart & Vascular Center, Medical University of South Carolina, Ashley River Tower, 25 Courtenay Drive Charleston, SC 29425-2260 (United States); Department of Diagnostic and Interventional Radiology, University Hospital Frankfurt, Theodor-Stern-Kai 7, 60590 Frankfurt (Germany); Fuller, Stephen R.; Rier, Jeremy D.; Bayer, Richard R.; Steinberg, Daniel H. [Heart & Vascular Center, Medical University of South Carolina, Ashley River Tower, 25 Courtenay Drive Charleston, SC 29425-2260 (United States); De Cecco, Carlo N. [Heart & Vascular Center, Medical University of South Carolina, Ashley River Tower, 25 Courtenay Drive Charleston, SC 29425-2260 (United States); Departments of Radiological Sciences, Oncology, and Pathology, University of Rome “Sapienza”-Polo Pontino, Latina, Viale Regina Elena, 324-00161 Roma (Italy); Baumann, Stefan [Heart & Vascular Center, Medical University of South Carolina, Ashley River Tower, 25 Courtenay Drive Charleston, SC 29425-2260 (United States); First Department of Medicine, University Medical Centre Mannheim, University of Heidelberg, Theodor-Kutzer-Ufer 1-3, 68167 Mannheim (Germany)

    2015-08-15

    Highlights: • Evaluation of the diagnostic performance of CCTA predictors for coronary stenosis. • TAG was unable to detect hemodynamically significant coronary lesions. • CT-FFR, LL/MLD{sup 4} and CCO provide enhanced diagnostic performance over CCTA. • CT-FFR was the best parameter. - Abstract: Objective: To evaluate the diagnostic performance of CCTA-derived stenosis predictors including CT-FFR for the detection of ischemia-inducing stenosis compared to invasive FFR. Materials and methods: Stenosis parameters were assessed using dual-source CT (DSCT). All patients underwent both CCTA and invasive FFR within 3 months and were retrospectively analyzed. Observers visually assessed all CCTA studies and performed multiple lesion measurements. Lesion length/minimal luminal diameter{sup 4} (LL/MLD{sup 4}), transluminal attenuation gradient (TAG), corrected coronary attenuation (CCO) and CT-FFR were calculated. Results: The cohort included 32 patients (58 ± 12 years, 66%male). Among 32 coronary lesions, 8 (25%) were considered hemodynamically significant with an FFR <0.80. Compared to invasive FFR, the per-vessel sensitivity and specificity of CCTA, CT-FFR, LL/MLD{sup 4}, CCO and TAG for detecting hemodynamically significant lesions were 100% and 54%, 100% and 91%, 85% and 92%, 66% and 88%, 37% and 58%, respectively. Receiver operating characteristics analysis resulted in an area under the curve of 0.91 for CT-FFR (p = 0.0005), 0.88 for LL/MLD{sup 4} (p < 0.0001), 0.85 for CCO (p < 0.0001). TAG with an AUC of 0.67 (p = 0.152) was unable to discriminate between vessels with or without hemodynamically significant lesions. Conclusion: CT-FFR, LL/MLD{sup 4} and CCO provide enhanced diagnostic performance over CCTA analysis alone for discrimination of hemodynamically significant coronary stenosis.

  11. Inspiratory flow reserve in boys with Duchenne muscular dystrophy.

    Science.gov (United States)

    De Bruin, P F; Ueki, J; Bush, A; Y Manzur, A; Watson, A; Pride, N B

    2001-06-01

    Patients with advanced muscular dystrophy frequently develop ventilatory failure. Currently respiratory impairment usually is assessed by measuring vital capacity and the mouth pressure generated during a maximal inspiratory maneuver (PI,max), neither of which directly measures ventilatory capacity. We assessed inspiratory flow reserve in 26 boys [mean (SD) age 12.8 (3.8) years] with Duchenne muscular dystrophy (DMD) without ventilatory failure and in 28 normal boys [mean (SD) age 12.6 (1.9) years] by analyzing the ratio between the largest inspiratory flow during tidal breathing (V'I,max(t)) and during a forced vital capacity maneuver (V'I,max(FVC), (V'I,max(t)/V'I,maxFVC). We have compared this ratio with the forced vital capacity FVC and PI,max measured at functional residual capacity. Mean PI,max was -90(30)cmH2O, average 112% (range 57-179%) of predicted values in control boys and -31(11)cmH2O, average 40% predicted values in DMD boys (control vs DMD, P ratio was higher in DMD 0.22 (0.08) than in controls 0.12 (0.03) (P reserve in DMD. Inspiratory flow reserve was within the normal range in 8 of 19 DMD patients with PI,max less than 50% of predicted values. We conclude that measurement of inspiratory flow reserve (V'I,max(t)/V'I,maxFVC ratio) provides a simple and direct assessment of dynamic inspiratory muscle function which is not replicated by static measurement of PI,max or vital capacity and might be useful in assessment of respiratory impairment in boys with Duchenne muscular dystrophy. Follow-up studies are required to establish whether measures of inspiratory flow reserve are of clinical value in predicting subsequent ventilatory failure.

  12. Concordance between myocardial perfusion scan assessed by SPECT and fractional flow reserve findings for detection of significant ischemia

    Directory of Open Access Journals (Sweden)

    Morteza Safi

    2016-09-01

    Conclusion: FFR and MPI with SPECT techniques showed significant concordance for detection of myocardial ischemia, regardless of the type of diseased coronary arteries. In this context, SPECT has high sensitivity and NPV for detection of ischemia compared with FFR.

  13. [Role of measurement of fractional flow reserve in coronary artery atherosclerosis].

    Science.gov (United States)

    Kopylovi, F Yu; Bykova, A A; Vasilevsky, Yu V; Simakov, S S

    2015-01-01

    The paper considers coronary flow in health and coronary flow autoregulation in health and disease. It gives basic methods used to estimate coronary flow reserve in patients with coronary atherosclerosis. The physiological bases for determining fractional flow reserve are presented. Clinical trials investigating the use of fractional flow reserve in patients with coronary heart disease are analyzed.

  14. FFR result post PCI is suboptimal in long diffuse coronary artery disease.

    Science.gov (United States)

    Baranauskas, Arvydas; Peace, Aaron; Kibarskis, Aleksandras; Shannon, Joanne; Abraitis, Vytautas; Bajoras, Vilhelmas; Bilkis, Valdas; Aidietis, Audrius; Laucevicius, Aleksandras; Davidavicius, Giedrius

    2016-12-20

    The aim of this study was to evaluate the functional result immediately post PCI and at nine-month follow-up, and to ascertain how often a functionally optimal result of >0.95 can be achieved in long coronary lesions treated with long second- or newer-generation DES. Patients receiving DES measuring ≥30 mm with FFR value ≤0.8 were included in the study. Stent length was defined as long (30 to 49 mm; L-DES) and ultra-long (≥50 mm; UL-DES). Angiographic and FFR evaluation was performed before and after PCI and at nine-month follow-up. A total of 74 patients each received a mean stent length of 50.72±14.6 mm. Mean FFR post PCI was 0.88±0.06. An optimal post PCI FFR value of >0.95 was achieved in only 9/74 patients (12.2%), and was not achieved in any UL-DES patients. Only 12/74 (16.2%) had FFR post PCI of 0.91 to 0.95; 8/74 (10.8%) patients remained ischaemic (≤0.8). FFR gradient across the stent was higher in UL-DES patients compared to L-DES patients (0.07±0.03 vs. 0.04±0.03; p=0.001). At follow-up, the angiographic restenosis rate was 4.7%, and the functional restenosis rate was 15.1%. The FFR result post PCI was suboptimal in the majority of patients treated with long DES and was particularly poor when the total stent length exceeded 50 mm.

  15. The deep hydrogeologic flow system underlying the Oak Ridge Reservation

    Energy Technology Data Exchange (ETDEWEB)

    Nativ, R. [Hebrew Univ., Jerusalem (IL); Hunley, A.E. [Oak Ridge National Lab., TN (United States)

    1993-07-01

    The deep hydrogeologic system underlying the Oak Ridge Reservation contains some areas contaminated with radionuclides, heavy metals, nitrates, and organic compounds. The groundwater at that depth is saline and has previously been considered stagnant. On the basis of existing and newly collected data, the nature of flow of the saline groundwater and its potential discharge into shallow, freshwater systems was assessed. Data used for this purpose included (1) spatial and temporal pressures and hydraulic heads measured in the deep system, (2) hydraulic parameters of the formations in question, (3) spatial temperature variations, and (4) spatial and temporal chemical and isotopic composition of the saline groundwater. In addition, chemical analyses of brine in adjacent areas in Tennessee, Kentucky, Ohio, Pennsylvania, and West Virginia were compared with the deep water underlying the reservation to help assess the origin of the brine. Preliminary conclusions suggest that the saline water contained at depth is old but not isolated (in terms of recharge and discharge) from the overlying active and freshwater-bearing units. The confined water (along with dissolved solutes) moves along open fractures (or man-made shortcuts) at relatively high velocity into adjacent, more permeable units. Groundwater volumes involved in this flow probably are small.

  16. Functional assessment of lesion severity without using the pressure wire: coronary imaging and blood flow simulation.

    Science.gov (United States)

    Papafaklis, Michail I; Mavrogiannis, Michail C; Siogkas, Panagiotis K; Lakkas, Lampros S; Katsouras, Christos S; Fotiadis, Dimitrios I; Michalis, Lampros K

    2017-09-19

    Hemodynamic indices derived from measurements with the pressure wire (primarily fractional flow reserve [FFR]) have been established as a reliable tool for assessing coronary stenoses and improving clinical decision making. However, the use of the pressure wire constitutes a hurdle for the universal adoption of physiology-guided patient management. Technological advancements have enabled the large-scale application of blood flow simulation (computational fluid dynamics [CFD]) to medical imaging, thereby enabling the virtual assessment of coronary physiology. Areas covered: This review summarizes the stand-alone non-invasive (coronary computed tomographic imaging) and invasive (coronary angiography) imaging approaches which were initially used for predicting FFR, and focuses on the use of blood flow modeling for functional assessment of coronary lesions in clinical practice. Expert commentary: Validation studies of CFD-derived methodologies for functional assessment have shown that virtual indices correlate well and have good diagnostic accuracy compared to pressure wire-FFR despite inherent limitations of spatial resolution and assumptions regarding boundary conditions in flow modeling. Beyond point-to-point agreement with FFR, further studies are needed to demonstrate the clinical safety/efficacy of these computational tools regarding patient outcomes. Such evidence base could support the incorporation of these methodologies into routine patient management for decision making and reliable risk stratification.

  17. MR assessment of absolute myocardial blood flow and vasodilator flow reserve in patients with hypertrophic cardiomyopathy

    Energy Technology Data Exchange (ETDEWEB)

    Kawada, Nanaka; Sakuma, Hajime; Takeda, Kan; Nakagawa, Tsuyoshi; Yamakado, Tetsu; Nakano, Takeshi [Mie Univ., Tsu (Japan). School of Medicine

    1997-04-01

    Absolute coronary blood flow per myocardial mass and coronary flow reserve for the entire left ventricle were evaluated in normals and in patients with hypertrophic cardiomyopathy (HCM) by using fast cine MR imaging and fast velocity encoded cine (VENC) MR imaging. Nine healthy volunteers and 8 patients with HCM were studied with a 1.5 T imager. Breath-hold cine MR images encompassing the whole left ventricle were acquired on short axis imaging planes in order to evaluate myocardial mass. A fast VENC MR images were obtained to measure blood flow volume in the coronary sinus before and after dipyridamole administration (TR/TE=15/5 ms, FOV=28 x 22 cm, slice thickness=5 mm). Coronary flow reserve was calculated as a ratio of hyperemic to baseline coronary flow volumes. In the baseline state, coronary blood flow per myocardial mass was significantly lower in patients with HCM than in normal myocardium (0.56{+-}0.23 vs. 0.78{+-}0.27 ml/min/g, p<0.05). After dipyridamole administration, coronary blood flow per myocardial mass in patients with HCM increased substantially less than that in healthy subjects (0.99{+-}0.38 vs. 2.22{+-}0.55 ml/min/g, p<0.01), resulting in the significantly decreased coronary flow reserve ratio in HCM in comparison with that in normal myocardium (1.86{+-}0.56 vs. 3.11{+-}1.37, p<0.05). In conclusion, breath-hold velocity encoded cine MR imaging is a noninvasive technique which can provide assessments of altered coronary blood flow volume per myocardial mass and vasodilator flow reserve in patients with HCM. (author)

  18. Efficient Resource Allocation and Sectorization for Fractional Frequency Reuse (FFR in LTE Femtocell Systems

    Directory of Open Access Journals (Sweden)

    M. T. Kawser

    2015-12-01

    Full Text Available The Fractional Frequency Reuse (FFR is a resource allocation technique that can effectively mitigate inter-cell interference (ICI in LTE based HetNets and it is a promising solution. Various FFR schemes have been suggested to address the challenge of interference in femtocell systems. In this paper, we study the scopes of interference mitigation and capacity improvement. We propose a resource allocation scheme that gradually varies frequency resource share with distance from the eNodeB for both macrocells and femtocells in order to attain better utilization of the resources. This is performed effectively using three layers in the cell. The proposal also employs high number sectors in a cell, low interference and good frequency reuse. Monte-Carlo simulations are performed, which show that the proposed scheme achieves significantly better throughput compared to the existing FFR schemes.

  19. Coronary Flow Velocity Reserve Assessed by Transthoracic Doppler

    DEFF Research Database (Denmark)

    Michelsen, Marie M; Peña, Adam; Mygind, Naja D

    2016-01-01

    the feasibility and factors associated with the quality of CFVR obtained in a large prospective study of women suspected of having microvascular disease. METHODS: Women with angina-like chest pain and no obstructive coronary artery disease on coronary angiography (stenosis) were consecutively examined......BACKGROUND: Coronary flow velocity reserve (CFVR) measured by transthoracic Doppler echocardiography is a noninvasive measure of microvascular function, but it has not achieved widespread use, mainly because of concerns of validity and feasibility. The aim of this study was to describe...... by transthoracic Doppler echocardiography of the left anterior descending coronary artery to measure CFVR (n = 947). Quality was evaluated on the basis of (1) identification of the left anterior descending coronary artery, (2) maintained probe position throughout the examination, (3) visibility and configuration...

  20. Anatomical and functional assessment of Tryton bifurcation stent before and after final kissing balloon dilatation: Evaluations by three-dimensional coronary angiography, optical coherence tomography imaging and fractional flow reserve.

    Science.gov (United States)

    Pyxaras, Stylianos A; Toth, Gabor G; Di Gioia, Giuseppe; Ughi, Giovanni J; Tu, Shengxian; Rusinaru, Dan; Adriaenssens, Tom; Reiber, Johan H C; Leon, Martin B; Bax, Jeroen J; Wijns, William

    2017-07-01

    To assess the anatomical and functional impact of final kissing balloon inflation (FKBI) after implantation of a dedicated bifurcation stent system. Current evidence suggests clinical benefit of FKBI in patients undergoing bifurcation dilatation using the Tryton side branch stent (Tryton-SBS). We hypothesized that FKBI improves anatomical reconstruction and functional results of bifurcation treated by Tryton-SBS. An unselected group of patients with complex bifurcation coronary lesions undergoing percutaneous coronary intervention (PCI) with Tryton-SBS underwent paired anatomical assessment with two- and three-dimensional quantitative coronary analysis (2D- and 3D-QCA), and optical coherence tomography (OCT), including 3D reconstruction before and after FKBI. Functional assessment by fractional flow reserve (FFR) was performed in the main branch (MB) and side branch (SB) before and after FKBI. Paired pre- and post-FKBI data were obtained in 10 patients. By OCT imaging, FKBI increased both the SB ostial area (4.93 ± 2.81 vs. 7.43 ± 2.87 mm(2) , P < 0.001) and the SB maximum diameter (3.12 ± 0.98 vs. 3.82 ± 1.10 mm, P = 0.003). These findings were associated with a significant increase in FFR in the SB (0.90 ± 0.05 vs. 0.94 ± 0.03; P = 0.011), with no significant change in the MB (0.91 ± 0.05 vs. 0.92 ± 0.04; P = 0.470). In patients with complex bifurcation stenosis undergoing PCI with a dedicated bifurcation system, FKBI is associated with improved anatomical and functional results at the SB level, without compromising the result at the MB. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  1. The diastolic flow velocity-pressure gradient relation and dpv50 to assess the hemodynamic significance of coronary stenoses.

    Science.gov (United States)

    Marques, Koen M J; van Eenige, Machiel J; Spruijt, Hugo J; Westerhof, Nico; Twisk, Jos; Visser, Cees A; Visser, Frans C

    2006-12-01

    To evaluate the hemodynamic impact of coronary stenoses, the fractional (FFR) or coronary flow velocity reserve (CFVR) usually is measured. The combined measurement of instantaneous flow velocity and pressure gradient (v-dp relation) is rarely used in humans. We derived from the v-dp relation a new index, dp(v50) (pressure gradient at flow velocity of 50 cm/s), and compared the diagnostic performance of dp(v50), CFVR, and FFR. Before coronary angiography was performed, patients underwent noninvasive stress testing. In all coronary vessels with an intermediate or severe stenosis, the flow velocity, aortic, and distal coronary pressure were measured simultaneously with a Doppler and pressure guidewire after induction of hyperemia. After regression analysis of all middiastolic flow velocity and pressure gradient data, the dp(v50) was calculated. With the use of the results of noninvasive stress testing, the dp(v50) cutoff value was established at 22.4 mmHg. In 77 patients, 124 coronary vessels with a mean 39% (SD 19) diameter stenosis were analyzed. In 43 stenoses, ischemia was detected. We found a sensitivity, specificity, and accuracy of 56%, 86%, and 76% for CFVR; 77%, 99%, and 91% for FFR; and 95%, 95%, and 95% for dp(v50). To establish that dp(v50) is not dependent on maximal hyperemia, dp(v50) was recalculated after omission of the highest quartile of flow velocity data, showing a difference of 3%. We found that dp(v50) provided the highest sensitivity and accuracy compared with FFR and CFVR in the assessment of coronary stenoses. In contrast to CFVR and FFR, assessment of dp(v50) is not dependent on maximal hyperemia.

  2. Turbulent flow as a cause for underestimating coronary flow reserve measured by Doppler guide wire

    Directory of Open Access Journals (Sweden)

    Richartz Barbara M

    2006-03-01

    Full Text Available Abstract Background Doppler-tipped coronary guide-wires (FW are well-established tools in interventional cardiology to quantitatively analyze coronary blood flow. Doppler wires are used to measure the coronary flow velocity reserve (CFVR. The CFVR remains reduced in some patients despite anatomically successful coronary angioplasty. It was the aim of our study to test the influence of changes in flow profile on the validity of intra-coronary Doppler flow velocity measurements in vitro. It is still unclear whether turbulent flow in coronary arteries is of importance for physiologic studies in vivo. Methods We perfused glass pipes of defined inner diameters (1.5 – 5.5 mm with heparinized blood in a pulsatile flow model. Laminar and turbulent flow profiles were achieved by varying the flow velocity. The average peak velocity (APV was recorded using 0.014 inch FW. Flow velocity measurements were also performed in 75 patients during coronary angiography. Coronary hyperemia was induced by intra-coronary injection of adenosine. The APV maximum was taken for further analysis. The mean luminal diameter of the coronary artery at the region of flow velocity measurement was calculated by quantitative angiography in two orthogonal planes. Results In vitro, the measured APV multiplied with the luminal area revealed a significant correlation to the given perfusion volumes in all diameters under laminar flow conditions (r2 > 0.85. Above a critical Reynolds number of 500 – indicating turbulent flow – the volume calculation derived by FW velocity measurement underestimated the actual rate of perfusion by up to 22.5 % (13 ± 4.6 %. In vivo, the hyperemic APV was measured irrespectively of the inherent deviation towards lower velocities. In 15 of 75 patients (20% the maximum APV exceeded the velocity of the critical Reynolds number determined by the in vitro experiments. Conclusion Doppler guide wires are a valid tool for exact measurement of coronary flow

  3. Clinical and experimental aspects of functional and flow reserve of the myocardium

    NARCIS (Netherlands)

    E.O. McFalls (Edward)

    1991-01-01

    textabstractBasic research over the past 50 years has provided the clinician with important concepts for understanding human coronary physiology. One such tool is the determination of coronary blood flow reserve. Defined as the ratio of maximal to resting coronary flow, flow reserve may be helpful i

  4. Does intracoronary papaverine dilate epicardial coronary arteries? Implications for the assessment of coronary flow reserve

    NARCIS (Netherlands)

    F. Zijlstra (Felix); J.H.C. Reiber (Johan); P.W.J.C. Serruys (Patrick)

    1988-01-01

    textabstractIntracoronary papaverine is used as a means to induce a strong and short-lasting hyperemia in several recently developed methods to measure coronary flow reserve. Changes in stenosis geometry from papaverine would influence the measured coronary flow reserve. Therefore, we investigated

  5. Nonuniform loss of regional flow reserve during myocardial ischemia in dogs.

    Science.gov (United States)

    Coggins, D L; Flynn, A E; Austin, R E; Aldea, G S; Muehrcke, D; Goto, M; Hoffman, J I

    1990-08-01

    To determine whether coronary vasodilator reserve that persists during myocardial ischemia is present in all left ventricular regions, we measured regional blood flow in 192 left ventricular pieces (mean weight, 201 mg) in each of eight dogs by using radioactive microspheres while perfusing the left main coronary artery at 70, 50, 40, and 30 mm Hg. Flows were measured before and during adenosine infusion to determine flow reserve. Perfusion at 40 and 30 mm Hg produced ischemia in all dogs. At 70 mm Hg, 100% of left ventricular regions had significant flow reserve, compared with 92%, 55%, and 8% during perfusion at 50, 40, and 30 mm Hg, respectively. A greater amount of flow reserve and a greater number of regions responded to adenosine in the subepicardium than in the subendocardium at 50, 40, and 30 mm Hg. We conclude that coronary flow reserve persists in only a subset of left ventricular regions during ischemia and that the number of regions with persistent flow reserve decreases with perfusion pressure. These findings may best be explained by a model in which regional ischemia is a maximal coronary vasodilator and persistent pharmacological vasodilator reserve seen when global markers indicate ischemia simply reflects persistent endogenous flow reserve in myocardial regions not yet ischemic.

  6. A Methodology for Modeling the Flow of Military Personnel Across Air Force Active and Reserve Components

    Science.gov (United States)

    2016-01-01

    for pilots will depend on the • number of active component pilots who separate • fraction of separating pilots who affiliate with the reserve ...when tracking economic output over a period of time. GDP data were collected from the Federal Reserve Economic Data (FRED), Federal Reserve Bank of St...C O R P O R A T I O N Research Report A Methodology for Modeling the Flow of Military Personnel Across Air Force Active and Reserve Components

  7. Marine Forces Reserve: Accelerating Knowledge Flow through Asynchronous Learning Technologies

    Science.gov (United States)

    2014-12-19

    pedagogic techniques that are infeasible in the classroom , and they suggest that in some respects technologically intermediated learning can be even better...frameworks and technologies to examine I-I knowledge flows, and from the practitioner perspective, we bring to bear deep inside knowledge of the focal...ASYNCHRONOUS LEARNING TECHNOLOGIES by Mark Nissen, Robert McGuiness and Anthony Davis December 2014 Further distribution of all or part of this

  8. Current status of assessment of fractional flow reserve

    Institute of Scientific and Technical Information of China (English)

    FANG Yi-min; Grisana Grootenhuijs-Triyasut; Pieter A. Doevendans; Yolande Appelman

    2009-01-01

    @@ Coronary angiography presently remains the main method for the diagnosis and instruction of epicardial coronary disease. However, precise characterization of the significance for any given stenosis is limited by the inability to identify intermediate coronary lesions responsible for ischemia.1-3 In clinical practice, in addition to the assessment of the anatomical details of vessel narrowing, a more precise assessment of the impediment to coronary blood flow has become extremely important. At present, several physiological parameters have been introduced to improve discrimination in functional coronary lesion severity during cardiac catheterization.

  9. Profound spatial heterogeneity of coronary reserve. Discordance between patterns of resting and maximal myocardial blood flow.

    Science.gov (United States)

    Austin, R E; Aldea, G S; Coggins, D L; Flynn, A E; Hoffman, J I

    1990-08-01

    We examined the ability of individual regions of the canine left ventricle to increase blood flow relative to baseline rates of perfusion. Regional coronary flow was measured by injecting radioactive microspheres over 90 seconds in seven anesthetized mongrel dogs. Preliminary experiments demonstrated a correlation between the regional distributions of blood flow during asphyxia and pharmacological vasodilatation with adenosine (mean r = 0.75; 192 regions in each of two dogs), both of which resulted in increased coronary flow. Subsequent experiments, during which coronary perfusion pressure was held constant at 80 mm Hg, examined the pattern of blood flow in 384 regions (mean weight, 106 mg) of the left ventricular free wall during resting flow and during maximal coronary flow effected by intracoronary adenosine infusion. We found that resting and maximal flow patterns were completely uncorrelated to each other in a given dog (mean r = 0.06, p = NS; n = 3 dogs). Furthermore, regional coronary reserve, defined as the ratio of maximal to resting flow, ranged from 1.75 (i.e., resting flow was 57% of maximum) to 21.9 (resting flow was 4.5% of maximum). Thus, coronary reserve is spatially heterogeneous and determined by two distinct perfusion patterns: the resting (control) pattern and the maximal perfusion pattern. Normal hearts, therefore, contain small regions that may be relatively more vulnerable to ischemia. This may explain the patchy nature of infarction with hypoxia and at reduced perfusion pressures as well as the difficulty of using global parameters to predict regional ischemia. Despite the wide dispersion of coronary reserve, we found, by autocorrelation analysis, that reserve in neighboring regions (even when separated by a distance of several tissue samples) was significantly correlated. This also applied to patterns of resting myocardial flow. Thus, both resting coronary blood flow and reserve appear to be locally continuous and may define functional

  10. [Diffuse atherosclerotic disease unmasked by invasive physiologic assessment of coronary flow].

    Science.gov (United States)

    Sant'Anna, Fernando Mendes; Silva, Expedito E Ribeiro da; Batista, Leonardo Alves; Ventura, Fábio Machado; Barrozo, Carlos Alberto Mussel; Pijls, Nico H J

    2005-08-01

    It is known that coronary atherosclerosis is a diffuse process, very little visible at angiography. This article describes a stable angina patient, three months after acute myocardial infarction (AMI), and a severe lesion in anterior descending artery (ADA), evinced by coronariography. Myocardial fractional flow reserve (FFR), obtained through intracoronary pressure measurements, was 0.37 during maximum hyperemia, clearly showing the presence of ischemia. A stent was implanted in ADA and, despite the excellent angiographic result, post-stent FFR was only 0.75, the minimum limit, below which there is ischemia. When the pressure wire (PW) was slowly drawn back from the distal portion of ADA to its proximal portion, a continuous and gradual increase in intracoronary pressure was noted, which clearly indicates diffuse atherosclerosis and not focal stenosis. A gradient was not observed at the stent place. The patient was kept under medical treatment and has been asymptomatic so far.

  11. Clinical outcomes of fractional flow reserve by computed tomographic angiography-guided diagnostic strategies vs. usual care in patients with suspected coronary artery disease: the prospective longitudinal trial of FFRCT: outcome and resource impacts study

    Science.gov (United States)

    Douglas, Pamela S.; Pontone, Gianluca; Hlatky, Mark A.; Patel, Manesh R.; Norgaard, Bjarne L.; Byrne, Robert A.; Curzen, Nick; Purcell, Ian; Gutberlet, Matthias; Rioufol, Gilles; Hink, Ulrich; Schuchlenz, Herwig Walter; Feuchtner, Gudrun; Gilard, Martine; Andreini, Daniele; Jensen, Jesper M.; Hadamitzky, Martin; Chiswell, Karen; Cyr, Derek; Wilk, Alan; Wang, Furong; Rogers, Campbell; De Bruyne, Bernard

    2015-01-01

    Aims In symptomatic patients with suspected coronary artery disease (CAD), computed tomographic angiography (CTA) improves patient selection for invasive coronary angiography (ICA) compared with functional testing. The impact of measuring fractional flow reserve by CTA (FFRCT) is unknown. Methods and results At 11 sites, 584 patients with new onset chest pain were prospectively assigned to receive either usual testing (n = 287) or CTA/FFRCT (n = 297). Test interpretation and care decisions were made by the clinical care team. The primary endpoint was the percentage of those with planned ICA in whom no significant obstructive CAD (no stenosis ≥50% by core laboratory quantitative analysis or invasive FFR < 0.80) was found at ICA within 90 days. Secondary endpoints including death, myocardial infarction, and unplanned revascularization were independently and blindly adjudicated. Subjects averaged 61 ± 11 years of age, 40% were female, and the mean pre-test probability of obstructive CAD was 49 ± 17%. Among those with intended ICA (FFRCT-guided = 193; usual care = 187), no obstructive CAD was found at ICA in 24 (12%) in the CTA/FFRCT arm and 137 (73%) in the usual care arm (risk difference 61%, 95% confidence interval 53–69, P< 0.0001), with similar mean cumulative radiation exposure (9.9 vs. 9.4 mSv, P = 0.20). Invasive coronary angiography was cancelled in 61% after receiving CTA/FFRCT results. Among those with intended non-invasive testing, the rates of finding no obstructive CAD at ICA were 13% (CTA/FFRCT) and 6% (usual care; P = 0.95). Clinical event rates within 90 days were low in usual care and CTA/FFRCT arms. Conclusions Computed tomographic angiography/fractional flow reserve by CTA was a feasible and safe alternative to ICA and was associated with a significantly lower rate of invasive angiography showing no obstructive CAD. PMID:26330417

  12. Net Capital Flows, Macroeconomic Shocks and Reserve Assets. The Case of Argentina (1994-2013

    Directory of Open Access Journals (Sweden)

    Luis N. Lanteri

    2014-06-01

    Full Text Available International reserves have been used as a source of protection against the vulnerability of the balance of payments, or alternatively, as an attempt to keep a competitive real exchange rate and to promote exports. This paper explores the correlation between the net capital flows and reserves. Similarly, the impact of some macroeconomic shocks on that variable is assessed. Estimates are carried out through both, the VEC (Vector Error Correction models and quarterly data of the Argentine economy for the period 1994-2013. Results show a negative correlation between international reserves and net capital flows (reserve accumulation through current account surpluses. At the same time, the expansionary fiscal policies and the continuing and widespread price increases would adversely affect the reserves.

  13. Significant regional heterogeneity of coronary flow reserve in paediatric hypertrophic cardiomyopathy

    Energy Technology Data Exchange (ETDEWEB)

    Tadamura, E.; Kudoh, T.; Kubo, S.; Konishi, J. [Kyoto Univ. (Japan). School of Medicine; Yoshibayashi, M.; Yonemura, T. [Dept. of Pediatrics, Kyoto Univ. Graduate School of Medicine, Kyoto (Japan); Motooka, M.; Nohara, R.; Matsumori, A.; Sasayama, S. [Third Div., Dept. of Internal Medicine, Kyoto Univ. Graduate School of Medicine, Kyoto (Japan); Matsuda, T. [Dept. of Medical Informatics, Kyoto Univ. Graduate School of Medicine, Kyoto (Japan); Tamaki, N. [Dept. of Nuclear Medicine, Hokkaido Univ. School of Medicine, Sapporo (Japan)

    2000-09-01

    Previous studies have indicated that cardiac events in young patients with hypertrophic cardiomyopathy (HCM) are related to ischaemia rather than to arrhythmia. We measured coronary flow reserve in paediatric HCM and compared the values with those in adult HCM. We studied 12 patients with HCM including six paediatric (<20 years old; mean 13 years) and six adult patients (>20 years old: mean 62 years), and six healthy young adults (mean 29 years) as controls. Every patient underwent magnetic resonance imaging (MRI) for anatomical assessment. Myocardial blood flow at rest and after dipyridamole infusion was measured with dynamic nitrogen-13 ammonia positron emission tomography (PET). Partial volume effect was corrected for using the anatomical data obtained with MRI. In adult patients with HCM, coronary flow reserve in the hypertrophied septal region was not significantly different from that in the non-hypertrophied lateral wall (1.38{+-}0.29 vs 1.77{+-}0.39, respectively). In the paediatric patients, coronary flow reserve in the hypertrophied septal region was significantly lower than in the non-hypertrophied lateral wall (0.84{+-}0.33 vs 2.74{+-}0.90, respectively, P<0.01). In addition, coronary flow reserve in adult patients was lower than in control subjects both in the septal wall (1.38{+-}0.29 vs 2.94{+-}0.35, respectively, P<0.0001) and in the lateral wall (1.77{+-}0.39 vs 2.85{+-}0.69, respectively, P<0.05). In contrast, coronary flow reserve in paediatric patients was not significantly different from that in control subjects in the lateral wall (2.74{+-}0.90 vs 2.85{+-}0.69, respectively), while absolute reduction of myocardial blood flow was noted after pharmacological vasodilatation in the hypertrophied septal region. In conclusion, significant regional differences of coronary flow reserve were present in the paediatric patients with HCM. These results suggest that paediatric patients with HCM intrinsically have the potential to experience significant

  14. Endothelial and non-endothelial coronary blood flow reserve and left ventricular dysfunction in systemic hypertension

    Directory of Open Access Journals (Sweden)

    Aloísio Marchi Rocha

    2009-04-01

    Full Text Available OBJECTIVES: We evaluated the impairment of endothelium-dependent and endothelium-independent coronary blood flow reserve after administration of intracoronary acetylcholine and adenosine, and its association with hypertensive cardiac disease. INTRODUCTION: Coronary blood flow reserve reduction has been proposed as a mechanism for the progression of compensated left ventricular hypertrophy to ventricular dysfunction. METHODS: Eighteen hypertensive patients with normal epicardial coronary arteries on angiography were divided into two groups according to left ventricular fractional shortening (FS. Group 1 (FS >0.25: n=8, FS=0.29 ± 0.03; Group 2 (FS <0.25: n=10, FS= 0.17 ± 0.03. RESULTS: Baseline coronary blood flow was similar in both groups (Group 1: 80.15 ± 26.41 mL/min, Group 2: 100.09 ± 21.51 mL/min, p=NS. In response to adenosine, coronary blood flow increased to 265.1 ± 100.2 mL/min in Group 1 and to 300.8 ± 113.6 mL/min (p <0.05 in Group 2. Endothelium-independent coronary blood flow reserve was similar in both groups (Group 1: 3.31 ± 0.68 and Group 2: 2.97 ± 0.80, p=NS. In response to acetylcholine, coronary blood flow increased to 156.08 ± 36.79 mL/min in Group 1 and to 177.8 ± 83.6 mL/min in Group 2 (p <0.05. Endothelium-dependent coronary blood flow reserve was similar in the two groups (Group 1: 2.08 ± 0.74 and group Group 2: 1.76 ± 0.61, p=NS. Peak acetylcholine/peak adenosine coronary blood flow response (Group 1: 0.65 ± 0.27 and Group 2: 0.60 ± 0.17 and minimal coronary vascular resistance (Group 1: 0.48 ± 0.21 mmHg/mL/min and Group 2: 0.34 ± 0.12 mmHg/mL/min were similar in both groups (p= NS. Casual diastolic blood pressure and end-systolic left ventricular stress were independently associated with FS. CONCLUSIONS: In our hypertensive patients, endothelium-dependent and endothelium-independent coronary blood flow reserve vasodilator administrations had similar effects in patients with either normal or decreased left

  15. Simulation of the regional groundwater-flow system of the Menominee Indian Reservation, Wisconsin

    Science.gov (United States)

    Juckem, Paul F.; Dunning, Charles P.

    2015-01-01

    A regional, two-dimensional, steady-state groundwater-flow model was developed to simulate the groundwater-flow system and groundwater/surface-water interactions within the Menominee Indian Reservation. The model was developed by the U.S. Geological Survey (USGS), in cooperation with the Menominee Indian Tribe of Wisconsin, to contribute to the fundamental understanding of the region’s hydrogeology. The objectives of the regional model were to improve understanding of the groundwater-flow system, including groundwater/surface-water interactions, and to develop a tool suitable for evaluating the effects of potential regional water-management programs. The computer code GFLOW was used because of the ease with which the model can simulate groundwater/surface-water interactions, provide a framework for simulating regional groundwater-flow systems, and be refined in a stepwise fashion to incorporate new data and simulate groundwater-flow patterns at multiple scales. Simulations made with the regional model reproduce groundwater levels and stream base flows representative of recent conditions (1970–2013) and illustrate groundwater-flow patterns with maps of (1) the simulated water table and groundwater-flow directions, (2) probabilistic areas contributing recharge to high-capacity pumped wells, and (3) estimation of the extent of infiltrated wastewater from treatment lagoons.

  16. Performance Analysis of the United States Marine Corps War Reserve Materiel Program Process Flow

    Science.gov (United States)

    2016-12-01

    NAVAL POSTGRADUATE SCHOOL MONTEREY, CALIFORNIA MBA PROFESSIONAL REPORT PERFORMANCE ANALYSIS OF THE UNITED STATES MARINE CORPS...PERFORMANCE ANALYSIS OF THE UNITED STATES MARINE CORPS WAR RESERVE MATERIEL PROGRAM PROCESS FLOW 5. FUNDING NUMBERS 6. AUTHOR(S) Nathan A. Campbell...an item is requested but not maintained in the WRM inventory. By conducting a process analysis and using computer modeling, our recommendations are

  17. Quantification of myocardial blood flow and blood flow reserve in the presence of arterial dispersion: a simulation study.

    Science.gov (United States)

    Schmitt, Melanie; Viallon, Magalie; Thelen, Manfred; Schreiber, Wolfgang G

    2002-04-01

    Myocardial blood flow (MBF) can be quantified using dynamic T1-weighted MRI of diffusible tracers and a mathematical model of underlying vasculature. Quantification of MBF by means of T1- weighted MRI requires knowledge of the arterial input function (AIF). The AIF can be estimated from the left ventricular (LV) cavity. However, dispersion may occur between the LV and the tissue of interest because of the laminar blood flow profiles, branching of venules, and because of stenosis. To evaluate the influence of dispersion on the results of MBF quantification, a simulation study was performed. The dispersion was described as a convolution of the AIF with an exponential residue function. Synthetic tissue and AIF curves were analyzed and the derived parameters fit to the simulated parameters. The results show that an unaccounted dispersion may result in a systematic underestimation of MBF up to approximately 50%. Underestimation increases with increasing dispersion and with increasing MBF. Assuming equal dispersion at rest and during hyperemia, myocardial perfusion reserve (MPR) estimates are also susceptible to underestimation of approximately 20%. An unaccounted dispersion therefore can lead to systematic underestimation of both blood flow and perfusion reserve.

  18. Echocardiographic and hemodynamic determinants of right coronary artery flow reserve and phasic flow pattern in advanced non-ischemic cardiomyopathy

    Directory of Open Access Journals (Sweden)

    Mady Charles

    2007-09-01

    Full Text Available Abstract Background In patients with advanced non-ischemic cardiomyopathy (NIC, right-sided cardiac disturbances has prognostic implications. Right coronary artery (RCA flow pattern and flow reserve (CFR are not well known in this setting. The purpose of this study was to assess, in human advanced NIC, the RCA phasic flow pattern and CFR, also under right-sided cardiac disturbances, and compare with left coronary circulation. As well as to investigate any correlation between the cardiac structural, mechanical and hemodynamic parameters with RCA phasic flow pattern or CFR. Methods Twenty four patients with dilated severe NIC were evaluated non-invasively, even by echocardiography, and also by cardiac catheterization, inclusive with Swan-Ganz catheter. Intracoronary Doppler (Flowire data was obtained in RCA and left anterior descendent coronary artery (LAD before and after adenosine. Resting RCA phasic pattern (diastolic/systolic was compared between subgroups with and without pulmonary hypertension, and with and without right ventricular (RV dysfunction; and also with LAD. RCA-CFR was compared with LAD, as well as in those subgroups. Pearson's correlation analysis was accomplished among echocardiographic (including LV fractional shortening, mass index, end systolic wall stress more hemodynamic parameters with RCA phasic flow pattern or RCA-CFR. Results LV fractional shortening and end diastolic diameter were 15.3 ± 3.5 % and 69.4 ± 12.2 mm. Resting RCA phasic pattern had no difference comparing subgroups with vs. without pulmonary hypertension (1.45 vs. 1.29, p = NS either with vs. without RV dysfunction (1.47 vs. 1.23, p = NS; RCA vs. LAD was 1.35 vs. 2.85 (p Conclusion In patients with chronic advanced NIC, RCA phasic flow pattern has a mild diastolic predominance, less marked than in LAD, with no effects from pulmonary artery hypertension or RV dysfunction. There is no significant correlation between any cardiac mechanical-structural or

  19. Adenosine-induced coronary flow reserve in Watanabe heritable hyperlipidemic rabbits

    Energy Technology Data Exchange (ETDEWEB)

    Shimada, Kazuhiro; Yoshida, Katsuya [Chiba Univ. (Japan). School of Medicine; Tadokoro, Hiroyuki [and others

    2000-12-01

    The Watanabe heritable hyperlipidemic (WHHL) rabbit develops coronary atherosclerosis and hypercholesterolemia because of a genetic deficiency of low-density lipoprotein receptors and is therefore a good animal model for studying the relationships of coronary atherosclerosis, hypercholesterolemia and coronary flow reserve. The aim of the present study was to assess myocardial perfusion at baseline and during adenosine infusion (0.2 mg{center_dot}kg{sup -1}{center_dot}min{sup -1}) in 8 WHHL rabbits (13.8{+-}0.5 months) with {sup 13}N-ammonia, small-animal positron emission tomography (PET) and colored microspheres. Results were compared with those from 6 age-matched Japanese white rabbits. Plaque distribution was also examined in the extramural coronary arteries. All 8 WHHL rabbits had coronary plaques, with 6 showing multiple plaques. Mean global myocardial blood flow (ml{center_dot}min{sup -1}{center_dot}g{sup -1}) did not differ significantly between control and WHHL groups both at baseline (3.67{+-}0.72 vs 4.26{+-}1.12 ml{center_dot}min{sup -1}{center_dot}g{sup -1}, p=NS) and with adenosine (7.92{+-}2.00 vs 9.27{+-}2.91 ml{center_dot}min{sup -1}{center_dot}g{sup -1}, p=NS), nor did coronary flow reserve (2.16{+-}0.37 vs 2.18{+-}0.41, p=NS). None showed evidence of regional perfusion abnormalities by visual and semiquantitative analyses of PET images. It was concluded that WHHL rabbits preserve adenosine-induced coronary flow reserve despite coronary atherosclerosis and hypercholesterolemia, suggesting that a compensatory mechanism develops in this animal model. (author)

  20. Coronary flow reserve measurement in the coronary sinus in pre and post CABG status

    Directory of Open Access Journals (Sweden)

    M Hajaghaei

    2007-11-01

    Full Text Available Background: Coronary flow reserve (CFR is defined as a maximal(hyperemic to resting ratio of coronary blood flow. It is a physiologicparameter of coronary circulation and depends on the patency of the epicardialcoronary arteries and integrity of the microvascular circulation.CFR measurement has many clinical applications including functional assessmentof intermediate stenosis, detection of critical stenosis monitoring of coronaryflow in the post angioplasty period, assessment of post infarct blood flow andassessment of coronary graft patency. The aim of this study was to measure CFRin the coronary sinus through the transthoracic echocardiographic approach, inpatients who were candidate for coronary artery bypass graft surgery (CABGbefore and one month after operation.Patients and Methods: The present study included 19 patients (meanage=56±9.1 including 15 males and 4 females, admitted for CABG. All patientshad a sinus rhythm, normal wall thickness, normal RV systolic pressure, andtricuspid valvular regurgitation equal or less than grade 2. The antegrade phaseof coronary flow in the coronary sinus moving into the right atrium was analyzedin two phases (systolic and diastolic. Each wave was determined considering thepeak velocity and velocity time integral (VTI. The volumetric blood flow in thecoronary sinus calculated at the baseline and then in hyperemic phase was usedfor determination of CFR both before and after CABG.Results: There was a significant increase in the diameter of the coronarysinus after CABG (9.4±1.2mm compared with that of before CABG values (8.6±1.05mm. Also there was a trend of increasing the diameter in the hyperemicphase before and after CABG. The absolute increase in mean coronary sinusdiameter was 0.5 mm before and 1.5 mm after CABG. Coronary flow reserve (CFRwas significantly higher after surgery, despite a significant increase insystolic velocity ratio (hyperemic/baseline after CABG. This is also true forsystolic

  1. Coronary Flow Velocity Reserve in Burn Injury: A Prospective Clinical Cohort Study.

    Science.gov (United States)

    Caliskan, Mustafa; Turk, Emin; Karagulle, Erdal; Ciftci, Ozgur; Oguz, Hakan; Kostek, Osman; Moray, Gokhan; Haberal, Mehmet

    2016-01-01

    The authors sought to evaluate coronary microvascular function and left ventricular diastolic dysfunction using transthoracic Doppler echocardiography in burn patients. In this study, 32 adult burn patients with partial or full-thickness scald burns that were hospitalized and treated were included. The control group was matched for age and sex and was composed of otherwise healthy volunteers. Transthoracic Doppler echocardiography examinations and simultaneous laboratory tests for cardiac evaluation were performed on the sixth month after burn injury as well as with the control group. High-sensitivity C-reactive protein levels were significantly higher in the burn patients than in controls (5.17 ± 3.86 vs 2.42 ± 1.78; P = .001). Lateral isovolumic relaxation time was significantly higher in the burn injury group than in the control group (92.7 ± 15.7 vs 85.5 ± 8.3; P = .03). Baseline coronary diastolic peak flow velocity of the left anterior descending artery was similar in both groups. However, hyperemic diastolic peak flow velocity and coronary flow velocity reserve (2.26 ± 0.48 vs 2.94 ± 0.47; P < .001) were significantly lower in the burn injury group than in the control group. Coronary flow velocity reserve was significantly and inversely correlated with high-sensitivity C-reactive protein, burn ratio, creatinine, and mitral A-wave max velocity. At the sixth month of treatment, burn patients had high-sensitivity C-reactive protein levels during this period, suggesting that inflammation still exists. In addition, subclinical coronary microvascular and left ventricular diastolic dysfunction can occur in burn patients without traditional cardiovascular risk factors. However, these results must be supported by additional studies.

  2. Association of arterial stiffness with coronary flow reserve in revascularized coronary artery disease patients

    Institute of Scientific and Technical Information of China (English)

    Vlassis Tritakis; Stavros Tzortzis; Ignatios Ikonomidis; Kleanthi Dima; Georgios Pavlidis; Paraskevi Trivilou; Ioannis Paraskevaidis; Giorgos Katsimaglis; John Parissis; John Lekakis

    2016-01-01

    AIM: To investigate the association of arterial wave reflection with coronary flow reserve(CFR) in coronary artery disease(CAD) patients after successful revascularization.METHODS: We assessed 70 patients with angiographically documented CAD who had undergone recent successful revascularization. We measured(1) reactive hyperemia index(RHI) using fingertip peripheral arterial tonometry(RH-PAT Endo-PAT);(2) carotid to femoral pulse wave velocity(PWVc-Complior);(3) augmentation index(AIx), the diastolic area(DAI%) and diastolic reflection area(DRA) of the central aortic pulse wave(Arteriograph);(4) CFR using Doppler echocardiography; and(5) blood levels of lipoprotein-phospholipase A2(LpPLA2).RESULTS: After adjustment for age, sex, blood pressure parameter, lipidemic, diabetic and smoking status, we found that coronary flow reserve was independently related to AIx(b =-0.38, r = 0.009), DAI(b = 0.36, P = 0.014), DRA(b = 0.39, P = 0.005) and RT(b =-0.29,P = 0.026). Additionally, patients with CFR < 2.5 had higher PWVc(11.6 ± 2.3 vs 10.2 ± 1.4 m/s, P = 0.019), SBPc(139.1 ± 17.8 vs 125.2 ± 19.1 mm Hg, P = 0.026), AIx(38.2% ± 14.8% vs 29.4% ± 15.1%, P = 0.011) and lower RHI(1.26 ± 0.28 vs 1.50 ± 0.46, P = 0.012), DAI(44.3% ± 7.9% vs 53.9% ± 6.7%, P = 0.008), DRA(42.2 ± 9.6 vs 51.6 ± 11.4, P = 0.012) and Lp PLA2(268.1 ± 91.9 vs 199.5 ± 78.4 ng/m L, P = 0.002) compared with those with CFR ≥ 2.5. Elevated Lp PLA2 was related with reduced CFR(r =-0.33, P = 0.001), RHI(r =-0.37, P < 0.001) and DRA(r =-0.35, P = 0.001) as well as increased PWVc(r = 0.34, P = 0.012) and AIx(r = 0.34, P = 0.001). CONCLUSION: Abnormal arterial wave reflections are related with impaired coronary flow reserve despite successful revascularization in CAD patients. There is a common inflammatory link between impaired aortic wall properties, endothelial dysfunction and coronary flow impairment in CAD.

  3. Diagnostic Accuracy of Stress Myocardial Perfusion Imaging Compared to Invasive Coronary Angiography With Fractional Flow Reserve Meta-Analysis

    NARCIS (Netherlands)

    Takx, Richard A. P.; Blomberg, Bjorn A.; El Aidi, Hamza; Habets, Jesse; de Jong, Pim A.; Nagel, Eike; Hoffmann, Udo; Leiner, Tim

    2015-01-01

    Background-Hemodynamically significant coronary artery disease is an important indication for revascularization. Stress myocardial perfusion imaging is a noninvasive alternative to invasive fractional flow reserve for evaluating hemodynamically significant coronary artery disease. The aim was to det

  4. Lesion flow coefficient: a combined anatomical and functional parameter for detection of coronary artery disease--a clinical study.

    Science.gov (United States)

    Peelukhana, Srikara V; Effat, Mohamed; Kolli, Kranthi K; Arif, Imran; Helmy, Tarek; Leesar, Massoud; Kerr, Hanan; Back, Lloyd H; Banerjee, Rupak

    2015-01-01

    Invasive diagnosis of coronary artery disease utilizes either anatomical or functional measurements. In this study, we tested a futuristic parameter, lesion flow coefficient (LFC, defined as the ratio of percent coronary area stenosis (%AS) to the square root of the ratio of the pressure drop across the stenosis to the dynamic pressure in the throat region), that combines both the anatomical (%AS) and functional measurements (pressure and flow) for application in a clinical setting. In 51 vessels, simultaneous pressure and flow readings were obtained using a 0.014" Combowire (Volcano Corporation). Anatomical details were assessed using quantitative coronary angiography (QCA). Fractional flow reserve (FFR), coronary flow reserve (CFR), hyperemic stenosis resistance index (HSR), and hyperemic microvascular index (HMR) were obtained at baseline and adenosine-induced hyperemia. QCA data were corrected for the presence of guidewire and then the LFC values were calculated. LFC was correlated with FFR, CFR, HSR, and HMR, individually and in combination with %AS, under both baseline and hyperemic conditions. Further, in 5 vessels, LFC group mean values were compared between pre-PCI and post-PCI groups. Panatomically measured %AS were combined (r = 0.64; Panatomical and functional endpoints, has potential for application in a clinical setting for stenosis evaluation, under both hyperemic and baseline conditions.

  5. Transthoracic Doppler echocardiography – noninvasive diagnostic window for coronary flow reserve assessment

    Directory of Open Access Journals (Sweden)

    Dimitrow Paweł

    2003-04-01

    Full Text Available Abstract This review focuses on transthoracic Doppler echocardiography as noninvasive method used to assess coronary flow reserve (CFR in a wide spectrum of clinical settings. Transthoracic Doppler echocardiography is rapidly gaining appreciation as popular tool to measure CFR both in stenosed and normal epicardial coronary arteries (predominantly in left anterior descending coronary artery. Post-stenotic CFR measurement is helpful in: functional assessment of moderate stenosis, detection of significant or critical stenosis, monitoring of restenosis after revascularization. In the absence of stenosis in the epicardial coronary artery, decreased CFR enable to detect impaired microvascular vasodilatation in: reperfused myocardial infarct, arterial hypertension with or without left ventricular hypertrophy, diabetes mellitus, hypercholesterolemia, syndrome X, hypertrophic cardiomyopathy. In these diseases, noninvasive transthoracic Doppler echocardiography allows for serial CFR evaluations to explore the effect of various pharmacological therapies.

  6. Blood flow, flow reserve, and glucose utilization in viable and nonviable myocardium in patients with ischemic cardiomyopathy.

    Science.gov (United States)

    Zhang, Xiaoli; Schindler, Thomas H; Prior, John O; Sayre, James; Dahlbom, Magnus; Huang, Sung-Cheng; Schelbert, Heinrich R

    2013-04-01

    The aim of the study was to determine whether glucose uptake in viable myocardium of ischemic cardiomyopathy patients depends on rest myocardial blood flow (MBF) and the residual myocardial flow reserve (MFR). Thirty-six patients with ischemic cardiomyopathy (left ventricular ejection fraction 25 ± 10 %) were studied with (13)N-ammonia and (18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET). Twenty age-matched normals served as controls. Regional MBF was determined at rest and during dipyridamole hyperemia and regional FDG extraction was estimated from regional FDG to (13)N-ammonia activity ratios. Rest MBF was reduced in viable (0.42 ± 0.18 ml/min per g) and nonviable regions (0.32 ± 0.09 ml/min per g) relative to remote regions (0.68 ± 0.23 ml/min per g, p MFRs did not differ significantly (p > 0.05). Compared to MFR in remote myocardium, MFRs in viable regions were similar (1.39 ± 0.56 vs 1.70 ± 0.45, p > 0.05) but were significantly lower in nonviable regions (1.23 ± 0.43, p MFRs (r =-0.424, p MFRs in viable myocardium are associated with increasing glucose extraction that likely reflects a metabolic adaptation of remodeling hibernating myocytes.

  7. Target heart rate to determine the normal value of coronary flow reserve during dobutamine stress echocardiography

    Directory of Open Access Journals (Sweden)

    Rousse Maria G

    2011-04-01

    Full Text Available Abstract Background The determination of coronary flow reserve (CFR is an essential concept at the moment of decision-making in ischemic heart disease. There are several direct and indirect tests to evaluate this parameter. In this sense, dobutamine stress echocardiography is one of the pharmacological method most commonly used worldwide. It has been previously demonstrated that CFR can be determined by this technique. Despite our wide experience with dobutamine stress echocardiography, we ignored the necessary heart rate to consider sufficient the test for the analysis of CFR. For this reason, our main goal was to determine the velocity of coronary flow in each stage of dobutamine stress echocardiography and the heart rate value necessary to double the baseline values of coronary flow velocity in the territory of the left anterior descending (LAD coronary artery. Methods A total of 33 consecutive patients were analyzed. The patients included had low risk for coronary artery disease. All the participants underwent dobutamine stress echocardiography and coronary artery flow velocity was evaluated in the distal segment of LAD coronary artery using transthoracic color-Doppler echocardiography. Results The feasibility of determining CFR in the territory of the LAD during dobutamine stress echocardiography was high: 31/33 patients (94%. Mean CFR was 2.67 at de end of dobutamine test. There was an excellent concordance between delta HR (difference between baseline HR and maximum HR and the increase in the CFR (correlation coefficient 0.84. In this sense, we found that when HR increased by 50 beats, CFR was ≥ 2 (CI 93-99.2%. In addition, 96.4% of patients reached a CFR ≥ 2 (IC 91.1 - 99% at 75% of their predicted maximum heart rate. Conclusions We found that the feasibility of dobutamine stress echocardiography to determine CFR in the territory of the LAD coronary artery was high. In this study, it was necessary to achieve a difference of 50 bpm

  8. Environmental flow calculation for the maintenance of the water reserve of the Piaxtla River, Sinaloa, Mexico

    Directory of Open Access Journals (Sweden)

    Guadalupe de la Lanza Espino

    2014-03-01

    status to be achieved within the watershed to maintain the integrity of existing ecosystems or when they believe that they are degraded, contributing to the recovery or rehabilitation; and annual percentage rate recommended for environmental protection. Based on this, the purpose of this study was to quantify the river flow of the Piaxtla river, in the state of Sinaloa. The river runoff data bases for 36 and nine years were compared, showed differences mainly between the frequency of maximum runoff and its origin, and indicated that it is advisable to use a data base of more than 20 years. However, results were similar in the final calculation of the environmental or ecological river flows; that is to say, total runoff volume was 62.1% considering 36 years and 57.7% for nine years of information. We conclude that the ecological importance of Piaxtla river was very high and the use of water pressure was low (considering that database runoff only included until 1999 and did not take into account population growth and activities. To determine the final volume reserved for the environment or ecological flow, could be estimated not only with a database of 36 years, but for nine years also confirming that those rivers that have databases of 10 years can the methodology used hydrological indicated by the NMX said. Particularly in this study it was determined that for parameters more detailed as the volume of the base rate of the annual volume, according to the frequency of occurrence, both very dry years, dry, average and wet, and influence of meteorological events that determine periods separate return, it is advisable to use minimum data bases as brand NMX 20 years.

  9. Effects of hypoxia on coronary flow reserve as determined by myocardial contrast echocardiography in swine

    Institute of Scientific and Technical Information of China (English)

    YANG Yuan 杨源; LI Shu-qing 李树清; Barry Peters; Anthony N DeMaria

    2004-01-01

    Background Time-intensity curves derived from microbubble destruction/refilling sequences and recorded using myocardial contrast echocardiography (MCE) can provide parameters that correlate with coronary blood flow. The response of these parameters to adenosine vasodilatation correlates with coronary flow reserve (CFR) measured by fluorescent microsphere techniques (FMT). Currently, no data exist regarding the effect of physiological variables, such as hypoxia, on the determination of CFR by MCE. The purpose of this study was to define the effects of decreases in blood partial pressure of oxygen (PO2) on CFR as measured by MCE. Methods Studies were performed in 9 closed chest swine. Low-energy, real-time MCE was performed with commercial instruments in short axis view at papillary muscle level while infusing BR1 at 30 ml/h. High-energy ultrasound bursts (referred to as FLASH frames) destroyed the bubbles every 15 cardiac cycles, and resultant time-intensity curves derived from these sequences were fitted to the exponential function y = A (1-e-bt) +c, from which the rate of signal rise (b) was obtained. CFR was calculated as the ratio of b values after adenosine infusion to baseline and was obtained during the control period and after decreasing blood PO2 by giving nitrogen via a respirator to create artificial hypoxic conditions. CFR was independently determined by FMT. Results Nitrogen led to significant decreases in mean PO2, from (120.6±18.9) mmHg to (51.8±15.9) mmHg (P0.05 compared with the baseline). Conclusions CFR values diminish under hypoxic conditions according to both MCE and FMT. The reductions in CFR involve both an increase in resting values and a decrease in post adenosine measurements, as determined by both techniques. The reduction in CFR under hypoxia is slightly greater using MCE than using FMT. Physiological variables, such as hypoxia, must be taken into consideration when assessing CFR by MCE.

  10. Vascular flow reserve as a link between long-term blood pressure level and physical performance capacity in mammals

    DEFF Research Database (Denmark)

    Poulsen, Christian B; Damkjær, Mads; Hald, Bjørn O

    2016-01-01

    function producing a high precapillary resistance and thus a high vascular flow reserve is associated with an increase in network inlet pressure. Assuming that network properties are independent of body mass, and that inlet pressure of the microvascular network is a proxy for arterial pressure, the study......Mean arterial pressure (MAP) is surprisingly similar across different species of mammals, and it is, in general, not known which factors determine the arterial pressure level. Mammals often have a pronounced capacity for sustained physical performance. This capacity depends on the vasculature...... having a flow reserve that comes into play as tissue metabolism increases. We hypothesize that microvascular properties allowing for a large vascular flow reserve is linked to the level of the arterial pressure.To study the interaction between network properties and network inlet pressure, we developed...

  11. Coronary flow reserve in hypertrophic cardiomyopathy: relation with microvascular dysfunction and pathophysiological characteristics.

    Science.gov (United States)

    Kofflard, M J; Michels, M; Krams, R; Kliffen, M; Geleijnse, M L; Ten Cate, F J; Serruys, P W

    2007-01-01

    BACKGROUND.: The decrease in coronary flow reserve (CFR) in hypertrophic cardiomyopathy (HCM) predisposes to myocardial ischaemia, systolic dysfunction and cardiac death. In this study we investigate to which extent haemodynamic, echocardiographic, and histological parameters contribute to the reduction of CFR. METHODS.: In ten HCM patients (mean age 44+/-14 years) and eight heart transplant (HTX) patients (mean age 51+/-6 years) CFR was calculated in the left anterior descending coronary artery. In all subjects haemodynamic, echocardiographic and histological parameters were assessed. The relationship between these variables and CFR was determined using linear regression analysis. RESULTS.: CFR was reduced in HCM compared with HTX patients (1.6+/-0.7 vs. 2.7+/-0.8, p<0.01). An increase in septal thickness (p<0.005), indexed left ventricular (LV) mass (p<0.005), LV end-diastolic pressure (p<0.001), LV outflow tract gradient (p<0.05) and a decrease in arteriolar lumen size (p<0.05) were all related to a reduction in CFR. CONCLUSION.: In HCM patients haemodynamic (LV end-diastolic pressure, LV outflow tract gradient), echocardiographic (indexed LV mass) and histological (% luminal area of the arterioles) changes are responsible for a decrease in CFR. (Neth Heart J 2007;15:209-15.).

  12. Hypertension as a predictor of adverse cardiac events in patients with borderline fractional flow reserve.

    Science.gov (United States)

    Arslan, Fatih; Kaya, Mehmet G; van der Heijden, Geert; Timurkaynak, Timur; Cengel, Atiye

    2007-08-01

    The cut-off value myocardial fractional flow reserve (FFRmyo) or = 0.75. Other clinical characteristics may affect such treatment decision. Therefore, we studied the association between baseline characteristics and clinical outcomes in an unselected patient cohort with coronary artery disease, with intermediate coronary stenosis, initially referred for PCI, but in whom the intervention was deferred on the basis of FFRmyo > or = 0.75. Angiographic analysis and follow-up were performed in 152 patients with stable or unstable angina pectoris with intermediate coronary stenosis severity and normal left ventricular function. A major adverse cardiac event (MACE) was defined as postprocedural acute myocardial infarction (AMI), target vessel revascularization (TVR) and verified cardiac death. More adverse cardiac events occurred in patients with 0.75 or = 0.80 (9/97) (P < 0.001). Hypertension, diabetes and hyperlipidaemia were significantly associated with the occurrence of MACE in the univariate analyses. Logistic regression analyses showed that only hypertension remained as a significant independent predictor of MACE for patients with 0.75 < or = FFRmyo < 0.80 (P < 0.10). In an unselected patient population with coronary artery disease, a FFRmyo cut-off value of 0.8 should be used in hypertensive patients to discriminate between clinically significant coronary stenosis.

  13. Computed tomography derived fractional flow reserve testing in stable patients with typical angina pectoris

    DEFF Research Database (Denmark)

    Møller Jensen, Jesper; Erik Bøtker, Hans; Norling Mathiassen, Ole

    2017-01-01

    June 2016 all patients (N = 774) referred to non-emergent ICA or coronary CTA at Aarhus University Hospital on a suspicion of CAD had frontline CTA performed. Downstream testing and treatment within 3 months and adverse events ≥90 days were registered. Patients were divided into two groups according......Aims: To assess the use of downstream coronary angiography (ICA) and short-term safety of frontline coronary CT angiography (CTA) with selective CT-derived fractional flow reserve (FFRCT) testing in stable patients with typical angina pectoris. Methods and results: Between 1 January 2016 and 30...... to the presence of typical angina pectoris, which according to local practice would have resulted in referral to ICA, (low-intermediate-risk, n = 593 [76%]; high-risk, n = 181 [24%]) with mean pre-test probability of CAD of 31 ± 16% and 67 ± 16%, respectively. Coronary CTA was performed in 745 (96%) patients...

  14. Coronary flow reserve in the remote myocardium predicts left ventricular remodeling following acute myocardial infarction.

    Science.gov (United States)

    Cheng, Rongchao; Wei, Guoqian; Yu, Longhao; Su, Zhendong; Wei, Li; Bai, Xiuping; Tian, Jiawei; Li, Xueqi

    2014-07-01

    Coronary flow reserve (CFR) in the non-infarcted myocardium is often impaired following acute myocardial infarction (AMI). However, the clinical significance of CFR in the non-infarcted myocardium is not fully understood. The objective of the present study was to assess whether a relationship exists between CFR and left ventricular remodeling following AMI. We enrolled 18 consecutive patients undergoing coronary intervention. Heart function was analyzed using real-time myocardial contrast echocardiography at one week and six months after coronary angioplasty. Ten subjects were enrolled as the control group and were examined using the same method at the same time to assess CFR. Cardiac troponin I (cTnI) levels were routinely analyzed to estimate peak concentration. CFR was 1.55±0.11 in the infarcted zone and 2.05±0.31 in the remote zone (p2.05). The levels of cTnI were higher in Group I compared to Group II on admission (36.40 vs. 21.38, p<0.05). Furthermore, left ventricular end diastolic volume was higher in Group I compared to Group II at six months following coronary angioplasty. Microvascular dysfunction is commonly observed in the remote myocardium. The CFR value accurately predicts adverse ventricular remodeling following AMI.

  15. Higher CHADS2 score is associated with impaired coronary flow reserve: A study using phase contrast cine magnetic resonance imaging.

    Science.gov (United States)

    Kirigaya, Hidekuni; Kato, Shingo; Gyotoku, Daiki; Yamada, Nao; Iinuma, Naoki; Kusakawa, Yuka; Iguchi, Kohei; Miki, Yuko; Nakachi, Tatsuya; Fukui, Kazuki; Iwasawa, Tae; Kimura, Kazuo

    2016-10-15

    The presence of coronary microvascular dysfunction (CMD) is an important prognostic marker for coronary artery disease (CAD) patients. The purpose of this study was to investigate whether the CHADS2 score is associated with CMD evaluated by magnetic resonance imaging (MRI). One hundred forty three patients with known or suspected CAD (mean age 70.3±9.5years) were enrolled. All patients did not have any significant coronary stenosis on X-ray coronary angiography (CAG) at the time of MRI acquisition. By using a 1.5T MRI scanner, breath-hold phase contrast cine MRI images of coronary sinus (CS) were obtained to assess the blood flow of CS both at rest and during adenosine triphosphate (ATP) infusion. Coronary flow reserve (CFR) was calculated as CS blood flow during ATP infusion divided by CS blood flow at rest. CMD was defined as CFRcine MRI. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  16. Effect of streptozotocin-induced diabetes on myocardial blood flow reserve assessed by myocardial contrast echocardiography in rats

    OpenAIRE

    Weytjens Caroline; Garbar Christian; Degaillier Céline; Hernot Sophie; Droogmans Steven; Cosyns Bernard; Roosens Bram; Schoors Danny; Lahoutte Tony; Franken Philippe R; Van Camp Guy

    2008-01-01

    Abstract The role of structural and functional abnormalities of small vessels in diabetes cardiomyopathy remains unclear. Myocardial contrast echocardiography allows the quantification of myocardial blood flow at rest and during dipyridamole infusion. The aim of the study was to determine the myocardial blood flow reserve in normal rats compared with Streptozotocin-induced diabetic rats using contrast echocardiography. Methods We prospectively studied 40 Wistar rats. Diabetes was induced by ...

  17. Evaluation of myocardial blood flow reserve in patients with chronic congestive heart failure due to idiopathic dilated cardiomyopathy.

    Science.gov (United States)

    Canetti, Menahem; Akhter, Mohammed W; Lerman, Amir; Karaalp, Ilyas S; Zell, Jason A; Singh, Harpreet; Mehra, Anilkumar; Elkayam, Uri

    2003-11-15

    This study demonstrates a significant impairment in coronary blood flow reserve in most patients with idiopathic dilated cardiomyopathy despite normal epicardial coronary arteries. This change may prevent appropriate increases in coronary blood flow and thus lead to myocardial ischemia and progression of disease. An association between decreased response to adenosine and acetylcholine supports previous observations indicating that adenosine-induced vasodilation of coronary microcirculation is dependent on endothelial nitric oxide production.

  18. Coronary pressure and flow relationships in humans: phasic analysis of normal and pathological vessels and the implications for stenosis assessment: a report from the Iberian–Dutch–English (IDEAL) collaborators

    Science.gov (United States)

    Nijjer, Sukhjinder S.; de Waard, Guus A.; Sen, Sayan; van de Hoef, Tim P.; Petraco, Ricardo; Echavarría-Pinto, Mauro; van Lavieren, Martijn A.; Meuwissen, Martijn; Danad, Ibrahim; Knaapen, Paul; Escaned, Javier; Piek, Jan J.; Davies, Justin E.; van Royen, Niels

    2016-01-01

    Background Our understanding of human coronary physiological behaviour is derived from animal models. We sought to describe physiological behaviour across a large collection of invasive pressure and flow velocity measurements, to provide a better understanding of the relationships between these physiological parameters and to evaluate the rationale for resting stenosis assessment. Methods and results Five hundred and sixty-seven simultaneous intracoronary pressure and flow velocity assessments from 301 patients were analysed for coronary flow velocity, trans-stenotic pressure gradient (TG), and microvascular resistance (MVR). Measurements were made during baseline and hyperaemic conditions. The whole cardiac cycle and the diastolic wave-free period were assessed. Stenoses were assessed according to fractional flow reserve (FFR) and quantitative coronary angiography DS%. With progressive worsening of stenoses, from unobstructed angiographic normal vessels to those with FFR ≤ 0.50, hyperaemic flow falls significantly from 45 to 19 cm/s, Ptrend stenosis severity and was consistent across all strata of stenosis (Ptrend > 0.05 for all). Trans-stenotic pressure gradient rose with stenosis severity for both rest and hyperaemic measures (Ptrend stenosis severity under resting conditions (Ptrend stenosis severity, TG rises. However, while hyperaemic flow falls significantly, resting coronary flow is maintained by compensatory reduction of MVR, demonstrating coronary auto-regulation. These data support the translation of coronary physiological concepts derived from animals to patients with coronary artery disease and furthermore, suggest that resting pressure indices can be used to detect the haemodynamic significance of coronary artery stenoses. PMID:26612582

  19. Coronary Flow Reserve Predicts Cardiopulmonary Fitness in Patients with Coronary Artery Disease Independently of Systolic and Diastolic Function

    DEFF Research Database (Denmark)

    Snoer, Martin; Olsen, Rasmus Huan; Monk-Hansen, Tea

    2014-01-01

    Aims Despite revascularization and optimal medical treatment, patients with coronary artery disease (CAD) have reduced exercise capacity. In the absence of coronary artery stenosis, coronary flow reserve (CFR) is a measure of coronary microvascular function, and a marker of future poor outcome...... early (E) and late (A) inflow velocities, and tissue Doppler diastolic (e′) and systolic (s′) velocities. Peak coronary flow velocity (CFV) was measured in the LAD using pulse-wave Doppler. CFR was calculated as the ratio between peak CFV at rest and during vasodilator stress. Median CFR was 2.22 (1....... Conclusions Coronary flow reserve measured noninvasively predicts cardiopulmonary fitness independently of resting systolic and diastolic function in CAD patients, indicating that cardiac output during maximal exercise is dependent on the ability of the coronary circulation to adapt to the higher metabolic...

  20. Safety of guidewire-based measurement of fractional flow reserve and the index of microvascular resistance using intravenous adenosine in patients with acute or recent myocardial infarction.

    Science.gov (United States)

    Ahmed, Nadeem; Layland, Jamie; Carrick, David; Petrie, Mark C; McEntegart, Margaret; Eteiba, Hany; Hood, Stuart; Lindsay, Mitchell; Watkins, Stuart; Davie, Andrew; Mahrous, Ahmed; Carberry, Jaclyn; Teng, Vannesa; McConnachie, Alex; Curzen, Nick; Oldroyd, Keith G; Berry, Colin

    2016-01-01

    Coronary guidewire-based diagnostic assessments with hyperemia may cause iatrogenic complications. We assessed the safety of guidewire-based measurement of coronary physiology, using intravenous adenosine, in patients with an acute coronary syndrome. We prospectively enrolled invasively managed STEMI and NSTEMI patients in two simultaneously conducted studies in 6 centers (NCT01764334; NCT02072850). All of the participants underwent a diagnostic coronary guidewire study using intravenous adenosine (140 μg/kg/min) infusion for 1-2 min. The patients were prospectively assessed for the occurrence of serious adverse events (SAEs) and symptoms and invasively measured hemodynamics were also recorded. 648 patients (n=298 STEMI patients in 1 hospital; mean time to reperfusion 253 min; n=350 NSTEMI in 6 hospitals; median time to angiography from index chest pain episode 3 (2, 5) days) were included between March 2011 and May 2013. Two NSTEMI patients (0.3% overall) experienced a coronary dissection related to the guidewire. No guidewire dissections occurred in the STEMI patients. Chest symptoms were reported in the majority (86%) of patient's symptoms during the adenosine infusion. No serious adverse events occurred during infusion of adenosine and all of the symptoms resolved after the infusion ceased. In this multicenter analysis, guidewire-based measurement of FFR and IMR using intravenous adenosine was safe in patients following STEMI or NSTEMI. Self-limiting symptoms were common but not associated with serious adverse events. Finally, coronary dissection in STEMI and NSTEMI patients was noted to be a rare phenomenon. Copyright © 2015 The Authors. Published by Elsevier Ireland Ltd.. All rights reserved.

  1. Quantitative assessment of blood flow reserve using {sup 99m}Tc-HMPAO in carotid stenosis

    Energy Technology Data Exchange (ETDEWEB)

    Garai, I.; Varga, J.; Galuska, L. [Department of Nuclear Medicine, University of Debrecen Medical and Health Centre, Debrecen (Hungary); Szomjak, E. [3. Department of Internal Medicine, University of Debrecen Medical and Health Centre, Debrecen (Hungary); Toth, C.; Olvaszto, S. [1. Department of Surgery, University of Debrecen Medical and Health Centre, Debrecen (Hungary); Bank, J. [Department of Neurology, Kenezy Hospital (Hungary); Ficzere, A. [Department of Neurology, University of Debrecen Medical and Health Centre, Debrecen (Hungary)

    2002-02-01

    Dynamic imaging of the inflow of technetium-99m hexamethylpropylene amine oxime (HMPAO) to the brain has been proved to allow estimation of the hemispherical cerebral blood flow (CBF) using the Patlak plot. In this study, we compared the hemispherical CBF (in ml/min/100 g) of different patient groups. A total of 25 patients (comprising 13 with migraine and 12 scheduled for endarterectomy owing to angiographically confirmed severe stenosis of the internal carotid artery on at least one side) underwent baseline and acetazolamide {sup 99m}Tc-HMPAO brain perfusion studies. In addition, acetazolamide {sup 99m}Tc-HMPAO studies were performed in 12 healthy subjects (no baseline study was performed for ethical reasons.) Dynamic studies were acquired by means of a dual-detector gamma camera with a large field of view (HELIX, Elscint). Special difference images were created to make definition of the aortic arch and hemispherical brain regions easier and more reproducible. A semi-automatic method was developed to determine the transit time from the aorta to the brain, making the generation of the Patlak plot even more robust. The baseline CBF values did not significantly depend on the disease (P>0.1), whereas the CBF values obtained after acetazolamide provocation did do so (ANOVA, P<0.001). Patients suffering from migraine showed a significant increase in global CBF values after acetazolamide provocation (paired t test, P<0.05), but we could not find any effect of the provocation in patients awaiting carotid endarterectomy, indicating a lack of cerebrovascular reserve capacity. Comparison of the results of the acetazolamide study in patients and the control group revealed the CBF values to be significantly lower in patients with carotid stenosis (two-sample t-test, P<0.001), but not in those with migraine (P>0.1). In summary, using quantitative analysis of {sup 99m}Tc-HMPAO brain studies we could objectively compare the CBF of patients suffering from different diseases

  2. Simulation of groundwater flow and interaction of groundwater and surface water on the Lac du Flambeau Reservation, Wisconsin

    Science.gov (United States)

    Juckem, Paul F.; Fienen, Michael N.; Hunt, Randall J.

    2014-01-01

    The Lac du Flambeau Band of Lake Superior Chippewa and Indian Health Service are interested in improving the understanding of groundwater flow and groundwater/surface-water interaction on the Lac du Flambeau Reservation (Reservation) in southwest Vilas County and southeast Iron County, Wisconsin, with particular interest in an understanding of the potential for contamination of groundwater supply wells and the fate of wastewater that is infiltrated from treatment lagoons on the Reservation. This report describes the construction, calibration, and application of a regional groundwater flow model used to simulate the shallow groundwater flow system of the Reservation and water-quality results for groundwater and surface-water samples collected near a system of waste-water-treatment lagoons. Groundwater flows through a permeable glacial aquifer that ranges in thickness from 60 to more than 200 feet (ft). Seepage and drainage lakes are common in the area and influence groundwater flow patterns on the Reservation. A two-dimensional, steady-state analytic element groundwater flow model was constructed using the program GFLOW. The model was calibrated by matching target water levels and stream base flows through the use of the parameter-estimation program, PEST. Simulated results illustrate that groundwater flow within most of the Reservation is toward the Bear River and the chain of lakes that feed the Bear River. Results of analyses of groundwater and surface-water samples collected downgradient from the wastewater infiltration lagoons show elevated levels of ammonia and dissolved phosphorus. In addition, wastewater indicator chemicals detected in three downgradient wells and a small downgradient stream indicate that infiltrated wastewater is moving southwest of the lagoons toward Moss Lake. Potential effects of extended wet and dry periods (within historical ranges) were evaluated by adjusting precipitation and groundwater recharge in the model and comparing the

  3. Coronary flow reserve as a link between diastolic and systolic function and exercise capacity in heart failure

    DEFF Research Database (Denmark)

    Snoer, Martin; Monk-Hansen, Tea; Olsen, Rasmus Huan

    2012-01-01

    AIMS: In heart failure, a reduced exercise capacity is the prevailing symptom and an important prognostic marker of future outcome. The purpose of the study was to assess the relation of coronary flow reserve (CFR) to diastolic and systolic function in heart failure and to determine which...... are the limiting factors for exercise capacity. METHODS AND RESULTS: Forty-seven patients with left ventricular ejection fraction (LVEF)...

  4. Cerebral blood flow and cerebrovascular reserve capacity: estimation by dynamic magnetic resonance imaging.

    Science.gov (United States)

    Schreiber, W G; Gückel, F; Stritzke, P; Schmiedek, P; Schwartz, A; Brix, G

    1998-10-01

    We have developed a new method for estimation of regional CBF (rCBF) and cerebrovascular reserve capacity on a pixel-by-pixel basis by means of dynamic magnetic resonance imaging (MRI). Thirteen healthy volunteers, 8 patients with occlusion and/or high grade stenosis of the internal carotid artery (ICA), and 2 patients with acute stroke underwent dynamic susceptibility-weighted contrast enhanced MRI. Using principles of indicator dilution theory and deconvolution analysis, maps of rCBF, regional cerebral blood volume, and of the mean transit time (MTT) were calculated. In patients with ICA occlusion/stenosis, cerebrovascular reserve capacity was assessed by the rCBF increase after acetazolamide stimulation. Mean gray and white matter rCBF values in normals were 67.1 and 23.7 mL x 100 g(-1) x min(-1), respectively. Before acetazolamide stimulation, six of eight patients with ICA occlusions showed decreased rCBF values; and in seven patients increased MTT values were observed in tissue ipsilateral to the occlusion. After acetazolamide stimulation, decreased cerebrovascular reserve capacity was observed in five of eight patients with ICA occlusion. In acute stroke, rCBF in the central core of ischemia was less than 8 mL x 100 g(-1) x min(-1). In peri-infarct tissue, rCBF and MTT were higher than in unaffected tissue but rCBF was normal. Dynamic MRI provides important clinical information on the hemodynamic state of brain tissue in patients with occlusive cerebrovascular disease or acute stroke.

  5. Resource Flows of Villages with Contrasting Lifestyles in Nanda Devi Biosphere Reserve, Central Himalaya, India

    Institute of Scientific and Technical Information of China (English)

    K. S. Rao; S. Nautiyal; R. K. Maikhuri; K. G. Saxena

    2005-01-01

    Resource use efficiency analyses of village ecosystem are necessary for effective and efficient planning of resource utilization. This paper deals with economic and energy input-output analyses of different components of village ecosystem in representative buffer zone villages, which are practicing transhumance and settled way of lifestyles in Nanda Devi Biosphere Reserve (NDBR) of Garhwal Himalaya. While the villages practicing transhumance used various natural resources spatially segregated,the villages practicing settled way of lifestyle have to manage resources from a limited spatial area through rotation and varied extraction intensities. Forests subsidized the production activity in both type of villages and the per capita resource extractions were found to be greater in transhumance village than settled village. Though crops provided maximum energy, in terms of economic criteria, animal husbandry played important role in both settled and transhumance villages. As villages representing both the situations showed different ways of adjustments to the conservation oriented land use changes,management authority needs to address the eco-development plans fulfilling the aspirations of all people traditionally using the resources of the Reserve to reduce the conflicts and encourage their participation in the conservation of the area.

  6. Numerical Simulation and Clinical Implications of Stenosis in Coronary Blood Flow

    Science.gov (United States)

    Zhong, Liang; Luo, Tong; Huo, Yunlong; Tan, Swee Yaw; Wong, Aaron Sung Lung; Su, Boyang; Zhao, Xiaodan; Kassab, Ghassan S.; Khoo, Boo Cheong; Kang, Chang-Wei; Tan, Ru San

    2014-01-01

    Fractional flow reserve (FFR) is the gold standard to guide coronary interventions. However it can only be obtained via invasive angiography. The objective of this study is to propose a noninvasive method to determine FFRCT by combining computed tomography angiographic (CTA) images and computational fluid dynamics (CFD) technique. Utilizing the method, this study explored the effects of diameter stenosis (DS), stenosis length, and location on FFRCT. The baseline left anterior descending (LAD) model was reconstructed from CTA of a healthy porcine heart. A series of models were created by adding an idealized stenosis (with DS from 45% to 75%, stenosis length from 4 mm to 16 mm, and at 4 locations separately). Through numerical simulations, it was found that FFRCT decreased (from 0.89 to 0.74), when DS increased (from 45% to 75%). Similarly, FFRCT decreased with the increase of stenosis length and the stenosis located at proximal position had lower FFRCT than that at distal position. These findings are consistent with clinical observations. Applying the same method on two patients' CTA images yielded FFRCT close to the FFR values obtained via invasive angiography. The proposed noninvasive computation of FFRCT is promising for clinical diagnosis of CAD. PMID:24987691

  7. Relationship between glycosylated hemoglobin A1c and coronary flow reserve in patients with Type 2 diabetes mellitus.

    Science.gov (United States)

    Huang, Runqing; Abdelmoneim, Sahar S; Nhola, Lara F; Basu, Rita; Basu, Ananda; Mulvagh, Sharon L

    2015-04-01

    Type 2 diabetes mellitus patients are at increased risk for macrovascular and microvascular complications. Both in vivo and in vitro studies of small arteries and arterioles of diabetic subjects demonstrate impaired endothelial function without anatomic lesions. Coronary flow reserve (CFR) is a surrogate marker of coronary microcirculatory endothelial function in diabetic patients without significant stenosis of the associated epicardial coronary artery. Glycosylated hemoglobin A1c is related to likelihood of occurrence of microvascular events. The objective of this article is to report on recent developments in multiple noninvasive techniques to assess CFR and their use in aiding the understanding of the relationship of CFR, glycemic control and cardiovascular outcomes.

  8. Relationship between coronary flow reserve evaluated by phase-contrast cine cardiovascular magnetic resonance and serum eicosapentaenoic acid

    Science.gov (United States)

    2013-01-01

    Background Long-term intake of long-chain n-3 polyunsaturated fatty acids (n-3 PUFAs), especially eicosapentaenoic acid (EPA) is associated with a low risk for cardiovascular disease. Phase-contrast cine cardiovascular magnetic resonance (PC cine CMR) can assess coronary flow reserve (CFR). The present study investigates the relationship between CFR evaluated by PC cine CMR and the serum EPA. Methods We studied 127 patients (male, 116 (91%); mean age, 72.2 ± 7.4 years) with known or suspected coronary artery disease (CAD). X-ray coronary angiography revealed no significant coronary arterial stenoses (defined as luminal diameter reduction ≥50% on quantitative coronary angiogram (QCA) analysis) in all study participants. Breath-hold PC cine CMR images of the coronary sinus (CS) were acquired to assess blood flow of the CS both at rest and during adenosine triphosphate (ATP) infusion. We calculated CFR as CS blood flow during ATP infusion divided by that at rest. Patients were allocated to groups according to whether they had high (n = 64, EPA ≥ 75.8 μg/mL) or low (n = 63, EPA  2.5, which is the previously reported lower limit of normal flow reserve without obstructive CAD. Multivariate analysis revealed that EPA is an independent predictor of CFR > 2.5 (odds ratio, 1.01; 95% confidence interval, 1.00 – 1.02, p = 0.008). Conclusions The serum EPA is significantly correlated with CFR in CAD patients without significant coronary artery stenosis. PMID:24359564

  9. Normal Myocardial Flow Reserve in HIV-Infected Patients on Stable Antiretroviral Therapy

    DEFF Research Database (Denmark)

    Knudsen, Andreas; Christensen, Thomas E; Ghotbi, Adam Ali

    2015-01-01

    ), which can quantify the coronary microvascular function. MFR has proved highly predictive of future coronary artery disease and cardiovascular events in the general population.In a prospective cross-sectional study, HIV-infected patients all receiving antiretroviral therapy (ART) with full viral....... The HIV-infected patients had a mean age of 53 years (range 37-68 years) with 23% active smokers. The controls had a mean age of 52 years (range 36-68 years) and 26% active smokers. In the HIV-infected group 73% had a normal MFR, 17% borderline, and 10% low values of MFR. Among controls these values were...... 71%, 19%, and 10%, respectively (P = 0.99). However, the HIV-infected group had lower values of stress myocardial blood flow (MBF) (2.63 ± 0.09 mL/g/min vs 2.99 ± 0.14 mL/g/min; P = 0.03). We found no evidence of decreased MFR as assessed by 82Rb PET among HIV-infected patients on stable ART...

  10. Optimization of flow reserve measurement using SPECT technology to evaluate the determinants of coronary microvascular dysfunction in diabetes

    Energy Technology Data Exchange (ETDEWEB)

    Marini, Cecilia [CNR Institute of Bioimages and Molecular Physiology, Milan, Section of Genoa (Italy); Bezante, GianPaolo; Modonesi, Elisa; Rollando, Daniela; Balbi, Manrico; Brunelli, Claudio [University of Genoa, Department of Internal Medicine, Cardiology, Genoa (Italy); Gandolfo, Patrizia; Morbelli, Silvia D.; Armonino, Riccardo [University of Genoa, Department of Internal Medicine, Nuclear Medicine, Genoa (Italy); DePascale, Angelo; Maggi, Davide; Albertelli, Manuela; Cordera, Renzo [University of Genoa, Department of Endocrinological Metabolic Sciences, Diabetology, Genoa (Italy); Sambuceti, Gianmario [University of Genoa, Department of Internal Medicine, Nuclear Medicine, Genoa (Italy); Advanced Biotechnology Center, Genoa (Italy)

    2010-02-15

    The aim of this study was to validate a new method to measure regional myocardial perfusion reserve (MPR) with technetium-labelled tracers in patients with type 2 diabetes mellitus (DM2). A total of 40 consecutive DM2 patients without history of coronary artery disease (CAD) and 7 control subjects were recruited. Dipyridamole myocardial blood flow index (MBF) was assessed by measuring first transit counts in the pulmonary artery and myocardial count rate from gated SPECT images using {sup 99m}Tc-labelled tracers. The corresponding MBF index was estimated 2 h later according to the same procedure. Regional myocardial perfusion reserve (MPR) was defined as the ratio between dipyridamole and baseline MBF using a 17-segment left ventricular (LV) model. Coronary flow reserve (CFR) was estimated by transthoracic contrast echo Doppler monitoring of flow velocity in the left anterior descending coronary artery (LAD) during the same session. Estimated MPR was higher in control subjects than in patients (3.36 {+-} 0.66 vs 1.91 {+-} 0.61, respectively, p < 0.01). In patients, LAD CFR and LAD MPR were 2.01 {+-} 0.78 vs 1.93 {+-} 0.63, respectively (p = ns). The agreement between the two techniques was documented by their close correlation (r = 0.92, p < 0.001) and confirmed by the Bland-Altman analysis. Reversible perfusion defects occurred in 13 patients (32%) who showed similar MPR values as the remaining 27 (2.10 {+-} 0.71 vs 1.83 {+-} 0.71, respectively, p = ns). Finally, MPR was closely correlated with age (r = -0.50, p < 0.01) and time elapsed from the diagnosis of DM2 (r = -0.51, p < 0.01). LV regional MPR can be accurately estimated with the broadly available single photon technology. Application of this method to DM2 patients documents the presence of a microvascular dysfunction homogeneously distributed throughout the LV walls and most frequently not associated with reversible perfusion defects. (orig.)

  11. Patient-specific coronary artery blood flow simulation using myocardial volume partitioning

    Science.gov (United States)

    Kim, Kyung Hwan; Kang, Dongwoo; Kang, Nahyup; Kim, Ji-Yeon; Lee, Hyong-Euk; Kim, James D. K.

    2013-03-01

    Using computational simulation, we can analyze cardiovascular disease in non-invasive and quantitative manners. More specifically, computational modeling and simulation technology has enabled us to analyze functional aspect such as blood flow, as well as anatomical aspect such as stenosis, from medical images without invasive measurements. Note that the simplest ways to perform blood flow simulation is to apply patient-specific coronary anatomy with other average-valued properties; in this case, however, such conditions cannot fully reflect accurate physiological properties of patients. To resolve this limitation, we present a new patient-specific coronary blood flow simulation method by myocardial volume partitioning considering artery/myocardium structural correspondence. We focus on that blood supply is closely related to the mass of each myocardial segment corresponding to the artery. Therefore, we applied this concept for setting-up simulation conditions in the way to consider many patient-specific features as possible from medical image: First, we segmented coronary arteries and myocardium separately from cardiac CT; then the myocardium is partitioned into multiple regions based on coronary vasculature. The myocardial mass and required blood mass for each artery are estimated by converting myocardial volume fraction. Finally, the required blood mass is used as boundary conditions for each artery outlet, with given average aortic blood flow rate and pressure. To show effectiveness of the proposed method, fractional flow reserve (FFR) by simulation using CT image has been compared with invasive FFR measurement of real patient data, and as a result, 77% of accuracy has been obtained.

  12. Quantitation of myocardial blood flow and myocardial flow reserve with {sup 99m}Tc-sestamibi dynamic SPECT/CT to enhance detection of coronary artery disease

    Energy Technology Data Exchange (ETDEWEB)

    Hsu, Bailing [University of Missouri-Columbia, Nuclear Science and Engineering Institute, Columbia, MO (United States); Chen, Fu-Chung; Chen, Chien-Cheng [Show Chwan Memorial Hospital, Section of Cardiology, Department of Internal Medicine, Changhua (China); Wu, Tao-Cheng [Taipei Veterans General Hospital, Section of Cardiology, Department of Internal Medicine, Taipei (China); Huang, Wen-Sheng [Changhua Christian Hospital, Department of Medical Research and Department of Nuclear Medicine, Changhua (China); Hou, Po-Nien [Chang Bing Show Chwan Memorial Hospital, Department of Nuclear Medicine, Lukong Town, Changhua Shien (China); Hung, Guang-Uei [Chang Bing Show Chwan Memorial Hospital, Department of Nuclear Medicine, Lukong Town, Changhua Shien (China); Central Taiwan University of Science and Technology, Department of Medical Imaging and Radiological Science, Taichung (China); China Medical University, Department of Biomedical Imaging and Radiological Science, Taichung (China)

    2014-12-15

    Conventional dual-head single photon emission computed tomography (SPECT)/CT systems capable of fast dynamic SPECT (DySPECT) imaging have a potential for flow quantitation. This study introduced a new method to quantify myocardial blood flow (MBF) and myocardial flow reserve (MFR) with DySPECT scan and evaluated the diagnostic performance of detecting coronary artery disease (CAD) compared with perfusion using invasive coronary angiography (CAG) as the reference standard. This study included 21 patients with suspected or known CAD who had received DySPECT, ECG-gated SPECT (GSPECT), and CAG (13 with ≥50 % stenosis in any vessel; non-CAD group: 8 with patent arteries or <50 % stenosis). DySPECT and GSPECT scans were performed on a widely used dual-head SPECT/CT scanner. The DySPECT imaging protocol utilized 12-min multiple back-and-forth gantry rotations during injections of {sup 99m}Tc-sestamibi (MIBI) tracer at rest or dipyridamole-stress stages. DySPECT images were reconstructed with full physical corrections and converted to the physical unit of becquerels per milliliter. Stress MBF (SMBF), rest MBF (RMBF), and MFR were quantified by a one-tissue compartment flow model using time-activity curves derived from DySPECT images. Perfusion images were processed for GSPECT scan and interpreted to obtain summed stress score (SSS) and summed difference score (SDS). Receiver-operating characteristic (ROC) analyses were conducted to evaluate the diagnostic performance of flow and perfusion. Using the criteria of ≥50 % stenosis as positive CAD, areas under the ROC curve (AUCs) of flow assessment were overall significantly greater than those of perfusion. For patient-based analysis, AUCs for MFR, SMBF, SSS, and SDS were 0.91 ± 0.07, 0.86 ± 0.09, 0.64 ± 0.12, and 0.59 ± 0.13. For vessel-based analysis, AUCs for MFR, SMBF, SSS, and SDS were 0.81 ± 0.05, 0.76 ± 0.06, 0.62 ± 0.07, and 0.56 ± 0.08, respectively. The preliminary data suggest that MBF quantitation with a

  13. The Bolivar Channel Ecosystem of the Galapagos Marine Reserve: Energy flow structure and role of keystone groups

    Science.gov (United States)

    Ruiz, Diego J.; Wolff, Matthias

    2011-08-01

    The Bolivar Channel Ecosystem (BCE) is among the most productive zones in the Galapagos Marine Reserve (GMR). It is exposed to relatively cool, nutrient-rich waters of the Cromwell current, which are brought to the photic zone through topographic upwelling. The BCE is characterized by a heterogeneous rocky reef habitat covered by dense algae beds and inhabited by numerous invertebrate and fish species, which represent the food for higher predators including seals and sharks and exploited fish species. In addition, plankton and detritus based food chains channel large amounts of energy through the complex food web. Important emblematic species of the Galapagos archipelagos reside in this area such as the flightless cormorant, the Galapagos penguin and the marine iguanas. A trophic model of BCE was constructed for the habitats barracudas should be emphasized for their great contribution to the trophic flows and biomass of the system.

  14. Coronary flow reserve evaluated by {sup 201}Tl myocardial perfusion SPECT after coronary artery bypass grafting (CABG) for angina pectoris

    Energy Technology Data Exchange (ETDEWEB)

    Ishino, Yoichi; Nakata, Hajime [Univ. of Occupational and Environmental Health, Kitakyusyu, Fukuoka (Japan)

    2000-11-01

    We compared the flow reserves of the coronary bypass vessels between arterial and venous grafts by {sup 201}Tl myocardial perfusion SPECT on the patients with angina pectoris who had no past history of myocardial infarction or intervention therapy such as PTCA. Thirty two patients had undergone a total of 70 bypass grafts and 66 of them were proved to be patent at postoperative CAG. Reversible defects were observed in 6 of 40 segments (15.0%) covered by patent venous grafts, and in 11 of 26 segments (42.3%) by patent arterial grafts. The rate of postoperative reversible defects was higher in the areas grafted by artery but this had no relation with the severity of coronary artery stenosis before CABG. This reversible defect is most likely to be caused by the character of artery graft itself and this should not be considered to highly suggest the restenosis or occlusion of the graft vessel. (author)

  15. Feasibility and diagnostic power of transthoracic coronary Doppler for coronary flow velocity reserve in patients referred for myocardial perfusion imaging

    Directory of Open Access Journals (Sweden)

    Nylander Eva

    2008-03-01

    Full Text Available Abstract Background Myocardial perfusion imaging (MPI, using single photon emission computed tomography (SPECT is a validated method for detecting coronary artery disease. Transthoracic Doppler echocardiography (TTDE of flow at rest and during adenosine provocation has previously been evaluated in selected patient groups. We therefore wanted to compare the diagnostic ability of TTDE in the left anterior descending coronary artery (LAD to that of MPI in an unselected population of patients with chest pain referred for MPI. Our hypothesis was that TTDE with high accuracy would identify healthy individuals and exclude them from the need for further studies, enabling invasive investigations to be reserved for patients with a high probability of disease. Methods Sixty-nine patients, 44 men and 25 women, age 61 ± 10 years (range 35–82, with a clinical suspicion of stress induced myocardial ischemia, were investigated. TTDE was performed at rest and during adenosine stress for myocardial scintigraphy. Results We found that coronary flow velocity reserve (CFVR determined from diastolic measurements separated normal from abnormal MPI findings with statistical significance. TTDE identified coronary artery disease, defined from MPI, as reversible ischemia and/or permanent defect, with a sensitivity of 60% and a specificity of 79%. The positive predictive value was 43% and the negative predictive value was 88%. There was an overlap between groups which could be due to abnormal endothelial function in patients with normal myocardial perfusion having either hypertension or diabetes. Conclusion TTDE is an attractive non-invasive method to evaluate chest pain without the use of isotopes, but the diagnostic power is strongly dependent on the population investigated. Even in our heterogeneous clinical cardiac population, we found that CFVR>2 in the LAD excluded significant coronary artery disease detected by MPI.

  16. 导管室护士在FFR检测术中配合及护理%International Nurses in FFR Detection of Intraoperative Cooperation and Nursing

    Institute of Scientific and Technical Information of China (English)

    何彩勤

    2013-01-01

    目的:探讨导管室护士在FFR检测术中的护理配合。方法对20例行FFR检测术的患者进行术中护理配合和严密观察病情。结果20例患者均顺利完成手术,1例患者的并发症得到了及时发现与及时处理,无一例死亡。结论导管室护士的护理配合是手术顺利进行的重要保证。%Objective to study the international nurses in perioperative nursing cooperation in FFR detection. Methods 20 patients with routine FFR detection technique for intraoperative nursing cooperation and observe closely. Results 20 patients were successful y completed surgery, 1 case of patients with complications timely detection and timely treatment, with no deaths. Conclusion the international nurses nursing cooperation is important guarantee for the smooth operation.

  17. Impaired myocardial blood flow reserve in subjects with metabolic syndrome analyzed using positron emission tomography and N-13 labeled ammonia

    Energy Technology Data Exchange (ETDEWEB)

    Teragawa, Hiroki; Kihara, Yasuki [Hiroshima University Graduate School of Biomedical Sciences, Department of Cardiovascular Medicine, Hiroshima (Japan); Morita, Koichi; Tamaki, Nagara [Hokkaido University Graduate School of Medicine, Department of Nuclear Medicine, Sapporo (Japan); Shishido, Hiroki; Otsuka, Nobuaki; Hirokawa, Yutaka [Hiroshima Heiwa Clinic, Hiroshima (Japan); Chayama, Kazuaki [Hiroshima University Graduate School of Biomedical Sciences, Department of Molecular Science and Medicine, Hiroshima (Japan)

    2010-02-15

    Coronary vasomotor response might be impaired in metabolic syndrome (MS); however, the precise abnormality has not been elucidated. The aim of this study was to assess coronary-vasomotor response in MS subjects using N-13 labeled ammonia and positron emission tomography. Myocardial blood flow (MBF) was measured at rest and during adenosine infusion in MS subjects (n = 13, MS group) with no definite evidence of heart disease and in subjects without MS (n = 14, non-MS group). Coronary vascular resistance (CVR) was calculated by dividing the mean aortic blood pressure by MBF. Myocardial blood flow reserve (MFR) was calculated as the ratio of the MBF during adenosine infusion to that during rest. Blood chemical parameters were measured to evaluate their relationship with MFR. During adenosine infusion, MBF was lower (p = 0.0085) and CVR higher (p = 0.0128) in the MS group than in the non-MS group and MFR was significantly lower in the MS group than in the non-MS group (2.13 {+-} 0.99 vs. 3.38 {+-} 0.95, p = 0.0027). Multivariate analysis demonstrated that the homeostasis model assessment-insulin resistance (p < 0.05) and the presence of hypertension (p < 0.05) were independent determinants of MFR. The results indicate that MFR was impaired in MS subjects, suggesting that an abnormal coronary microvascular response occurred in these subjects. This abnormality may have been partially due to insulin resistance and hypertension. (orig.)

  18. Quantitative relationship between coronary calcium content and coronary flow reserve as assessed by integrated PET/CT imaging

    Energy Technology Data Exchange (ETDEWEB)

    Curillova, Zelmira [Brigham and Women' s Hospital, Division of Nuclear Medicine and Molecular Imaging, Department of Radiology, Boston, MA (United States); VA Boston Healthcare System, Division of Cardiology, Department of Medicine, West Roxbury, MA (United States); Yaman, Bettina F.; Sitek, Arkadius; El Fakhri, Georges [Brigham and Women' s Hospital, Division of Nuclear Medicine and Molecular Imaging, Department of Radiology, Boston, MA (United States); Dorbala, Sharmila [Brigham and Women' s Hospital, Division of Nuclear Medicine and Molecular Imaging, Department of Radiology, Boston, MA (United States); Brigham and Women' s Hospital, Noninvasive Cardiovascular Imaging Program, Departments of Medicine (Cardiology) and Radiology, Boston, MA (United States); Kwong, Raymond Y. [Harvard Medical School, Division of Cardiovascular Medicine, Department of Medicine, Brigham and Women' s Hospital, Boston, MA (United States); Brigham and Women' s Hospital, Noninvasive Cardiovascular Imaging Program, Departments of Medicine (Cardiology) and Radiology, Boston, MA (United States); Anagnostopoulos, Constantinos [Brigham and Women' s Hospital, Division of Nuclear Medicine and Molecular Imaging, Department of Radiology, Boston, MA (United States); Royal Brompton Hospital, Department of Nuclear Medicine, London (United Kingdom); Di Carli, Marcelo F. [Brigham and Women' s Hospital, Division of Nuclear Medicine and Molecular Imaging, Department of Radiology, Boston, MA (United States); Harvard Medical School, Division of Cardiovascular Medicine, Department of Medicine, Brigham and Women' s Hospital, Boston, MA (United States); Brigham and Women' s Hospital, Noninvasive Cardiovascular Imaging Program, Departments of Medicine (Cardiology) and Radiology, Boston, MA (United States); Brigham and Women' s Hospital, Division of Nuclear Medicine and Molecular Imaging, Boston, MA (United States)

    2009-10-15

    To evaluate the relationship between coronary artery calcium (CAC) and coronary vasodilator function. We evaluated 136 patients without known coronary artery disease (CAD) undergoing vasodilator stress {sup 82}Rb PET/CT and CAC scoring who showed normal myocardial perfusion. The CAC score, resting and hyperemic myocardial blood flow (MBF), coronary flow reserve (CFR) and coronary vascular resistance were analyzed. Global and regional CAC scores showed significant but weak inverse correlations with hyperemic MBF (r=-0.31 and r=-0.26, p{<=}0.0002 respectively) and CFR (r=-0.28 and r=-0.2, p{<=}0.001 respectively). With increasing CAC score, there was a modest stepwise decline in CFR on a per-patient basis (1.8{+-}0.5 vs 1.7{+-}0.5 vs 1.5{+-}0.4, p=0.048, with total CAC=0, 1-400 and >400, respectively) and on a per-vessel basis. In multivariable modeling only body mass index and CAC score were predictive of CFR. In patients with an intermediate likelihood of, but without overt, CAD, there is a statistically significant but weak inverse correlation between CAC content and coronary vasodilator function. The strength of this association weakens after adjusting CAC scores for age, gender and coronary risk factors. This suggests that CAC and coronary vasodilator function provide biologically different information regarding atherosclerosis. (orig.)

  19. Quantification of coronary flow reserve in patients with ischaemic and non-ischaemic cardiomyopathy and its association with clinical outcomes

    Science.gov (United States)

    Majmudar, Maulik D.; Murthy, Venkatesh L.; Shah, Ravi V.; Kolli, Swathy; Mousavi, Negareh; Foster, Courtney R.; Hainer, Jon; Blankstein, Ron; Dorbala, Sharmila; Sitek, Arkadiusz; Stevenson, Lynne W.; Mehra, Mandeep R.; Di Carli, Marcelo F.

    2015-01-01

    Aims Patients with left ventricular systolic dysfunction frequently show abnormal coronary vascular function, even in the absence of overt coronary artery disease. Moreover, the severity of vascular dysfunction might be related to the aetiology of cardiomyopathy. We sought to determine the incremental value of assessing coronary vascular dysfunction among patients with ischaemic (ICM) and non-ischaemic (NICM) cardiomyopathy at risk for adverse cardiovascular outcomes. Methods and results Coronary flow reserve (CFR, stress/rest myocardial blood flow) was quantified in 510 consecutive patients with rest left ventricular ejection fraction (LVEF) ≤45% referred for rest/stress myocardial perfusion PET imaging. The primary end point was a composite of major adverse cardiovascular events (MACE) including cardiac death, heart failure hospitalization, late revascularization, and aborted sudden cardiac death. Median follow-up was 8.2 months. Cox proportional hazards model was used to adjust for clinical variables. The annualized MACE rate was 26.3%. Patients in the lowest two tertiles of CFR (CFR ≤ 1.65) experienced higher MACE rates than those in the highest tertile (32.6 vs. 15.5% per year, respectively, P = 0.004), irrespective of aetiology of cardiomyopathy. Conclusion Impaired coronary vascular function, as assessed by reduced CFR by PET imaging, is common in patients with both ischaemic and non-ischaemic cardiomyopathy and is associated with MACE. PMID:25719181

  20. Impact of individual and cumulative coronary risk factors on coronary flow reserve assessed by dobutamine stress echocardiography.

    Science.gov (United States)

    Ahmari, Saeed A L; Bunch, T Jared; Modesto, Karen; Stussy, Vicky; Dichak, Amy; Seward, James B; Pellikka, Patricia A; Chandrasekaran, Krishnaswamy

    2008-06-15

    Traditional cardiovascular risk factors have been shown to cause microvascular dysfunction. Most studies that have evaluated microcirculation rely on invasive measurement tools. We used dobutamine stress echocardiography, a validated method to measure coronary flow velocity (CFV) and coronary flow reserve (CFR), in a previously unstudied population without known significant coronary artery disease to determine the impact of traditional risk factors on CFR. Consecutive patients who had no evidence of regional wall motion abnormalities at rest or during dobutamine stress echocardiography were studied. Left anterior descending artery CFV was measured at baseline and at peak dobutamine stress and CFR was calculated as the ratio of peak stress CFV to baseline CFV. Fifty-nine consecutive patients (28 men) with mean age of 66.8+/-14.5 years were studied. CFR was lower in patients with diabetes mellitus (DM) compared with those without (1.7+/-0.74 vs 2.48+/-0.98, p50 mm Hg), and obesity with a wide pulse pressure. In a multivariate model, DM, obesity, and wide pulse pressure were significantly associated with variation in CFR (p<0.0008). In conclusion, CFR was abnormal in patients with DM, hypertension, and obesity. CFR impairment is exaggerated as the number of risk factors increases. Despite a negative dobutamine stress echocardiographic result, aggressive risk factor assessment and control should be implemented in patients with coronary risk factors due to an underlying abnormal CFR.

  1. Assessment of endothelial function and myocardial flow reserve using {sup 15}O-water PET without attenuation correction

    Energy Technology Data Exchange (ETDEWEB)

    Tuffier, Stephane; Joubert, Michael; Bailliez, Alban [EA 4650, Normandie Universite, Caen (France); Legallois, Damien [EA 4650, Normandie Universite, Caen (France); Caen University Hospital, Department of Cardiology, Caen (France); Belin, Annette [Caen University Hospital, Department of Cardiac Surgery, Caen (France); Redonnet, Michel [Rouen University Hospital, Department of Cardiac Surgery, Rouen (France); Agostini, Denis [EA 4650, Normandie Universite, Caen (France); Caen University Hospital, Department of Nuclear Medicine, Caen (France); Manrique, Alain [EA 4650, Normandie Universite, Caen (France); Caen University Hospital, Department of Nuclear Medicine, Caen (France); Cyceron PET Centre, Caen (France)

    2016-02-15

    Myocardial blood flow (MBF) measurement using positron emission tomography (PET) from the washout rate of {sup 15}O-water is theoretically independent of tissue attenuation. The aim of this study was to evaluate the impact of not using attenuation correction in the assessment of coronary endothelial function and myocardial flow reserve (MFR) using {sup 15}O-water PET. We retrospectively processed 70 consecutive {sup 15}O-water PET examinations obtained at rest and during cold pressor testing (CPT) in patients with dilated cardiomyopathy (n = 58), or at rest and during adenosine infusion in heart transplant recipients (n = 12). Data were reconstructed with attenuation correction (AC) and without attenuation correction (NAC) using filtered backprojection, and MBF was quantified using a single compartmental model. The agreement between AC and NAC data was assessed using Lin's concordance correlation coefficient followed by Bland-Altman plot analysis. Regarding endothelial function, NAC PET showed poor reproducibility and poor agreement with AC PET data. Conversely, NAC PET demonstrated high reproducibility and a strong agreement with AC PET for the assessment of MFR. Non-attenuation-corrected {sup 15}O-water PET provided an accurate measurement of MFR compared to attenuation-corrected PET. However, non-attenuation-corrected PET data were less effective for the assessment of endothelial function using CPT in this population. (orig.)

  2. Subendocardial viability ratio as an index of impaired coronary flow reserve in hypertensives without significant coronary artery stenoses.

    Science.gov (United States)

    Tsiachris, D; Tsioufis, C; Syrseloudis, D; Roussos, D; Tatsis, I; Dimitriadis, K; Toutouzas, K; Tsiamis, E; Stefanadis, C

    2012-01-01

    Subendocardial viability ratio (SEVR), calculated through pulse wave analysis, is an index of myocardial oxygen supply and demand. Our aim was to evaluate the relationship between coronary flow reserve (CFR) and SEVR in 36 consecutive untreated hypertensives (aged 57.9 years, 12 males, all Caucasian) with indications of myocardial ischaemia and normal coronary arteries in coronary angiography. CFR was calculated by a 0.014-inch Doppler guidewire (Flowire, Volcano, San Diego, CA, USA) in response to bolus intracoronary administration of adenosine (30-60 μg). SEVR was calculated by radial applanation tonometry, while diastolic function was evaluated by means of transmitral flow and tissue Doppler imaging. Hypertensive patients with low CFR (n=24) compared with those with normal CFR (n=12) exhibited significantly decreased SEVR by 24.5% (P=0.002). In hypertensives with low CFR, CFR was correlated with SEVR (r=0.651, P=0.001). After applying multivariate linear regression analysis, age, left ventricular mass index, Em/Am, 24-h diastolic blood pressure (BP) and SEVR turned out to be the only independent predictors of CFR (adjusted R(2)=0.718). Estimation of SEVR by using applanation tonometry may provide a reliable tool for the assessment of coronary microcirculation in essential hypertensives with indications of myocardial ischaemia and normal coronary arteries.

  3. Transthoracic coronary flow reserve and dobutamine derived myocardial function: a 6-month evaluation after successful coronary angioplasty

    Directory of Open Access Journals (Sweden)

    Pardo Moira

    2004-12-01

    Full Text Available Abstract After percutaneous transluminal coronary angioplasty (PTCA, stress-echocardiography and gated single photon emission computerized tomography (g-SPECT are usually performed but both tools have technical limitations. The present study evaluated results of PTCA of left anterior descending artery (LAD six months after PTCA, by combining transthoracic Doppler coronary flow reserve (CFR and color Tissue Doppler (C-TD dobutamine stress. Six months after PTCA of LAD, 24 men, free of angiographic evidence of restenosis, underwent standard Doppler-echocardiography, transthoracic CFR of distal LAD (hyperemic to basal diastolic coronary flow ratio and C-TD at rest and during dobutamine stress to quantify myocardial systolic (Sm and diastolic (Em and Am, Em/Am ratio peak velocities in middle posterior septum. Patients with myocardial infarction, coronary stenosis of non-LAD territory and heart failure were excluded. According to dipyridamole g-SPECT, 13 patients had normal perfusion and 11 with perfusion defects. The 2 groups were comparable for age, wall motion score index (WMSI and C-TD at rest. However, patients with perfusion defects had lower CFR (2.11 ± 0.4 versus 2.87 ± 0.6, p m at high-dose dobutamine (p m of middle septum (r = 0.55, p In conclusion, even in absence of epicardial coronary restenosis, stress perfusion imaging reflects a physiologic impairment in coronary microcirculation function whose magnitude is associated with the degree of regional functional impairment detectable by C-TD.

  4. Usefulness of coronary flow reserve over regional wall motion when added to dual-imaging dipyridamole echocardiography.

    Science.gov (United States)

    Rigo, Fausto; Richieri, Margherita; Pasanisi, Emilio; Cutaia, Valeria; Zanella, Carlo; Della Valentina, Patrizia; Di Pede, Francesco; Raviele, Antonio; Picano, Eugenio

    2003-02-01

    Vasodilator stress echocardiography allows semi-simultaneous imaging of left anterior descending (LAD) coronary flow and regional wall function. To assess the relative (and additive?) value of regional flow and function for noninvasive identification of angiographically assessed LAD disease in patients with chest pain syndrome, we studied 230 consecutive in-hospital patients (134 men, aged 63.5 +/- 11 years) with chest pain syndrome and normal regional and global left ventricular function. All patients underwent stress echocardiography with dipyridamole (up to 0.84 mg/kg over 10 minutes), including wall motion analysis by 2-dimensional echocardiography and coronary flow reserve (CFR) evaluation of the LAD artery by Doppler, with or without contrast injection. A new regional wall motion abnormality in >or=2 contiguous segments was required for 2-dimensional echocardiographic positivity. CFR was evaluated as the ratio of dipyridamole to peak diastolic coronary blood flow velocity at rest. All patients underwent coronary angiography within 60 days; a quantitatively assessed diameter reduction >50% of the LAD artery was considered significant. Of the 230 patients, 70 had LAD disease. A regional wall motion abnormality in LAD territory was present in 52 patients, and reduced CFR (<1.9) in 62 patients. Sensitivity for detecting LAD disease was 74% for 2-dimensional echocardiography (95% confidence interval [CI] 64% to 84%) and 81% for CFR <1.9 (95% CI 72% to 90%); specificity was 91% (95% CI 87% to 96%) for 2-dimensional echocardiography and 84% for CFR (95% CI 79% to 90%). Accuracy was 86% for 2-dimensional echocardiography (95% CI 82% to 91%) and 83.5% for CFR (95% CI 79% to 88%). When 2-dimensional echocardiography and CFR criteria were considered, sensitivity increased to 93% (95% CI 87% to 99%), with 80.6% specificity (95% CI 74.5% to 86.7%). CFR was assessed during vasodilator stress echocardiography. Its diagnostic accuracy for detecting LAD disease was comparable

  5. Measurement of pulmonary flow reserve and pulmonary index of microcirculatory resistance for detection of pulmonary microvascular obstruction.

    Directory of Open Access Journals (Sweden)

    Rahn Ilsar

    Full Text Available BACKGROUND: The pulmonary microcirculation is the chief regulatory site for resistance in the pulmonary circuit. Despite pulmonary microvascular dysfunction being implicated in the pathogenesis of several pulmonary vascular conditions, there are currently no techniques for the specific assessment of pulmonary microvascular integrity in humans. Peak hyperemic flow assessment using thermodilution-derived mean transit-time (T(mn facilitate accurate coronary microcirculatory evaluation, but remain unvalidated in the lung circulation. Using a high primate model, we aimed to explore the use of T(mn as a surrogate of pulmonary blood flow for the purpose of measuring the novel indices Pulmonary Flow Reserve [PFR = (maximum hyperemic/(basal flow] and Pulmonary Index of Microcirculatory Resistance [PIMR = (maximum hyperemic distal pulmonary artery pressurex(maximum hyperemic T(mn]. Ultimately, we aimed to investigate the effect of progressive pulmonary microvascular obstruction on PFR and PIMR. METHODS AND RESULTS: Temperature- and pressure-sensor guidewires (TPSG were placed in segmental pulmonary arteries (SPA of 13 baboons and intravascular temperature measured. T(mn and hemodynamics were recorded at rest and following intra-SPA administration of the vasodilator agents adenosine (10-400 microg/kg/min and papaverine (3-24 mg. Temperature did not vary with intra-SPA sensor position (0.010+/-0.009 v 0.010+/-0.009 degrees C; distal v proximal; p = 0.1, supporting T(mn use in lung for the purpose of hemodynamic indices derivation. Adenosine (to 200 microg/kg/min & papaverine (to 24 mg induced dose-dependent flow augmentations (40+/-7% & 35+/-13% T(mn reductions v baseline, respectively; p<0.0001. PFR and PIMR were then calculated before and after progressive administration of ceramic microspheres into the SPA. Cumulative microsphere doses progressively reduced PFR (1.41+/-0.06, 1.26+/-0.19, 1.17+/-0.07 & 1.01+/-0.03; for 0, 10(4, 10(5 & 10(6 microspheres; p

  6. Assessment of Coronary Flow Velocity Reserve by Noninvasive Transthoracic Doppler Echocardiography in Patients with Angiographically Normal Coronary Arteries

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The measurement of coronary flow velocity reserve (CFVR) by transthoracic Doppler echocardiography (TTDE) with invasive intracoronary Doppler flow wire technique (ICD) was validated and the pathologicalfactors which influence CFVR in patients with angiographically normal coronary arteries were analyzed. CFVR was determined successfully in left anterior descending artery (LAD) in 37 of 40 patients with angiographically normal coronary arteries (men 22, women 15, age 20-75 years, mean age 54 ± 12 years). Coronary flow velocity was measured in the distal LAD by TTDE with contrast enhancement at baseline and during intravenous adenosine infusion of 140 μg/kg per min within 48 h after ICD technique. Average peak velocity at baseline (APVb), average peak velocity during hyperemia (APVh) and CFVR determined from TTDE were correlated closely with those from ICD measurements (APVb: y=0. 64x+5. 04, r=0. 86, P<0. 001;APVh: y=0.63x+14.36, r=0.82, P<0.001; CFVR: y=0.65x+0.92, r=0.88, P<0. 001).For CFVR measurements, the mean differences between TTDE and ICD methods were 0. 12 ±0.39. CFVR in patients with history of hypertension was significantly lower than that in patients without history of hypertension (P<0.05). Intravascular ultrasound (IVUS) was performed in 34patients. Plaque formation was found in LAD by IVUS in 17 (50 %) patients. No significant difference in CFVR was found between the patients without plaque formation (3. 11±0. 49) and those with plaque formation (2. 76±0.53, P=0. 056). It is suggested that TTDE with contrast enhancement provides reliable measurement of APV and CFVR in the distal LAD. The early stage of atherosclerosis could be detected by IVUS, which may be normal in angiography. CFVR is impaired in patients with history of hypertension compared with that in patients without history of hypertension.

  7. Stress Perfusion Coronary Flow Reserve Versus Cardiac Magnetic Resonance for Known or Suspected CAD.

    Science.gov (United States)

    Kato, Shingo; Saito, Naka; Nakachi, Tatsuya; Fukui, Kazuki; Iwasawa, Tae; Taguri, Masataka; Kosuge, Masami; Kimura, Kazuo

    2017-08-15

    Phase-contrast (PC) cine magnetic resonance imaging (MRI) of the coronary sinus is a noninvasive method to quantify coronary flow reserve (CFR). This study sought to compare the prognostic value of CFR by cardiac magnetic resonance (CMR) and stress perfusion CMR to predict major adverse cardiac events (MACE). Participants included 276 patients with known coronary artery disease (CAD) and 400 with suspected CAD. CFR was calculated as myocardial blood flow during adenosine triphosphate infusion divided by myocardial blood flow at rest using PC cine MRI of the coronary sinus. During a median follow-up of 2.3 years, 47 patients (7%) experienced MACE. Impaired CFR (10% ischemia on stress perfusion CMR were significantly associated with MACE in patients with known CAD (hazard ratio [HR]: 5.17 and HR: 5.10, respectively) and suspected CAD (HR: 14.16 and HR: 6.50, respectively). The area under the curve for predicting MACE was 0.773 for CFR and 0.731 for stress perfusion CMR (p = 0.58) for patients with known CAD, and 0.885 for CFR and 0.776 for stress perfusion CMR (p = 0.059) in the group with suspected CAD. In patients with known CAD, sensitivity, specificity, and positive and negative predictive values to predict MACE were 64%, 91%, 38%, and 97%, respectively, for CFR, and 82%, 59%, 15%, and 97%, respectively, for stress perfusion CMR. In the suspected CAD group, these values were 65%, 99%, 80%, and 97%, respectively, for CFR, and 72%, 83%, 22%, and 98%, respectively, for stress perfusion CMR. The predictive values of CFR and stress perfusion CMR for MACE were comparable in patients with known CAD. In patients with suspected CAD, CFR showed higher HRs and areas under the curve than stress perfusion CMR, suggesting that CFR assessment by PC cine MRI might provide better risk stratification for patients with suspected CAD. Copyright © 2017 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

  8. The deep hydrogeologic flow system underlying the Oak Ridge Reservation -- Assessing the potential for active groundwater flow and origin of the brine

    Energy Technology Data Exchange (ETDEWEB)

    Nativ, R. [Hebrew Univ. of Jerusalem (Israel). Dept. of Soil and Water Sciences; Halleran, A.; Hunley, A. [Oak Ridge National Lab., TN (United States). Environmental Sciences Div.

    1997-08-01

    The deep hydrogeologic system underlying the Oak Ridge Reservation (ORR) contains contaminants such as radionuclides, heavy metals, nitrates, and organic compounds. The groundwater in the deep system is saline and has been considered to be stagnant in previous studies. This study was designed to address the following questions: is groundwater in the deep system stagnant; is contaminant migration controlled by diffusion only or is advection a viable mechanism; where are the potential outlet points? On the basis of existing and newly collected data, the nature of saline groundwater flow and potential discharge into shallow, freshwater systems was assessed. Data used for this purpose included (1) spatial and temporal pressures and hydraulic heads measured in the deep system, (2) hydraulic parameters of the formations in question, (3) spatial and temporal temperature variations at depth, and (4) spatial and temporal chemical and isotopic composition of the saline groundwater. The observations suggest that the saline water contained at depth is old but not isolated (in terms of recharge and discharge) from the overlying active, freshwater-bearing units. Influx of recent water does occur. Groundwater volumes involved in this flow are likely to be small. The origin of the saline groundwater was assessed by using existing and newly acquired chemical and isotopic data. The proposed model that best fits the data is modification of residual brine from which halite has been precipitated. Other models, such as ultrafiltration and halite dissolution, were also evaluated.

  9. High gene flow in reef fishes and its implications for ad-hoc no-take marine reserves.

    Science.gov (United States)

    Matias, Ambrocio Melvin A; Anticamara, Jonathan A; Quilang, Jonas P

    2013-10-01

    Integration of genetic connectivity information in effective marine reserve (MR) design is important in sustaining marine biodiversity. Here, genetic connectivity based on mitochondrial DNA (mtDNA) of three reef fish species, namely Epinephelus merra (n = 67; 32 from Bolinao, 14 from Alaminos, and 21 from Masinloc), Parupeneus multifasciatus (n = 23; 12 from Bolinao and 11 from Masinloc), and Odonus niger (n = 35; 21 from Mabini and 14 from Tingloy), sampled across western Luzon, Philippines, was inferred by assessing their genetic diversity, population genetic structure, and historical demography. The results show high haplotype and nucleotide diversity in the three species. Tests for population structure indicate high gene flow and no spatial genetic structuring for the three species. Mismatch analyses suggest unimodal distribution for E. merra and P. multifasciatus, but bimodal distribution for O. niger. Even with differences in mismatch distributions, all the three species exhibit low raggedness index indicating demographic population expansion. The bimodal distribution of O. niger could be attributed to the mixing of two isolated populations. High gene flow between sampling locations implies genetic exchanges and connectivity between many small MRs and fishing grounds in western Luzon, Philippines, at a scale similar to our study. This research is among the first few to elucidate the high genetic connectivity of reef fish communities across the Philippines (here western Luzon), but it also calls for more support (i.e. government and academia) for genetic research that aims to (1) understand the maintenance of megadiversity of the country and (2) search for effective biodiversity conservation options for the coral reefs.

  10. Reduced coronary flow reserve in patients with primary hyperparathyroidism: a study by G-SPECT myocardial perfusion imaging

    Energy Technology Data Exchange (ETDEWEB)

    Marini, Cecilia [CNR Institute of Bioimages and Molecular Physiology Milan, Genoa (Italy); Giusti, Massimo; Vera, Lara; Minuto, Francesco [University of Genoa, Department of Endocrinological and Metabolic Sciences, Genoa (Italy); Armonino, Riccardo; Ghigliotti, Giorgio; Bezante, Gian Paolo; Morbelli, Silvia; Pomposelli, Elena; Massollo, Michela; Gandolfo, Patrizia; Sambuceti, Gianmario [University of Genoa, Department of Internal Medicine, Genoa (Italy)

    2010-12-15

    The mechanisms underlying increased cardiovascular risk in primary hyperparathyroidism (pHPT) have not been fully defined. Recently, this issue has become the subject of renewed interest due to the increasing evidence that the endothelium and vascular wall are targets for parathyroid hormone (PTH). The aim of this study was to measure regional coronary flow reserve (CFR) to determine whether the vascular damage induced by pHPT extends to affect the coronary microvascular function. A total of 22 pHPT patients without a history of coronary artery disease and 7 age-matched control subjects were recruited. Dipyridamole myocardial blood flow (MBF) was assessed using {sup 99m}Tc-sestamibi by measuring first-transit counts in the pulmonary artery and myocardial count rate from G-SPECT images. Baseline MBF was estimated 2 h later according to the same procedure. Regional CFR was defined as the ratio between dipyridamole and baseline MBF using a 17-segment left ventricular model. Three pHPT patients showed reversible perfusion defects and were excluded from the analysis. In the remaining 19, CFR was significantly lower with respect to the control subjects (1.88 {+-} 0.64 vs. 3.36 {+-} 0.66, respectively; p < 0.01). Moreover, patients studied for more than 28 months from pHPT diagnosis showed lower CFR values than the others (1.42 {+-} 0.18 vs. 2.25 {+-} 0.64, respectively; p < 0.01). Consequently, the time from diagnosis to the nuclear study showed a reasonable correlation with the degree of CFR impairment (Spearman's rho -0.667, p < 0.02). pHPT is associated with a significant dysfunction of the coronary microcirculation. This disorder might contribute to the high cardiovascular risk of conditions characterized by chronic elevations in serum PTH levels. (orig.)

  11. Simulations of fusion chamber dynamics and first wall response in a Z-pinch driven fusion–fission hybrid power reactor (Z-FFR)

    Energy Technology Data Exchange (ETDEWEB)

    Qi, J.M., E-mail: qjm06@sina.com [Laboratory of Advanced Nuclear Energy (LANE), Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621999 (China); Center for Fusion Energy Science and Technology (CFEST), China Academy of Engineering Physics, Mianyang 621999 (China); Wang, Z., E-mail: wangz_es@caep.cn [Laboratory of Advanced Nuclear Energy (LANE), Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621999 (China); Center for Fusion Energy Science and Technology (CFEST), China Academy of Engineering Physics, Mianyang 621999 (China); Chu, Y.Y., E-mail: chuyanyun@caep.cn [Laboratory of Advanced Nuclear Energy (LANE), Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621999 (China); Center for Fusion Energy Science and Technology (CFEST), China Academy of Engineering Physics, Mianyang 621999 (China); Li, Z.H., E-mail: lee_march@sina.com [Laboratory of Advanced Nuclear Energy (LANE), Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621999 (China)

    2016-03-15

    Highlights: • Z-FFR utilizes DT neutrons to drive a sub-critical fission blanket to produce energy. • A metal shell and Ar gas are employed in the fusion chamber for shock mitigation. • Massive materials can effectively mitigate the thermal heats on the chamber wall. • The W-coated Zr-alloy first wall exhibits good viability as a long-lived component. - Abstract: In a Z-pinch driven fusion–fission hybrid power reactor (Z-FFR), the fusion target will produce enormous energy of ∼1.5 GJ per pulse at a frequency of 0.1 Hz. Almost 20% of the fusion energy yield, approximately 300 MJ, is released in forms of pulsed X-rays. To prevent the first wall from fatal damages by the intense X-rays, a thin spherical metal shell and rare Ar buffer gas are introduced to mitigate the transient X-ray bursts. Radiation hydrodynamics in the fusion chamber were investigated by MULTI-1D simulations, and the corresponding thermal and mechanical loads on the first wall were also obtained. The simulations indicated that by optimizing the design parameters of the metal shell and Ar buffer gas, peak power flux of the thermal heats on the first wall could be mitigated to less than 10{sup 4} W/cm{sup 2} within a time scale of several milliseconds, while peak overpressures of the mechanical loads varying from 0.6 to 0.7 MPa. In addition, the thermomechanical response in a W–coated Zr-alloy first wall was performed by FWDR1D calculations using the derived thermal and mechanical loads as inputs. The temperature and stress fields were analyzed, and the corresponding elastic strains were conducted for primary lifetime estimations by using the Coffin–Manson relationships of both W and Zr-alloy. It was shown that the maximum temperature rises and stresses in the first wall were less than 50 K and 130 MPa respectively, and lifetime of the first wall would be in excess of 10{sup 9} cycles. The chamber exhibits good viability as a long-lived component to sustain the Z-FFR conceptual

  12. Reliability of fractional flow reserve on diagnosis of intermediate coronary stenosis in patients with diabetes%心肌血流储备分数评价糖尿病患者冠状动脉临界病变的可靠性

    Institute of Scientific and Technical Information of China (English)

    梁建文; 张东辉; 吴剑胜

    2015-01-01

    目的 通过测定冠状动脉中等程度狭窄的糖尿病和非糖尿病患者的心肌血流储备分数(fractional flow reserve,FFR)来评估糖尿病对FFR检测的影响.方法 本研究入组68例冠状动脉造影明确诊断为冠状动脉粥样硬化性心脏病(冠心病),且经量化冠状动脉造影(quantitative coronary angiography,QCA)诊断为中等程度狭窄的患者,分为糖尿病组和非糖尿病组;再根据病变处管腔狭窄程度进一步细分为50%~60%亚组和60%~70%亚组;根据糖化血红蛋白(glycated hemoglobin,GHb)水平分为GHb≥7.0亚组和GHb<7.0亚组.以三磷腺苷(ATP)为冠状动脉扩张剂.比较每两组间FFR的测量值(两次取平均值)及冠状动脉扩张前后的FFR差值.结果 冠状动脉狭窄程度相似的糖尿病组和非糖尿病组的FFR比较,差异无统计学意义[50%~60%亚组:(0.84±0.06)vs.(0.86±0.08),P=0.45;60%~70%亚组:[(0.76±0.09) vs.(0.81±0.07),P=0.061].糖尿病GHb≥7.0亚组的FFR高于糖尿病GHb<7.0亚组,差异有统计学意义[(0.77±0.06)ws.(0.72±0.11),P<0.05].结论 糖尿病对测定中等程度狭窄的冠状动脉的FFR没有明显影响,糖尿病且GHb≥7.0患者的FFR较GHb<7.0患者高.

  13. Persistent abnormal coronary flow reserve in association with abnormal glucose metabolism affects prognosis in acute myocardial infarction

    DEFF Research Database (Denmark)

    Løgstrup, Brian B; Høfsten, Dan E; Christophersen, Thomas B

    2011-01-01

    Objectives: To evaluate changes in coronary flow reserve (CFR) over time after acute myocardial infarction (AMI) in relation to left ventricular (LV) function and glucometabolic state and prognostic implication of abnormal CFR. Methods: 154 patients with first time AMI had a comprehensive...... baseline CFR (P = 0.004), S' (P = 0.045) and abnormal glucose metabolism (P = 0.001) were predictors of a decreased CFR at 3 months of follow-up. In multivariate analyses abnormal glucose metabolism (OR: 5.3; 95%CI: 1.9-14.4; P = 0.001) remained a predictor of decreased CFR at follow-up, furthermore...... baseline CFR (OR: 0.5; 95%CI: 0.25-0.94; P = 0.032) and S' (OR: 0.67; 95% CI: 0.47-0.94; P = 0.021) was predictors of decreased CFR. Finally, CFR was associated with a lower risk of cardiac events in patients with normal glucose metabolism (HR: 0.64; 95% CI: 0.22-1.9; P = 0.42) than in patients...

  14. Alterations of cerebral blood flow and cerebrovascular reserve in patients with chronic traumatic brain injury accompanying deteriorated intelligence

    Energy Technology Data Exchange (ETDEWEB)

    Song, Ho Chun; Bom, Hee Seung [Chonnam National Univ. Hospital, Kwangju (Korea, Republic of)

    2000-06-01

    The purpose of this study was to evaluate alterations of regional cerbral blood flow (CBF) and cerebrovascular reserve (CVR), and correlation between these alternations and cognitive dysfunctin in patients with chronic traumatic brain injury (TBI) and normal brain MRI findings. Thirty TBI patients and 19 healthy volunteers underwent rest/acetazolaminde brain SPECT using Tc-99m HMPAO. Korean-Wechsler Adult Intelligence scale test was also performed in the patient group. Statistical analysis was performed with statistical parametric mapping software (SPM '97). CBF was diminished in the left hemisphere including Wernicke's area in all patients with lower verbal scale scores. In addition, a reduction in CBF in the right frontal, temporal and parietal cortices was related with depressed scores in information, digital span, arithmetic and similarities. In patients with lower performance scale scores, CBF was mainly diminished in the right hemisphere including superior temporal and supramarginal gyri, premotor, primary somatomotor and a part of prefrontal cortices, left frontal lobe and supramarginal gyrus. CVR was diminished in sixty-four Brodmann's areas compared to control. A reduction in CVR was demonstrated bilaterally in the frontal and temporal lobes in patients with lower scores in both verbal and performance tests, and in addition, both inferior parietal and occipital lobes in information subset. Alterations of CBF and CVR were demonstrated in the symptomatic TBI patients with normal MRI finding. These alterations were correlated with the change of intelligence, of which the complex functions are subserved by multiple interconnected cortical structures.

  15. Cerebral blood flow and cerebrovascular reserve capacity in patients with occlusion or severe stenosis of cerebral arterial trunk

    Energy Technology Data Exchange (ETDEWEB)

    Yoshinaga, Shinya; Tanaka, Akira; Nakayama, Yoshiya; Tomonaga, Masamichi [Fukuoka Univ., Chikushino (Japan). Chikushi Hospital

    1997-12-01

    The cerebral blood flow (CBF) and the cerebrovascular reserve capacity (CVRC) were sequentially measured using a xenon enhanced CT scan in patients with transient ischemic attack or minor stroke due to an occlusion or a severe stenosis of the cerebral arterial trunk. The patients consisted of twelve males and one female ranging from 37 to 71 years of age (53 years on average). The vascular lesion was located in the internal carotid artery (7 patients) and in the middle cerebral artery (6 patients). Eleven patients received antiplatelet drug therapy, while two other patients underwent STA-MCA anastomosis. The CBF measurements were initially done within one month after the attack and then from 6 to 24 months (12 months on average) after the first study. Only one of 13 patients demonstrated a reattack during the period of observation and the CVRC decreased to 0% from the 14% level observed prior to the reattack, although the CBF was preserved. In the other twelve patients without a reattack, the CVRC was found to improve to 29.4% from 9.9% with statistical significance, even though the CBF remained the same in the first study. This study suggests hemodynamic insult to be closely related to the decreased in the CVRC, while STA-MCA anastomosis does not for prevent hemodynamic reattack based on a decrease in the CVRC in the early stage. (author)

  16. Comparison of quantitative myocardial perfusion imaging CT to fluorescent microsphere-based flow from high-resolution cryo-images

    Science.gov (United States)

    Eck, Brendan L.; Fahmi, Rachid; Levi, Jacob; Fares, Anas; Wu, Hao; Li, Yuemeng; Vembar, Mani; Dhanantwari, Amar; Bezerra, Hiram G.; Wilson, David L.

    2016-03-01

    Myocardial perfusion imaging using CT (MPI-CT) has the potential to provide quantitative measures of myocardial blood flow (MBF) which can aid the diagnosis of coronary artery disease. We evaluated the quantitative accuracy of MPI-CT in a porcine model of balloon-induced LAD coronary artery ischemia guided by fractional flow reserve (FFR). We quantified MBF at baseline (FFR=1.0) and under moderate ischemia (FFR=0.7) using MPI-CT and compared to fluorescent microsphere-based MBF from high-resolution cryo-images. Dynamic, contrast-enhanced CT images were obtained using a spectral detector CT (Philips Healthcare). Projection-based mono-energetic images were reconstructed and processed to obtain MBF. Three MBF quantification approaches were evaluated: singular value decomposition (SVD) with fixed Tikhonov regularization (ThSVD), SVD with regularization determined by the L-Curve criterion (LSVD), and Johnson-Wilson parameter estimation (JW). The three approaches over-estimated MBF compared to cryo-images. JW produced the most accurate MBF, with average error 33.3+/-19.2mL/min/100g, whereas LSVD and ThSVD had greater over-estimation, 59.5+/-28.3mL/min/100g and 78.3+/-25.6 mL/min/100g, respectively. Relative blood flow as assessed by a flow ratio of LAD-to-remote myocardium was strongly correlated between JW and cryo-imaging, with R2=0.97, compared to R2=0.88 and 0.78 for LSVD and ThSVD, respectively. We assessed tissue impulse response functions (IRFs) from each approach for sources of error. While JW was constrained to physiologic solutions, both LSVD and ThSVD produced IRFs with non-physiologic properties due to noise. The L-curve provided noise-adaptive regularization but did not eliminate non-physiologic IRF properties or optimize for MBF accuracy. These findings suggest that model-based MPI-CT approaches may be more appropriate for quantitative MBF estimation and that cryo-imaging can support the development of MPI-CT by providing spatial distributions of MBF.

  17. Reduced 123I-BMIPP uptake implies decreased myocardial flow reserve in patients with chronic stable angina.

    Science.gov (United States)

    Kageyama, Hiroyuki; Morita, Koichi; Katoh, Chietsugu; Tsukamoto, Takahiro; Noriyasu, Kazuyuki; Mabuchi, Megumi; Naya, Masanao; Kawai, Yuko; Tamaki, Nagara

    2006-01-01

    Long-chain fatty acid (LCFA) is the main energy source for normal myocardium at rest, but in ischemic myocardium, the main energy substrate shifts from LCFA to glucose. 123I-BMIPP is a radiolabeled LCFA analog. In chronic stable angina without previous infarction, we suppose that reduced 123I-BMIPP uptake is related to the substrate shift in myocardium with decreased myocardial flow reserve (MFR). The purpose of this study was to relate 123I-BMIPP uptake to rest myocardial blood flow (MBF), hyperemic MBF, and MFR assessed with 15O-water positron emission tomography (PET). We enrolled 21 patients with chronic stable angina without previous infarction, all of whom underwent 123I-BMIPP single-photon emission computed tomography (SPECT) and 15O-water PET. The left ventricle was divided into 13 segments. In each segment, rest MBF and hyperemic MBF were measured by PET. 123I-BMIPP uptake was evaluated as follows: score 0=normal, 1=slightly decreased uptake, 2=moderately decreased uptake, 3=severely decreased uptake, and 4=complete defect. 123I-BMIPP uptake was compared with rest MBF, hyperemic MBF, and MFR. The numbers of segments with 123I-BMIPP scores 0, 1, 2, 3, and 4 were 178, 40, 25, 24, and 0, respectively. The rest MBFs for scores 0, 1, 2, and 3 were 0.93+/-0.25, 0.86+/-0.21, 0.97+/-0.30, and 0.99+/-0.37 ml/min/g, respectively. The hyperemic MBFs for scores 0, 1, 2, and 3 were 2.76+/-1.29, 1.84+/-0.74, 1.37+/-0.39, and 1.08+/-0.40 ml/min/g, respectively. The MFRs for scores 0, 1, 2, and 3 were 3.01+/-1.38, 2.20+/-0.95, 1.44+/-0.22, and 1.10+/-0.26, respectively. As 123I-BMIPP uptake declined, hyperemic MBF and MFR decreased. In chronic stable angina without previous infarction, reduced 123I-BMIPP uptake implies decreased MFR.

  18. Reduced {sup 123}I-BMIPP uptake implies decreased myocardial flow reserve in patients with chronic stable angina

    Energy Technology Data Exchange (ETDEWEB)

    Kageyama, Hiroyuki; Morita, Koichi; Katoh, Chietsugu; Mabuchi, Megumi; Tamaki, Nagara [Hokkaido University Graduate School of Medicine, Department of Nuclear Medicine, Sapporo (Japan); Tsukamoto, Takahiro; Noriyasu, Kazuyuki; Naya, Masanao [Hokkaido University, Department of Cardiovascular Medicine, Sapporo (Japan); Hokkaido University Graduate School of Medicine, Department of Nuclear Medicine, Sapporo (Japan); Kawai, Yuko [Hokko Memorial Hospital, Department of Cardiovascular Medicine, Sapporo (Japan)

    2006-01-01

    Long-chain fatty acid (LCFA) is the main energy source for normal myocardium at rest, but in ischemic myocardium, the main energy substrate shifts from LCFA to glucose. {sup 123}I-BMIPP is a radiolabeled LCFA analog. In chronic stable angina without previous infarction, we suppose that reduced {sup 123}I-BMIPP uptake is related to the substrate shift in myocardium with decreased myocardial flow reserve (MFR). The purpose of this study was to relate {sup 123}I-BMIPP uptake to rest myocardial blood flow (MBF), hyperemic MBF, and MFR assessed with {sup 15}O-water positron emission tomography (PET). We enrolled 21 patients with chronic stable angina without previous infarction, all of whom underwent {sup 123}I-BMIPP single-photon emission computed tomography (SPECT) and {sup 15}O-water PET. The left ventricle was divided into 13 segments. In each segment, rest MBF and hyperemic MBF were measured by PET. {sup 123}I-BMIPP uptake was evaluated as follows: score 0=normal, 1=slightly decreased uptake, 2=moderately decreased uptake, 3=severely decreased uptake, and 4=complete defect. {sup 123}I-BMIPP uptake was compared with rest MBF, hyperemic MBF, and MFR. The numbers of segments with {sup 123}I-BMIPP scores 0, 1, 2, 3, and 4 were 178, 40, 25, 24, and 0, respectively. The rest MBFs for scores 0, 1, 2, and 3 were 0.93{+-}0.25, 0.86{+-}0.21, 0.97{+-}0.30, and 0.99{+-}0.37 ml/min/g, respectively. The hyperemic MBFs for scores 0, 1, 2, and 3 were 2.76{+-}1.29, 1.84{+-}0.74, 1.37{+-}0.39, and 1.08{+-}0.40 ml/min/g, respectively. The MFRs for scores 0, 1, 2, and 3 were 3.01{+-}1.38, 2.20{+-}0.95, 1.44{+-}0.22, and 1.10{+-}0.26, respectively. As {sup 123}I-BMIPP uptake declined, hyperemic MBF and MFR decreased. In chronic stable angina without previous infarction, reduced {sup 123}I-BMIPP uptake implies decreased MFR. (orig.)

  19. Myocardial Perfusion Imaging Versus Computed Tomography Angiography-Derived Fractional Flow Reserve Testing in Stable Patients With Intermediate-Range Coronary Lesions

    DEFF Research Database (Denmark)

    Nørgaard, Bjarne L; Gormsen, Lars C; Bøtker, Hans Erik

    2017-01-01

    BACKGROUND: Data on the clinical utility of coronary computed tomography angiography-derived fractional flow reserve (FFRCT) are sparse. In patients with intermediate (40-70%) coronary stenosis determined by coronary computed tomography angiography, we investigated the association of replacing st...

  20. Inability of coronary blood flow reserve measurements to assess the efficacy of coronary angioplasty in the first 24 hours in unselected patients

    NARCIS (Netherlands)

    G-J. Laarman (GertJan); P.W.J.C. Serruys (Patrick); H. Suryapranata (Harry); M.J.B.M. van den Brand (Marcel); P.R. Jonkers; P.J. de Feyter (Pim)

    1991-01-01

    textabstractTo determine functional and anatomic changes in the first 24 hours after coronary angioplasty, we studied at random 15 patients (9 men, mean age 60 years) who underwent coronary angioplasty of 16 coronary arteries. Quantitative coronary angiography and coronary flow reserve measurements

  1. Inability of coronary blood flow reserve measurements to assess the efficacy of coronary angioplasty in the first 24 hours in unselected patients

    NARCIS (Netherlands)

    G-J. Laarman (GertJan); P.W.J.C. Serruys (Patrick); H. Suryapranata (Harry); M.J.B.M. van den Brand (Marcel); P.R. Jonkers; P.J. de Feyter (Pim)

    1991-01-01

    textabstractTo determine functional and anatomic changes in the first 24 hours after coronary angioplasty, we studied at random 15 patients (9 men, mean age 60 years) who underwent coronary angioplasty of 16 coronary arteries. Quantitative coronary angiography and coronary flow reserve measurements

  2. Quantitative assessment of harmonic power doppler myocardial perfusion imaging with intravenous levovist™ in patients with myocardial infarction: comparison with myocardial viability evaluated by coronary flow reserve and coronary flow pattern of infarct-related artery

    Directory of Open Access Journals (Sweden)

    Nagai Kunihiko

    2005-08-01

    Full Text Available Abstract Background Myocardial contrast echocardiography and coronary flow velocity pattern with a rapid diastolic deceleration time after percutaneous coronary intervention has been reported to be useful in assessing microvascular damage in patients with acute myocardial infarction. Aim To evaluate myocardial contrast echocardiography with harmonic power Doppler imaging, coronary flow velocity reserve and coronary artery flow pattern in predicting functional recovery by using transthoracic echocardiography. Methods Thirty patients with anterior acute myocardial infarction underwent myocardial contrast echocardiography at rest and during hyperemia and were quantitatively analyzed by the peak color pixel intensity ratio of the risk area to the control area (PIR. Coronary flow pattern was measured using transthoracic echocardiography in the distal portion of left anterior descending artery within 24 hours after recanalization and we assessed deceleration time of diastolic flow velocity. Coronary flow velocity reserve was calculated two weeks after acute myocardial infarction. Left ventricular end-diastolic volumes and ejection fraction by angiography were computed. Results Pts were divided into 2 groups according to the deceleration time of coronary artery flow pattern (Group A; 20 pts with deceleration time ≧ 600 msec, Group B; 10 pts with deceleration time Conclusion The preserved microvasculature detecting by myocardial contrast echocardiography and coronary flow velocity reserve is related to functional recovery after acute myocardial infarction.

  3. 经深静脉和外周静脉泵入腺苷三磷酸测量血流储备分数的比较研究%Comparative study of fractional lfow reserve measurement by intravenous ATP infusion through ;femoral veins and hand dosal veins

    Institute of Scientific and Technical Information of China (English)

    刘晶晶; 曲涛; 张萌; 靳维华; 高炬; 王斌

    2014-01-01

    Objective To compare and evaluate fractional flow reserve (FFR) by intravenous infusion of adenosine 5’-triphosphate (ATP) through femoral veins and hand dosal veins. To find the feasibility of measuring FFR through ATP infusion at hand dosal veins. Methods A total of 27 patients receiving coronary angiography (CAG) were enrolled. FFR was measured by intravenous injection of ATP through femoral veins and hand dosal veins separately in 31 stenosed coronary arteries. Results A linear correlation between ATP infusion measuring FFR through femoral and hand dosal veins was observed. Heart rates, PR intervals and side effects were of no difference between the 2 routes of ATP infusion (P=0.79, P=0.56, P=0.85). It indicated that ATP infusion[160μg/(kg·min)]measuring FFR through hand dosal veins was compatable to which measuring FFR though femoral veins (y=0.945x+0.0043, R2=0.904, P=0.001). Compared with ATP infusion by femoral vein[from (53.7±15.8) s to (58.2±11.6) s], the time to FFR by infusion ATP measurement by hand dosal veins was longer[(48.7±17.9) s, P=0.015]. Conclusions The FFR measurement through ATP infusion at hand dosal veins has similar results with the FFR measured by femoral veins ATP infusion.%目的:经外周静脉(手背静脉)泵入腺苷三磷酸(ATP)的方法测定血流储备分数(FFR),并通过与标准的测量方法[深静脉(股静脉)泵入ATP]测量FFR的对比研究,评价经外周静脉泵入不同剂量ATP测定FFR的可行性。探讨经手背静脉泵入ATP测定是否能够准确测量FFR。方法针对航天中心医院27例患者冠状动脉造影术中的31条冠状动脉病变血管,进行外周静脉和股静脉冠状动脉造影术及两种途径测定的FFR数值测量与数据分析。结果经手背静脉泵入ATP[≥140μg/(kg · min)]测量的4组FFR值与标准方法测量FFR值的一致性、相关性。两种途径注射ATP后心率、PR间期、不良反应发生率比较,差异无统

  4. Preliminary investigation of groundwater flow and trichloroethene transport in the Surficial Aquifer System, Naval Industrial Reserve Ordnance Plant, Fridley, Minnesota

    Science.gov (United States)

    King, Jeffrey N.; Davis, J. Hal

    2016-05-16

    Industrial practices at the Naval Industrial Reserve Ordnance Plant, in Fridley, Minnesota, caused soil and groundwater contamination. Some volatile organic compounds from the plant might have discharged to the Mississippi River, forced by the natural hydraulic gradient in the surficial aquifer system. The U.S. Environmental Protection Agency included the Naval Industrial Reserve Ordnance Plant on the Superfund National Priorities List in 1989.

  5. Low density lipoprotein cholesterol level inversely correlated with coronary flow velocity reserve in patients with Type 2 diabetes

    Institute of Scientific and Technical Information of China (English)

    Jie Yu; Jiang-Li Han; Li-Yun He; Xin-Heng Feng; Wei-Hong Li; Jie-Ming Mao; Wei Gao; Guang Wang

    2013-01-01

    Objectives To evaluate the association of coronary artery endothelial function and plasma levels of low density lipoprotein cholesterol (LDL-C) and high density lipoprotein cholesterol (HDL-C) in patients with Type 2 Diabetes Mellitus (DM). Methods We investigated 90 participants from our institution between October 2007 to March 2010: non-DM (n = 60) and DM (n = 30). As an indicator of coronary endothelial dysfunction, we used non-invasive Doppler echocardiography to quantify coronary flow velocity reserve (CFVR) in the distal part of the left descending artery after rest and after intravenous adenosine administration. Results Plasma level of LDL-C was significantly higher in patients with DM than in non-DM (3.21 0.64 vs. 2.86 0.72 mmo/L, P < 0.05), but HDL-C level did not differ between the groups (1.01 0.17 vs. 1.05 0.19 mmo/L). Furthermore, the CFVR value was lower in DM patients than non-diabetics (2.45±0.62 vs. 2.98±0.68, P < 0.001). Plasma levels of LDL-C were negatively correlated with CFVR in all subjects (r = 0.35, P < 0.001; 95% confidence interval (CI): 0.52 -C0.15) and in the non-DM (r = 0.29, P < 0.05; 95% CI: 0.51–0.05), with an even stronger negative correlation in the DM group (r = 0.42, P < 0.05; 95% CI: 0.68 –0.06). Age (β = 0.019, s = 0.007, sβ = 0.435, 95% CI: 0.033 –0.005, P = 0.008), LDL-C (β = 0.217, s = 0.105, sβ = 0.282, 95% CI: 0.428 –0.005, P = 0.045) remained independently correlated with CFVR in the DM group. However, we found no correlation between HDL-C level and CFVR in any group. Conclusions Diabetes may contribute to coronary artery disease (CAD) by inducing dysfunction of the coronary artery endothelium. Increased LDL-C level may adversely impair coronary endothelial function in DM. HDL-C may lose its endothelial-protective effects, in part as a result of pathological conditions, especially under abnormal glucose metabolism.

  6. Impact of uncontrolled blood pressure on diagnostic accuracy of coronary flow reserve for detecting significant coronary stenosis in hypertensive patients

    Institute of Scientific and Technical Information of China (English)

    LI Wei-hong; XU Wei-xian; LI Zhao-ping; LI Cui-ping; WANG Xin-yu; HE Li-yun; ZHAO Wei

    2013-01-01

    Baciground Impaired coronary flow reserve (CFR) in patients with hypertension may be caused by epicardial coronary stenosis or microvascular dysfunction.Antihypertensive treatment has been shown to improve coronary microvascular dysfunction.The aim of this study was to evaluate the impact of uncontrolled blood pressure (BP) on diagnostic accuracy of CFR for detecting significant coronary stenosis.Methods A total of 98 hypertensive patients scheduled for coronary angiography (CAG) due to chest pain were studied.Of them,45 patients had uncontrolled BP (defined as the office BP >140/90 mmHg (1 mmHg=0.133 kPa) in general hypertensive patients,or >130/80 mmHg in hypertensive individuals with diabetes mellitus),and the remaining 53 patients had well-controlled BP.CFR was measured in the left anterior descending coronary artery (LAD) during adenosine triphosphate-induced hyperemia by non-invasive transthoracic Doppler echocardiography (TTDE) within 48 hours prior to CAG.Significant LAD stenosis was defined as >70% luminal narrowing.Diagnostic accuracy of CFR for detecting significant coronary stenosis was analyzed with a receiver operating characteristic analysis.Results CFR was significantly lower in patients with uncontrolled BP than in those with well-controlled BP (2.1±0.6 vs.2.6±0.9,P <0.01).Multivariate linear regression analysis of the study showed that the value of CFR was independently associated with the angiographically determined degree of LAD stenosis (β=-0.445,P <0.0001) and the presence of uncontrolled BP (β=-0.272,P=0.014).With a receiver operating characteristic analysis,CFR <2.2 was the optimal cut-off value for detecting LAD stenosis in all hypertensive patients (AUC 0.83,95%C/0.75-0.91) with a sensitivity of 75%,a specificity of 78%,and an accuracy of 77%.A significant reduction of diagnostic specificity was observed in patients with uncontrolled BP compared with those with well-controlled BP (67% vs.93%,P=0

  7. Prognostic Value of Coronary Flow Reserve Obtained on Dobutamine Stress Echocardiography and its Correlation with Target Heart Rate.

    Science.gov (United States)

    Abreu, José Sebastião de; Rocha, Eduardo Arrais; Machado, Isadora Sucupira; Parahyba, Isabelle O; Rocha, Thais Brito; Paes, Fernando José Villar Nogueira; Diogenes, Tereza Cristina Pinheiro; Abreu, Marília Esther Benevides de; Farias, Ana Gardenia Liberato Ponte; Carneiro, Marcia Maria; Paes, José Nogueira

    2017-05-01

    Normal coronary flow velocity reserve (CFVR) (≥ 2) obtained in the left anterior descending coronary artery (LAD) from transthoracic echocardiography is associated with a good prognosis, but there is no study correlating CFVR with submaximal target heart rate (HR). To evaluate the prognostic value of CFVR obtained in the LAD of patients with preserved (>50%) left ventricular ejection fraction (LVEF) who completed a dobutamine stress echocardiography (DSE), considering target HR. Prospective study of patients with preserved LVEF and CFVR obtained in the LAD who completed DSE. In Group I (GI = 31), normal CFVR was obtained before achieving target HR, and, in Group II (GII = 28), after that. Group III (G III=24) reached target HR, but CFVR was abnormal. Death, acute coronary insufficiency, coronary intervention, coronary angiography without further intervention, and hospitalization were considered events. In 28 ± 4 months, there were 18 (21.6%) events: 6% (2/31) in GI, 18% (5/28) in GII, and 46% (11/24) in GIII. There were 4 (4.8%) deaths, 6 (7.2%) coronary interventions and 8 (9.6%) coronary angiographies without further intervention. In event-free survival by regression analysis, GIII had more events than GI (p 50%) e ecocardiograma sob estresse com dobutamina (EED) concluído, considerando a FC alvo submáxima. studo prospectivo de pacientes com FEVE preservada e RVFC obtida na ADA durante EED concluído. No Grupo I (GI=31), a RVFC adequada foi obtida antes de se atingir a FC alvo, e no Grupo II (G II=28), após. O Grupo III (G III=24) atingiu a FC alvo, mas a RVFC foi inadequada. Foram considerados eventos: óbito, insuficiência coronariana aguda, intervenção coronariana, coronariografia sem intervenção subsequente e internamento hospitalar. Em 28 ± 4 meses, ocorreram 18 (21,6%) eventos, sendo 6% (2/31) no GI, 18% (5/28) no GII e 46% (11/24) no GIII. Foram 4 (4,8%) óbitos, 6 (7,2%) intervenções coronarianas e 8 (9,6%) coronariografias sem interven

  8. Impact of the Mobile Telecommunication Network’s Milk Flow Project on the Livelihoods of Pastoralists in Ladugga Grazing Reserve, Kaduna State, Nigeria

    Directory of Open Access Journals (Sweden)

    John Gambo Laah

    2013-12-01

    Full Text Available The paper aims at assessing the impact of Mobile Telecommunication Network (MTN Milk-Flow Project on the livelihoods of pastoralists in Ladugga Grazing Reserve in Kaduna State, Nigeria. A structured questionnaire was administered to 242 pastoralists in Ladugga. To complement the quantitative source of data, Focus Group Discussions (FGDs and in-depth interviews (IDIs were conducted to assess the benefits and impact of the Milk Flow Project. A total of four (4 FGD sand four (4 IDIs were held with Fulani pastoralists and stakeholders in Ladugga Grazing Reserve. The mean age for male respondents was 55 years while that of the females was 42 years. The result reveals that the milk-flow project has led to: formation and membership of cooperative societies; significant increase in milk production and consequently income; a reduction in morbidity and mortality rates of cows due to better health seeking behaviours; the development of pasture farms and an increase in school enrolment. The paper suggested the need to encourage more private sector participation in supporting pastoralists’ livelihoods within the grazing reserve systems.

  9. Impairment of Coronary Flow Reserve Evaluated by Phase Contrast Cine-Magnetic Resonance Imaging in Patients With Heart Failure With Preserved Ejection Fraction.

    Science.gov (United States)

    Kato, Shingo; Saito, Naka; Kirigaya, Hidekuni; Gyotoku, Daiki; Iinuma, Naoki; Kusakawa, Yuka; Iguchi, Kohei; Nakachi, Tatsuya; Fukui, Kazuki; Futaki, Masaaki; Iwasawa, Tae; Kimura, Kazuo; Umemura, Satoshi

    2016-02-23

    Phase contrast (PC) cine-magnetic resonance imaging (MRI) of the coronary sinus allows for noninvasive evaluation of coronary flow reserve (CFR), which is an index of left ventricular microvascular function. The objective of this study was to investigate coronary flow reserve in patients with heart failure with preserved ejection fraction (HFpEF). We studied 25 patients with HFpEF (mean and SD of age: 73±7 years), 13 with hypertensive left ventricular hypertrophy (LVH) (67±10 years), and 18 controls (65±15 years). Breath-hold PC cine-MRI images of the coronary sinus were obtained to assess blood flow at rest and during ATP infusion. CFR was calculated as coronary sinus blood flow during ATP infusion divided by coronary sinus blood flow at rest. Impairment of CFR was defined as CFR <2.5 according to a previous study. The majority (76%) of HFpEF patients had decreased CFR. CFR was significantly decreased in HFpEF patients in comparison to hypertensive LVH patients and control subjects (CFR: 2.21±0.55 in HFpEF vs 3.05±0.74 in hypertensive LVH, 3.83±0.73 in controls; P<0.001 by 1-way ANOVA). According to multivariable linear regression analysis, CFR independently and significantly correlated with serum brain natriuretic peptide level (β=-68.0; 95% CI, -116.2 to -19.7; P=0.007). CFR was significantly lower in patients with HFpEF than in hypertensive LVH patients and controls. These results indicated that impairment of CFR might be a pathophysiological factor for HFpEF and might be related to HFpEF disease severity. © 2016 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley Blackwell.

  10. Coronary artery and thoracic aorta calcification is inversely related to coronary flow reserve as measured by 82Rb PET/CT in intermediate risk patients

    OpenAIRE

    Kim, Jongho; Bravo, Paco E.; Gholamrezanezhad, Ali; Sohn, Seil; Rafique, Ash; Travis, Arlene; Machac, Josef

    2013-01-01

    Background The strength and nature of the relationship between myocardial perfusion imaging (MPI), coronary flow reserve (CFR), and coronary artery calcium (CAC) and thoracic aorta calcium (TAC) remain to be clarified. Methods Dynamic rest-pharmacological stress 82Rb positron emission tomography/computed tomography MPI with CFR, CAC, and TAC was performed in 75 patients (59 ± 13 years; F/M = 38/37) with intermediate risk of coronary artery disease. Results A total of 29 (39%) patients had isc...

  11. Relationship between HgbA1c and Myocardial Blood Flow Reserve in Patients with Type 2 Diabetes Mellitus: Noninvasive Assessment Using Real-Time Myocardial Perfusion Echocardiography

    Directory of Open Access Journals (Sweden)

    Runqing Huang

    2014-01-01

    Full Text Available To study the relationship between glycosylated hemoglobin (HgbA1c and myocardial perfusion in type 2 diabetes mellitus (T2DM patients, we prospectively enrolled 24 patients with known or suspected coronary artery disease (CAD who underwent adenosine stress by real-time myocardial perfusion echocardiography (RTMPE. HgbA1c was measured at time of RTMPE. Microbubble velocity (β min−1, myocardial blood flow (MBF, mL/min/g, and myocardial blood flow reserve (MBFR were quantified. Quantitative MCE analysis was feasible in all patients (272/384 segments, 71%. Those with HgbA1c > 7.1% had significantly lower βreserve and MBFR than those with HgbA1c ≤ 7.1% (P 2 as normal, HgbA1c > 7.1% significantly increased the risk for abnormal MBFR, (adjusted odds ratio: 1.92, 95% CI: 1.12–3.35, P=0.02. Optimal glycemic control is associated with preservation of MBFR as determined by RTMPE, in T2DM patients at risk for CAD.

  12. Myocardial blood flow and left ventricular functional reserve in hypertrophic cardiomyopathy: a {sup 13}NH{sub 3} gated PET study

    Energy Technology Data Exchange (ETDEWEB)

    Sciagra, Roberto; Calabretta, Raffaella; Passeri, Alessandro; Castello, Angelo; Pupi, Alberto [University of Florence, Nuclear Medicine Unit, Department of Experimental and Clinical Biomedical Sciences ' ' Mario Serio' ' , Florence (Italy); Cipollini, Fabrizio [University of Florence, Department of Statistics, Florence (Italy); Cecchi, Franco; Olivotto, Iacopo [Careggi University Hospital, Referral Centre for Myocardial Diseases, Florence (Italy)

    2017-05-15

    Ischemia in hypertrophic cardiomyopathy (HCM) is caused by coronary microvascular dysfunction (CMD), which is detected by measuring myocardial blood flow (MBF) with PET. Whether CMD may be associated with ischemic left ventricular (LV) dysfunction is unclear. We therefore assessed LV ejection fraction (EF) reserve in HCM patients undergoing dipyridamole (Dip) PET. Resting and stress {sup 13}NH{sub 3} dynamic as well as gated PET were performed in 34 HCM patients. Segmental MBF and transmural perfusion gradient (TPG = subendocardial / subepicardial MBF) were assessed. LVEF reserve was considered abnormal if Dip LVEF decreased more than 5 units as compared to rest. Eighteen patients had preserved (group A) and 16 abnormal LVEF reserve (group B; range -7 to -32). Group B patients had greater wall thickness than group A, but resting volumes, LVEF, resting and Dip MBF, and myocardial flow reserve were similar. Group B had slightly higher summed stress score and summed difference score in visual analysis than group A, and a significantly higher summed stress wall motion score. In group B, resting TPG was slightly lower (1.31 ± 0.29 vs. 1.37 ± 0.34, p <0.05), and further decreased after Dip, whilst in group A it increased (B = 1.20 ± 0.39, p < 0.0001 vs. rest and vs. A = 1.40 ± 0.43). The number of segments per patient with TPG <1 was higher than in group A (p < 0.001) and was a significant predictor of impaired LVEF reserve (OR 1.86, p < 0.02), together with wall thickness (OR 1.3, p < 0.02). Abnormal LVEF response is common in HCM patients following Dip, and is related to abnormal TPG, suggesting that subendocardial ischemia might occur under Dip and cause transient LV dysfunction. Although in vivo this effect may be hindered by the adrenergic drive associated with effort, these findings may have relevance in understanding exercise limitation and heart failure symptoms in HCM. (orig.)

  13. A simplified double-injection method to quantify cerebral blood flow and vascular reserve using iodine-123 IMP-SPECT

    Energy Technology Data Exchange (ETDEWEB)

    Toyoda, Hiroshi; Nishizawa, Sadahiko; Shiozaki, Toshiki; Ueno, Makoto; Konishi, Junji [Kyoto Univ. (Japan). Graduate School of Medicine

    2002-04-01

    We developed and evaluated a simplified double-injection method for iodine-123 N-isopropyl-p-iodoamphetamine (IMP) to quantify regional cerebral blood flow (rCBF) twice in a single SPECT session. The method enabled rapid calculations of rCBF with five 10-minute SPECT scans, a fixed distribution volume (V{sub d}), and one-point arterial blood sampling to calibrate a standard input function (SIF). Sixty neurological patients were examined to measure rCBF twice in a single session of IMP-SPECT. Patients underwent frequent arterial blood sampling with two injections of IMP and acetazolamide challenge. We generated the SIF and determined the optimal V{sub d} and calibration time (t{sub cal}) for the SIF in 30 patients. Validities of the fixed t{sub cal} and V{sub d} were assessed in the remaining 30 patients. Simulation studies were also performed to evaluate the error sensitivity of the method. The optimal t{sub cal} and V{sub d} were 34 min and 30 ml/ml, respectively. The method was robust in rCBF calculation with noisy SPECT data and yielded rCBF with negligible bias and acceptable errors compared with those obtained by the double-injection method previously reported. The method can be applied to measure rCBF twice in a single SPECT session more easily and less invasively. (author)

  14. Uncertainty quantification in coronary blood flow simulations: Impact of geometry, boundary conditions and blood viscosity.

    Science.gov (United States)

    Sankaran, Sethuraman; Kim, Hyun Jin; Choi, Gilwoo; Taylor, Charles A

    2016-08-16

    Computational fluid dynamic methods are currently being used clinically to simulate blood flow and pressure and predict the functional significance of atherosclerotic lesions in patient-specific models of the coronary arteries extracted from noninvasive coronary computed tomography angiography (cCTA) data. One such technology, FFRCT, or noninvasive fractional flow reserve derived from CT data, has demonstrated high diagnostic accuracy as compared to invasively measured fractional flow reserve (FFR) obtained with a pressure wire inserted in the coronary arteries during diagnostic cardiac catheterization. However, uncertainties in modeling as well as measurement results in differences between these predicted and measured hemodynamic indices. Uncertainty in modeling can manifest in two forms - anatomic uncertainty resulting in error of the reconstructed 3D model and physiologic uncertainty resulting in errors in boundary conditions or blood viscosity. We present a data-driven framework for modeling these uncertainties and study their impact on blood flow simulations. The incompressible Navier-Stokes equations are used to model blood flow and an adaptive stochastic collocation method is used to model uncertainty propagation in the Navier-Stokes equations. We perform uncertainty quantification in two geometries, an idealized stenosis model and a patient specific model. We show that uncertainty in minimum lumen diameter (MLD) has the largest impact on hemodynamic simulations, followed by boundary resistance, viscosity and lesion length. We show that near the diagnostic cutoff (FFRCT=0.8), the uncertainty due to the latter three variables are lower than measurement uncertainty, while the uncertainty due to MLD is only slightly higher than measurement uncertainty. We also show that uncertainties are not additive but only slightly higher than the highest single parameter uncertainty. The method presented here can be used to output interval estimates of hemodynamic indices

  15. Safety of guidewire-based measurement of fractional flow reserve and the index of microvascular resistance using intravenous adenosine in patients with acute or recent myocardial infarction

    Science.gov (United States)

    Ahmed, Nadeem; Layland, Jamie; Carrick, David; Petrie, Mark C.; McEntegart, Margaret; Eteiba, Hany; Hood, Stuart; Lindsay, Mitchell; Watkins, Stuart; Davie, Andrew; Mahrous, Ahmed; Carberry, Jaclyn; Teng, Vannesa; McConnachie, Alex; Curzen, Nick; Oldroyd, Keith G.; Berry, Colin

    2016-01-01

    Aims Coronary guidewire-based diagnostic assessments with hyperemia may cause iatrogenic complications. We assessed the safety of guidewire-based measurement of coronary physiology, using intravenous adenosine, in patients with an acute coronary syndrome. Methods We prospectively enrolled invasively managed STEMI and NSTEMI patients in two simultaneously conducted studies in 6 centers (NCT01764334; NCT02072850). All of the participants underwent a diagnostic coronary guidewire study using intravenous adenosine (140 μg/kg/min) infusion for 1–2 min. The patients were prospectively assessed for the occurrence of serious adverse events (SAEs) and symptoms and invasively measured hemodynamics were also recorded. Results 648 patients (n = 298 STEMI patients in 1 hospital; mean time to reperfusion 253 min; n = 350 NSTEMI in 6 hospitals; median time to angiography from index chest pain episode 3 (2, 5) days) were included between March 2011 and May 2013. Two NSTEMI patients (0.3% overall) experienced a coronary dissection related to the guidewire. No guidewire dissections occurred in the STEMI patients. Chest symptoms were reported in the majority (86%) of patient's symptoms during the adenosine infusion. No serious adverse events occurred during infusion of adenosine and all of the symptoms resolved after the infusion ceased. Conclusions In this multicenter analysis, guidewire-based measurement of FFR and IMR using intravenous adenosine was safe in patients following STEMI or NSTEMI. Self-limiting symptoms were common but not associated with serious adverse events. Finally, coronary dissection in STEMI and NSTEMI patients was noted to be a rare phenomenon. PMID:26418191

  16. Comparison of Coronary CT Angiography, SPECT, PET, and Hybrid Imaging for Diagnosis of Ischemic Heart Disease Determined by Fractional Flow Reserve.

    Science.gov (United States)

    Danad, Ibrahim; Raijmakers, Pieter G; Driessen, Roel S; Leipsic, Jonathon; Raju, Rekha; Naoum, Chris; Knuuti, Juhani; Mäki, Maija; Underwood, Richard S; Min, James K; Elmore, Kimberly; Stuijfzand, Wynand J; van Royen, Niels; Tulevski, Igor I; Somsen, Aernout G; Huisman, Marc C; van Lingen, Arthur A; Heymans, Martijn W; van de Ven, Peter M; van Kuijk, Cornelis; Lammertsma, Adriaan A; van Rossum, Albert C; Knaapen, Paul

    2017-08-16

    At present, the choice of noninvasive testing for a diagnosis of significant coronary artery disease (CAD) is ambiguous, but nuclear myocardial perfusion imaging with single-photon emission tomography (SPECT) or positron emission tomography (PET) and coronary computed tomography angiography (CCTA) is predominantly used for this purpose. However, to date, prospective head-to-head studies are lacking regarding the diagnostic accuracy of these imaging modalities. Furthermore, the combination of anatomical and functional assessments configuring a hybrid approach may yield improved accuracy. To establish the diagnostic accuracy of CCTA, SPECT, and PET and explore the incremental value of hybrid imaging compared with fractional flow reserve. A prospective clinical study involving 208 patients with suspected CAD who underwent CCTA, technetium 99m/tetrofosmin-labeled SPECT, and [15O]H2O PET with examination of all coronary arteries by fractional flow reserve was performed from January 23, 2012, to October 25, 2014. Scans were interpreted by core laboratories on an intention-to-diagnose basis. Hybrid images were generated in case of abnormal noninvasive anatomical or functional test results. Hemodynamically significant stenosis in at least 1 coronary artery as indicated by a fractional flow reserve of 0.80 or less and relative diagnostic accuracy of SPECT, PET, and CCTA in detecting hemodynamically significant CAD. Of the 208 patients in the study (76 women and 132 men; mean [SD] age, 58 [9] years), 92 (44.2%) had significant CAD (fractional flow reserve ≤0.80). Sensitivity was 90% (95% CI, 82%-95%) for CCTA, 57% (95% CI, 46%-67%) for SPECT, and 87% (95% CI, 78%-93%) for PET, whereas specificity was 60% (95% CI, 51%-69%) for CCTA, 94% (95% CI, 88%-98%) for SPECT, and 84% (95% CI, 75%-89%) for PET. Single-photon emission tomography was found to be noninferior to PET in terms of specificity (P  .99) using the predefined absolute margin of 10%. Diagnostic accuracy was

  17. Myocardial blood flow quantification for evaluation of coronary artery disease by computed tomography

    Science.gov (United States)

    Seitun, Sara; Clemente, Alberto; La Grutta, Ludovico; Toia, Patrizia; Runza, Giuseppe; Midiri, Massimo; Maffei, Erica

    2017-01-01

    During the last decade coronary computed tomography angiography (CTA) has become the preeminent non-invasive imaging modality to detect coronary artery disease (CAD) with high accuracy. However, CTA has a limited value in assessing the hemodynamic significance of a given stenosis due to a modest specificity and positive predictive value. In recent years, different CT techniques for detecting myocardial ischemia have emerged, such as CT-derived fractional flow reserve (FFR-CT), transluminal attenuation gradient (TAG), and myocardial CT perfusion (CTP) imaging. Myocardial CTP imaging can be performed with a single static scan during first pass of the contrast agent, with monoenergetic or dual-energy acquisition, or as a dynamic, time-resolved scan during stress by using coronary vasodilator agents (adenosine, dipyridamole, or regadenoson). A number of CTP techniques are available, which can assess myocardial perfusion in both a qualitative, semi-quantitative or quantitative manner. Once used primarily as research tools, these modalities are increasingly being used in routine clinical practice. All these techniques offer the substantial advantage of combining anatomical and functional evaluation of flow-limiting coronary stenosis in the same examination that would be beneficial for clinical decision-making. This review focuses on the state-of the-art and future trends of these evolving imaging modalities in the field of cardiology for the physiologic assessments of CAD. PMID:28540209

  18. N-terminal pro-brain natriuretic peptide is related with coronary flow velocity reserve and diastolic dysfunction in patients with asymmetric hypertrophic cardiomyopathy.

    Science.gov (United States)

    Tesic, Milorad; Seferovic, Jelena; Trifunovic, Danijela; Djordjevic-Dikic, Ana; Giga, Vojislav; Jovanovic, Ivana; Petrovic, Olga; Marinkovic, Jelena; Stankovic, Sanja; Stepanovic, Jelena; Ristic, Arsen; Petrovic, Milan; Mujovic, Nebojsa; Vujisic-Tesic, Bosiljka; Beleslin, Branko; Vukcevic, Vladan; Stankovic, Goran; Seferovic, Petar

    2017-10-01

    The relations of elevated N-terminal pro-brain natriuretic peptide (NT-pro-BNP) and cardiac ischemia in hypertrophic cardiomyopathy (HCM) patients is uncertain. Therefore we designed the study with the following aims: (1) to analyze plasma concentrations of NT-pro-BNP in various subsets of HCM patients; (2) to reveal the correlations of NT-pro-BNP, myocardial ischemia, and diastolic dysfunction; (3) to assess predictors of the elevated plasma levels of NT-pro-BNP. In 61 patients (mean age 48.9±16.3 years; 26 male) with asymmetric HCM plasma levels of NT-pro-BNP were obtained. Standard transthoracic examination, tissue Doppler echocardiography with measurement of transthoracic coronary flow velocity reserve (CFVR) in left anterior descending artery (LAD) was done. Mean natural logarithm value of NT-pro-BNP was 7.11±0.95pg/ml [median value 1133 (interquartile range 561-2442)pg/ml]. NT-pro-BNP was significantly higher in patients with higher NYHA class, in obstructive HCM, more severe mitral regurgitation, increased left atrial volume index (LAVI), presence of calcified mitral annulus, elevated left ventricular (LV) filling pressure and in decreased CFVR. Levels of NT-pro-BNP significantly correlated with the ratio of E/e' (r=0.534, ppro-BNP. Plasma levels of NT-pro-BNP were significantly higher in HCM patients with more advanced disease. Elevated NT-pro-BNP not only reflects the diastolic impairment of the LV, but it might also be the result of cardiac ischemia in patients with HCM. Copyright © 2017 Japanese College of Cardiology. Published by Elsevier Ltd. All rights reserved.

  19. Ovarian reserve

    NARCIS (Netherlands)

    Macklon, NS; Fauser, BCJM

    2005-01-01

    The tendency to delay childbirth has increased the importance of ovarian reserve as a determinant of infertility treatment outcome. In the context of assisted reproduction technology, effective strategies to overcome the impact of ovarian aging and diminished ovarian reserve on pregnancy chances rem

  20. Resolution of Angina Pectoris and Improvement of the Coronary Flow Reserve after Ranolazine Treatment in a Woman with Isolated Impaired Coronary Microcirculation

    Directory of Open Access Journals (Sweden)

    Alessandro Santoro

    2013-01-01

    Full Text Available In a 61-year-old woman with well controlled arterial hypertension, hypercholesterolemia, and smoke and suffering from recurrent angina pectoris despite angiographically normal epicardial coronary vessels and maximal therapy, the replacement of nitrates with novel antiangina drug ranolazine, after 6-month therapy, induced a complete relief of angina and a relevant rising of the transthoracic Doppler-derived coronary flow reserve (CFR. The present clinical case underlines therefore how in patients with chronic ischemic heart disease without epicardial coronary stenosis ranolazine can induce an improvement till the complete solution of the angina symptoms and a substantial increase of CFR as expression of the enhancement of the microvascular coronary function. The improvement of both symptoms and coronary microvascular function is strictly linked to the mechanism of action of the drug. Ranolazine induces in fact a reduction of the intracellular late sodium current that leads to a reduction of the intracellular calcium concentration thus producing a better myocardial diastolic relaxation process which in its turns enhances the myocardial perfusion. The ranolazine acts therefore as a lusitropic drug that improves the diastolic dysfunction and the segmental ischemia thus affecting one of the first steps of the ischemic cascade.

  1. The effect of EC-IC bypass surgery on resting cerebral blood flow and cerebrovascular reserve capacity studied with stable Xe-CT and acetazolamide test

    Energy Technology Data Exchange (ETDEWEB)

    Yamashita, T.; Kashiwagi, S.; Nakano, S.; Takasago, T.; Abiko, S.; Shiroyama, Y.; Hayashi, M.; Ito, H. (Yamaguchi Univ. School of Medicine (Japan). Dept. of Neurosurgery)

    1991-06-01

    Cerebral blood flow (CBF) and cerebrovascular reserve capacity (CRC) were measured by stable xenon computerized tomography (Xe-CT) and acetazolamide test in 15 patients with cerebrovascular disease before and after extracranial-intracranial (EC-IC) bypass surgery for minor stroke, reversible ischemic neurological deficit or transient ischemic attack. All had angiographically shown occlusive lesions of the major arterial trunk. In the present series, global analysis showed that the bypass did not increase the resting rCBF, but did increase the rCRC. We divided the patients into four groups according to the preoperative resting rCBF and rCRC. All 3 patients with normal resting rCBF and reduced rCRC showed postoperative improvement of rCRC. Of 6 patients with reduced CBF and reduced CRC, three had postoperative increase in resting CBF and four had increased CRC. One of two patients with reduced CBF and normal CRC showed only an increase in CRC. We propose that reduced CRC or reduced CBF with reduced CRC are criteria for selection of candidates for bypass surgery. We conclude that Xe-CT with the Diamox test is a useful and simple method for evaluating cerebral hemodynamics. Preoperative grouping with a combination of preoperative resting rCBF and preoperative rCRC is useful for predicting the effect of EC-IC bypass surgery. (orig.).

  2. 76 FR 77834 - Scientific Information Request on Intravascular Diagnostic and Imaging Medical Devices

    Science.gov (United States)

    2011-12-14

    ... Intravascular Diagnostic and Imaging Medical Devices AGENCY: Agency for Healthcare Research and Quality (AHRQ... intravascular diagnostic and imaging medical devices, including: Fractional Flow Reserve (FFR), Coronary Flow... Resonance Imaging (MRI), Elastrography, and Thermography. Scientific information is being solicited to...

  3. Change of cerebral blood flow distribution and vascular reserver according to age in Koreans measured by Tc-99m HMPAO brain SPECT

    Energy Technology Data Exchange (ETDEWEB)

    Song, Ho Cheon; Bom, Hee Seung; Sohn, Hye Kyung; Jeong, Hwan Jeong; Min, Jung Jun; Kim, Ji Yeol [College of Medicine, Chonnam National Univ., Kwangju (Korea, Republic of); Lee Jae Tae [College of Medicine, Kyungpook National Univ., Taegu (Korea, Republic of); Moon, Dae Hyuk; Lee, Hee Kyung [College of Medicine, Ulsan Univ., Seoul (Korea, Republic of)

    1999-02-01

    The aim of this study was to evaluate the normal values of regional cerebral blood flow (rCBF) and cerebrovascular reserve (CVR) in normal children to aged volunteers using Tc-99m HMPAO. Thirty four right-handed normal volunteers (20 males, 14 females, mean age 40.3{+-}24.9 years, range 4 to 82 years) were underwent rest/acetazolamide (ACZ) brain SPECT using Tc-99m HMPAO and the sequential injection and subtraction method. rCBF was estimated on the basis of a semiquantitative approach by means of right/left ratio, region/cerebellum and region to whole brain ratios in frontal, parietal, temporal, and occipital lobes, basal ganglia, thalami, and cerebellum. CVR was measured by means of % perfusion increase calculated as % mean count change compared to rest rCBF in each regions. Mean values of right to left ratios range from 1.004 to 1.018. rCBF was highest in cerebellum and lowest in basal ganglia and thalami. Frontal and temporal rCBF decreased while occipital and thalamic rCBF increased according to age. No sexual difference of rCBF was noted. Mean CVR was 29.9{+-}12.9%. Mean CVR significantly increased to late teens, and declined thereafter. After 6th decade, CVR in both frontal lobes, left parietal lobe and right basal ganglia decreased significantly with advancing age. There was no sexual difference of CVR. Quantitative assessment of CVR was possible by ACZ Tc-99m MHPAO brain SPECT. It revealed that rCBF and CVR changed according to age in normal Korean volunteers. There was no sexual difference.

  4. Recent changes (1973-2014 versus 1903-1972) in the flow regime of the Lower Paraná River and current fluvial pollution warnings in its Delta Biosphere Reserve.

    Science.gov (United States)

    Puig, Alba; Olguín Salinas, Héctor F; Borús, Juan A

    2016-06-01

    Alterations in flow regimes of large rivers may originate or increase risks to ecosystems and humans. The Paraná River basin (South America) undergoes human pressures (e.g., heavy damming in the upper basin, deforestation, and mixed pollution) that may affect the water quantity and quality of its terminal Delta (Argentina). In this study, after applying univariate and multivariate change-point detection and trend analyses to the daily data series of flows incoming to the Delta (Paraná-Santa Fe section), flow characteristics were compared by Indicators of Hydrologic Alteration (IHA) and Environmental Flow Components (EFC). Some flood characteristics were also compared from hydrometric levels in the middle Delta (San Pedro station). Chemical and microbiological water variables in the main rivers of the "Paraná Delta" Biosphere Reserve were examined during two extreme hydrologic years (October 2008 to July 2010) to detect potential risk factors in association with hydrologic conditions. In the Lower Paraná River, a historical period (1903-1972) and two more altered periods (1973-1999 wet period and 2000-2014 dry period) were identified. Flow duration curves evidenced different changes in both altered periods, reflecting the joint effect of climatic variability and human influence. The most evident alterations in the flow regime were the lack of record of the extreme-low-flow component, the attenuation of monthly flow seasonality, and the increase in the number of reversals (dry period) and in the variability of maximum and minimum flow dates. These alterations are consistent with the monthly and daily flow regulation by upstream dams evidenced by available data from the current dry period. In the middle Delta, the marked monthly seasonality in flood days decreased only in the wet period. The proportion between the number of flood days exceeding the evacuation level and that of those exceeding the warning level doubled in the wet period but decreased only

  5. Recent changes (1973-2014 versus 1903-1972) in the flow regime of the Lower Paraná River and current fluvial pollution warnings in its Delta Biosphere Reserve

    Science.gov (United States)

    Puig, Alba; Olguín Salinas, Héctor F.; Borús, Juan A.

    2016-06-01

    Alterations in flow regimes of large rivers may originate or increase risks to ecosystems and humans. The Paraná River basin (South America) undergoes human pressures (e.g., heavy damming in the upper basin, deforestation, and mixed pollution) that may affect the water quantity and quality of its terminal Delta (Argentina). In this study, after applying univariate and multivariate change-point detection and trend analyses to the daily data series of flows incoming to the Delta (Paraná-Santa Fe section), flow characteristics were compared by Indicators of Hydrologic Alteration (IHA) and Environmental Flow Components (EFC). Some flood characteristics were also compared from hydrometric levels in the middle Delta (San Pedro station). Chemical and microbiological water variables in the main rivers of the "Paraná Delta" Biosphere Reserve were examined during two extreme hydrologic years (October 2008 to July 2010) to detect potential risk factors in association with hydrologic conditions. In the Lower Paraná River, a historical period (1903-1972) and two more altered periods (1973-1999 wet period and 2000-2014 dry period) were identified. Flow duration curves evidenced different changes in both altered periods, reflecting the joint effect of climatic variability and human influence. The most evident alterations in the flow regime were the lack of record of the extreme-low-flow component, the attenuation of monthly flow seasonality, and the increase in the number of reversals (dry period) and in the variability of maximum and minimum flow dates. These alterations are consistent with the monthly and daily flow regulation by upstream dams evidenced by available data from the current dry period. In the middle Delta, the marked monthly seasonality in flood days decreased only in the wet period. The proportion between the number of flood days exceeding the evacuation level and that of those exceeding the warning level doubled in the wet period but decreased only slightly

  6. Effect of a single IV administration of L-propionylcarnitine on myocardial microcirculation assessed by coronary flow velocity reserve measurement in patients with systemic sclerosis: a pilot study.

    Science.gov (United States)

    Montisci, Roberta; Ruscazio, Massimo; Lai, Stefania; Vacca, Alessandra; Cauli, Alberto; Passiu, Giuseppe; Montisci, Massimo; Meloni, Luigi; Mathieu, Alessandro; Iliceto, Sabino

    2007-01-01

    Scleroderma-related cardiac involvement primarily affects coronary microvascular structures and function. The microvasculature disorder is responsible for impairment of coronary flow velocity reserve (CFVR), which has been reported in studies of patients with systemic sclerosis (SSc). L-propionylcarnitine (L-PC) is a metabolic substance that is associated with a beneficial effect on both microcirculation and myocyte function. The objective of this study was to determine whether or not CFVR was acutely improved or restored in patients with SSc after a single administration of IV L-PC. In this pilot study, we screened volunteers with SSc who had no clinical evidence of ischemic heart disease. CFVR was determined by a blinded investigator by evaluating the left anterior descending coronary artery (LADCA) by transthoracic echocardiography during adenosine infusion (140 microg/kg x min(-1) for 5 minutes), 30 minutes before and 15 minutes after administration of L-PC (300 mg IV in 5-minute bolus). Thirty-three patients were screened for this study. Fourteen patients (mean [SD] age, 54.3 [11.2] years; mean [SD] weight, 63.8 [14.5] kg; mean [SD] height, 156.3 [8.7] cm) with SSc and no evidence of coronary heart disease were included in the study; 13 women and 1 man (4 with the diffuse cutaneous form of SSc and 10 with the limited cutaneous form). After administration of L-PC to patients with SSc, median CFVR was significantly increased from 2.60 to 3.23 (P < 0.001), whereas peak diastolic velocity in the LADCA decreased significantly at the basal evaluation (30.0 vs 26.0, P = 0.009) and significantly increased (80.0 vs 87.5, P = 0.005) during adenosine infusion. No adverse events occurred before, during, or after L-PC infusion. Acute administration of L-PC was associated with a short-term beneficial effect on CFVR in this pilot study of patients with SSc. These results suggest that further, randomized, controlled, double-blind evaluation of longer-term administration to

  7. Exploring Coronary Circulatory Response to Stenosis and Its Association with Invasive Physiologic Indices Using Absolute Myocardial Blood Flow and Coronary Pressure.

    Science.gov (United States)

    Lee, Joo Myung; Hwang, Doyeon; Park, Jonghanne; Zhang, Jinlong; Tong, Yaliang; Kim, Chee Hae; Bang, Ji-In; Suh, Minseok; Paeng, Jin Chul; Cheon, Gi Jeong; Koo, Bon-Kwon

    2017-08-29

    Background -Although invasive physiologic assessment for coronary stenosis has become a standard practice to guide treatment strategy, coronary circulatory response and changes in invasive physiologic indices, according to different anatomical and hemodynamic lesion severity, have not been fully demonstrated in patients with coronary artery disease. Methods -One hundred fifteen patients with left anterior descending artery stenosis who underwent both (13)N-ammonia positron emission tomography (PET) and invasive physiologic measurement were analyzed. Myocardial blood flow (MBF) measured using PET and invasively measured coronary pressures were used to calculate microvascular resistance (MVR) and stenosis resistance. Results -With progressive worsening of angiographic stenosis severity, both resting and hyperemic trans-stenotic pressure gradient and stenosis resistance increased (Pstenosis severity, stenosis resistance, and trans-stenotic pressure gradient increased, and hyperemic MBF decreased (all P valuescoronary flow reserve (CFR), the diagnostic accuracy of FFR and iFR did not differ, regardless of cut-off values of hyperemic MBF and CFR. Conclusions -This study demonstrated how the coronary circulation changes in response to increasing coronary stenosis severity using (13)N-ammonium PET-derived MBF and invasively measured pressure data. Currently used resting and hyperemic pressure-derived invasive physiologic indices have similar patterns of relationships to the different anatomic and hemodynamic lesion severity. Clinical Trial Registration -URL: https://clinicaltrials.gov Unique Identifier: NCT01366404.

  8. Evaluation of myocardial blood flow and coronary flow reserve after implantation of a bioresorbable vascular scaffold versus metal drug-eluting stent: an interim one-month analysis of the VANISH trial.

    Science.gov (United States)

    Stuijfzand, Wijnand J; Raijmakers, Pieter G; Driessen, Roel S; Lammertsma, Adriaan A; van Rossum, Albert C; Nap, Alexander; Appelman, Yolande; Lemkes, Jorrit S; van Leeuwen, Maarten A; van Royen, Niels; Knaapen, Paul

    2016-08-05

    A randomised clinical trial of bioresorbable vascular scaffold (BVS) vs. metal drug-eluting stent (DES) was initiated, using positron emission tomography (PET) perfusion imaging to assess the effects of both treatments on (hyperaemic) myocardial blood flow (MBF) and coronary flow reserve (CFR) over a three-year period (VANISH trial). In the present study, early, i.e., after one month, MBF and CFR are reported. Sixty patients (45 men [75%], 55±7 years) with a documented single-vessel type A or B1 lesion were included in this single-blind randomised clinical trial. Patients were randomised to implantation of a BVS or DES in a one-to-one fashion. Approximately one month after percutaneous coronary intervention, patients underwent [15O]H2O PET to assess (hyperaemic) MBF, cold pressor test MBF, and CFR. One patient refused PET perfusion at one-month follow-up (in the DES arm). MBF of the treated myocardial territory during rest, CPT, and hyperaemia were not different in BVS-treated patients as compared to DES-treated patients (1.02±0.28 vs. 0.96±0.24 mL·min-1·g-1, p=0.38, 1.20±0.38 vs. 1.08±0.23 mL·min-1·g-1, p=0.16, and 3.04±0.80 vs. 3.33±0.77 mL·min-1·g-1, p=0.16, respectively). CFR of the treated myocardial territory was significantly lower in the BVS-treated patients (3.09±0.94 vs. 3.57±0.85, p<0.05). No differences in PET-derived absolute myocardial perfusion were observed between BVS-treated patients as compared to DES-treated patients at one-month follow-up. CFR was attenuated in BVS-treated patients, although still within the normal range.

  9. Diagnostic value of transmural perfusion ratio derived from dynamic CT-based myocardial perfusion imaging for the detection of haemodynamically relevant coronary artery stenosis

    NARCIS (Netherlands)

    A. Coenen (Adriaan); M. Lubbers (Marisa); A. Kurata (Akira); A.K. Kono (Atsushi K.); A. Dedic (Admir); R.G. Chelu (Raluca Gabriela); M.L. Dijkshoorn (Marcel); Rossi, A. (Alexia); R.J.M. van Geuns (Robert Jan); K. Nieman (Koen)

    2016-01-01

    textabstractObjectives: To investigate the additional value of transmural perfusion ratio (TPR) in dynamic CT myocardial perfusion imaging for detection of haemodynamically significant coronary artery disease compared with fractional flow reserve (FFR). Methods: Subjects with suspected or known coro

  10. Micro-level stochastic loss reserving

    NARCIS (Netherlands)

    Antonio, K.; Plat, R.

    2010-01-01

    To meet future liabilities general insurance companies will set-up reserves. Predicting future cash-flows is essential in this process. Actuarial loss reserving methods will help them to do this in a sound way. The last decennium a vast literature about stochastic loss reserving for the general insu

  11. Calculation of the index of microcirculatory resistance without coronary wedge pressure measurement in the presence of epicardial stenosis.

    Science.gov (United States)

    Yong, Andy S; Layland, Jamie; Fearon, William F; Ho, Michael; Shah, Maulik G; Daniels, David; Whitbourn, Robert; Macisaac, Andrew; Kritharides, Leonard; Wilson, Andrew; Ng, Martin K

    2013-01-01

    This study sought to investigate a novel method to calculate the index of microcirculatory resistance (IMR) in the presence of significant epicardial stenosis without the need for balloon dilation to measure the coronary wedge pressure (P(w)). The IMR provides a quantitative measure of coronary microvasculature status. However, in the presence of significant epicardial stenosis, IMR calculation requires incorporation of the coronary fractional flow reserve (FFR(cor)), which requires balloon dilation within the coronary artery for P(w) measurement. A method to calculate IMR by estimating FFR(cor) from myocardial FFR (FFR(myo)), which does not require P(w) measurement, was developed from a derivation cohort of 50 patients from a single institution. This method to calculate IMR was then validated in a cohort of 72 patients from 2 other different institutions. Physiology measurements were obtained with a pressure-temperature sensor wire before coronary intervention in both cohorts. From the derivation cohort, a strong linear relationship was found between FFR(cor) and FFR(myo) (FFR(cor) = 1.34 × FFR(myo) - 0.32, r(2) = 0.87, p measured FFR(cor) (21.2 ± 12.9 U vs. 20.4 ± 13.6 U, p = 0.161). There was good correlation (r = 0.93, p measured IMR. The FFR(cor), and, by extension, microcirculatory resistance can be derived without the need for P(w). This method enables assessment of coronary microcirculatory status before or without balloon inflation, in the presence of epicardial stenosis. Copyright © 2013 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

  12. Replacing reserve requirements

    OpenAIRE

    Edward J. Stevens

    1993-01-01

    An examination of the fading significance of the Federal Reserve System's reserve requirements and the recent flowering of required clearing balances, a rapidly growing feature of Reserve Bank operations.

  13. Replacing reserve requirements

    OpenAIRE

    Edward J. Stevens

    1993-01-01

    An examination of the fading significance of the Federal Reserve System's reserve requirements and the recent flowering of required clearing balances, a rapidly growing feature of Reserve Bank operations.

  14. Reserves and cash flows under stochastic retirement

    DEFF Research Database (Denmark)

    Gad, Kamille Sofie Tågholt; Nielsen, Jeppe Woetmann

    2016-01-01

    Uncertain time of retirement and uncertain structure of retirement benefits are risk factors for life insurance companies. Nevertheless, classical life insurance models assume these are deterministic. In this paper, we include the risk from stochastic time of retirement and stochastic benefit...... structure in a classical finite-state Markov model for a life insurance contract. We include discontinuities in the distribution of the retirement time. First, we derive formulas for appropriate scaling of the benefits according to the time of retirement and discuss the link between the scaling...

  15. Prognostic Value of Gai's Plaque Score and Agatston Coronary Artery Calcium Score for Functionally Significant Coronary Artery Stenosis

    Institute of Scientific and Technical Information of China (English)

    Chuang Zhang; Shuang Yang; Lu-Yue Gai; Zhi-Qi Han; Qian Xin; Xiao-Bo Yang; Jun-Jie Yang

    2016-01-01

    Background:The prognostic values of the coronary computed tomography angiography (CCTA) score for predicting future cardiovascular events have been previously demonstrated in numerous studies.However,few studies have used the rich information available from CCTA to detect functionally significant coronary lesions.We sought to compare the prognostic values of Gai's plaque score and the coronary artery calcium score (CACS) of CCTA for predicting functionally significant coronary lesions,using fractional flow reserve (FFR) as the gold standard.Methods:We retrospectively analyzed 107 visually assessed significant coronary lesions in 88 patients (mean age,59.6 ± 10.2 years;76.14% of males) who underwent CCTA,invasive coronary angiography,and invasive FFR measurement.An FFR <0.80 indicated hemodynamically significant coronary stenosis.Lesions were divided into two groups using an FFR cutoff value of 0.80.We compared Gai's plaque scores and CACS between the two groups and evaluated the correlations of these scores with FFR.The statistical methods included unpaired t-test,Mann-Whitney U-test,and Spearman's correlation coefficients.Results:Coronary lesions with FFR <0.80 had higher Gai's scores than those with FFR ≥0.80.Gai's score had the strongest correlation with FFR (r =-0.48,P < 0.01) and had a greater area under the curve =0.72 (95% confidence interval:0.61-0.82;P < 0.01) than the CACS of whole arteries and a single artery.Conclusions:Both CACS in a single artery and Gai's plaque score demonstrated a good capacity to assess functionally significant coronary artery stenosis when compared to the gold standard FFR.However,Gai's plaque score was more predictive of FFR <0.80.Gai's score can be easily calculated in daily clinical practice and could be used when considering revascularization.

  16. Oil Reserve Center Established

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Like other countries,China has started to grow its strategic oil reserve in case oil supplies are cut On December 18,2007,the National Development and Reform Commission(NDRC),China’s top economic planner,announced that the national oil reserve center has been officially launched.The supervisory system over the oil reserves has three levels: the energy department of the NDRC,the oil reserve center,and the reserve bases.

  17. Diagnostic performance of instantaneous wave-free ratio for the evaluation of coronary stenosis severity confirmed by fractional flow reserve: A PRISMA-compliant meta-analysis of randomized studies.

    Science.gov (United States)

    Man, Wanrong; Hu, Jianqiang; Zhao, Zhijing; Zhang, Mingming; Wang, Tingting; Lin, Jie; Duan, Yu; Wang, Ling; Wang, Haichang; Sun, Dongdong; Li, Yan

    2016-09-01

    The instantaneous wave-free ratio (iFR) is a new vasodilator-free index of coronary stenosis severity. The aim of this meta-analysis is to assess the diagnostic performance of iFR for the evaluation of coronary stenosis severity with fractional flow reserve as standard reference. We searched PubMed, EMBASE, CENTRAL, ProQuest, Web of Science, and International Clinical Trials Registry Platform (ICTRP) for publications concerning the diagnostic value of iFR. We used a random-effects covariate to synthesize the available data of sensitivity, specificity, positive likelihood ratio (LR+), negative likelihood ratio (LR-), and diagnostic odds ratio (DOR). Overall test performance was summarized by the summary receiver operating characteristic curve (sROC) and the area under the curve (AUC). Eight studies with 1611 subjects were included in the meta-analysis. The pooled sensitivity, specificity, LR+, LR-, and DOR for iFR were respectively 73.3% (70.1-76.2%), 86.4% (84.3-88.3%), 5.71 (4.43-7.37), 0.29 (0.22-0.38), and 20.54 (16.11-26.20). The area under the summary receiver operating characteristic curves for iFR was 0.8786. No publication bias was identified. The available evidence suggests that iFR may be a new, simple, and promising technology for coronary stenosis physiological assessment.

  18. Simulated Groundwater Flow in the Ogallala and Arikaree Aquifers, Rosebud Indian Reservation Area, South Dakota-Revisions with Data Through Water Year 2008 and Simulations of Potential Future Scenarios

    Science.gov (United States)

    Long, Andrew J.; Putnam, Larry D.

    2010-01-01

    The Ogallala and Arikaree aquifers are important water resources in the Rosebud Indian Reservation area and are used extensively for irrigation, municipal, and domestic water supplies. Drought or increased withdrawals from the Ogallala and Arikaree aquifers in the Rosebud Indian Reservation area have the potential to affect water levels in these aquifers. This report documents revisions and recalibration of a previously published three-dimensional, numerical groundwater-flow model for this area. Data for a 30-year period (water years 1979 through 2008) were used in steady-state and transient numerical simulations of groundwater flow. In the revised model, revisions include (1) extension of the transient calibration period by 10 years, (2) the use of inverse modeling for steady-state calibration, (3) model calibration to base flow for an additional four surface-water drainage basins, (4) improved estimation of transient aquifer recharge, (5) improved delineation of vegetation types, and (6) reduced cell size near large capacity water-supply wells. In addition, potential future scenarios were simulated to assess the potential effects of drought and increased groundwater withdrawals. The model comprised two layers: the upper layer represented the Ogallala aquifer and the lower layer represented the Arikaree aquifer. The model's grid had 168 rows and 202 columns, most of which were 1,640 feet (500 meters) wide, with narrower rows and columns near large water-supply wells. Recharge to the Ogallala and Arikaree aquifers occurs from precipitation on the outcrop areas. The average recharge rates used for the steady-state simulation were 2.91 and 1.45 inches per year for the Ogallala aquifer and Arikaree aquifer, respectively, for a total rate of 255.4 cubic feet per second (ft3/s). Discharge from the aquifers occurs through evapotranspiration, discharge to streams as base flow and spring flow, and well withdrawals. Discharge rates for the steady-state simulation were 171

  19. Improvement in coronary haemodynamics after percutaneous coronary intervention: assessment using instantaneous wave-free ratio

    Science.gov (United States)

    Nijjer, Sukhjinder S; Sen, Sayan; Petraco, Ricardo; Sachdeva, Rajesh; Cuculi, Florim; Escaned, Javier; Broyd, Christopher; Foin, Nicolas; Hadjiloizou, Nearchos; Foale, Rodney A; Malik, Iqbal; Mikhail, Ghada W; Sethi, Amarjit S; Al-Bustami, Mahmud; Kaprielian, Raffi R; Khan, Masood A; Baker, Christopher S; Bellamy, Michael F; Hughes, Alun D; Mayet, Jamil; Kharbanda, Rajesh K; Di Mario, Carlo; Davies, Justin E

    2013-01-01

    Objective To determine whether the instantaneous wave-free ratio (iFR) can detect improvement in stenosis significance after percutaneous coronary intervention (PCI) and compare this with fractional flow reserve (FFR) and whole cycle Pd/Pa. Design A prospective observational study was undertaken in elective patients scheduled for PCI with FFR ≤0.80. Intracoronary pressures were measured at rest and during adenosine-mediated vasodilatation, before and after PCI. iFR, Pd/Pa and FFR values were calculated using the validated fully automated algorithms. Setting Coronary catheter laboratories in two UK centres and one in the USA. Patients 120 coronary stenoses in 112 patients were assessed. The mean age was 63±10 years, while 84% were male; 39% smokers; 33% with diabetes. Mean diameter stenosis was 68±16% by quantitative coronary angiography. Results Pre-PCI, mean FFR was 0.66±0.14, mean iFR was 0.75±0.21 and mean Pd/Pa 0.83±0.16. PCI increased all indices significantly (FFR 0.89±0.07, pcoronary haemodynamics elicited by PCI. FFR and iFR have a significantly larger dynamic range than resting Pd/Pa. iFR might be used to objectively document improvement in coronary haemodynamics following PCI in a similar manner to FFR. PMID:24047640

  20. Number and function of bone-marrow derived angiogenic cells and coronary flow reserve in women without obstructive coronary artery disease: a substudy of the NHLBI-sponsored Women's Ischemia Syndrome Evaluation (WISE.

    Directory of Open Access Journals (Sweden)

    Rajesh Mohandas

    Full Text Available BACKGROUND: In women with ischemia and no obstructive coronary artery disease, the Women's Ischemic Syndrome Evaluation (WISE observed that microvascular coronary dysfunction (MCD is the best independent predictor of adverse cardiovascular events. Since coronary microvascular tone is regulated in part by endothelium, we hypothesized that circulating endothelial cells (CEC, which reflect endothelial injury, and the number and function of bone-marrow derived angiogenic cells (BMDAC, which could help repair damaged endothelium, may serve as biomarkers for decreased coronary flow reserve (CFR and MCD. METHODS: We studied 32 women from the WISE cohort. CFR measurements in response to intracoronary adenosine were taken as an index of MCD. We enumerated BMDAC colonies and CEC in peripheral blood samples. BMDAC function was assessed by assay of migration of CD34+ cells toward SDF-1 and measurement of bioavailable nitric oxide (NO. These findings were compared with a healthy reference group and also entered into a multivariable model with CFR as the dependent variable. RESULTS: Compared with a healthy reference group, women with MCD had lower numbers of BMDAC colonies [16 (0, 81 vs. 24 (14, 88; P = 0.01] and NO [936 (156, 1875 vs. 1168 (668, 1823; P = 0.02]. Multivariable regression analysis showed strong correlation of CFR to the combination of BMDAC colony count and CD34+ cell function (migration and NO (R(2 = 0.45; P<0.05. CONCLUSIONS: The BMDAC function and numbers of BMDAC colonies are decreased in symptomatic women with MCD and are independently associated with CFR. These circulating cells may provide mechanistic insights into MCD in women with ischemia.

  1. Impaired coronary flow reserve is the most important marker of viable myocardium in the myocardial segment-based analysis of dual-isotope gated myocardial perfusion single-photon emission computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Won Woo [Dept. of Nuclear Medicine, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam (Korea, Republic of); So, Young [Dept. of Nuclear Medicine, Konkuk University School of Medicine, Seoul (Korea, Republic of); Kim, Ki Bong; Lee, Dong Soo [Seoul National University Hospital, Seoul National University College of Medicine, Seoul (Korea, Republic of)

    2014-04-15

    The aim of this study was to investigate the most robust predictor of myocardial viability among stress/rest reversibility (coronary flow reserve [CFR] impairment), {sup 201}Tl perfusion status at rest, {sup 201}Tl 24 hours redistribution and systolic wall thickening of {sup 99m}Tc-methoxyisobutylisonitrile using a dual isotope gated myocardial perfusion single-photon emission computed tomography (SPECT) in patients with coronary artery disease (CAD) who were re-vascularized with a coronary artery bypass graft (CABG) surgery. A total of 39 patients with CAD was enrolled (34 men and 5 women), aged between 36 and 72 years (mean 58 ± 8 standard in years) who underwent both pre- and 3 months post-CABG myocardial SPECT. We analyzed 17 myocardial segments per patient. Perfusion status and wall motion were semi-quantitatively evaluated using a 4-point grading system. Viable myocardium was defined as dysfunctional myocardium which showed wall motion improvement after CABG. The left ventricular ejection fraction (LVEF) significantly increased from 37.8 ± 9.0% to 45.5 ± 12.3% (p < 0.001) in 22 patients who had a pre-CABG LVEF lower than 50%. Among 590 myocardial segments in the re-vascularized area, 115 showed abnormal wall motion before CABG and 73.9% (85 of 115) had wall motion improvement after CABG. In the univariate analysis (n = 115 segments), stress/rest reversibility (p < 0.001) and {sup 201}Tl rest perfusion status (p = 0.024) were significant predictors of wall motion improvement. However, in multiple logistic regression analysis, stress/rest reversibility alone was a significant predictor for post-CABG wall motion improvement (p < 0.001). Stress/rest reversibility (impaired CFR) during dual-isotope gated myocardial perfusion SPECT was the single most important predictor of wall motion improvement after CABG.

  2. Global Reserve Cooperation

    Science.gov (United States)

    2011-03-24

    St ra te gy R es ea rc h Pr oj ec t GLOBAL RESERVE COOPERATION BY LIEUTENANT COLONEL PAMELA L. MCGAHA United States Army National Guard...DATES COVERED (From - To) 4. TITLE AND SUBTITLE Global Reserve Cooperation 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM...decade, the United States, its allies, and partner nations have greatly increased their reliance on Reserve Component forces. This global

  3. Ovarian reserve parameters

    DEFF Research Database (Denmark)

    Bentzen, J G; Forman, Julie Lyng; Pinborg, Anja;

    2012-01-01

    was observed between duration of hormonal-contraception use and ovarian reserve parameters. No dose-response relation was found between the dose of ethinyloestradiol and AMH or AFC. This study indicates that ovarian reserve markers are lower in women using sex steroids for contraception. Thus, AMH...

  4. HYDROCARBONS RESERVES IN VENEZUELA

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez Cruz, D.J.

    2007-07-01

    Venezuela is an important player in the energy world, because of its hydrocarbons reserves. The process for calculating oil and associated gas reserves is described bearing in mind that 90% of the gas reserves of Venezuela are associated to oil. Likewise, an analysis is made of the oil reserves figures from 1975 to 2003. Reference is also made to inconsistencies found by international experts and the explanations offered in this respect by the Ministry of Energy and Petroleum (MENPET) and Petroleos de Venezuela (PDVSA) regarding the changes that took place in the 1980s. In turn, Hubbert's Law is explained to determine peak production of conventional oil that a reservoir or field will reach, as well as its relationship with remaining reserves. Emphasis is placed on the interest of the United Nations on this topic. The reserves of associated gas are presented along with their relationship with the different crude oils that are produced and with injected gas, as well as with respect to the possible changes that would take place in the latter if oil reserves are revised. Some recommendations are submitted so that the MENPET starts preparing the pertinent policies ruling reserves. (auth)

  5. Forex Reserve Puzzle

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    China faces pressure of preserving the value of its $3 trillion foreign exchange reserves While already under pressure to revalue its currency,the yuan,against the U.S.dollar,China also faces the challenge of stifling vast losses to its foreign exchange reserve,mostly denominated in U.S.dollars.These losses to foreign exchange

  6. Blueprint for Energy Reserves

    Institute of Scientific and Technical Information of China (English)

    Hao Zhenying

    2008-01-01

    @@ The government is drafting a strategic reserve blueprint to ensure energy security-the move coming close on the heels of the construction of four oil reserve bases, according to Ma Fucai, deputy director of the Office of the National Energy Leading Group.

  7. Interpretation of Biosphere Reserves.

    Science.gov (United States)

    Merriman, Tim

    1994-01-01

    Introduces the Man and the Biosphere Programme (MAB) to monitor the 193 biogeographical provinces of the Earth and the creation of biosphere reserves. Highlights the need for interpreters to become familiar or involved with MAB program activities. (LZ)

  8. Professor reveals darter reserve

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Newspaper article on on reserve population of watercress darter in Pinson, AL to help save the population in Roebuck Spring after a significant fish kill in 2008.

  9. Qual o erro da angiografia na definição de isquemia miocárdica durante intervenções coronarianas percutâneas? What is the angiography error when defining myocardial ischemia during percutaneous coronary interventions?

    Directory of Open Access Journals (Sweden)

    Fernando Mendes Sant'Anna

    2008-09-01

    Full Text Available FUNDAMENTO: A angiografia vem sendo utilizada como padrão de referência para definição de doença arterial coronariana (DAC, embora suas limitações sejam conhecidas. O valor da medida do fluxo fracionado de reserva do miocárdio (FFR na avaliação da DAC está bem estabelecido. OBJETIVO: O objetivo deste estudo é avaliar a acurácia da angiografia em definir as lesões isquêmicas e sua correlação com o FFR. MÉTODOS: Duzentos e cinqüenta pacientes foram incluídos no estudo (471 vasos. Todas as estenoses > 50% pela estimativa visual da angiografia (EVA foram avaliadas medindo-se o FFR. Se o FFR 0,75 a lesão não foi tratada. As lesões foram divididas em moderadas (BACKGROUND: The angiography has been used as a reference standard to define coronary artery disease (CAD, although its limitations are well-known. The significance of the myocardial fractional flow reserve (FFR in the assessment of CAD is well established. OBJECTIVE: The aim of this study was to evaluate the accuracy of angiography when defining ischemic lesions and its correlation with FFR. METHODS: Two hundred and fifty consecutive patients (471 arteries were included in this study. All stenoses > 50% at the angiography visual estimate (AVE were assessed by FFR measurements. When FFR was 0.75, no interventional treatment was carried out. Offline quantitative coronary angiography (QCA was performed in all stenoses, which were divided in intermediate (< 70% - 327 and severe (125. The correlation coefficients between the diameter of the stenosis (%DS and FFR and the accuracy of VA of the angiography when assessing ischemia were determined. RESULTS: FFR could be obtained in 452 lesions (96%. Mean %DS and FFR were 56 ± 8% and 0.74 and 76 ± 6% and 0.48 for moderate and severe stenoses, respectively. Concordance between QCA and FFR was poor, especially in intermediate stenoses (Spearman's rho = - 0.33, p<0.0001. Visual assessment resulted in an accuracy of 57% and 96% in

  10. 冠脉造影正常患者内皮功能与冠脉血流储备能力的研究%Clinical study of Endothelial Function and Coronary Flow Reserve in Patients with Normal Coronary Arteriograms

    Institute of Scientific and Technical Information of China (English)

    张勇; 唐小霞; 曹邦明; 任淑红; 王新宇; 陈兴新

    2014-01-01

    Objective Coronary Flow Reserve ( CFR ) of patients with normal coronary arteriograms were measured by the use of angiographic digital tracking and endothelial function were evaluated by intracoronary acetyl -choline(Ach) test and high-sensitivity C-reactive protein (hsCRP) levels.The change of CFR and endothelial function in patients with different risk factors were observed and analysed .Methods In selected 118 cases ( The mean age 61 ±11 years old ) with suspected coronary artery disease were divided into 6 groups according to different risk factors:hypertension , hypercholesterolemia , obesity , smoking , type 2 diabetes mellitus and ≥2 risk factors groups while 24 healthy subjects ( The mean age 56 ±12 years old ) as matched .CFR of patients with normal coro-nary arteriograms were measured by the use of angiographic digital tracking and endothelial function were evaluated by intracoronary Ach test and hsCRP levels .The change of CFR , positive rates of Ach test , hsCRP levels were ob-served and analysed .Results CFR in group of hypertension , smoking and≥2 risk factors were lower and positive rates of Ach test ,hsCRP levels were higher than those of the control group .CFR in group of hypercholesterolemia , Obesity , Type 2 Diabetes Mellitus groups were lower and positive rates of Ach test were higher than those of the control group but there were no significant differences between them .hsCRP levels of Type 2 Diabetes Mellitus group were higher than those of the control group .Conclusion Angiography digital tracking method can be easily used in measuring CFR .Lower CFR and endothelial dysfunction in people with different risk factors were observed in this reaserch .%目的:通过常规冠脉造影,运用数字跟踪技术软件测定冠脉造影正常患者冠脉血流储备( Coro-nary Flow Reserve,CFR),冠脉内注射乙酰胆碱(Acetylcholine,Ach)并检测高敏C反应蛋白( high Sensitivi-ty,hsCRP)含量评价内皮功能,

  11. Biomarkers of Ovarian Reserve

    Directory of Open Access Journals (Sweden)

    William E. Roudebush

    2008-01-01

    Full Text Available The primary function of the female ovary is the production of a mature and viable oocyte capable of fertilization and subsequent embryo development and implantation. At birth, the ovary contains a finite number of oocytes available for folliculogenesis. This finite number of available oocytes is termed “the ovarian reserve”. The determination of ovarian reserve is important in the assessment and treatment of infertility. As the ovary ages, the ovarian reserve will decline. Infertility affects approximately 15-20% of reproductive aged couples. The most commonly used biomarker assay to assess ovarian reserve is the measurement of follicle stimulating hormone (FSH on day 3 of the menstrual cycle. However, antimüllerian hormone and inhibin-B are other biomarkers of ovarian reserve that are gaining in popularity since they provide direct determination of ovarian status, whereas day 3 FSH is an indirect measurement. This review examines the physical tools and the hormone biomarkers used to evaluate ovarian reserve.

  12. Wash-in and wash-out of sevoflurane in a test-lung model: A comparison between Aisys and FLOW-i [version 2; referees: 2 approved, 1 approved with reservations

    Directory of Open Access Journals (Sweden)

    Petter Jakobsson

    2017-04-01

    Full Text Available Background: Modern anaesthesia workstations are reassuringly tight and are equipped with effective gas monitoring, thus providing good opportunities for low/minimal flow anaesthesia. A prerequisite for effective low flow anaesthesia is the possibility to rapidly increase and decrease gas concentrations in the circle system, thereby controlling the depth of anaesthesia.  Methods: We studied the wash-in and wash-out of sevoflurane in the circle system with fixed fresh gas flow and vaporizer setting. We compared two modern anaesthesia work stations, the Aisys (GE, Madison, WI, USA and FLOW-i (Maquet, Solna, Sweden in a test lung model.  Results: We found fresh-gas flow to have, as expected, a major influence on wash-in, as well as wash-out of sevoflurane. The wash-in time to reach a stable circle 1 MAC (2.1% decreased from an average of 547 ± 83 seconds with a constant fresh gas flow of 300 ml/min and vaporizer setting of 8%, to a mean of 38 ± 6 seconds at a fresh gas flow of 4 L/min. There were only minor differences between the two works-stations tested; the Aisys was slightly faster at both 300 and 4 L/min flow. Time to further increase circle end-tidal concentration from 1-1.5 MAC showed likewise significant associations to fresh gas and decreased from 330 ± 24 seconds at 300 ml/min. to less than a minute at constant 4 L/min (17 ± 11 seconds, without anaesthetic machine difference. Wash-out was also fresh gas flow dependent and plateaued at 7.5 L/min.  Conclusions: Circle system wash-in and wash-out show clear fresh gas dependency and varies somewhat between the Aisys and Flow-i. The circle saturation, reaching 1 MAC end-tidal or increasing from 1-1.5 MAC can be achieved with both work-stations within 1.5 minutes at a constant fresh gas flow of 2 and 4 L/min. Wash-out plateaued at 7.5 L/min.

  13. Handbook on loss reserving

    CERN Document Server

    Schmidt, Klaus; Schnaus, Anja

    2016-01-01

    This handbook presents the basic aspects of actuarial loss reserving. Besides the traditional methods, it also includes a description of more recent ones and a discussion of certain problems occurring in actuarial practice, like inflation, scarce data, large claims, slow loss development, the use of market statistics, the need for simulation techniques and the task of calculating best estimates and ranges of future losses. In property and casualty insurance the provisions for payment obligations from losses that have occurred but have not yet been settled usually constitute the largest item on the liabilities side of an insurer's balance sheet. For this reason, the determination and evaluation of these loss reserves is of considerable economic importance for every property and casualty insurer. Actuarial students, academics as well as practicing actuaries will benefit from this overview of the most important actuarial methods of loss reserving by developing an understanding of the underlying stochastic models...

  14. MR angiography and determination of the flow reserve after minimal invasive direct coronary artery bypass (MIDCAB) surgery of the left internal mammary arteria in comparison to the multidetector-row CT; MR-Angiographie und Flussreservenbestimmung nach minimalinvasiver direkter Koronararterien-Bypass(MIDCAB)-Operation der linken Arteria mammaria interna im Vergleich zur Mehrzeilen-CT

    Energy Technology Data Exchange (ETDEWEB)

    Stauder, N.I.; Fenchel, M.; Kuettner, A.; Kramer, U.; Claussen, C.D.; Miller, S. [Abt. Radiologische Diagnostik, Universitaetsklinik Tuebingen (Germany); Stauder, H.; Scheule, A.M. [Abt. Thorax-, Herz- und Gefaesschirurgie, Universitaetsklinik Tuebingen (Germany)

    2005-08-01

    Purpose: To evaluate graft patency, flow and flow reserve in patients with minimal invasive direct coronary artery bypass (MIDCAB) of internal mammary artery (IMA) grafts using a combined MR protocol with phase-contrast technique and MR angiography. Material and methods: At a 1.5T Magnetom Sonata (SIEMENS), 19 symptomatic (angina CCS I-III, intermittent thoracic discomfort, scar disorders) patients (59.9{+-}7.9 years old) with 19 left internal mammary artery (LIMA) grafts implanted in minimal invasive technique were examined 6.9{+-}1.5 years post surgery. Contrast enhanced MR angiography (TR 2.5 ms, TE 1 ms, flip angle 20 , spatial resolution 1.4 x 0.9 x 1.0 mm{sup 3}, breath hold technique, no ECG-triggering, 25 ml Gd-DTPA) was performed to assess bypass patency. Phase-contrast flow measurements with retrospective gating (TR 41 msec, TE 3.2 msec, flip angle 30 , spatial resolution 1.1 x 1.1 x 5 mm{sup 3}, temporal resolution 42 msec, venc 90 cm/sec) were applied in the IMA grafts at rest and after stress induction with dipyridamole (0.56 mg/kg/BW). For comparison, graft patency was evaluated by multidetector-row computed tomography (16-row CT). In 9 patients a selective catheter angiography was performed. Results: MIDCAB grafts were occluded in 4/19 patients. In 4 patients the anastomosis to LAD was highly stenotic (>70%) at MDCT (2 experienced investigators in consensus reading). In MRA 9 grafts could be delineated completely including the distal anastomosis to LAD (47%). In 9 patients the distal part could not be evaluated. In patients with patent grafts (MDCT), a significant improvement of graft flow (at rest 75.4{+-}33.3 ml/min; after stress 202.7{+-}49.6; P<0.002) and flow reserve (patent grafts 3.0{+-}1.1; stenotic grafts 1.5{+-}0.2, P<0.02; occluded grafts 0.9{+-}0.2, P<0.01) after stress induction was detected. Diastolic-to-systolic peak velocity ratios (D/S-PVR) at baseline were not significant between patent and stenotic grafts. Mean flow at baseline and

  15. School Shootings Stun Reservation

    Science.gov (United States)

    Borja, Rhea R.; Cavanagh, Sean

    2005-01-01

    This article deals with the impact brought by the school shootings at Red Lake Indian Reservation in Minnesota to the school community. A deeply troubled 16-year-old student shot and killed seven other people and himself at a high school. The nation's deadliest school attack since the 1999 slayings at Colorado's suburban Columbine High School took…

  16. The Study of Foreign Currency Reserve,Flow of Currency and CPI%外汇储备、货币供应量与物价水平三者关系的实证研究

    Institute of Scientific and Technical Information of China (English)

    马岩; 赵文昆

    2011-01-01

    Huge foreign exchange reserves,money supply continued to increase with rising price levels in China's economy has become a prominent issue.This paper regards:The use of ADF test,the multivariate cointegration test,error correction model and Granger causality test from the perspective of econometric relations between verified.Foreign exchange reserves and the price level,money supply existslong-term cointegration relationship.foreign exchange reserves increase the money supply caused inflation which led to the empirical test is set up.In this paper,a reasonable regulation of foreign exchange reserves in order to control inflation has been given.%外汇储备规模巨大、货币供应量持续增加与物价水平不断攀升已成为我国经济运行中凸显的问题。本文运用ADF检验、多变量协整检验、误差修正模型和Granger因果关系检验从计量经济学的角度验证了三者关系,即外汇储备与物价水平、货币供应量存在长期协整关系,而且外汇储备增加引发货币供应量增加进而导致通货膨胀,这一结论在实证检验上是成立的。最后,本文提出了合理调控外汇储备以控制通货膨胀的建议。

  17. Poor ovarian reserve

    Directory of Open Access Journals (Sweden)

    Padma Rekha Jirge

    2016-01-01

    Full Text Available Poor ovarian reserve (POR is an important limiting factor for the success of any treatment modality for infertility. It indicates a reduction in quantity and quality of oocytes in women of reproductive age group. It may be age related as seen in advanced years of reproductive life or may occur in young women due to diverse etiological factors. Evaluating ovarian reserve and individualizing the therapeutic strategies are very important for optimizing the success rate. Majority or women with POR need to undergo in vitro fertilization to achieve pregnancy. However, pregnancy rate remains low despite a plethora of interventions and is associated with high pregnancy loss. Early detection and active management are essential to minimize the need for egg donation in these women.

  18. Payment of Interest on Reserves

    National Research Council Canada - National Science Library

    Weiner, Stuart E

    1985-01-01

    .... These reserve requirements, in conjunction with control over the reserve supply, effectively place an upper limit on deposit creation and thus help the Federal Reserve System control the growth of money...

  19. 77 FR 66361 - Reserve Requirements of Depository Institutions: Reserves Simplification

    Science.gov (United States)

    2012-11-05

    ... AD 83 Reserve Requirements of Depository Institutions: Reserves Simplification AGENCY: Board of... Regulation D (Reserve Requirements of Depository Institutions) published in the Federal Register on April 12... simplifications related to the administration of reserve requirements: 1. Create a common two-week...

  20. Fractional Reserve Banking

    OpenAIRE

    Andreasen, Niels; Bjerregaard, Mads; Lund, Jonas; Olsen, Ove Bitsch; Rasmussen, Andreas Dalgas

    2012-01-01

    Projektet er bygget op omkring kritisk realisme, som er det gennemgående videnskabelige fundament til undersøgelsen af hvilke strukturelle grunde der er til finansiel ustabilitet i Danmark. Projektet går i dybden med Fractional Reserve Banking og incitamentsstrukturen i banksystemet. Vi bevæger os både på det makro- og mikroøkonomiske niveau i analysen. På makro niveau bruger vi den østrigske skole om konjunktur teori (The Positive Theory of the Cycle). På mikro niveau arbejder vi med princip...

  1. Fractional Reserve Banking

    OpenAIRE

    Andreasen, Niels; Bjerregaard, Mads; Lund, Jonas; Olsen, Ove Bitsch; Rasmussen, Andreas Dalgas

    2012-01-01

    Projektet er bygget op omkring kritisk realisme, som er det gennemgående videnskabelige fundament til undersøgelsen af hvilke strukturelle grunde der er til finansiel ustabilitet i Danmark. Projektet går i dybden med Fractional Reserve Banking og incitamentsstrukturen i banksystemet. Vi bevæger os både på det makro- og mikroøkonomiske niveau i analysen. På makro niveau bruger vi den østrigske skole om konjunktur teori (The Positive Theory of the Cycle). På mikro niveau arbejder vi med princip...

  2. Reserves in western basins

    Energy Technology Data Exchange (ETDEWEB)

    Caldwell, R.H.; Cotton, B.W. [Scotia Group, Dallas, TX (United States)

    1995-04-01

    The objective of this project is to investigate the reserves potential of tight gas reservoirs in three Rocky Mountain basins: the Greater Green River (GGRB), Uinta and Piceance basins. The basins contain vast gas resources that have been estimated in the thousands of Tcf hosted in low permeability clastic reservoirs. This study documents the productive characteristics of these tight reservoirs, requantifies gas in place resources, and characterizes the reserves potential of each basin. The purpose of this work is to promote understanding of the resource and to encourage its exploitation by private industry. At this point in time, the GGRB work has been completed and a final report published. Work is well underway in the Uinta and Piceance basins which are being handled concurrently, with reports on these basins being scheduled for the middle of this year. Since the GGRB portion of the project has been completed, this presentation win focus upon that basin. A key conclusion of this study was the subdivision of the resource, based upon economic and technological considerations, into groupings that have distinct properties with regard to potential for future producibility, economics and risk profile.

  3. Maximum currents in the Northeast Corridor Reserve during November 2013.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A 2D numerical model, CMS-Flow, was implemented for the Northeast Corridor Reserve (NECR) using a telescoping grid. Tide and wind forcing was provided to the model...

  4. Land Use Change Around Nature Reserves: Implications for Sustaining Biodiversity

    Science.gov (United States)

    Hansen, A. J.; Defries, R.; Curran, L.; Liu, J.; Reid, R.; Turner, B.

    2004-12-01

    The effects of land use change outside of reserves on biodiversity within reserves is not well studied. This paper draws on research from Yellowstone, East Africa, Yucatan, Borneo, and Wolong, China to examine land use effects on nature reserves. Objectives are: quantify rates of change in land use around reserves; examine consequences for biodiversity within the context of specific ecological mechanisms; and draw implications for regional management. Within each of the study regions, semi-natural habitats around nature reserves have been converted to agricultural, rural residential, or urban land uses. Rates vary from 0.2-0.4 %/yr in Yucatan, to 9.5 %/yr in Borneo. Such land use changes may be important because nature reserves are often parts of larger ecosystems that are defined by flows in energy, materials, and organisms. Land use outside of reserves may disrupt these flows and alter biodiversity within reserves. Ecological mechanisms that connect biodiversity to these land use changes include habitat size, ecological flows, crucial habitats, and edge effects. For example, the effective size of the East African study area has been reduced by 45% by human activities. Based on the species area relationship, this reduction in habitat area will lead to a loss of 14% of bird and mammal species. A major conclusion is that the viability of nature reserves can best be ensured by managing them in the context of the surrounding region. Knowledge of the ecological mechanisms by which land use influences nature reserves provides design criteria for this regional management.

  5. Geometry-based pressure drop prediction in mildly diseased human coronary arteries

    NARCIS (Netherlands)

    J.T.C. Schrauwen (Jelle); J.J. Wentzel (Jolanda); A.F.W. van der Steen (Ton); F.J.H. Gijsen (Frank)

    2014-01-01

    textabstractPressure drop (△. p) estimations in human coronary arteries have several important applications, including determination of appropriate boundary conditions for CFD and estimation of fractional flow reserve (FFR). In this study a △. p prediction was made based on geometrical features deri

  6. Adrenocortical reserves in hyperthyroidism.

    Science.gov (United States)

    Agbaht, Kemal; Gullu, Sevim

    2014-02-01

    Explicit data regarding the changes in adrenocortical reserves during hyperthyroidism do not exist. We aimed to document the capability (response) of adrenal gland to secrete cortisol and DHEA-S during hyperthyroidism compared to euthyroidism, and to describe factors associated with these responses. A standard-dose (0.25 mg/i.v.) ACTH stimulation test was performed to the same patients before hyperthyroidism treatment, and after attainment of euthyroidism. Baseline cortisol (Cor(0)), DHEA-S (DHEA-S(0)), cortisol binding globulin (CBG), ACTH, calculated free cortisol (by Coolen's equation = CFC), free cortisol index (FCI), 60-min cortisol (Cor(60)), and DHEA-S (DHEA-S(60)), delta cortisol (ΔCor), delta DHEA-S (ΔDHEA-S) responses were evaluated. Forty-one patients [22 females, 49.5 ± 15.2 years old, 32 Graves disease, nine toxic nodular goiter] had similar Cor(0), DHEA-S(0), CFC, FCI, and DHEA-S(60) in hyperthyroid and euthyroid states. Cor(60), ΔCor, and ΔDHEA-S were lower in hyperthyroidism. In four (10 %) patients the peak ACTH-stimulated cortisol values were lower than 18 μg/dL. When the test repeated after attainment of euthyroidism, all of the patients had normal cortisol response. Regression analysis demonstrated an independent association of Cor(60) with free T3 in hyperthyroidism. However, the predictors of CFC, FCI, and DHEA-S levels were serum creatinine levels in hyperthyroidism, and both creatinine and transaminase levels in euthyroidism. ACTH-stimulated peak cortisol, delta cortisol, and delta DHEA-S levels are decreased during hyperthyroidism, probably due to increased turnover. Since about 10 % of the subjects with hyperthyroidism are at risk for adrenal insufficiency, clinicians dealing with Graves' disease should be alert to the possibility of adrenal insufficiency during hyperthyroid stage.

  7. Reserve requirements: A modern perspective

    OpenAIRE

    Scott E. Hein; Jonathan D. Stewart

    2002-01-01

    The discussion in many money and banking textbooks would suggest that the Federal Reserve requires depository institutions to hold a minimum level of non-interest-earning reserves because (1) reserve requirements are a monetary policy tool that allows the Fed to expand the money supply and lower interest rates, and (2) reserve requirements improve the safety and soundness of depository institutions. This article argues that this "conventional wisdom" view is too narrow. ; The Fed often uses r...

  8. Fractional Reserve in Banking System

    OpenAIRE

    Valkonen, Maria

    2016-01-01

    This thesis is aimed to provide understanding of the role of the fractional reserve in the mod-ern banking system worldwide and particularly in Finland. The fractional reserve banking is used worldwide, but the benefits of this system are very disputable. On the one hand, experts say that the fractional reserve is a necessary instrument for the normal business and profit making. On the other hand, sceptics openly criticize the fractional reserve system and blame it for fiat money (money n...

  9. Fractional Reserve in Banking System

    OpenAIRE

    Valkonen, Maria

    2016-01-01

    This thesis is aimed to provide understanding of the role of the fractional reserve in the mod-ern banking system worldwide and particularly in Finland. The fractional reserve banking is used worldwide, but the benefits of this system are very disputable. On the one hand, experts say that the fractional reserve is a necessary instrument for the normal business and profit making. On the other hand, sceptics openly criticize the fractional reserve system and blame it for fiat money (money n...

  10. 77 FR 40253 - Reserve Account

    Science.gov (United States)

    2012-07-09

    .... 3. One commentator also agreed with the change to the reserve account requirements as the change... regulation to change the Reserve Account for new construction for the Sections 514/516 Farm Labor Housing... Development based its reserve account on a set percentage of a property's total development cost (TDC). With...

  11. Biosphere reserves: Attributes for success.

    Science.gov (United States)

    Van Cuong, Chu; Dart, Peter; Hockings, Marc

    2017-03-01

    Biosphere reserves established under the UNESCO Man and the Biosphere Program aim to harmonise biodiversity conservation and sustainable development. Concerns over the extent to which the reserve network was living up to this ideal led to the development of a new strategy in 1995 (the Seville Strategy) to enhance the operation of the network of reserves. An evaluation of effectiveness of management of the biosphere reserve network was called for as part of this strategy. Expert opinion was assembled through a Delphi Process to identify successful and less successful reserves and investigate common factors influencing success or failure. Ninety biosphere reserves including sixty successful and thirty less successful reserves in 42 countries across all five Man and the Biosphere Program regions were identified. Most successful sites are the post-Seville generation while the majority of unsuccessful sites are pre-Seville that are managed as national parks and have not been amended to conform to the characteristics that are meant to define a biosphere reserve. Stakeholder participation and collaboration, governance, finance and resources, management, and awareness and communication are the most influential factors in the success or failure of the biosphere reserves. For success, the biosphere reserve concept needs to be clearly understood and applied through landscape zoning. Designated reserves then need a management system with inclusive good governance, strong participation and collaboration, adequate finance and human resource allocation and stable and responsible management and implementation. All rather obvious but it is difficult to achieve without commitment to the biosphere reserve concept by the governance authorities. Copyright © 2016 Elsevier Ltd. All rights reserved.

  12. Nuclear, uranium, reserves, sustainability, independence; Nucleaire, Uranium, reserves, durabilite, independance

    Energy Technology Data Exchange (ETDEWEB)

    Acket, C

    2007-06-15

    In order to evaluate the energy independence concerning the nuclear energy, the author takes the state of the art about the uranium. He details the fuel needs, the reserves on the base of the today available techniques, the reserves on the base of the future techniques and concludes positively on the energy independence for the nuclear. (A.L.B.)

  13. 77 FR 21846 - Reserve Requirements of Depository Institutions: Reserves Simplification

    Science.gov (United States)

    2012-04-12

    ... liabilities of depository institutions for the purpose of implementing monetary policy. The Board's Regulation... monetary policy. If the Federal Reserve changes its monetary policy framework, which includes the payment... affect the Federal Reserve's ability to implement monetary policy in the event that all depository...

  14. Marine reserves with ecological uncertainty.

    Science.gov (United States)

    Grafton, R Quentin; Kompas, Tom; Lindenmayer, David

    2005-09-01

    To help manage the fluctuations inherent in fish populations scientists have argued for both an ecosystem approach to management and the greater use of marine reserves. Support for reserves includes empirical evidence that they can raise the spawning biomass and mean size of exploited populations, increase the abundance of species and, relative to reference sites, raise population density, biomass, fish size and diversity. By contrast, fishers often oppose the establishment and expansion of marine reserves and claim that reserves provide few, if any, economic payoffs. Using a stochastic optimal control model with two forms of ecological uncertainty we demonstrate that reserves create a resilience effect that allows for the population to recover faster, and can also raise the harvest immediately following a negative shock. The tradeoff of a larger reserve is a reduced harvest in the absence of a negative shock such that a reserve will never encompass the entire population if the goal is to maximize the economic returns from harvesting, and fishing is profitable. Under a wide range of parameter values with ecological uncertainty, and in the 'worst case' scenario for a reserve, we show that a marine reserve can increase the economic payoff to fishers even when the harvested population is not initially overexploited, harvesting is economically optimal and the population is persistent. Moreover, we show that the benefits of a reserve cannot be achieved by existing effort or output controls. Our results demonstrate that, in many cases, there is no tradeoff between the economic payoff of fishers and ecological benefits when a reserve is established at equal to, or less than, its optimum size.

  15. Complete revascularisation versus treatment of the culprit lesion only in patients with ST-segment elevation myocardial infarction and multivessel disease (DANAMI-3—PRIMULTI)

    DEFF Research Database (Denmark)

    Engstrøm, Thomas; Kelbæk, Henning; Helqvist, Steffen

    2015-01-01

    BACKGROUND: Patients with acute ST-segment elevation myocardial infarction (STEMI) and multivessel coronary disease have a worse prognosis compared with individuals with single-vessel disease. We aimed to study the clinical outcome of patients with STEMI treated with fractional flow reserve (FFR...... in the infarct-related artery were included. After successful percutaneous coronary intervention (PCI) of the infarct-related artery, patients were randomly allocated (in a 1:1 ratio) either no further invasive treatment or complete FFR-guided revascularisation before discharge. Randomisation was done...... of the infarct-related artery only and in 40 (13%) patients who had complete revascularisation (hazard ratio 0∙56, 95% CI 0∙38–0∙83; p=0∙004). INTERPRETATION: In patients with STEMI and multivessel disease, complete revascularisation guided by FFR measurements significantly reduces the risk of future events...

  16. Major Nature Reserves in China

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    At the end of 2010,China had 2,588 nature reserves,covering 14.9 percent of its land area.These nature reserves have effectively protected more than 90 percent of land ecosystems,85 percent of wild animals and 65 percent of higher plant species

  17. Operating Reserves and Variable Generation

    Energy Technology Data Exchange (ETDEWEB)

    Ela, E.; Milligan, M.; Kirby, B.

    2011-08-01

    This report tries to first generalize the requirements of the power system as it relates to the needs of operating reserves. It also includes a survey of operating reserves and how they are managed internationally in system operations today and then how new studies and research are proposing they may be managed in the future with higher penetrations of variable generation.

  18. Can Creativity Predict Cognitive Reserve?

    Science.gov (United States)

    Palmiero, Massimiliano; Di Giacomo, Dina; Passafiume, Domenico

    2016-01-01

    Cognitive reserve relies on the ability to effectively cope with aging and brain damage by using alternate processes to approach tasks when standard approaches are no longer available. In this study, the issue if creativity can predict cognitive reserve has been explored. Forty participants (mean age: 61 years) filled out: the Cognitive Reserve…

  19. Can Creativity Predict Cognitive Reserve?

    Science.gov (United States)

    Palmiero, Massimiliano; Di Giacomo, Dina; Passafiume, Domenico

    2016-01-01

    Cognitive reserve relies on the ability to effectively cope with aging and brain damage by using alternate processes to approach tasks when standard approaches are no longer available. In this study, the issue if creativity can predict cognitive reserve has been explored. Forty participants (mean age: 61 years) filled out: the Cognitive Reserve…

  20. Coronary flow reserve : a functional measure of stenosis severity

    NARCIS (Netherlands)

    F. Zijlstra (Felix)

    1988-01-01

    textabstractIn 1959 Sones developed selective coronary cineangiography. To date, this technique has remained the only means available for the visualization of the coronary arterial system with such image contrast and resolution, that the presence and severity of coronary stenosis can be

  1. Restoration seed reserves for assisted gene flow within seed orchards

    Science.gov (United States)

    C.S. Echt; B.S. Crane

    2017-01-01

    Changing climate and declining forest populations imperil the future of certain forest tree species. To complement forest management and genetic conservation plans, we propose a new paradigm for seedling seed orchards: foster genetic mixing among a variety of seed sources to increase genetic diversity and adaptive potential of seed supplies used for forest restoration...

  2. ASSESSMENT OF CORONARY FLOW RESERVE IN PATIENTS WITH ANGINA PECTORIS

    Institute of Scientific and Technical Information of China (English)

    沈卫峰; 蔡煦; 张大东; 张宪; 郑爱芳; 龚兰生

    1995-01-01

    ASSESSMENTOFCORONARYFLOWRESERVEINPATIENTSWITHANGINAPECTORISShengWeifeng(沈卫峰);CaiXu(蔡煦);ZhangDadong(张大东);ZhangXian(张宪);ZhengAi...

  3. Cognitive Reserve Scale and ageing

    Directory of Open Access Journals (Sweden)

    Irene León

    2016-01-01

    Full Text Available The construct of cognitive reserve attempts to explain why some individuals with brain impairment, and some people during normal ageing, can solve cognitive tasks better than expected. This study aimed to estimate cognitive reserve in a healthy sample of people aged 65 years and over, with special attention to its influence on cognitive performance. For this purpose, it used the Cognitive Reserve Scale (CRS and a neuropsychological battery that included tests of attention and memory. The results revealed that women obtained higher total CRS raw scores than men. Moreover, the CRS predicted the learning curve, short-term and long-term memory, but not attentional and working memory performance. Thus, the CRS offers a new proxy of cognitive reserve based on cognitively stimulating activities performed by healthy elderly people. Following an active lifestyle throughout life was associated with better intellectual performance and positive effects on relevant aspects of quality of life.

  4. Estimating Foreign Exchange Reserve Adequacy

    Directory of Open Access Journals (Sweden)

    Abdul Hakim

    2013-04-01

    Full Text Available Accumulating foreign exchange reserves, despite their cost and their impacts on other macroeconomics variables, provides some benefits. This paper models such foreign exchange reserves. To measure the adequacy of foreign exchange reserves for import, it uses total reserves-to-import ratio (TRM. The chosen independent variables are gross domestic product growth, exchange rates, opportunity cost, and a dummy variable separating the pre and post 1997 Asian financial crisis. To estimate the risky TRM value, this paper uses conditional Value-at-Risk (VaR, with the help of Glosten-Jagannathan-Runkle (GJR model to estimate the conditional volatility. The results suggest that all independent variables significantly influence TRM. They also suggest that the short and long run volatilities are evident, with the additional evidence of asymmetric effects of negative and positive past shocks. The VaR, which are calculated assuming both normal and t distributions, provide similar results, namely violations in 2005 and 2008.

  5. Ultrasound in evaluating ovarian reserve

    OpenAIRE

    Eman Ahmaed Shawky Sabek; Ola I. Saleh; Howida A. Ahmed

    2015-01-01

    The objective of this study was to compare the diagnostic accuracy of transvaginal ultrasound (TVS), as a less invasive technique instead of hormonal assay to evaluate the ovarian reserve. This study included fifty-five females with breast cancer and we compared the ovarian reserve for these patients by hormonal assay through measuring the serum AntiMullerian Hormone (AMH) level and follicular stimulating hormone (FSH) level before and after chemotherapy, and by transvaginal ultrasound throug...

  6. Fractional Reserve Banking: Some Quibbles

    OpenAIRE

    Bagus, Philipp; Howden, David

    2010-01-01

    We explore several unaddressed issues in George Selgin’s (1988) claim that the best monetary system to maintain monetary equilibrium is a fractional reserve free banking one. The claim that adverse clearing balances would limit credit expansion in a fractional reserve free banking system is more troublesome than previously reckoned. Both lengthened clearing periods and interbank agreements render credit expansion unrestrained. “The theory of free banking” confuses increases in money held with...

  7. Reserve growth during financial volatility in a technologically challenging world

    Science.gov (United States)

    Klett, Timothy R.; Gautier, Donald L.

    2010-01-01

    Reserve growth (growth-to-known) is the addition of oil and gas quantities to reported proved or proved-plus-probable reserves in discovered fields. The amount of reserve growth fluctuates through time with prevailing economic and technological conditions. Most reserve additions are the result of investment in field operations and in development technology. These investments can be justified by higher prices of oil and gas, the desire to maintain cash flow, and by greater recovery efficiency in well established fields. The price/cost ratio affects decisions for field abandonment and (or) implementation of improved recovery methods. Although small- to medium-size fields might show higher percentages of reserve growth, a relatively few giant fields contribute most volumetric reserve growth, indicating that companies may prefer to invest in existing fields with low geologic and production risk and an established infrastructure in order to increase their price/cost relationship. Whereas many previous estimates of reserve growth were based on past trends of reported reserves, future reserve growth is expected to be greatly affected by financial volatility and fluctuating economic and technological conditions.

  8. Demand as frequency controlled reserve

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Z.; Togeby, M.; OEstergaard, J.

    2008-09-15

    Using demand as frequency controlled reserve (DFR) is an emerging technology which allow demand to participate actively in maintaining the system operation without reducing the energy service delivered to the customer and without need of user interaction. The basic premise is that traditional frequency controlled reserves from power plants and interconnections with neighbouring systems can be costly, slow and not fulfil the need for future power grids with a high share of wind power and fewer central power plants, and an intention to perform flexible operation such as is landing. Electricity demands, on the other hand, have advantages as frequency reserve including fast activation speed, smooth linear activation, low expected costs, and well-dispersed in the distribution grid. The main challenge of DFR is new methods for monitoring the available capacity. This project has investigated the technology of using electricity demands for providing frequency reserve to power systems. Within the project the potential and economy of DFR compatible loads in Denmark has been investigated, control logic has been designed, power system impact has been investigated, potential business models has been evaluated and an implementation strategy has been suggested. The tasks and goals of the project have been successfully accomplished based on which the conclusion and future recommendation are made. This project has developed the DFR technology that enables electricity demands to autonomously disconnect or reconnect to the grid in response to system frequency variations. The developed DFR technology is proved to be a promising technology from several perspectives. Technically, using DFR is feasible to provide reserves and enhance power system frequency control, while fulfilling technical requirements such as linear activation (or reconnection) according to frequency (or time). Environmentally, the DFR technology is pollution free in contrast to traditional reserves from generation

  9. The Coal Reserves Database Program

    Energy Technology Data Exchange (ETDEWEB)

    Bonskowski, R. (Energy Information Administration, Washington, DC (United States))

    1993-01-01

    The Energy Information Administration (EIA) initiated the Coal Reserves Data Base (CRDB) Program in October, 1990 in order to update and improve the inherent applicability of EIA's national coal reserves database. Currently, EIA's database is derived from the demonstrated reserve base (DRB) of coal, a compilation of data from published sources, unified by adherence to standardized physical criteria of minability, but never intended for the detailed coal supply and policy analyses demanded today. The CRDB Program is designed to engage the expertise available at State geological surveys in compiling best current State-level estimates of both quantities and quality of available coal reserves through cooperative agreements with EIA. The CRDB emphasizes integration of more data on coal quality, use of data from unpublished sources, cooperation with industry and other government sources, and flexibility of criteria to take into account local accessibility and mining conditions and utilize computerized geographic information systems or coal resource software. The results of pilot projects in Ohio and Wyoming are summarized. Areas nominated for support in the program include 15 additional priority coal regions in 14 States, which comprise 95 percent of the current reserve estimates and most of the coal-bearing areas of low sulfur potential. 8 refs., 3 figs., 3 tabs.

  10. Leveraging the Reserve Component: Associating Active and Reserve Aviation Units

    Science.gov (United States)

    2013-03-01

    capabilities, forces for large-scale conventional campaigns, balance stress across the Total Force, include a larger portion of American citizenry defending...Integration will also relieve stress on the Active Duty force and provide a cost-effective force multiplier. Finally, it will leverage the high...heavily.18 Other identified organizational challenges included cross- acculturation between active and reserve component career

  11. Hydrocarbon Reserves: Abundance or Scarcity

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2005-07-01

    IFP and the OAPEC jointly organize a regular international seminar dealing with world oil-related problems appearing in the news. For the first time, this seminar has been opened to oil and gas company specialists, service companies, research centers and independents. This year's theme concerns oil and gas reserves: are they abundant or are we headed towards the shortages announced by some experts? This theme is especially topical in that: oil and gas currently meet two thirds of world energy needs and almost completely dominate the transport sector; the reserves declared by the OAPEC countries account for nearly half of world reserves; the price of a barrel of oil went through the roof in 2004; world energy demand is growing fast and alternative sources of energy are far from ready to take over from oil and gas in the next few decades. Since the reserves correspond to the volume it is technically and economically viable to produce, the seminar has, of course, dealt with the technical and economic questions that arise in connection with exploration and production, but it has also considered changes in the geopolitical context. Presentations by the leading companies of the OAPEC countries and by the IFP group were completed by presentation from the International Energy Agency (IEA), the United States Geological Survey (USGS), the IHS Energy Group, Total and Gaz de France. This document gathers the transparencies of the following presentations: Hydrocarbon reserves in OAPEC members countries: current and future (M. Al-Lababidi); Non OAPEC liquid reserves and production forecasts (Y. Mathieu); World oil and gas resources and production outlook (K. Chew); Global investments in the upstream (F. Birol); Total's policy in the oil and gas sector (C. de Margerie); Gaz de France's policy in the oil and gas sector (J. Abiteboul); NOC/IOC's opportunities in OPEC countries (I. Sandrea); Relationships between companies, countries and investors: How they may

  12. Cognitive reserve: The warehouse within

    Directory of Open Access Journals (Sweden)

    Jyoti Prakash

    2011-01-01

    Full Text Available Dementia is characterized by progressive and mostly irreversible memory loss. Other neuropsychiatric disorders affect cognition in varying manner. Are all people affected with such disorders manifest clinically in similar manner or does our brain have some reserve to tolerate insults? Relevant researches over the last two decades were scrutinized to understand brain reserve, appreciate the conceptual change in the same over years, and how the same can be improved for better cognition and memory over the year. Literature evidence suggests that the cognitive reserve (CR is a dynamic and functional concept. There is adequate evidence to suggest that enriched environment and various other measures are likely to improve CR across all age. Improving CR may delay or reverse the effects of aging or brain pathology.

  13. Individual loss reserving with the Multivariate Skew Normal distribution

    NARCIS (Netherlands)

    Pigeon, M.; Antonio, K.; Denuit, M.

    2012-01-01

    The evaluation of future cash flows and solvency capital recently gained importance in general insurance. To assist in this process, our paper proposes a novel loss reserving model, designed for individual claims in discrete time. We model the occurrence of claims, as well as their reporting delay,

  14. China's Ultimate Recoverable Reserves Calculated

    Institute of Scientific and Technical Information of China (English)

    Fu Hong

    2003-01-01

    @@ A nationwide project is being launched to assess the potential capacity of China's oil and natural gas resources, a senior official from the Ministry of Land and Resources said in early December. Based on the existing data, China's oil and natural gas reserves are estimated at 106.9 billion tons and 53trillion cubic meters respectively at the present time.

  15. Strategic petroleum reserve annual report

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-02-15

    Section 165 of the Energy Policy and Conservation Act (Public Law 94- 163), as amended, requires the Secretary of Energy to submit annual reports to the President and the Congress on activities of the Strategic Petroleum Reserve (SPR). This report describes activities for the year ending December 31, 1995.

  16. FEA Reports on Proved Reserves

    Science.gov (United States)

    Geotimes, 1975

    1975-01-01

    Explains the way in which oil and gas reserves are estimated, and the variation in these estimates according to the year of the resources' estimation and the group undertaking the survey. A recent Federal Energy Administration study suggests that recoverable oil and gas resources have limits that may be approached in the next 50 years. (MLH)

  17. Demand as Frequency Controlled Reserve

    DEFF Research Database (Denmark)

    Xu, Zhao; Østergaard, Jacob; Togeby, Mikael

    2011-01-01

    Relying on generation side alone is deemed insufficient to fulfill the system balancing needs for future Danish power system, where a 50% wind penetration is outlined by the government for year 2025. This paper investigates using the electricity demand as frequency controlled reserve (DFR) as a new...

  18. Storage Reliability of Reserve Batteries

    Science.gov (United States)

    2007-11-02

    batteries – Environmental concerns, lack of business – Non-availability of some critical materials • Lithium Oxyhalides are systems of choice – Good...exhibit good corrosion resistance to neutral electrolytes (LiAlCl4 in thionyl chloride and sulfuryl chloride ) • Using AlCl3 creates a much more corrosive...Storage Reliability of Reserve Batteries Jeff Swank and Allan Goldberg Army Research Laboratory Adelphi, MD 301-394-3116 jswank@arl.army.mil ll l

  19. Demand Response Spinning Reserve Demonstration

    Energy Technology Data Exchange (ETDEWEB)

    Eto, Joseph H.; Nelson-Hoffman, Janine; Torres, Carlos; Hirth,Scott; Yinger, Bob; Kueck, John; Kirby, Brendan; Bernier, Clark; Wright,Roger; Barat, A.; Watson, David S.

    2007-05-01

    The Demand Response Spinning Reserve project is a pioneeringdemonstration of how existing utility load-management assets can providean important electricity system reliability resource known as spinningreserve. Using aggregated demand-side resources to provide spinningreserve will give grid operators at the California Independent SystemOperator (CAISO) and Southern California Edison (SCE) a powerful, newtool to improve system reliability, prevent rolling blackouts, and lowersystem operating costs.

  20. Neurotransplantation therapy and cerebellar reserve.

    Science.gov (United States)

    Cendelin, Jan; Mitoma, Hiroshi; Manto, Mario

    2017-08-10

    Neurotransplantation has been recently the focus of interest as a promising therapy to substitute lost cerebellar neurons and improve cerebellar ataxias. However, since cell differentiation and synaptic formation are required to obtain a functional circuitry, highly integrated reproduction of cerebellar anatomy is not a simple process. Rather than a genuine replacement, recent studies have shown that grafted cells rescue surviving cells from neurodegeneration by exerting trophic effects, supporting mitochondrial function, modulating neuroinflammation, stimulating endogenous regenerative processes, and facilitating cerebellar compensatory properties thanks to neural plasticity. On the other hand, accumulating clinical evidence suggests that the self-recovery capacity is still preserved even if the cerebellum is affected by a diffuse and progressive pathology. We put forward the period with intact recovery capacity as "restorable stage" and the notion of reversal capacity as "cerebellar reserve". The concept of cerebellar reserve is particularly relevant, both theoretically and practically, to target recovery of cerebellar deficits by neurotransplantation. Reinforcing the cerebellar reserve and prolonging the restorable stage can be envisioned as future endpoints of neurotransplantation. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  1. Ultrasound in evaluating ovarian reserve

    Directory of Open Access Journals (Sweden)

    Eman Ahmaed Shawky Sabek

    2015-12-01

    Full Text Available The objective of this study was to compare the diagnostic accuracy of transvaginal ultrasound (TVS, as a less invasive technique instead of hormonal assay to evaluate the ovarian reserve. This study included fifty-five females with breast cancer and we compared the ovarian reserve for these patients by hormonal assay through measuring the serum AntiMullerian Hormone (AMH level and follicular stimulating hormone (FSH level before and after chemotherapy, and by transvaginal ultrasound through the ovarian volume (OV calculation and counting the Antral follicles (AFC before and after chemotherapy treatment. There was decline in the AntiMullerian Hormone level after chemotherapy by 27 ± 11.19% and decrease in the Antral follicle counts by 21 ± 13.43%. In conclusion there was strong relation between AMH level and AFC which makes the use of transvaginal ultrasound is a reliable alternative method to the hormonal assay to detect the ovarian reserve.

  2. Traumatic brain injury and reserve.

    Science.gov (United States)

    Bigler, Erin D; Stern, Yaakov

    2015-01-01

    The potential role of brain and cognitive reserve in traumatic brain injury (TBI) is reviewed. Brain reserve capacity (BRC) refers to preinjury quantitative measures such as brain size that relate to outcome. Higher BRC implies threshold differences when clinical deficits will become apparent after injury, where those individuals with higher BRC require more pathology to reach that threshold. Cognitive reserve (CR) refers to how flexibly and efficiently the individual makes use of available brain resources. The CR model suggests the brain actively attempts to cope with brain damage by using pre-existing cognitive processing approaches or by enlisting compensatory approaches. Standard proxies for CR include education and IQ although this has expanded to include literacy, occupational attainment, engagement in leisure activities, and the integrity of social networks. Most research on BRC and CR has taken place in aging and degenerative disease but these concepts likely apply to the effects of TBI, especially with regards to recovery. Since high rates of TBI occur in those under age 35, both CR and BRC factors likely relate to how the individual copes with TBI over the lifespan. These factors may be particularly relevant to the relationship of developing dementia in the individual who has sustained a TBI earlier in life.

  3. Optimal Reserve Management Pattern for Turkish Banks

    OpenAIRE

    Anil Talasli; Suheyla Ozyildirim

    2013-01-01

    In this paper we model a representative bank’s optimal reserve management pattern by adopting institutional aspects of the Turkish required reserve regime. The cost minimization problem, in general, takes into account the expected opportunity cost of holding reserves and penalty costs for not fulfilling the liability of reserve requirement. We extend this problem for reserve carry-over provision and use of late liquidity window facility and compute the optimal reserve pattern by dynamic progr...

  4. Reserve a seat! Intelligent transportation reservation system for tourists

    Energy Technology Data Exchange (ETDEWEB)

    Truett, L.F.; Tonn, B. [Oak Ridge National Lab., TN (United States); Conley, T. [GTE Wireless, Nashville, TN (United States)

    1998-07-01

    Providing safe, predictable, and efficient transportation for tourists to and from various venues presents a major challenge. Special-event transportation is notoriously unreliable and usually congested at peak times. The rural nature of certain tourist locations (e.g., the Grand Canyon) further complicates the problem. The proposed Intelligent Transportation Reservation System will have three components, each of which performs different functions. On-vehicle component: this component has three purposes: (1) to keep a running count of the passengers on the bus in order to determine how many additional passengers can be accommodated based on the total capacity of the vehicle; (2) through use of Global Positioning Satellite (GPS) technology, to be able to determine the location of the bus at all times; (3) to transmit information to a central data facility. Together these three features provide location, available-space, and condition information to controllers at a central data facility and to prospective riders of the bus. Kiosk component: located at every loading/unloading point, the purpose is to allow passengers-to-be to determine when the next bus (or buses) will arrive and the availability of seating. Individuals can make a reservation for the next bus with sufficient seating and will know when that bus will arrive at the kiosk. Information component: located within hotels and at venue sites, this component will provide information on the buses in the system (e.g. route and current capacity), and loading/unloading locations throughout the network at any point in time.

  5. Reserve a seat! Intelligent transportation reservation system for tourists

    Energy Technology Data Exchange (ETDEWEB)

    Truett, L.F.; Tonn, B. [Oak Ridge National Lab., TN (United States); Conley, T. [GTE Wireless, Nashville, TN (United States)

    1998-07-01

    Providing safe, predictable, and efficient transportation for tourists to and from various venues presents a major challenge. Special-event transportation is notoriously unreliable and usually congested at peak times. The rural nature of certain tourist locations (e.g., the Grand Canyon) further complicates the problem. The proposed Intelligent Transportation Reservation System will have three components, each of which performs different functions. On-vehicle component: this component has three purposes: (1) to keep a running count of the passengers on the bus in order to determine how many additional passengers can be accommodated based on the total capacity of the vehicle; (2) through use of Global Positioning Satellite (GPS) technology, to be able to determine the location of the bus at all times; (3) to transmit information to a central data facility. Together these three features provide location, available-space, and condition information to controllers at a central data facility and to prospective riders of the bus. Kiosk component: located at every loading/unloading point, the purpose is to allow passengers-to-be to determine when the next bus (or buses) will arrive and the availability of seating. Individuals can make a reservation for the next bus with sufficient seating and will know when that bus will arrive at the kiosk. Information component: located within hotels and at venue sites, this component will provide information on the buses in the system (e.g. route and current capacity), and loading/unloading locations throughout the network at any point in time.

  6. Offshore fresh groundwater reserves as a global phenomenon

    Science.gov (United States)

    Post, Vincent E. A.; Groen, Jacobus; Kooi, Henk; Person, Mark; Ge, Shemin; Edmunds, W. Mike

    2013-12-01

    The flow of terrestrial groundwater to the sea is an important natural component of the hydrological cycle. This process, however, does not explain the large volumes of low-salinity groundwater that are found below continental shelves. There is mounting evidence for the global occurrence of offshore fresh and brackish groundwater reserves. The potential use of these non-renewable reserves as a freshwater resource provides a clear incentive for future research. But the scope for continental shelf hydrogeology is broader and we envisage that it can contribute to the advancement of other scientific disciplines, in particular sedimentology and marine geochemistry.

  7. Foreign Exchange Reserves: Bangladesh Perspective

    Directory of Open Access Journals (Sweden)

    Md Zahangir Alam

    2013-10-01

    Full Text Available This study is about foreign exchangereserves of Bangladesh. The mainpurpose of this study is to the influence of exchange rates on foreign exchangereserves to the Bangladesh context.  Both the primary and secondary data has been used inthis study. The primary data has been collected through a structuredquestionnaire from 50 respondents. The secondary data, namely Bangladeshforeign exchange reserves (FER, Bangladesh current account balance (CAB,Bangladesh capital andfinancial account balance (CFAB, and BDT/USD exchange rates (ER.  This study covers yearly data from July 01,1996 to June 30, 2005 and quarterly data from July 01, 2005 to June 30, 2012. Findingsof this study shows that out of the selected 16 factors affecting foreignexchange reserves, exchange rates occupy the first position, weighted averagescore (WAS being 4.56. Foreign exchange reserves (FER and current accountbalance (CAB have increased by 502.9087% and 1451.218%,whereas capital and financial account (CFAB has decreased by -649.024% on June30, 2012 compared to June 30, 1997. The influence of other factors heldconstant, as ER changes by 285.6894 units due to one unit change in FER, onaverage in the same direction which represents that ER has positive effect on theFER and this relationship is statistically significant.  62.1526 percentof the variation in FER is explained by ER. The outcomes of Breusch-Godfrey test (LM test, ARCHtest, and the Normality test are that there is a serial correlation among residuals, the variance of residuals is notconstant, and the residuals are not normally distributed.

  8. Deposit Reserve Rate No Panacea

    Institute of Scientific and Technical Information of China (English)

    Mark; A.DeWeaver

    2006-01-01

    To rein in runaway investment, China's central bank, the People's Bank of China (PBOC), took several measures in mid-June, including the most dramatic step of raising the deposit reserve rate by 0.5 percentage point According to Mark A. DeWeaver, who manages Quantrarian Asia Hedge, a fund that invests in Asian equities, the PBOC's measures may lower money supply growth in the short term; that is, the effect of these measures "may be only temporary." He believes that "attempts to slow money supply growth ...

  9. Time-averaged currents in the Northeast Corridor Reserve during November 2013.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A 2D numerical model, CMS-Flow, was implemented for the Northeast Corridor Reserve (NECR) using a telescoping grid. Tide and wind forcing was provided to the model...

  10. Veterinary Science Students, Center Changing a Reservation

    Science.gov (United States)

    Blackwater, Jasmine

    2011-01-01

    Kayenta is a rural community located in northeastern Arizona on a Navajo reservation. On the reservation, many families rely on their livestock for income, and as a result, many reservation high school students show a great interest in agricultural education. Having livestock on the reservation is not just a source of income, but also part of a…

  11. Vascular and cardiac contractile reserve in the dog heart with chronic multiple coronary occlusions.

    Science.gov (United States)

    Schwarz, F; Flameng, W; Mack, B; Türschmann, W; Schaper, W

    1976-11-01

    Nineteen mongrel dogs survived chronic occlusion of the left circumflex and of the right coronary artery without infarction due to the timely development of a collateral circulation. Only 38 per cent of the conductance of the arteries before occlusion was restored by collateral vessels. In these animals and in 15 control dogs with normal coronary arteries myocardial contractility, contractility reserve, and myocardial blood flow were studied. The same was done in dogs with chronic coronary artery occlusion after aortocoronary bypass. Myocardial blood flow was determined woth the tracer microsphere technique. Contractility reserve was tested and defined as isovolumetric left ventricular pressure and dp/dt max with norepinephrine infusion and cross-clamping of the aorta. Contractile reserve was not significantly different between normal dogs and dogs with chronic coronary artery occlusion before and after aortocoronary bypass. Myocardial blood flow during control conditions was homogenously distributed in all three groups studied. The ratio of blood flow to the endocardium and the epicardium was not significantly different from inity. Coronary reserve was determined at peak reactive hyperemia following a 20 second period of coronary artery occlusion, with ongoing norepinephrine infusion. Under these conditions subendocardial fow in normal dogs rose by a factor of 7.9 while subepicardial flow increased 7.4 times. In dogs with chronic occlusion of two coronary arteries the increase of myocardial flow was nonnomogenous; subendocardial flow to areas supplied by a normal coronary artery rose by a factor of 7.0 while subepicardial flow increased 5.7 times control. Subendocardial collateral flow rose by a factor of 2.4 and subepicardial collateral flow increased 3.5 times control. In normal dogs norepinephrine alone did not result in maximal coronary flow but only 57 per cent thereof. Dogs with chronic coronary occlusion, however, required the entire coronary reserve in

  12. A Comprehensive Comparison of Current Operating Reserve Methodologies

    Energy Technology Data Exchange (ETDEWEB)

    Krad, Ibrahim; Ibanez, Eduardo; Gao, Wenzhong

    2016-05-05

    Electric power systems are currently experiencing a paradigm shift from a traditionally static system to a system that is becoming increasingly more dynamic and variable. Emerging technologies are forcing power system operators to adapt to their performance characteristics. These technologies, such as distributed generation and energy storage systems, have changed the traditional idea of a distribution system with power flowing in one direction into a distribution system with bidirectional flows. Variable generation, in the form of wind and solar generation, also increases the variability and uncertainty in the system. As such, power system operators are revisiting the ways in which they treat this evolving power system, namely by modifying their operating reserve methodologies. This paper intends to show an in-depth analysis on different operating reserve methodologies and investigate their impacts on power system reliability and economic efficiency.

  13. Clinical evaluation of application of myocardial fractional flow reserve on elective percutaneous coronary intervention in patients with ST-segment elevation myocardial infarction%心肌血流储备分数指导ST段抬高心肌梗死患者择期经皮冠状动脉介入的临床评价

    Institute of Scientific and Technical Information of China (English)

    邬冬梅; 王慧峰; 王凤群; 王鲲; 张永红

    2015-01-01

    目的:探讨心肌血流储备分数(FFRmyo)对ST段抬高心肌梗死(STEMI)患者择期经皮冠状动脉介入治疗(PCI)的意义。方法 STEMI行早期溶栓治疗或血栓自溶择期冠状动脉造影(CAG)的患者75例,其中FFRmyo<0.75者33例,行PCI治疗21例(A组),拒绝行PCI 治疗12例(B组),FFRmyo≥0.75者42例(C组)。记录患者一般临床资料,比较各组罪犯血管特点及临床事件发生情况。结果各组患者一般临床资料无统计学差异。随访一年,患者临床事件包括死亡、心肌梗死、靶血管血运重建及再住院的总发生率在A组及C组均显著低于B组(分别为P<0.05)。结论 FFRmyo测定对STEMI患者制定合理的治疗策略具有参考价值。%Objective To explore the application of myocardial fractional flow reserve (FFRmyo) on elective percutaneous coronary intervention (PCI) in patients with ST-segment elevation myocardial infarction (STEMI). Methods In all, 75 STEMI patients undergoing early thrombolysis treatment or spontaneous recanalization with elective PCI were recruited in this study. There were 33 patients with FFRmyo0.05). Fellowed one year, the total incidence of the clinical events including death, myocardial infarction, target vessel revascularization and rehospitalization was significantly lower in both Group A and Group C compared with Group B (P<0.05, respectively). Conclusion FFRmyo detection has a reference value on the establishment of treatment strategies for patients with STEMI.

  14. Designing Tone Reservation PAR Reduction

    Directory of Open Access Journals (Sweden)

    Johansson Albin

    2006-01-01

    Full Text Available Tone reservation peak-to-average (PAR ratio reduction is an established area when it comes to bringing down signal peaks in multicarrier (DMT or OFDM systems. When designing such a system, some questions often arise about PAR reduction. Is it worth the effort? How much can it give? How much does it give depending on the parameter choices? With this paper, we attempt to answer these questions without resolving to extensive simulations for every system and every parameter choice. From a specification of the allowed spectrum, for instance prescribed by a standard, including a PSD-mask and a number of tones, we analytically predict achievable PAR levels, and thus implicitly suggest parameter choices. We use the ADSL2 and ADSL2+ systems as design examples.

  15. Reserved-Length Prefix Coding

    CERN Document Server

    Baer, Michael B

    2008-01-01

    Huffman coding finds an optimal prefix code for a given probability mass function. Consider situations in which one wishes to find an optimal code with the restriction that all codewords have lengths that lie in a user-specified set of lengths (or, equivalently, no codewords have lengths that lie in a complementary set). This paper introduces a polynomial-time dynamic programming algorithm that finds optimal codes for this reserved-length prefix coding problem. This has applications to quickly encoding and decoding lossless codes. In addition, one modification of the approach solves any quasiarithmetic prefix coding problem, while another finds optimal codes restricted to the set of codes with g codeword lengths for user-specified g (e.g., g=2).

  16. Z' reservation at LEP2

    CERN Document Server

    Montagna, G.; Piccinini, F.; Renard, F.M.; Verzegnassi, C.

    1995-01-01

    We consider the possibility that one extra Z\\equiv Z' exists with arbitrary mass and fermion couplings that do not violate (charged) lepton universality. We show that, in such a situation, a functional relationship is generated between the \\underline{deviations} from the SM values of three leptonic observables of two-fermion production at future e^+e^- colliders that is completely independent of the values of the Z' mass and couplings. This selects a certain region in the 3-d space of the deviations that is \\underline{characteristic} of the model (Z' "reservation"). As a specific and relevant example, we show the picture that would emerge at LEP2 under realistic experimental conditions.

  17. Influence Of Different Methods Of Operative Treatment On Ovarian Reserve.

    Directory of Open Access Journals (Sweden)

    V Simrok

    2012-04-01

    Full Text Available This research paper presents the results of ovarian reserve estimation for 125 women with the Polycystic Ovary Syndrome (PCOS who have undergone various methods of surgical treatment - resection of the ovaries, thermokauterisation and drilling by laser (Ho-Yag. Ovarian reserve was estimated according to the amount of antral follicles, level of follitropin and Müllerian inhibiting substance (MIS, also named anti-Müllerian hormone (AMH. Blood flow in ovarian tissue was also examined after various methods of surgical treatment. The study has shown that the gentlest method of surgical treatment is drilling by Ho-Yag laser, which is least likely to injure the tissue of ovaries, and also this method is most effective in enhancing and preserving ovarian reserve.

  18. Bioenergetics, overcompensation, and the source-sink status of marine reserves

    NARCIS (Netherlands)

    Claessen, D.; Vos, A.S.; de Roos, A.M.

    2009-01-01

    One of the hypothesized functions of marine protected areas (MPAs) is to serve as sources of biomass, with biomass spilling over from the reserve into neighbouring, harvested areas. We argue that the net larval flow (from or to the marine reserve) depends on between-area differences in the populatio

  19. Marine reserves: size and age do matter.

    Science.gov (United States)

    Claudet, Joachim; Osenberg, Craig W; Benedetti-Cecchi, Lisandro; Domenici, Paolo; García-Charton, José-Antonio; Pérez-Ruzafa, Angel; Badalamenti, Fabio; Bayle-Sempere, Just; Brito, Alberto; Bulleri, Fabio; Culioli, Jean-Michel; Dimech, Mark; Falcón, Jesús M; Guala, Ivan; Milazzo, Marco; Sánchez-Meca, Julio; Somerfield, Paul J; Stobart, Ben; Vandeperre, Frédéric; Valle, Carlos; Planes, Serge

    2008-05-01

    Marine reserves are widely used throughout the world to prevent overfishing and conserve biodiversity, but uncertainties remain about their optimal design. The effects of marine reserves are heterogeneous. Despite theoretical findings, empirical studies have previously found no effect of size on the effectiveness of marine reserves in protecting commercial fish stocks. Using 58 datasets from 19 European marine reserves, we show that reserve size and age do matter: Increasing the size of the no-take zone increases the density of commercial fishes within the reserve compared with outside; whereas the size of the buffer zone has the opposite effect. Moreover, positive effects of marine reserve on commercial fish species and species richness are linked to the time elapsed since the establishment of the protection scheme. The reserve size-dependency of the response to protection has strong implications for the spatial management of coastal areas because marine reserves are used for spatial zoning.

  20. Introducing optional reserve ratios in Hungary

    OpenAIRE

    Lóránt Varga

    2010-01-01

    As of the reserve maintenance period commencing in November 2010, Hungarian credit institutions will be free to decide whether to apply the previously valid 2% reserve ratio, or to apply a higher mandatory reserve ratio. Credit institutions required to hold reserves may select from reserve ratios of 2, 3, 4 and 5%, and may change their decision on a semi-annual basis. In line with the international best practice, the purpose of the MNB’s reserve requirement system is to support credit institu...

  1. Detecting larval export from marine reserves.

    Science.gov (United States)

    Pelc, R A; Warner, R R; Gaines, S D; Paris, C B

    2010-10-26

    Marine reserve theory suggests that where large, productive populations are protected within no-take marine reserves, fished areas outside reserves will benefit through the spillover of larvae produced in the reserves. However, empirical evidence for larval export has been sparse. Here we use a simple idealized coastline model to estimate the expected magnitude and spatial scale of larval export from no-take marine reserves across a range of reserve sizes and larval dispersal scales. Results suggest that, given the magnitude of increased production typically found in marine reserves, benefits from larval export are nearly always large enough to offset increased mortality outside marine reserves due to displaced fishing effort. However, the proportional increase in recruitment at sites outside reserves is typically small, particularly for species with long-distance (on the order of hundreds of kilometers) larval dispersal distances, making it very difficult to detect in field studies. Enhanced recruitment due to export may be detected by sampling several sites at an appropriate range of distances from reserves or at sites downcurrent of reserves in systems with directional dispersal. A review of existing empirical evidence confirms the model's suggestion that detecting export may be difficult without an exceptionally large differential in production, short-distance larval dispersal relative to reserve size, directional dispersal, or a sampling scheme that encompasses a broad range of distances from the reserves.

  2. Reserve Growth of Alberta Oil Pools

    Science.gov (United States)

    Verma, Mahendra K.; Cook, Troy

    2008-01-01

    This Open-File Report is based on a presentation delivered at the Fourth U.S. Geological Survey Workshop on Reserve Growth on March 10-11, 2008. It summarizes the results of a study of reserve growth of oil pools in Alberta Province, Canada. The study is part of a larger effort involving similar studies of fields in other important petroleum provinces around the world, with the overall objective of gaining a better understanding of reserve growth in fields with different geologic/reservoir parameters and different operating environments. The goals of the study were to: 1. Evaluate historical oil reserve data and assess reserve growth. 2. Develop reserve growth models/functions to help forecast hydrocarbon volumes. 3. Study reserve growth sensitivity to various parameters ? for example, pool size, porosity, oil gravity, and lithology. 4. Compare reserve growth in oil pools/fields of Alberta provinces with those from other large petroleum provinces.

  3. Marine reserve effects on fishery profit.

    Science.gov (United States)

    White, Crow; Kendall, Bruce E; Gaines, Steven; Siegel, David A; Costello, Christopher

    2008-04-01

    Some studies suggest that fishery yields can be higher with reserves than under conventional management. However, the economic performance of fisheries depends on economic profit, not fish yield. The predictions of higher yields with reserves rely on intensive fishing pressures between reserves; the exorbitant costs of harvesting low-density populations erode profits. We incorporated this effect into a bioeconomic model to evaluate the economic performance of reserve-based management. Our results indicate that reserves can still benefit fisheries, even those targeting species that are expensive to harvest. However, in contrast to studies focused on yield, only a moderate proportion of the coast in reserves (with moderate harvest pressures outside reserves) is required to maximize profit. Furthermore, reserve area and harvest intensity can be traded off with little impact on profits, allowing for management flexibility while still providing higher profit than attainable under conventional management.

  4. Reserving by detailed conditioning on individual claim

    Science.gov (United States)

    Kartikasari, Mujiati Dwi; Effendie, Adhitya Ronnie; Wilandari, Yuciana

    2017-03-01

    The estimation of claim reserves is an important activity in insurance companies to fulfill their liabilities. Recently, reserving method of individual claim have attracted a lot of interest in the actuarial science, which overcome some deficiency of aggregated claim method. This paper explores the Reserving by Detailed Conditioning (RDC) method using all of claim information for reserving with individual claim of liability insurance from an Indonesian general insurance company. Furthermore, we compare it to Chain Ladder and Bornhuetter-Ferguson method.

  5. Mordovia State Nature Reserve's 80th anniversary

    OpenAIRE

    Elena V. Vargot

    2016-01-01

    Brief physical-geographical characteristics, history of creation and development of the Mordovia State Nature Reserve territory are presented. We listed aims and objectives assigned for the Mordovia Reserve in different periods. During the first years of the Mordovia Reserve the forest conservation was aimed at reforestation of the southern area of the taiga zone; the investigation of harmful insect fauna to timely response on infection foci of trees; enriching of the fauna of the Reserve. At...

  6. 40 CFR 35.2020 - Reserves.

    Science.gov (United States)

    2010-07-01

    ... under § 35.2025. The Regional Administrator may waive this reserve requirement where a State can... 40 Protection of Environment 1 2010-07-01 2010-07-01 false Reserves. 35.2020 Section 35.2020... ASSISTANCE Grants for Construction of Treatment Works § 35.2020 Reserves. In developing its priority list the...

  7. Poverty and corruption compromise tropical forest reserves.

    Science.gov (United States)

    Wright, S Joseph; Sanchez-Azofeifa, G Arturo; Portillo-Quintero, Carlos; Davies, Diane

    2007-07-01

    We used the global fire detection record provided by the satellite-based Moderate Resolution Imaging Spectroradiometer (MODIS) to determine the number of fires detected inside 823 tropical and subtropical moist forest reserves and for contiguous buffer areas 5, 10, and 15 km wide. The ratio of fire detection densities (detections per square kilometer) inside reserves to their contiguous buffer areas provided an index of reserve effectiveness. Fire detection density was significantly lower inside reserves than in paired, contiguous buffer areas but varied by five orders of magnitude among reserves. The buffer: reserve detection ratio varied by up to four orders of magnitude among reserves within a single country, and median values varied by three orders of magnitude among countries. Reserves tended to be least effective at reducing fire frequency in many poorer countries and in countries beset by corruption. Countries with the most successful reserves include Costa Rica, Jamaica, Malaysia, and Taiwan and the Indonesian island of Java. Countries with the most problematic reserves include Cambodia, Guatemala, Paraguay, and Sierra Leone and the Indonesian portion of Borneo. We provide fire detection density for 3964 tropical and subtropical reserves and their buffer areas in the hope that these data will expedite further analyses that might lead to improved management of tropical reserves.

  8. 42 CFR 417.934 - Reserve requirement.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 3 2010-10-01 2010-10-01 false Reserve requirement. 417.934 Section 417.934 Public... PLANS Administration of Outstanding Loans and Loan Guarantees § 417.934 Reserve requirement. (a) Timing... section 1305 of the PHS Act was required to establish a restricted reserve account on the earlier of...

  9. Reserve Requirements and Monetary Management; An Introduction

    OpenAIRE

    International Monetary Fund

    1993-01-01

    Reserve requirements are widely used by central banks as a means to improve monetary control, an instrument for policy implementation, a source of revenue, and a safeguard of bank liquidity. The effectiveness of reserve requirements in fulfilling these functions is reviewed, and the detailed modalities of their use are examined. Reserve requirements in a sample of developing countries are described.

  10. 5 CFR 890.503 - Reserves.

    Science.gov (United States)

    2010-01-01

    ... any, of the contingency reserve over the preferred minimum balance. OMP must authorize this payment... charge consists of the rate approved by OPM for payment to the plan for each enrollee, plus 4 percent, of... charge set aside for the administrative reserve. The administrative reserve is available for payment of...

  11. 40 CFR 35.2123 - Reserve capacity.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 1 2010-07-01 2010-07-01 false Reserve capacity. 35.2123 Section 35... STATE AND LOCAL ASSISTANCE Grants for Construction of Treatment Works § 35.2123 Reserve capacity. EPA will limit grant assistance for reserve capacity as follows: (a) If EPA awarded a grant for a Step...

  12. Army Reserve (AR) Educational Assistance (EA) Study

    Science.gov (United States)

    2008-06-01

    NAME(S) AND ADDRESS(ES) US Army TRADOC Analysis Center Ft. Lee, VA 8. PERFORMING ORGANIZATION REPORT NUMBER 9. SPONSORING/ MONITORING AGENCY NAME(S...Programs REAP: Reserve Education Assistance Program; MGIB-SR: Montgomery GI Bill – Selected Reserve; SRK: Selected Reserve Kicker ; OFF: Officer; EM

  13. Reserve Requirements and Monetary Management; An Introduction

    OpenAIRE

    International Monetary Fund

    1993-01-01

    Reserve requirements are widely used by central banks as a means to improve monetary control, an instrument for policy implementation, a source of revenue, and a safeguard of bank liquidity. The effectiveness of reserve requirements in fulfilling these functions is reviewed, and the detailed modalities of their use are examined. Reserve requirements in a sample of developing countries are described.

  14. Role of Coronary Calcium Scoring in the Assessment of Physiological Ischemia in Patients with Intermediate Stenosis

    Science.gov (United States)

    Horie, Kazunori; Kikuchi, Yuichi; Takizawa, Kaname; Inoue, Naoto

    2015-01-01

    Although coronary artery calcium (CAC) is an established marker of coronary atherosclerosis, whether it also reflects the physiological significance is unknown. This study aims to evaluate if CAC could indicate physiological ischemia in intermediate stenosis defined by an invasive fractional flow reserve (FFR). CAC score (CACS) derived from either whole coronary arteries or individual arteries was measured by computed tomography among patients with intermediate de novo lesions (percent diameter stenosis from 30% to less than 70%). All stenoses were evaluated by invasive FFR; lesions with an FFR ≤ 0.80 were considered significant. We enrolled 119 patients with 143 lesions. Of these, 42 lesions (29.4%) demonstrated significant ischemia by FFR measurement. FFR values had modest but significant correlations with CACS in individual arteries with intermediate stenosis (r = − 0.290; p stenosis had 71.4% sensitivity and 67.3% specificity as a predictor of significant ischemia at a cut off value of 145.9. Multivariable analysis showed that percent diameter stenosis and CACS in individual arteries with intermediate stenosis were independent predictors for significant ischemia. By net reclassification improvement analysis, CACS in individual arteries with intermediate stenosis provided incremental prediction for significant ischemia over minimum lumen diameter, percent diameter stenosis, and lesion length. CACS measured in each artery, but not the total CACS, provides additional information as to whether an angiographically intermediate stenosis within the artery is significant enough to cause myocardial ischemia. PMID:26648671

  15. Flow visualization

    CERN Document Server

    Merzkirch, Wolfgang

    1974-01-01

    Flow Visualization describes the most widely used methods for visualizing flows. Flow visualization evaluates certain properties of a flow field directly accessible to visual perception. Organized into five chapters, this book first presents the methods that create a visible flow pattern that could be investigated by visual inspection, such as simple dye and density-sensitive visualization methods. It then deals with the application of electron beams and streaming birefringence. Optical methods for compressible flows, hydraulic analogy, and high-speed photography are discussed in other cha

  16. Accounting for system dynamics in reserve design.

    Science.gov (United States)

    Leroux, Shawn J; Schmiegelow, Fiona K A; Cumming, Steve G; Lessard, Robert B; Nagy, John

    2007-10-01

    Systematic conservation plans have only recently considered the dynamic nature of ecosystems. Methods have been developed to incorporate climate change, population dynamics, and uncertainty in reserve design, but few studies have examined how to account for natural disturbance. Considering natural disturbance in reserve design may be especially important for the world's remaining intact areas, which still experience active natural disturbance regimes. We developed a spatially explicit, dynamic simulation model, CONSERV, which simulates patch dynamics and fire, and used it to evaluate the efficacy of hypothetical reserve networks in northern Canada. We designed six networks based on conventional reserve design methods, with different conservation targets for woodland caribou habitat, high-quality wetlands, vegetation, water bodies, and relative connectedness. We input the six reserve networks into CONSERV and tracked the ability of each to maintain initial conservation targets through time under an active natural disturbance regime. None of the reserve networks maintained all initial targets, and some over-represented certain features, suggesting that both effectiveness and efficiency of reserve design could be improved through use of spatially explicit dynamic simulation during the planning process. Spatial simulation models of landscape dynamics are commonly used in natural resource management, but we provide the first illustration of their potential use for reserve design. Spatial simulation models could be used iteratively to evaluate competing reserve designs and select targets that have a higher likelihood of being maintained through time. Such models could be combined with dynamic planning techniques to develop a general theory for reserve design in an uncertain world.

  17. Demand for International Reserves in Turkey

    Directory of Open Access Journals (Sweden)

    Yimaz Sinem

    2014-06-01

    Full Text Available Having an important place in the international monetary system, international reserves held by central bank usually reflect country’s economic strength in terms of international finance and trade. There are many reasons for holding international reserves by central banks such as financing the deficit in the balance of payment, managing the monetary and exchange rate policies, minimizing the negative effects of external shocks and reducing the cost of borrowing. Continuously changing and diversifying characteristics of these reasons affect the demand for reserves depending to the economic conditions of the country. Over the last ten years, there has been a tremendous increase in international reserves held by Turkish Central Bank. From 2002 to 2012, the reserves of the bank have risen from 20 billion dollars to 96 billion dollars, showing an increase more than four times. This sudden and huge increase in the foreign reserves drove us to determine and investigate the factors which induce the Turkish Central Bank to hold high level of reserves. Thus, the purpose of this study is to estimate and analyze the demand for international reserves held by central banks using the buffer stock model in the case of Turkey. The data used in the study is monthly and cover the period of 1990:03-2012:10. The buffer stock model was econometrically estimated by using the OLS method for three different models. Our findings indicate that the opportunity cost affected reserve demand much stronger than the reserve volatility in Turkish case.

  18. Evaluation and Analysis of Gas Turbine Internal Flow Restrictors.

    Science.gov (United States)

    1986-08-01

    JAPAN, VOL 1.. NO. 3, 1981. PP. 173-177. SIEDER . E .N , AND G.E. TATE. "HEAT TRAN,.FFR AND PR! ,SURE DROP 01 LIQUIDS IN TUBEn". INDUSTRIAL...CURRENT PAPER NO. 13, IQO5, 112329 . SIEDER , E.N., AND G.E. TATE. "HEAT TRANSFER AND PRESSURE DROP OF LIQUIDS IN TUBES", INDUSTRIAL ENGINEERINGCHEMISTRY

  19. How to Maintain an Operational Reserve? Further Engaging Army Reserve Component Forces in the Coming Decade

    Science.gov (United States)

    2015-02-17

    with mobilizing Reserve Component units for overseas missions. This flexibility will allow the Army to meet ongoing mission requirements , while... reserve will impose an increased cost on the Army. First (and most obviously), the Army will have to fund the additional pay and allowances required ...AIR WAR COLLEGE AIR UNIVERSITY HOW TO MAINTAIN AN OPERATIONAL RESERVE ? FURTHER ENGAGING ARMY RESERVE COMPONENT FORCES IN

  20. China has proven 2974 iron ore reserve and 1248 copper reserve

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    <正>Recently national mineral resource evaluation has achieved preliminary progress. At present a total of 2974 iron ore reserves have been proven, including 121 large-scale reserves; as well as 1248 copper reserves, including 37 large-scale reserves. Preliminary findings of the evaluation have indicated that retained iron re-

  1. Reserves and trade jointly determine exposure to food supply shocks

    Science.gov (United States)

    Marchand, Philippe; Carr, Joel A.; Dell'Angelo, Jampel; Fader, Marianela; Gephart, Jessica A.; Kummu, Matti; Magliocca, Nicholas R.; Porkka, Miina; Puma, Michael J.; Ratajczak, Zak; Rulli, Maria Cristina; Seekell, David A.; Suweis, Samir; Tavoni, Alessandro; D'Odorico, Paolo

    2016-09-01

    While a growing proportion of global food consumption is obtained through international trade, there is an ongoing debate on whether this increased reliance on trade benefits or hinders food security, and specifically, the ability of global food systems to absorb shocks due to local or regional losses of production. This paper introduces a model that simulates the short-term response to a food supply shock originating in a single country, which is partly absorbed through decreases in domestic reserves and consumption, and partly transmitted through the adjustment of trade flows. By applying the model to publicly-available data for the cereals commodity group over a 17 year period, we find that differential outcomes of supply shocks simulated through this time period are driven not only by the intensification of trade, but as importantly by changes in the distribution of reserves. Our analysis also identifies countries where trade dependency may accentuate the risk of food shortages from foreign production shocks; such risk could be reduced by increasing domestic reserves or importing food from a diversity of suppliers that possess their own reserves. This simulation-based model provides a framework to study the short-term, nonlinear and out-of-equilibrium response of trade networks to supply shocks, and could be applied to specific scenarios of environmental or economic perturbations.

  2. A General Business Model for Marine Reserves

    Science.gov (United States)

    Sala, Enric; Costello, Christopher; Dougherty, Dawn; Heal, Geoffrey; Kelleher, Kieran; Murray, Jason H.; Rosenberg, Andrew A.; Sumaila, Rashid

    2013-01-01

    Marine reserves are an effective tool for protecting biodiversity locally, with potential economic benefits including enhancement of local fisheries, increased tourism, and maintenance of ecosystem services. However, fishing communities often fear short-term income losses associated with closures, and thus may oppose marine reserves. Here we review empirical data and develop bioeconomic models to show that the value of marine reserves (enhanced adjacent fishing + tourism) may often exceed the pre-reserve value, and that economic benefits can offset the costs in as little as five years. These results suggest the need for a new business model for creating and managing reserves, which could pay for themselves and turn a profit for stakeholder groups. Our model could be expanded to include ecosystem services and other benefits, and it provides a general framework to estimate costs and benefits of reserves and to develop such business models. PMID:23573192

  3. A general business model for marine reserves.

    Directory of Open Access Journals (Sweden)

    Enric Sala

    Full Text Available Marine reserves are an effective tool for protecting biodiversity locally, with potential economic benefits including enhancement of local fisheries, increased tourism, and maintenance of ecosystem services. However, fishing communities often fear short-term income losses associated with closures, and thus may oppose marine reserves. Here we review empirical data and develop bioeconomic models to show that the value of marine reserves (enhanced adjacent fishing + tourism may often exceed the pre-reserve value, and that economic benefits can offset the costs in as little as five years. These results suggest the need for a new business model for creating and managing reserves, which could pay for themselves and turn a profit for stakeholder groups. Our model could be expanded to include ecosystem services and other benefits, and it provides a general framework to estimate costs and benefits of reserves and to develop such business models.

  4. Substantiating the Incurred but not Reported Reserve

    Directory of Open Access Journals (Sweden)

    Georgeta Vintilã

    2009-12-01

    Full Text Available In order to handle past and future liability taken by insurance contracts concluded, any insurance company must constitute and maintain technical reserves. Substantiating technical reserves is done through actuarial methods and its over-evaluation or under-evaluation influence solvency and financial performance of the insurance companies, in the sense of reducing solvency through over-evaluating reserves and, respectively, influencing profit (hence of outstanding tax through under-evaluating reserves. An important reserve for insurance companies is represented by the incurred but not reported reserve, as it allows the estimation of the liability the company may confront in the future, generated by events occurred in the past, which are not currently known in the present but will be reported in the future.

  5. A general business model for marine reserves.

    Science.gov (United States)

    Sala, Enric; Costello, Christopher; Dougherty, Dawn; Heal, Geoffrey; Kelleher, Kieran; Murray, Jason H; Rosenberg, Andrew A; Sumaila, Rashid

    2013-01-01

    Marine reserves are an effective tool for protecting biodiversity locally, with potential economic benefits including enhancement of local fisheries, increased tourism, and maintenance of ecosystem services. However, fishing communities often fear short-term income losses associated with closures, and thus may oppose marine reserves. Here we review empirical data and develop bioeconomic models to show that the value of marine reserves (enhanced adjacent fishing + tourism) may often exceed the pre-reserve value, and that economic benefits can offset the costs in as little as five years. These results suggest the need for a new business model for creating and managing reserves, which could pay for themselves and turn a profit for stakeholder groups. Our model could be expanded to include ecosystem services and other benefits, and it provides a general framework to estimate costs and benefits of reserves and to develop such business models.

  6. CHINA'S RESERVE REQUIREMENTS: PRACTICES, EFFECTS, AND IMPLICATIONS

    OpenAIRE

    GUONAN MA; XIANDONG YAN; XI LIU

    2012-01-01

    This paper examines the role of reserve requirements as a cheaper substitute for the open-market operations of the People's Bank of China (PBC) to sterilize foreign exchange interventions in recent years. China's reserve requirements have also been used to address a range of other policy objectives, not least macroeconomic management, financial stability, and credit policy. The preference for reserve requirements reflects the size of China's FX sterilization and the associated costs, in a qua...

  7. The Euro as a Reserve Currency

    OpenAIRE

    Adamczyk, Marzena

    2010-01-01

    There has been an unusual accumulation of foreign exchange reserves in recent years. Central banks have to diversify their reserves away from the US dollar, especially towards the euro. The same situation is in a private sector, where investors reduce the share of dollar denominated assets. This process has progressed gradually, but it is possible that the euro’s role as a reserve currency will continue to increase. The purpose of ...

  8. Reserve valuation in electric power systems

    Science.gov (United States)

    Ruiz, Pablo Ariel

    Operational reliability is provided in part by scheduling capacity in excess of the load forecast. This reserve capacity balances the uncertain power demand with the supply in real time and provides for equipment outages. Traditionally, reserve scheduling has been ensured by enforcing reserve requirements in the operations planning. An alternate approach is to employ a stochastic formulation, which allows the explicit modeling of the sources of uncertainty. This thesis compares stochastic and reserve methods and evaluates the benefits of a combined approach for the efficient management of uncertainty in the unit commitment problem. Numerical studies show that the unit commitment solutions obtained for the combined approach are robust and superior with respect to the traditional approach. These robust solutions are especially valuable in areas with a high proportion of wind power, as their built-in flexibility allows the dispatch of practically all the available wind power while minimizing the costs of operation. The scheduled reserve has an economic value since it reduces the outage costs. In several electricity markets, reserve demand functions have been implemented to take into account the value of reserve in the market clearing process. These often take the form of a step-down function at the reserve requirement level, and as such they may not appropriately represent the reserve value. The value of reserve is impacted by the reliability, dynamic and stochastic characteristics of system components, the system operation policies, and the economic aspects such as the risk preferences of the demand. In this thesis, these aspects are taken into account to approximate the reserve value and construct reserve demand functions. Illustrative examples show that the demand functions constructed have similarities with those implemented in some markets.

  9. Reserve requirement systems in OECD countries

    OpenAIRE

    Yueh-Yun C. O’Brien

    2007-01-01

    This paper compares the reserve requirements of OECD countries. Reserve requirements are the minimum percentages or amounts of liabilities that depository institutions are required to keep in cash or as deposits with their central banks. To facilitate monetary policy implementation, twenty-four of the thirty OECD countries impose reserve requirements to influence their banking systems’ demand for liquidity. These include twelve OECD countries that are also members of the European Economic and...

  10. Naval Reserve: an organization in transition.

    OpenAIRE

    Mazza, Richard Charles

    1992-01-01

    Approved for public release; distribution is unlimited The purpose of this thesis is to examine the issues facing the Naval Reserve as it transitions from its cold war mission to new and, possibly, expanded roles under the New National Military Strategy. The thesis further provides an overview of the changed strategic environment and budgetary concerns that serve as drivers for change within the Naval Reserve. The evolution of the present Naval Reserve organization, manpower an...

  11. Reserve requirement systems in OECD countries

    OpenAIRE

    Yueh-Yun C. O’Brien

    2007-01-01

    This paper compares the reserve requirements of OECD countries. Reserve requirements are the minimum percentages or amounts of liabilities that depository institutions are required to keep in cash or as deposits with their central banks. To facilitate monetary policy implementation, twenty-four of the thirty OECD countries impose reserve requirements to influence their banking systems’ demand for liquidity. These include twelve OECD countries that are also members of the European Economic and...

  12. Fiji's largest marine reserve benefits reef sharks

    Science.gov (United States)

    Goetze, J. S.; Fullwood, L. A. F.

    2013-03-01

    To provide more information about whether sharks benefit from no-take marine reserves, we quantified the relative abundance and biomass of reef sharks inside and outside of Namena, Fiji's largest reserve (60.6 km2). Using stereo baited remote underwater video systems (stereo-BRUVs), we found that the abundance and biomass of sharks was approximately two and four times greater in shallow and deep locations, respectively, within the Namena reserve compared to adjacent fished areas. The greater abundance and biomass of reef sharks inside Namena is likely a result of greater prey availability rather than protection from fishing. This study demonstrates that marine reserves can benefit sharks.

  13. Reservation system with graphical user interface

    KAUST Repository

    Mohamed, Mahmoud A. Abdelhamid

    2012-01-05

    Techniques for providing a reservation system are provided. The techniques include displaying a scalable visualization object, wherein the scalable visualization object comprises an expanded view element of the reservation system depicting information in connection with a selected interval of time and a compressed view element of the reservation system depicting information in connection with one or more additional intervals of time, maintaining a visual context between the expanded view and the compressed view within the visualization object, and enabling a user to switch between the expanded view and the compressed view to facilitate use of the reservation system.

  14. The conical stent in coronary artery improves hemodynamics compared with the traditional cylindrical stent.

    Science.gov (United States)

    Yu, Yi; Zhou, Yujie; Ma, Qian; Jia, Shuo; Wu, Sijing; Sun, Yan; Liu, Xiaoli; Zhao, Yingxin; Liu, Yuyang; Shi, Dongmei

    2017-01-15

    This study sought to explore the efficacy of the conical stent implantation in the coronary artery by comparing the effects of cylindrical and conical stents on wall shear stress (WSS) and velocity of flow and fractional flow reserve (FFR). The traditional cylindrical stent currently used in the percutaneous coronary intervention (PCI) has a consistent diameter, which does not match the physiological change of the coronary artery. On the contrary, as a new patent, the conical stent with tapering lumen is consistent with the physiological change of vascular diameter. However, the effect of the conical stent implantation on the coronary hemodynamics remains unclear. The coronary artery, artery stenosis and two stent models were established by Solidworks software. All models were imported into the computational fluid dynamics (CFD) software ANSYS ICEM-CFD to establish the fluid model. After the boundary conditions were set, CFD analysis was proceeded to compare the effects of two stent implantation on the change of WSS, velocity of flow and FFR. Hemodynamic indexes including FFR, blood flow velocity distribution (BVD) and WSS were improved by either the cylindrical or the conical stent implantation. However, after the conical stent implantation, the change of FFR seemed to be slower and more homogenous; the blood flow velocity was more appropriate without any obvious blood stagnation and direction changes; the WSS after the conical stent implantation was uniform from the proximal to distal side of the stent. Compared with the cylindrical stent, the conical stent implantation in the coronary artery can make the changes of vascular hemodynamic more closer to the physiological condition, which can reduce the incidence of intra-stent restenosis and thrombosis, thus making it more suitable for PCI therapy. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  15. 21 CFR 216.23 - [Reserved

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 4 2010-04-01 2010-04-01 false [Reserved] 216.23 Section 216.23 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) DRUGS: GENERAL PHARMACY COMPOUNDING Compounded Drug Products § 216.23 [Reserved] ...

  16. The dynamics of the primordial follicle reserve.

    Science.gov (United States)

    Kerr, Jeffrey B; Myers, Michelle; Anderson, Richard A

    2013-12-01

    The female germline comprises a reserve population of primordial (non-growing) follicles containing diplotene oocytes arrested in the first meiotic prophase. By convention, the reserve is established when all individual oocytes are enclosed by granulosa cells. This commonly occurs prior to or around birth, according to species. Histologically, the 'reserve' is the number of primordial follicles in the ovary at any given age and is ultimately depleted by degeneration and progression through folliculogenesis until exhausted. How and when the reserve reaches its peak number of follicles is determined by ovarian morphogenesis and germ cell dynamics involving i) oogonial proliferation and entry into meiosis producing an oversupply of oocytes and ii) large-scale germ cell death resulting in markedly reduced numbers surviving as the primordial follicle reserve. Our understanding of the processes maintaining the reserve comes primarily from genetically engineered mouse models, experimental activation or destruction of oocytes, and quantitative histological analysis. As the source of ovulated oocytes in postnatal life, the primordial follicle reserve requires regulation of i) its survival or maintenance, ii) suppression of development (dormancy), and iii) activation for growth and entry into folliculogenesis. The mechanisms influencing these alternate and complex inter-related phenomena remain to be fully elucidated. Drawing upon direct and indirect evidence, we discuss the controversial concept of postnatal oogenesis. This posits a rare population of oogonial stem cells that contribute new oocytes to partially compensate for the age-related decline in the primordial follicle reserve.

  17. A Guide to Federal Reserve Regulations.

    Science.gov (United States)

    Federal Reserve Bank of New York, NY.

    The Board of Governors of the Federal Reserve System and the Federal Reserve Banks administer more than two dozen regulations affecting a wide variety of financial activities. The regulations concern the functions of the central bank and its relationships with financial institutions, the activities of commercial banks and bank holding companies,…

  18. Marine reserves demonstrate trophic interactions across habitats.

    Science.gov (United States)

    Langlois, Timothy J; Anderson, Marti J; Babcock, Russell C; Kato, Shin

    2006-02-01

    Several infaunal bivalve taxa show patterns of decreased biomass in areas with higher densities of adjacent reef-associated predators (the snapper, Pagrus auratus and rock lobster, Jasus edwardsii). A caging experiment was used to test the hypothesis that patterns observed were caused by predation, using plots seeded with a known initial density of the bivalve Dosinia subrosea to estimate survivorship. The caging experiment was replicated at several sites inside and outside two highly protected marine reserves: predators are significantly more abundant inside these reserves. Survivorship in fully caged, partially caged and open plots were then compared at sites having either low (non reserve) or high (reserve) predator density. The highest rates of survivorship of the bivalve were found in caged plots inside reserves and in all treatments outside reserves. However, inside reserves, open and partially caged treatments exhibited low survivorship. It was possible to specifically attribute much of this mortality to predation by large rock lobsters, due to distinctive marks on the valves of dead D. subrosea. This suggests that predation by large rock lobster could indeed account for the distributional patterns previously documented for certain bivalve populations. Our results illustrate that protection afforded by marine reserves is necessary to investigate how depletion through fishing pressure can change the role of upper-level predators and trophic processes between habitats.

  19. 75 FR 6539 - Healthy Forests Reserve Program

    Science.gov (United States)

    2010-02-10

    ... Conservation Service 7 CFR Part 625 RIN 0578-AA52 Healthy Forests Reserve Program AGENCY: Natural Resources... amends Natural Resources Conservation Service (NRCS) regulations for the Healthy Forests Reserve Program... benefit cost assessment has not been undertaken. Federal Crop Insurance Reform and Department of...

  20. CNGC Secured More Copper Reserves in 2011

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    <正>According to China Land and Resources Newspaper, the reporter learnt from the work- ing conference of China National Gold Group Corporation (CNGC) that the corporation has again achieved great achievements in terms of its reserve increase strategy in 2011. The corporation increased its reserves by 215 tons of gold, 370,000 tons of copper and 580,000 tons

  1. Nutrient reserve dynamics of breeding canvasbacks

    Science.gov (United States)

    Barzen, J.A.; Serie, J.R.

    1990-01-01

    We compared nutrients in reproductive and nonreproductive tissues of breeding Canvasbacks (Aythya valisineria) to assess the relative importance of endogenous reserves and exogenous foods. Fat reserves of females increased during rapid follicle growth and varied more widely in size during the early phase of this period. Females began laying with ca. 205 g of fat in reserve and lost 1.8 g of carcass fat for every 1 g of fat contained in their ovary and eggs. Females lost body mass (primarily fat) at a declining rate as incubation advanced. Protein reserves increased directly with dry oviduct mass during rapid follicle growth. This direct relationship was highly dependent upon data from 2 birds and likely biased by structural size. During laying, protein reserves did not vary with the combined mass of dry oviduct and dry egg protein. Between laying and incubation, mean protein reserves decreased by an amount equal to the protein found in 2.1 Canvasback eggs. Calcium reserves did not vary with the cumulative total of calcium deposited in eggs. Mean calcium reserve declined by the equivalent content of 1.2 eggs between laying and incubation. We believe that protein and calcium were stored in small amounts during laying, and that they were supplemented continually by exogenous sources. In contrast, fat was stored in large amounts and contributed significantly to egg production and body maintenance. Male Canvasbacks lost fat steadily--but not protein or calcium--as the breeding season progressed.

  2. Body reserves in intra-African migrants

    NARCIS (Netherlands)

    Nwaogu, Chima; Cresswell, Will

    Avian migration has been shown to be a life history strategy for surviving environmental resource variability, but it requires increased body reserves for long distance flight. Fat reserves make excellent energy stores for barrier crossing, whereas proteins generate less energy for the same mass of

  3. 7 CFR 3560.306 - Reserve account.

    Science.gov (United States)

    2010-01-01

    ...) As projects age, the required reserve account level may be adjusted to meet anticipated “life-cycle... AGRICULTURE DIRECT MULTI-FAMILY HOUSING LOANS AND GRANTS Financial Management § 3560.306 Reserve account. (a) Purpose. To meet the major capital expense needs of a housing project, borrowers must establish and...

  4. The Economics of NASA Mission Cost Reserves

    Science.gov (United States)

    Whitley, Sally; Shinn, Stephen

    2012-01-01

    Increases in NASA mission costs are well-noted but not well-understood, and there is little evidence that they are decreasing in frequency or amount over time. The need to control spending has led to analysis of the causes and magnitude of historical mission overruns, and many program control efforts are being implemented to attempt to prevent or mitigate the problem (NPR 7120). However, cost overruns have not abated, and while some direct causes of increased spending may be obvious (requirements creep, launch delays, directed changes, etc.), the underlying impetus to spend past the original budget may be more subtle. Gaining better insight into the causes of cost overruns will help NASA and its contracting organizations to avoid .them. This paper hypothesizes that one cause of NASA mission cost overruns is that the availability of reserves gives project team members an incentive to make decisions and behave in ways that increase costs. We theorize that the presence of reserves is a contributing factor to cost overruns because it causes organizations to use their funds less efficiently or to control spending less effectively. We draw a comparison to the insurance industry concept of moral hazard, the phenomenon that the presence of insurance causes insureds to have more frequent and higher insurance losses, and we attempt to apply actuarial techniques to quantifY the increase in the expected cost of a mission due to the availability of reserves. We create a theoretical model of reserve spending motivation by defining a variable ReserveSpending as a function of total reserves. This function has a positive slope; for every dollar of reserves available, there is a positive probability of spending it. Finally, the function should be concave down; the probability of spending each incremental dollar of reserves decreases progressively. We test the model against available NASA CADRe data by examining missions with reserve dollars initially available and testing whether

  5. Naval Petroleum and Oil Shale Reserves. Annual report of operations, Fiscal year 1992

    Energy Technology Data Exchange (ETDEWEB)

    1992-12-31

    During fiscal year 1992, the reserves generated $473 million in revenues, a $181 million decrease from the fiscal year 1991 revenues, primarily due to significant decreases in oil and natural gas prices. Total costs were $200 million, resulting in net cash flow of $273 million, compared with $454 million in fiscal year 1991. From 1976 through fiscal year 1992, the Naval Petroleum and Oil Shale Reserves generated more than $15 billion in revenues and a net operating income after costs of $12.5 billion. In fiscal year 1992, production at the Naval Petroleum Reserves at maximum efficient rates yielded 26 million barrels of crude oil, 119 billion cubic feet of natural gas, and 164 million gallons of natural gas liquids. From April to November 1992, senior managers from the Naval Petroleum and Oil Shale Reserves held a series of three workshops in Boulder, Colorado, in order to build a comprehensive Strategic Plan as required by Secretary of Energy Notice 25A-91. Other highlights are presented for the following: Naval Petroleum Reserve No. 1--production achievements, crude oil shipments to the strategic petroleum reserve, horizontal drilling, shallow oil zone gas injection project, environment and safety, and vanpool program; Naval Petroleum Reserve No. 2--new management and operating contractor and exploration drilling; Naval Petroleum Reserve No. 3--steamflood; Naval Oil Shale Reserves--protection program; and Tiger Team environmental assessment of the Naval Petroleum and Oil Shale Reserves in Colorado, Utah, and Wyoming.

  6. Flow Control

    Science.gov (United States)

    2013-04-08

    an aerodynamic design. A few examples of this type of flow control are winglets , fins, or dimples on a golf ball. The other type of flow control is...represented the density states of the flow field. The first parameter was the composition of the regression vector, Θ j. This regression vector was...Development Using Proper Orthogonal De- composition and Volterra Theory. In AIAA 2003-1922, 2003. A. Mani, M. Wang, and P. Moin. Resolution requirements

  7. Instantaneous wave-free ratio derived from coronary computed tomography angiography in evaluation of ischemia-causing coronary stenosis

    Science.gov (United States)

    Ma, Yue; Liu, Hui; Hou, Yang; Qiao, Aike; Hou, Yingying; Yang, Qingqing; Guo, Qiyong

    2017-01-01

    Abstract The instantaneous wave-free ratio (iFR) closely related to fractional flow reserve (FFR) is a adenosine-independent physiologic index of coronary stenosis severity. We sought to evaluate whether iFR derived from coronary computed tomographic angiography (iFRCT) can be used as a novel noninvasive method for diagnosis of ischemia-causing coronary stenosis. We retrospectively enrolled 33 patients (47 lesions) with coronary artery disease (CAD) and examined with coronary computed tomographic angiography (CTA), invasive coronary angiography (ICA), and FFR. Patient-specific anatomical model of the coronary artery was built by original resting end-diastolic CTA images. Based on the model and computational fluid dynamics, individual boundary conditions were set to calculate iFRCT as the mean pressure distal to the stenosis divided by the mean aortic pressure during the diastolic wave-free period of rest state. Ischemia was assessed by an FFR of up to 0.8, while anatomically obstructive CAD was defined by a stenosis of at least 50% by ICA. The correlation between iFRCT and FFR was evaluated. The receiver operating characteristic (ROC) curve was used to select the cut-off value of iFRCT for diagnosis of ischemia-causing stenosis. The diagnostic performances of iFRCT, coronary CTA, and iFRCT plus CTA for ischemia-causing stenosis were compared with ROC curve and Delong method. On a per-vessel basis, iFRCT and FFR had linear correlation (r = 0.75, p coronary CTA (AUC = 0.60), iFRCT yielded diagnostic improvement over stenosis assessment with AUC increasing from 0.6 by CTA to 0.87 (P coronary CTA for detection of ischemia-causing coronary stenosis. PMID:28121952

  8. Effect of phentolamine on the hyperemic response to adenosine in patients with microvascular disease.

    Science.gov (United States)

    Aarnoudse, Wilbert; Geven, Maartje; Barbato, Emanuele; Botman, Kees-joost; De Bruyne, Bernard; Pijls, Nico H J

    2005-12-15

    For accurate measurement of the fractional flow reserve (FFR) of the myocardium, the presence of maximum hyperemia is of paramount importance. It has been suggested that the hyperemic effect of the conventionally used hyperemic stimulus, adenosine, could be submaximal in patients who have microvascular dysfunction and that adding alpha-blocking agents could augment the hyperemic response in these patients. We studied the effect of the nonselective alpha-blocking agent phentolamine, which was administered in addition to adenosine after achieving hyperemia, in patients who had microvascular disease and those who did not. Thirty patients who were referred for percutaneous coronary intervention were selected. Of these 30 patients, 15 had strong indications for microvascular disease and 15 did not. FFR was measured using intracoronary adenosine, intravenous adenosine, and intracoronary papaverine before and after intracoronary administration of the nonselective alpha blocker phentolamine. In patients who did not have microvascular disease, no differences in hyperemic response to adenosine were noted, whether or not alpha blockade was given before adenosine administration; FFR levels before and after phentolamine were 0.76 and 0.75, respectively, using intracoronary adenosine (p = 0.10) and 0.75 and 0.74, respectively, using intravenous adenosine (p = 0.20). In contrast, in patients who had microvascular disease, some increase in hyperemic response was observed after administration of phentolamine; FFR levels decreased from 0.74 to 0.70 using intracoronary adenosine (p = 0.003) and from 0.75 to 0.72 using intravenous adenosine (p = 0.04). Although statistically significant, the observed further decrease in microvascular resistance after addition of phentolamine was small and did not affect clinical decision making in any patient. In conclusion, when measuring FFR, routinely adding an alpha-blocking agent to adenosine does not affect clinical decision making.

  9. Rotating flow

    CERN Document Server

    Childs, Peter R N

    2010-01-01

    Rotating flow is critically important across a wide range of scientific, engineering and product applications, providing design and modeling capability for diverse products such as jet engines, pumps and vacuum cleaners, as well as geophysical flows. Developed over the course of 20 years' research into rotating fluids and associated heat transfer at the University of Sussex Thermo-Fluid Mechanics Research Centre (TFMRC), Rotating Flow is an indispensable reference and resource for all those working within the gas turbine and rotating machinery industries. Traditional fluid and flow dynamics

  10. Abnormalities in myocardial contractility, metabolism and perfusion reserve in non-stenotic coronary segments in heart failure patients

    NARCIS (Netherlands)

    van den Heuvel, AFM; Bax, JJ; Blanksma, PK; Vaalburg, W; Crijns, HJGM; van Veldhuisen, DJ

    2002-01-01

    Objective: Myocardial blood flow (MBF) reserve is impaired in congestive heart failure (CHF), while fluorine-18-deoxyglucose ((18)FDG) uptake is relatively preserved. To determine whether this mismatch could be interpreted as ischemia, we performed dobutamine stress echocardiography (DSE). Methods:

  11. On the optimal size of marine reserves.

    Science.gov (United States)

    Bensenane, M; Moussaoui, A; Auger, P

    2013-03-01

    The excessive and unsustainable exploitation of our marine resources has led to the promotion of marine reserves as a fisheries management tool. Marine reserves, areas in which fishing is restricted or prohibited, can offer opportunities for the recovery of exploited stock and fishery enhancement. This study examines the impact of the creation of marine protected areas, from both economic and biological perspectives. The consequences of reserve establishment on the long-run equilibrium fish biomass and fishery catch levels are evaluated. We include reserve size as control variable to maximize catch at equilibrium. A continuous time model is used to simulate the effects of reserve size on fishing catch. Fish movements between the sites is assumed to take place at a faster time scale than the variation of the stock and the change of the fleet size. We take advantage of these two time scales to derive a reduced model governing the dynamics of the total fish stock and the fishing effort. Simulation results suggest that the establishment of a protected marine reserve will always lead to an increase in total fish biomass, an optimal size of a marine reserve can achieve to maximize the catch at equilibrium.

  12. US coal reserves: A review and update

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-08-01

    This report is the third in series of ``U.S. Coal Reserves`` reports. As part of the Administration of the Energy Information Administration (EIA) program to provide information on coal, it presents detailed estimates of domestic coal reserves, which are basic to the analysis and forecasting of future coal supply. It also describes the data, methods, and assumptions used to develop such estimates and explain terminology related to recent data programs. In addition, the report provides technical documentation for specific revisions and adjustments to the demonstrated reserve base (DRB) of coal in the United States and for coal quality and reserve allocations. It makes the resulting data available for general use by the public. This report includes data on recoverable coal reserves located at active mines and on the estimated distribution of rank and sulfur content in those reserves. An analysis of the projected demand and depletion in recoverable reserves at active mines is used to evaluate the areas and magnitude of anticipated investment in new mining capacity.

  13. The Investment Portfolio of China's Foreign Reserves——An Endogenous Perspective of Foreign Reserves Flow Cycle%中国外汇储备投资组合选择——基于外汇储备循环路径的内生性分析

    Institute of Scientific and Technical Information of China (English)

    刘澜飚; 张靖佳

    2012-01-01

    This article has established a Stackelberg and a Cournot game model,involving the central banks,financial markets of China and the U.S.as well as the real economic sector of China in order to depict a cycle of the foreign investment of China's foreign exchange reserves through the perspective of the essential differences of China and the U.S..Besides,we have simulated the optimal investment portfolio of China's foreign reserves and its contribution to China's domestic economy.The results have shown that the risky assets investment of China's foreign exchange reserves on the U.S.assets will affect the proportion of which China's reserves transform indirectly into the FDI to China from the U.S..However,the reaction of our central bank has been relatively slow.Therefore,in order to enable our central bank to gain profits,we suggest that it is necessary to bring down the CRRA coefficient of our residents,and improve our financial market development as well.%本文从中美两国经济的本质性差异出发,通过刻画中国外汇储备对外投资的"循环路径",构建了包括央行、金融市场和实体经济的斯塔克尔伯格及古诺模型,进而模拟出中国外汇储备对外投资对本国经济的间接贡献、合意的外汇储备投资组合,以及最优外汇储备投资规模。研究结果表明,中国外汇储备投资于美国风险资产的规模将影响外汇储备间接转化为美国对中国FDI的比例。同时,中国央行外汇储备规模及投资策略对危机时期的反应不足。改变外汇储备投资收益的主要方法包括降低居民的相对风险回避系数,通过政策引导促进居民消费,以及大力发展中国金融市场,降低对美国金融市场的依赖程度。

  14. China's National Oil Reserve Center was Born

    Institute of Scientific and Technical Information of China (English)

    Chun; Yi

    2008-01-01

      Aseries of events that occurred in October 2007, are rewriting the history of China's energy industry: November 3 an Energy Law Committee asked the public for suggestions on improvements; forty top experts came together to form the National Energy Expert Advisory Committee on November 6; and the National Oil Reserve Center (NORC)became the nerve centre of oil reserves on November 18. Yet, behind the progress of these recent activities remains the fact that international oil prices still hover around a very high price of US$ 90/barrel, and China's oil imports are close to accounting for half of its total oil reserves.……

  15. China's National Oil Reserve Center was Born

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    @@ Aseries of events that occurred in October 2007, are rewriting the history of China's energy industry: November 3 an Energy Law Committee asked the public for suggestions on improvements; forty top experts came together to form the National Energy Expert Advisory Committee on November 6; and the National Oil Reserve Center (NORC)became the nerve centre of oil reserves on November 18. Yet, behind the progress of these recent activities remains the fact that international oil prices still hover around a very high price of US$ 90/barrel, and China's oil imports are close to accounting for half of its total oil reserves.

  16. Strategic Petroleum Reserve: Annual/quarterly report

    Energy Technology Data Exchange (ETDEWEB)

    1994-02-16

    Section 165 of the Energy Policy and Conservation Act (Public Law 94-163), as amended, requires the Secretary of Energy to submit annual and quarterly reports to the President and the Congress on activities of the Strategic Petroleum Reserve. This report combines the fourth quarter 1993 Quarterly Report with the 1993 Annual Report. Key activities described include appropriations; life extension planning; expansion planning; Strategic Petroleum Reserve oil acquisition; the oil stabilization program; and the refined petroleum product reserve test programs. Sections of this report also describe the program mission; the storage facility development program; environmental compliance; budget and finance; and drawdown and distribution.

  17. CRISIS FOCUS Forex Reserves to The Rescue

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    When Premier Wen Jiabao told this year’s World Economic Forum in Davos that the Chinese Government was explor- ing more efficient ways to use its massive foreign exchange (forex) reserves to boost the domestic economy, he empha- sized that the reserves could only be used overseas. Zuo Xiaolei, Chief Economist of Beijing-based China Galaxy Securities Co. Ltd., recently wrote an article in the Securities Times explaining why the country’s forex reserves can only be used overseas and how they can help stimulate domestic development. Edited excerpts follow:

  18. Network Flows

    Science.gov (United States)

    1988-12-01

    Researchers have suggested other solution strategies, using ideas from nonlinear progamming for solving this general separable convex cost flow problems. Some...plane methods and branch and bound procedures of integer programming, primal-dual methods of linear and nonlinear programming, and polyhedral methods...Combinatorial Optimization: Networks and Matroids), Bazaraa and Jarvis [1978] (Linear Programming and Network Flows), Minieka [1978] (Optimization Algorithms for

  19. Vortical flows

    CERN Document Server

    Wu, Jie-Zhi; Zhou, Ming-De

    2015-01-01

    This book is a comprehensive and intensive book for graduate students in fluid dynamics as well as scientists, engineers and applied mathematicians. Offering a systematic introduction to the physical theory of vortical flows at graduate level, it considers the theory of vortical flows as a branch of fluid dynamics focusing on shearing process in fluid motion, measured by vorticity. It studies vortical flows according to their natural evolution stages,from being generated to dissipated. As preparation, the first three chapters of the book provide background knowledge for entering vortical flows. The rest of the book deals with vortices and vortical flows, following their natural evolution stages. Of various vortices the primary form is layer-like vortices or shear layers, and secondary but stronger form is axial vortices mainly formed by the rolling up of shear layers.  Problems are given at the end of each chapter and Appendix, some for helping understanding the basic theories, and some involving specific ap...

  20. Creation of Power Reserves Under the Market Economy Conditions

    Science.gov (United States)

    Mahnitko, A.; Gerhards, J.; Lomane, T.; Ribakov, S.

    2008-09-01

    The main task of the control over an electric power system (EPS) is to ensure reliable power supply at the least cost. In this case, requirements to the electric power quality, power supply reliability and cost limitations on the energy resources must be observed. The available power reserve in an EPS is the necessary condition to keep it in operation with maintenance of normal operating variables (frequency, node voltage, power flows via the transmission lines, etc.). The authors examine possibilities to create power reserves that could be offered for sale by the electric power producer. They consider a procedure of price formation for the power reserves and propose a relevant mathematical model for a united EPS, the initial data being the fuel-cost functions for individual systems, technological limitations on the active power generation and consumers' load. As the criterion of optimization the maximum profit for the producer is taken. The model is exemplified by a concentrated EPS. The computations have been performed using the MATLAB program.

  1. Development of an Ex Vivo, Beating Heart Model for CT Myocardial Perfusion

    Directory of Open Access Journals (Sweden)

    Gert Jan Pelgrim

    2015-01-01

    Full Text Available Objective. To test the feasibility of a CT-compatible, ex vivo, perfused porcine heart model for myocardial perfusion CT imaging. Methods. One porcine heart was perfused according to Langendorff. Dynamic perfusion scanning was performed with a second-generation dual source CT scanner. Circulatory parameters like blood flow, aortic pressure, and heart rate were monitored throughout the experiment. Stenosis was induced in the circumflex artery, controlled by a fractional flow reserve (FFR pressure wire. CT-derived myocardial perfusion parameters were analysed at FFR of 1 to 0.10/0.0. Results. CT images did not show major artefacts due to interference of the model setup. The pacemaker-induced heart rhythm was generally stable at 70 beats per minute. During most of the experiment, blood flow was 0.9–1.0 L/min, and arterial pressure varied between 80 and 95 mm/Hg. Blood flow decreased and arterial pressure increased by approximately 10% after inducing a stenosis with FFR ≤ 0.50. Dynamic perfusion scanning was possible across the range of stenosis grades. Perfusion parameters of circumflex-perfused myocardial segments were affected at increasing stenosis grades. Conclusion. An adapted Langendorff porcine heart model is feasible in a CT environment. This model provides control over physiological parameters and may allow in-depth validation of quantitative CT perfusion techniques.

  2. Historical beginnings.. the Federal Reserve System

    OpenAIRE

    Roger T. Johnson

    1999-01-01

    Traces the history of the banking system in the United States from 1789, discusses the banking problems of the 19th century, and describes the legislation that led to the formation of the Federal Reserve System.

  3. U.S. Federal Reserve Systems

    Data.gov (United States)

    Department of Homeland Security — This dataset is comprised of forty-five entities that are part of the United States Federal Reserve System according to the United States Department of Treasury. The...

  4. The Economics of NASA Mission Cost Reserves

    Science.gov (United States)

    Whitley, Sally; Shinn, Stephen

    2012-01-01

    Increases in NASA mission costs have led to analysis of the causes and magnitude of historical mission overruns as well as mitigation and prevention attempts. This paper hypothesizes that one cause is that the availability of reserves may reduce incentives to control costs. We draw a comparison to the insurance concept of moral hazard, and we use actuarial techniques to better understand the increase in mission costs due to the availability of reserves. NASA's CADRe database provided the data against which we tested our hypothesis and discovered that there is correlation between the amount of available reserves and project overruns, particularly for mission hardware cost increases. We address the question of how to prevent reserves from increasing mission spending without increasing cost risk to projects.

  5. Scientists Call for Strengthening Nature Reserve Management

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    @@ China has more than 10% of the total species of vascular plants and terrestrial vertebrates in the world, of which about half are endemic to this country. To protect its biodiversity, China has made remarkable achievements in nature reserve establishment.

  6. Conservation Reserve Program Acreage by County

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This dataset contains information regarding the acreages of land currently (as of 2004) enrolled in the Conservation Reserve Program (CRP) distributed by county and...

  7. 75 FR 67731 - Federal Reserve Bank Services

    Science.gov (United States)

    2010-11-03

    ...://www.fdic.gov/news/news/press/2010/pr10229.html . Table 6 shows the imputed PSAF elements, including... Advantage , FedLine Web , FedMail , and FedPhone .\\45\\ The Reserve Banks package these channels into...

  8. Suicides on a Southwestern American Indian Reservation.

    Science.gov (United States)

    Miller, Marv

    1979-01-01

    Results showed suicides clustered by day of the week, season, and reservation location, and typical victims as young, unmarried males holding unskilled or semiskilled jobs. Suggested are strategies maximizing suicide prevention efforts. Journal availability: see RC 503 481. (DS)

  9. Angiosperms, Los Tuxtlas Biosphere Reserve, Veracruz, Mexico

    Directory of Open Access Journals (Sweden)

    Mandujano, S.

    2009-01-01

    Full Text Available The Los Tuxtlas Reserve has been heavily deforested and fragmented since the 1970’s. Although the floraof Los Tuxtlas has been described previously, most floristic lists come from the large forest reserve of the Los Tuxtlasfield station. Here we present a check list of Angiosperms recorded in 45 rainforest fragments (< 1 to 266 ha located inthree landscapes with different levels of deforestation. We sampled all trees, shrubs, lianas, palms and herbs withdiameter at breast height (dbh

  10. Exmoor - Europe's first International Dark Sky Reserve

    Science.gov (United States)

    Owens, S.

    2011-12-01

    On 2011 October 9 Exmoor National Park in the southwest of England was designated as Europe's first International Dark Sky Reserve by the International Dark Skies Association. This is a huge achievement, and follows three years of work by park authorities, local astronomers, lighting engineers and the resident community. Exmoor Dark Sky Reserve follows in the footsteps of Galloway Forest Dark Sky Park, set up in 2009, and Sark Dark Sky Island, established in January 2011.

  11. Required reserves as a credit policy tool

    OpenAIRE

    Mimir, Yasin; Sunel, Enes; Taskin, Temel

    2012-01-01

    This paper conducts a quantitative investigation of the role of reserve requirements as a macroprudential policy tool. We build a monetary DSGE model with a banking sector in which (i) an agency problem between households and banks leads to endogenous capital constraints for banks in obtaining funds from households, (ii) banks are subject to time-varying reserve requirements that countercyclically respond to expected credit growth, (iii) households face cash-in-advance constraints, requiring ...

  12. Unanswered Quibbles with Fractional Reserve Free Banking

    OpenAIRE

    Philipp Bagus; David Howden

    2011-01-01

    In this article we reply to George Selgin’s counterarguments to our article “Fractional Reserve Free Banking: Some Quibbles”. Selgin regards holding cash as saving while we focus on the real savings necessary to maintain investment projects. Real savings are unconsumed real income. Variations in real savings are not necessarily equal to variations in cash holdings. We show that a coordinated credit expansion in a fractional reserve free banking (FRFB) system is possible and that precautionary...

  13. Unanswered Quibbles with Fractional Reserve Free Banking

    OpenAIRE

    Philipp Bagus; David Howden

    2011-01-01

    In this article we reply to George Selgin’s counterarguments to our article “Fractional Reserve Free Banking: Some Quibbles”. Selgin regards holding cash as saving while we focus on the real savings necessary to maintain investment projects. Real savings are unconsumed real income. Variations in real savings are not necessarily equal to variations in cash holdings. We show that a coordinated credit expansion in a fractional reserve free banking (FRFB) system is possible and that precautionary...

  14. Transformation of Taiwan’s Reserve Force

    Science.gov (United States)

    2017-01-01

    This report also includes an appendix with a brief comparative analysis of reserve force transformation in other countries (Finland, Singapore, Japan ...retention.18 Barring developments that offer Taiwan a substantive role in the emerging Asian security architecture and that make available, with...forces of other countries, we briefly reviewed the reserve forces of Finland, Singapore, Japan , and Georgia. We find that Finland and Singapore

  15. Estimating continuous monthly baseflow time series and their possible applications in the context of the ecological reserve

    CSIR Research Space (South Africa)

    Smakhtin, VU

    2001-04-01

    Full Text Available (IFRs) are used instead of reference natural streamflow time series. The corresponding groundwater storage time series will then represent the groundwater reserve. These storages may provisionally be called ?IFR driven?. Two component reserve time series... (river and groundwater) are, therefore, dependent. In this example, the assumption is that IFRs (river reserve flows) determine the extent to which groundwater resources may be impacted in the absence of any surface water resource development (the impacts...

  16. Statistical Method of Estimating Nigerian Hydrocarbon Reserves

    Directory of Open Access Journals (Sweden)

    Jeffrey O. Oseh

    2015-01-01

    Full Text Available Hydrocarbon reserves are basic to planning and investment decisions in Petroleum Industry. Therefore its proper estimation is of considerable importance in oil and gas production. The estimation of hydrocarbon reserves in the Niger Delta Region of Nigeria has been very popular, and very successful, in the Nigerian oil and gas industry for the past 50 years. In order to fully estimate the hydrocarbon potentials in Nigerian Niger Delta Region, a clear understanding of the reserve geology and production history should be acknowledged. Reserves estimation of most fields is often performed through Material Balance and Volumetric methods. Alternatively a simple Estimation Model and Least Squares Regression may be useful or appropriate. This model is based on extrapolation of additional reserve due to exploratory drilling trend and the additional reserve factor which is due to revision of the existing fields. This Estimation model used alongside with Linear Regression Analysis in this study gives improved estimates of the fields considered, hence can be used in other Nigerian Fields with recent production history

  17. Complete revascularisation versus treatment of the culprit lesion only in patients with ST-segment elevation myocardial infarction and multivessel disease (DANAMI-3—PRIMULTI)

    DEFF Research Database (Denmark)

    Engstrøm, Thomas; Kelbæk, Henning; Helqvist, Steffen

    2015-01-01

    )-guided complete revascularisation versus treatment of the infarct-related artery only. METHODS: We undertook an open-label, randomised controlled trial at two university hospitals in Denmark. Patients presenting with STEMI who had one or more clinically significant coronary stenosis in addition to the lesion......BACKGROUND: Patients with acute ST-segment elevation myocardial infarction (STEMI) and multivessel coronary disease have a worse prognosis compared with individuals with single-vessel disease. We aimed to study the clinical outcome of patients with STEMI treated with fractional flow reserve (FFR...... in the infarct-related artery were included. After successful percutaneous coronary intervention (PCI) of the infarct-related artery, patients were randomly allocated (in a 1:1 ratio) either no further invasive treatment or complete FFR-guided revascularisation before discharge. Randomisation was done...

  18. Design and implementation of land reservation system

    Science.gov (United States)

    Gao, Yurong; Gao, Qingqiang

    2009-10-01

    Land reservation is defined as a land management policy for insuring the government to control primary land market. It requires the government to obtain the land first, according to plan, by purchase, confiscation and exchanging, and then exploit and consolidate the land for reservation. Underlying this policy, it is possible for the government to satisfy and manipulate the needs of land for urban development. The author designs and develops "Land Reservation System for Eastern Lake Development District" (LRSELDD), which deals with the realistic land requirement problems in Wuhan Eastern Lake Development Districts. The LRSELDD utilizes modern technologies and solutions of computer science and GIS to process multiple source data related with land. Based on experiments on the system, this paper will first analyze workflow land reservation system and design the system structure based on its principles, then illustrate the approach of organization and management of spatial data, describe the system functions according to the characteristics of land reservation and consolidation finally. The system is running to serve for current work in Eastern Lake Development Districts. It is able to scientifically manage both current and planning land information, as well as the information about land supplying. We use the LRSELDD in our routine work, and with such information, decisions on land confiscation and allocation will be made wisely and scientifically.

  19. Repolarization reserve, arrhythmia and new drug development

    Directory of Open Access Journals (Sweden)

    Yang Li

    2013-05-01

    Full Text Available Repolarization-related lethal arrhythmias have led to the concept of “repolarization reserve”, which may help elucidate the relationship between K+ currents and other components of repolarization. Pharmacological manipulation as well as congenital and cardiac disease may affect repolarization and alter the repolarization reserve, leading to the development of arrhythmias. Pharmacological enhancement of outward currents or suppression of inward currents has been shown to be of therapeutic value. A number of newly found selective ion channel inhibitors or agonists have been investigated for their ability to enhance repolarization reserve and decrease the incidence of arrhythmia. In this paper we review the development, potential mechanisms, clinical application, and pharmacological significance of repolarization reserve in order to better understand, predict and prevent unexplained adverse cardiac events.

  20. Marine reserves can enhance ecological resilience.

    Science.gov (United States)

    Barnett, Lewis A K; Baskett, Marissa L

    2015-12-01

    The goals of ecosystem-based management (EBM) include protecting ecological resilience, the magnitude of a perturbation that a community can withstand and remain in a given state. As a tool to achieve this goal, no-take marine reserves may enhance resilience by protecting source populations or reduce it by concentrating fishing in harvested areas. Here, we test whether spatial management with marine reserves can increase ecological resilience compared to non-spatial (conventional) management using a dynamic model of a simplified fish community with structured predation and competition that causes alternative stable states. Relative to non-spatial management, reserves increase the resilience of the desired (predator-dominated) equilibrium state in both stochastic and deterministic environments, especially under intensive fishing. As a result, spatial management also increases the feasibility of restoring degraded (competitor-dominated) systems, particularly if combined with culling of competitors or stock enhancement of adult predators.

  1. Clinical and anatomical consequences of impaired cerebrovascular reserve as detectable by quantitative functional MR imaging

    NARCIS (Netherlands)

    Fierstra, J.

    2012-01-01

    Brain areas exhibiting impaired cerebrovascular reserve are believed to be at higher risk of ischemic tissue injury under circumstances in which cerebral blood flow is insufficient to meet metabolic demand. Other than for acute ischemia, which results in apparent (irreversible) loss of brain tissue

  2. Are All Measures of International Reserves Created Equal? An Empirical Comparison of International Reserve Ratios

    OpenAIRE

    Cheung, Yin-Wong; Yuk-Pang Wong, Clement

    2007-01-01

    Using available annual data of 174 economies since 1957, we examine the similarities and differences of seven international reserve ratios. While individual international reserve ratios display substantial variations across economies, they are associated with an economy?s characteristics including geographic location, income level, stage of development, degree of indebtedness, and exchange rate regime. The association pattern varies across time and type of international reserve ratios. Intere...

  3. Running on Empty? The Compensatory Reserve Index

    Science.gov (United States)

    2013-12-01

    Running on empty? The compensatory reserve index Steven L. Moulton, MD, Jane Mulligan , PhD, Greg Z. Grudic, PhD, and Victor A. Convertino, PhD, San...reserve index. 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Moulton S. L., Mulligan J., Grudic G. Z., Convertino V...2003;196:679Y684. 25. Convertino VA, Grudic GZ, Mulligan J, Moulton S. Estimation of individual-specific progression to cardiovascular instability using

  4. A critique of full reserve banking

    OpenAIRE

    Montagnoli, A; S Dow; Johnsen, G.

    2015-01-01

    Proposals for full reserve banking have been put forward as a radical way of preventing further financial crises. They rest on the argument that crises are caused by excessive money supply growth brought about by inadequately controlled bank credit creation. Our aim is to provide a critique of the theoretical assumptions underlying the plans for full reserve banking. In particular some of the plans rely on the view that the money supply is a key causal variable and that it is feasible for cen...

  5. Working marginal reserves using Auger technology

    Energy Technology Data Exchange (ETDEWEB)

    Celada Tamames, B.

    1988-03-01

    Following up an idea put forward at a meeting of the PEN (National Energy Plan) R and D working party held in Ponferrada in the province of Leon, Ocicarbon contracted Geocontrol SA to carry out a study on the possible use of Auger technology for working marginal coal reserves. This article summarises the most important points in the final report on this project: current state of Auger technology, inventory of marginal coal reserves in Spain and the use of Auger technology in Spain. 6 figs., 2 tabs.

  6. Estimating Quartz Reserves Using Compositional Kriging

    Directory of Open Access Journals (Sweden)

    J. Taboada

    2013-01-01

    Full Text Available The aim of this study was to determine spatial distribution and volume of four commercial quartz grades, namely, silicon metal, ferrosilicon, aggregate, and kaolin (depending on content in impurities in a quartz seam. The chemical and mineralogical composition of the reserves in the seam were determined from samples collected from outcrops, blasting operations, and exploratory drilling, and compositional kriging was used to calculate the volume and distribution of the reserves. A more accurate knowledge of the deposit ensures better mine planning, leading to higher profitability and an improved relationship with the environment.

  7. Oil Reserve Project Picks Up Speed

    Institute of Scientific and Technical Information of China (English)

    Zhao Zhen

    2011-01-01

    @@ China will ratchet up its efforts to construct the second phase of the national crude oil reserve base project in 2011, as part of the country's endeavor to secure strategically important natural resources and stabilize the petroleum market."We will accelerate the construction pace of the project and ensure its quality, aiming to put it into operation as early as possible," the National Energy Administration (NEA) said in its annual energy work target for 2011.The agency, which is under China's top economic planner, the National Development and Reform Commission (NDRC), will strengthen supervision to guarantee the safe operation of oil reserve bases.

  8. Wind offering in energy and reserve markets

    DEFF Research Database (Denmark)

    Soares, Tiago; Pinson, Pierre; Morais, Hugo

    2016-01-01

    their revenue, since currently wind turbine/farm technologies allow them to provide ancillary services. Thus, wind power producers are to develop offering strategies for participation in both energy and reserve markets, accounting for market rules, while ensuring optimal revenue. We consider a proportional...... offering strategy to optimally decide upon participation in both markets by maximizing expected revenue from day-ahead decisions while accounting for estimated regulation costs for failing to provide the services. An evaluation of considering the same proportional splitting of energy and reserve in both...

  9. Influence of arterial wall-stenosis compliance on the coronary diagnostic parameters.

    Science.gov (United States)

    Konala, Bhaskar Chandra; Das, Ashish; Banerjee, Rupak K

    2011-03-15

    Functional diagnostic parameters such as Fractional Flow Reserve (FFR), which is calculated from pressure measurements across stenosed arteries, are often used to determine the functional severity of coronary artery stenosis. This study evaluated the effect of arterial wall-stenosis compliance, with limiting scenarios of stenosis severity, on the diagnostic parameters. The diagnostic parameters considered in this study include an established index, FFR and two recently developed parameters: Pressure Drop Coefficient (CDP) and Lesion Flow Coefficient (LFC). The parameters were assessed for rigid artery (RR; signifying high plaque elasticity), compliant artery with calcified plaque (CC; intermediate plaque elasticity) and compliant artery with smooth muscle cell proliferation (CS; low plaque elasticity), with varying degrees of epicardial stenosis. A hyperelastic Mooney-Rivlin model was used to model the arterial wall and plaque materials. Blood was modeled as a shear thinning, non-Newtonian fluid using the Carreau model. The arterial wall compliance was evaluated using the finite element method. The present study found that, with an increase in stenosis severity, FFR decreased whereas CDP and LFC increased. The cutoff value of 0.75 for FFR was observed at 78.7% area stenosis for RR, whereas for CC and CS the cutoff values were obtained at higher stenosis severities of 81.3% and 82.7%, respectively. For a fixed stenosis, CDP value decreased and LFC value increased with a decrease in plaque elasticity (RR to CS). We conclude that the differences in diagnostic parameters with compliance at intermediate stenosis (78.7-82.7% area blockage) could lead to misinterpretation of the stenosis severity. Copyright © 2011 Elsevier Ltd. All rights reserved.

  10. Aeromedical Evacuation: Validating Civil Reserve Air Fleet

    Science.gov (United States)

    2009-02-25

    Aeromedical Evacuation: Validating Civil Reserve Air Fleet FORMAT : Civilian Research Paper DATE: 25 February 2009 WORDS: 10,172 PAGES: 56 CLASSIFICATION... Barrancas , Florida, in 1910. Unfortunately, on its first test flight, it flew only 500 yards at an altitude of 100 feet before crashing. This flight

  11. 25 CFR 162.500 - Crow Reservation.

    Science.gov (United States)

    2010-04-01

    ... 25 Indians 1 2010-04-01 2010-04-01 false Crow Reservation. 162.500 Section 162.500 Indians BUREAU... sections of this part 162, Crow Indians classified as competent under the Act of June 4, 1920 (41 Stat. 751...), as amended by the Act of March 15, 1948 (62 Stat. 80). However, at their election Crow Indians...

  12. Strategic petroleum reserve planning and modeling

    Energy Technology Data Exchange (ETDEWEB)

    Leiby, P.N.

    1996-06-01

    The Strategic Petroleum Reserve (SPR) is a government-owned stockpile of crude oil intended to serve as a buffer against possible oil market disruptions. The overall purpose of this project is to develop and apply improved models and tools for SPR management. Current project efforts emphasize developing new modeling tools to explicitly and flexibly portray oil market uncertainty and SPR planning risk.

  13. 49 CFR 193.2003 - [Reserved

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false [Reserved] 193.2003 Section 193.2003 Transportation Other Regulations Relating to Transportation (Continued) PIPELINE AND HAZARDOUS MATERIALS SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) PIPELINE SAFETY LIQUEFIED NATURAL GAS FACILITIES...

  14. 49 CFR 193.2015 - [Reserved

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false [Reserved] 193.2015 Section 193.2015 Transportation Other Regulations Relating to Transportation (Continued) PIPELINE AND HAZARDOUS MATERIALS SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) PIPELINE SAFETY LIQUEFIED NATURAL GAS FACILITIES...

  15. Wind offering in energy and reserve markets

    Science.gov (United States)

    Soares, T.; Pinson, P.; Morais, H.

    2016-09-01

    The increasing penetration of wind generation in power systems to fulfil the ambitious European targets will make wind power producers to play an even more important role in the future power system. Wind power producers are being incentivized to participate in reserve markets to increase their revenue, since currently wind turbine/farm technologies allow them to provide ancillary services. Thus, wind power producers are to develop offering strategies for participation in both energy and reserve markets, accounting for market rules, while ensuring optimal revenue. We consider a proportional offering strategy to optimally decide upon participation in both markets by maximizing expected revenue from day-ahead decisions while accounting for estimated regulation costs for failing to provide the services. An evaluation of considering the same proportional splitting of energy and reserve in both day- ahead and balancing market is performed. A set of numerical examples illustrate the behavior of such strategy. An important conclusion is that the optimal split of the available wind power between energy and reserve strongly depends upon prices and penalties on both market trading floors.

  16. Energy Law to Highlight Corporate Reserves

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    @@ The proposed Energy Law is expected to focus on fuel security by regulating commercial oil reserves at the corporate level, according to the reports extensively released by news media. As known to all, the law is being drafted as the country's energy demand, and dependency on imports, is increasing.

  17. Unanswered Quibbles with Fractional Reserve Free Banking

    Directory of Open Access Journals (Sweden)

    Philipp Bagus

    2011-07-01

    Full Text Available In this article we reply to George Selgin’s counterarguments to our article “Fractional Reserve Free Banking: Some Quibbles”. Selgin regards holding cash as saving while we focus on the real savings necessary to maintain investment projects. Real savings are unconsumed real income. Variations in real savings are not necessarily equal to variations in cash holdings. We show that a coordinated credit expansion in a fractional reserve free banking (FRFB system is possible and that precautionary reserves consequently do not pose a necessary limit. We discuss various instances in which a FRFB system may expand credit without a prior increase in real savings. These facets all demonstrate why a fractional reserve banking system – even a free banking one – is inherently unstable, and incentivized to impose a stabilizing central bank. We find that at the root of our disagreements with Selgin lies a different approach to monetary theory. Selgin subscribes to the aggregative equation of exchange, which impedes him from seeing the microeconomic problems that the stabilization of “MV” by a FRFB system causes.

  18. The Location Model with Reservation Prices

    NARCIS (Netherlands)

    Webers, H.M.

    1996-01-01

    In this paper, we analyze a variant of the standard Hotelling model of spatial competition where firms first choose locations along the line and then, given these locations, compete in prices.Consumers have a finite reservation price and incur a quadratic transportation cost.We show that there exist

  19. Is a Forex Reserves Handout Feasible?

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    China’s rapid economic development over the past decades has brought in huge social wealth, amassing the largest foreign exchange (forex) reserves in the world at $2 trillion. When financial turbulence crippled the global economy, the mammoth foreign currency holdings quickly shrank in value as a result of the U.S. dollar’s devaluation.

  20. Study on Online Hotel Reservation Systems

    OpenAIRE

    Alleweldt, Frank; Tonner, Klaus; McDonald, Marc

    2009-01-01

    This study, conducted by Civic Consulting, looks at both pre-contractual and contractual matters concerning online hotel reservation systems, examines relevant Community rules, identifies gaps and, where needed, discusses possible policy options. Key conclusions The study shows that the impact of Community law on online hotel

  1. 7 CFR 1940.590 - [Reserved

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 13 2010-01-01 2009-01-01 true [Reserved] 1940.590 Section 1940.590 Agriculture Regulations of the Department of Agriculture (Continued) RURAL HOUSING SERVICE, RURAL BUSINESS-COOPERATIVE... REGULATIONS (CONTINUED) GENERAL Methodology and Formulas for Allocation of Loan and Grant Program Funds § 1940...

  2. Appropriate reserves in the health care sector

    NARCIS (Netherlands)

    Feenstra, D.W.; Helden, G.J. van

    1999-01-01

    Organizations in the health care sector are increasingly managed and judged on the basis of economic criteria. At the same time they are faced with growing risks which necessitate ‘appropriate’ reserves. Various major risks are mentioned in this paper. Health care organizations are allowed to form p

  3. Reserve Component Personnel Issues: Questions and Answers

    Science.gov (United States)

    2013-07-12

    align reserve capabilities with active component requirements. See prepared statement of Vice Admiral John C. Harvey , Chief of Naval Personnel...before the Senate Armed Services Personnel Subcommittee, February 27, 2008, p. 5, http://armed-services.senate.gov/ statemnt/2008/February/ Harvey %2002-27...security and disaster relief missions in the aftermath of Hurricanes Katrina and Rita

  4. 31 CFR 308.5 - Reservations.

    Science.gov (United States)

    2010-07-01

    ... 31 Money and Finance: Treasury 2 2010-07-01 2010-07-01 false Reservations. 308.5 Section 308.5 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) FISCAL SERVICE, DEPARTMENT OF THE TREASURY BUREAU OF THE PUBLIC DEBT GENERAL REGULATIONS GOVERNING FULL-PAID...

  5. Oak Ridge Reservation Waste Management Plan

    Energy Technology Data Exchange (ETDEWEB)

    Turner, J.W. [ed.

    1995-02-01

    This report presents the waste management plan for the Oak Ridge Reservation facilities. The primary purpose is to convey what facilities are being used to manage wastes, what forces are acting to change current waste management systems, and what plans are in store for the coming fiscal year.

  6. Supermarket Defrost Cycles As Flexible Reserve

    DEFF Research Database (Denmark)

    Pedersen, Rasmus; Sloth, Christoffer; Wisniewski, Rafal

    2015-01-01

    This work analyses how supermarket defrost cycles can be used as flexible reserve in a smart grid context. The consumption flexibility originates from being able to shift defrost cycles in time, while adhering to the underlying refrigeration systems constraints. It is shown how this time...

  7. Impact of Asymmetric Dimethylarginine on Coronary Physiology Early After Heart Transplantation.

    Science.gov (United States)

    Parikh, Rushi V; Khush, Kiran K; Luikart, Helen; Pargaonkar, Vedant S; Kobayashi, Yuhei; Lee, Jang Hoon; Sinha, Seema; Cohen, Garrett; Valantine, Hannah A; Yeung, Alan C; Fearon, William F

    2017-09-15

    Cardiac allograft vasculopathy is a major cause of long-term graft failure following heart transplantation. Asymmetric dimethylarginine (ADMA), a marker of endothelial dysfunction, has been mechanistically implicated in the development of cardiac allograft vasculopathy, but its impact on coronary physiology early after transplantation is unknown. Invasive indices of coronary physiology, namely, fractional flow reserve (FFR), the index of microcirculatory resistance, and coronary flow reserve, were measured with a coronary pressure wire in the left anterior descending artery within 8 weeks (baseline) and 1 year after transplant. Plasma levels of ADMA were concurrently assayed using high-performance liquid chromatography. In 46 heart transplant recipients, there was a statistically significant correlation between elevated ADMA levels and lower FFR values at baseline (r = -0.33; p = 0.024); this modest association persisted 1 year after transplant (r = -0.39; p = 0.0085). Patients with a baseline FFR <0.90 (a prognostically validated cutoff) had significantly higher baseline ADMA levels (0.63 ± 0.16 vs 0.54 ± 0.12 µM; p = 0.034). Baseline ADMA (odds ratio 1.80 per 0.1 µM; 95% confidence interval 1.07 to 3.03; p = 0.027) independently predicted a baseline FFR <0.90 after multivariable adjustment. Even after dichotomizing ADMA (≥0.60 µM, provides greatest diagnostic accuracy by receiver operating characteristic curve), this association remained significant (odds ratio 7.52, 95% confidence interval 1.74 to 32.49; p = 0.006). No significant relationship between ADMA and index of microcirculatory resistance or coronary flow reserve was detected. In conclusion, baseline ADMA was a strong independent predictor of FFR <0.90, suggesting that elevated ADMA levels are associated with abnormal epicardial function soon after heart transplantation. Copyright © 2017 Elsevier Inc. All rights reserved.

  8. 76 FR 64250 - Reserve Requirements of Depository Institutions: Reserves Simplification and Private Sector...

    Science.gov (United States)

    2011-10-18

    ... institutions for the purpose of implementing monetary policy. The Board's Regulation D (Reserve Requirements of... role of reserve requirements in the implementation of monetary policy. The Board believes that these... institutions to enable the Board to conduct monetary policy). \\7\\ The exemption amount is the amount of an...

  9. Mosses from Kakenauwe Natural Reserve and Lambusango Game Reserve, Buton Island, Southeast Sulawesi

    Directory of Open Access Journals (Sweden)

    FLORENTINA INDAH WINDADRI

    2007-07-01

    Full Text Available Species diversity of Bryophyte in Kakenauwe Natural Reserve and Lambusango Game Reserve has never reported before. Recent floristic study recorded 14 species belong to 12 genus and 8 families occur in this area. Five species of them indicated as a new record for Sulawesi.

  10. Water quality monitoring in the Paul do Boquilobo Biosphere Reserve

    Science.gov (United States)

    Baptista, C.; Santos, L.

    2016-08-01

    The Paul do Boquilobo is an important wetland ecosystem classified by Unesco as a MAB Biosphere reserve also awarded Ramsar site status, representing one of the most important habitats for the resident nesting colony of Cattle Egret (Bulbucus ibis). Yet owing to its location, it suffers from human induced impacts which include industrial and domestic effluent discharges as well as agricultural land use which have negatively impacted water quality. The current study reports the results obtained from the introductory monitoring programme of surface water quality in the Nature Reserve to emphasize the detrimental impact of the anthropogenic activities in the water quality of such an important ecosystem. The study involved physicochemical and biotic variables, microbial parameters and biological indicators. Results after 3 years of monitoring bring to evidence a poor water quality further impaired by seasonal patterns. Statistical analysis of data attributed water quality variation to 3 main parameters - pH, dissolved oxygen and nitrates, indicating heavy contamination loads from both organic and agricultural sources. Seasonality plays a role in water flow and climatic conditions, where sampling sites presented variable water quality data, suggesting a depurative function of the wetland.

  11. Lubrication Flows.

    Science.gov (United States)

    Papanastasiou, Tasos C.

    1989-01-01

    Discusses fluid mechanics for undergraduates including the differential Navier-Stokes equations, dimensional analysis and simplified dimensionless numbers, control volume principles, the Reynolds lubrication equation for confined and free surface flows, capillary pressure, and simplified perturbation techniques. Provides a vertical dip coating…

  12. 12 CFR 204.4 - Computation of required reserves.

    Science.gov (United States)

    2010-01-01

    ... RESERVE REQUIREMENTS OF DEPOSITORY INSTITUTIONS (REGULATION D) § 204.4 Computation of required reserves. (a) In determining the reserve requirement under this part, the amount of cash items in process of... reserves are computed by applying the reserve requirement ratios below to net transaction...

  13. A relative quantitative assessment of myocardial perfusion by first-pass technique: animal study

    Science.gov (United States)

    Chen, Jun; Zhang, Zhang; Yu, Xuefang; Zhou, Kenneth J.

    2015-03-01

    The purpose of this study is to quantitatively assess the myocardial perfusion by first-pass technique in swine model. Numerous techniques based on the analysis of Computed Tomography (CT) Hounsfield Unit (HU) density have emerged. Although these methods proposed to be able to assess haemodynamically significant coronary artery stenosis, their limitations are noticed. There are still needs to develop some new techniques. Experiments were performed upon five (5) closed-chest swine. Balloon catheters were placed into the coronary artery to simulate different degrees of luminal stenosis. Myocardial Blood Flow (MBF) was measured using color microsphere technique. Fractional Flow Reserve (FFR) was measured using pressure wire. CT examinations were performed twice during First-pass phase under adenosine-stress condition. CT HU Density (HUDCT) and CT HU Density Ratio (HUDRCT) were calculated using the acquired CT images. Our study presents that HUDRCT shows a good (y=0.07245+0.09963x, r2=0.898) correlation with MBF and FFR. In receiver operating characteristic (ROC) curve analyses, HUDRCT provides excellent diagnostic performance for the detection of significant ischemia during adenosine-stress as defined by FFR indicated by the value of Area Under the Curve (AUC) of 0.927. HUDRCT has the potential to be developed as a useful indicator of quantitative assessment of myocardial perfusion.

  14. Value of cerebral perfusion and vascular reserve for the treatment of symptomatic intracranial arterial stenosis

    Institute of Scientific and Technical Information of China (English)

    Li'an Huang; Xuewen Song; Anding Xu

    2008-01-01

    intracranial vascular blood-flow does not suggest decreased perfusion to the blood-supply region. It is important to understand the cerebral perfusion and vascular reserve before performing interventional surgery in SICAS patients.

  15. Money Multiplier under Reserve Option Mechanism

    OpenAIRE

    Halit AKTURK; Gocen, Hasan; Duran, Suleyman

    2015-01-01

    This paper introduces a generalized money (M2) multiplier formula to the literature for a monetary system with Reserve Option Mechanism (ROM). Various features of the proposed multiplier are then explored using monthly Turkish data during the decade 2005 to 2015. We report a step increase in the magnitude and a slight upward adjustment in the long-run trend of the multiplier with the adoption of ROM. We provide evidence for substantial change in the seasonal pattern of the multiplier, cash ra...

  16. Liquidity and reserve requirements in Brazil

    OpenAIRE

    Patrice Robitaille

    2011-01-01

    The international reform initiative that followed the global financial crisis of 2008-09 has resulted in the introduction of liquidity requirements for banks. Under one requirement, the Liquidity Coverage Ratio (LCR), banks will need to hold enough highly liquid assets to survive for a month in a stress scenario. Banks' required reserve balances can be used to fulfill this liquidity requirement and this may be seen as an attractive option for emerging market economies, where financial sectors...

  17. OVARIAN RESERVE IN HEALTHY ADOLESCENT GIRLS

    Directory of Open Access Journals (Sweden)

    N.A. Buralkina

    2010-01-01

    Full Text Available Preserving reproductive health of girls is a pressing issue for the modern healthcare industry. The purpose of this study was to determine the metrics of ovarian reserve in healthy adolescent girls aged 15 to 17 in the Republic of Mordovia. 49 healthy adolescent girls aged 15 to 17 were examined in the study. A medical and social audit was conducted at the first state to study their medical history and hereditary factors. Their physical and sexual development (sexual form, characteristic of menstrual cycle, general and gynecological exam was assessed at the second stage. Hormonal status and ovarian reserve metrics were examined at the third stage. Ultrasonic examination of pelvic organs was conducted and concentrations of LH, FSH, estradiol and anti-Mullerian hormone (AMH in blood were determined. The study results obtained suggest that a reduced size of ovary in girls aged 16 compared with 15-year-old girls is accompanied with the tendency toward a reduced level of AMH and increased concentration of FSH in blood serum. A significant increase in the average size of both ovaries in 17-year-old adolescents is accompanied with the tendency toward increased AMH, and, by contrast, the tendency toward a reduced level of FSH. The level of estradiol significantly increases over age, i.e. over the period from 15 to 17 years. Hence, at ages 15 and 16 all reproductive system components continue to actively adjust to cyclical functioning. By age 17, a close relationship between ovarian reserve and hormonal status is established.Key words: reproductive health, ovarian reserve, hormonal status, girls. (Pediatric Pharmacology. – 2010; 7(5:38-43

  18. THE SOIL ALGAE OF CIBODAS FOREST RESERVE

    Directory of Open Access Journals (Sweden)

    Anne Johnson

    2014-01-01

    Full Text Available Three species of green algae and one blue-green alga were recorded from eight samples of soil found associated with bryophytes in the Cibodas Forest Reserve. Chemical analysis of the soil showed severe leaching of soluable mineral substances associated with a low pH. The low light intensity under forest conditions and the low pH may account for the limited algal flora.

  19. ffræðileg nýting á jarðhitagasi

    OpenAIRE

    Guðný Inga Ófeigsdóttir 1976

    2012-01-01

    Jarðhitagas, er aðallega samsett úr H2, H2S og CO2. Það er losað, sem afgas frá jarðhitaorkuverum. Ein leið til þess að hreinsa mengandi gastegundir eins og H2S og CO2 frá jarðhitamavirkjunum er að nýta örverur, sem hafa náttúrulega hæfileika til að vaxa á slíku gasi. Markmið þessa verkefnis var að þróa aðferðir til að rækta hitakærar örverur á jarðhitagasi frá jarðhitavirkjunum og binda það í lífmassa og föstum brennisteini. Með því væri gasið notað sem auðlind til framleiðslu afurða og um l...

  20. Stochastic and equilibrium pictures of the ultracold FFR molecular conversion rate

    CERN Document Server

    Yamakoshi, Tomotake; Zhang, Chen; Greene, Chris H

    2013-01-01

    The ultracold molecular conversion rate occurring in an adiabatic ramp through a Fano-Feshbach resonance is studied and compared in two statistical models. One model, the so-called stochastic phase space sampling (SPSS)[E.Hodby et al., PRL.94 120402(2005)] evaluates the overlap of two atomic distributions in phase space by sampling atomic pairs according to a phase-space criterion. The other model, the chemical equilibrium theory(ChET)[S.Watabe and T.Nikuni, PRA.77 013616(2008)] considers atomic and molecular distributions in the limit of the chemical and thermal equilibrium. The present study applies SPSS and ChET to a prototypical system of K+K K2 in all the symmetry combinations, namely Fermi-Fermi, Bose-Bose, and Bose-Fermi cases. To examine implications of the phase-space criterion for SPSS, the behavior of molecular conversion is analyzed using four distinct geometrical constraints. Our comparison of the results of SPSS with those of ChET shows that while they appear similar in most situations, the two ...

  1. Exploring the neural basis of cognitive reserve.

    Science.gov (United States)

    Stern, Yaakov; Zarahn, Eric; Hilton, H John; Flynn, Joseph; DeLaPaz, Robert; Rakitin, Brian

    2003-08-01

    There is epidemiologic and imaging evidence for the presence of cognitive reserve, but the neurophysiologic substrate of CR has not been established. In order to test the hypothesis that CR is related to aspects of neural processing, we used fMRI to image 19 healthy young adults while they performed a nonverbal recognition test. There were two task conditions. A low demand condition required encoding and recognition of single items and a titrated demand condition required the subject to encode and then recognize a larger list of items, with the study list size for each subject adjusted prior to scanning such that recognition accuracy was 75%. We hypothesized that individual differences in cognitive reserve are related to changes in neural activity as subjects moved from the low to the titrated demand task. To test this, we examined the correlation between subjects' fMRI activation and NART scores. This analysis was implemented voxel-wise in a whole brain fMRI dataset. During both the study and test phases of the recognition memory task we noted areas where, across subjects, there were significant positive and negative correlations between change in activation from low to titrated demand and the NART score. These correlations support our hypothesis that neural processing differs across individuals as a function of CR. This differential processing may help explain individual differences in capacity, and may underlie reserve against age-related or other pathologic changes.

  2. Micro-level stochastic loss reserving

    NARCIS (Netherlands)

    Antonio, K.; Plat, R.

    2010-01-01

    With the introduction of Solvency 2 (in 2012) and IFRS 4 Phase 2 (in 2013) insurers face major challenges. The measurement of future cash flows and its uncertainty becomes more and more important. That also gives rise to the question whether the currently used techniques can be improved. Antonio en

  3. OBSTRUCTIVE SLEEP APNEA: THE STATE OF CEREBRAL HEMODYNAMIC RESERVE

    Directory of Open Access Journals (Sweden)

    N. L. Kunelskaya

    2016-01-01

    Full Text Available Background: Individuals with obstructive  sleep apnea syndrome (OSAS have an increased risk of disabling disorders of the cardiovascular system, including  stroke.  The  mechanisms   of OSAS effects on cerebral blood flow and cerebral vascular autoregulation have not been clear enough. Aim: To study characteristics of cerebral blood flow in patients  with OSAS and the effect of CPAP therapy on cerebral hemodynamic reserve. Materials and  methods: One  hundred and  two  patients with various OSAS severity (61 male  and  41 female and  20 healthy  volunteers  participated in the study. We performed  ultrasound assessment of cerebral  blood  flow with functional  tests  and calculated  reactivity indices. Results: With more severe OSAS, no significant differences in cerebral vascular reactivity compared to the control group were  registered. However, there  was a trend  to some  decrease  in the  index of constriction  and dilation  in the  vertebral  arteries  and  the  basilar artery, as well as to its increase in the middle cerebral artery in severe and moderate OSAS. The index of vasomotor  reactivity of cerebral  arteries was significantly (р < 0.05 lower in patients with  severe  OSAS:  for vertebral  arteries,  up  to 38.9 ± 8.5 and for basilar artery, up to 36.8 ± 15.7, compared to  the  control  group  (52.1 ± 9.8 and 50.1 ± 11.2, respectively. In patients who initiated CPAP therapy, there were no changes  in velosity, resistance  and  reactivity parameters of cerebral vessels after 2 months. Conclusion: We were able to  confirm a significant  impairment  of cerebral vascular autoregulation  in patients  with severe OSAS, predominantly in the posterior circulatory region. CPAP-therapy of 2 months'  duration  did not lead to restoration  of cerebral hemodynamic reserve.

  4. 76 FR 2083 - National Estuarine Research Reserve System

    Science.gov (United States)

    2011-01-12

    ... requirement and sets a course for successful implementation of the goals and objectives of the Reserve. Since... National Oceanic and Atmospheric Administration National Estuarine Research Reserve System AGENCY: Estuarine Reserves Division, Office of Ocean and Coastal Resource Management, National Ocean...

  5. Flow Separation

    Science.gov (United States)

    1975-11-01

    Born, Constantin Caratheodory, Richard Couiant, Kurt Friedrichs, Werner Heisenberg, Gustav Herglotz, Erich von Hoist, Pascual Jordan, Walther Nernst...existence of these two flow regimes in boundary layers was discovered by PRANDTL when EIFFEL [8] published in 1912 his measurements on the drag of...simultaneously by G. EIFFEL in Paris and became so successful that other wind tunnels were modelled after it in many countries. Fig. 18 gives an impression of

  6. Media Flow

    DEFF Research Database (Denmark)

    Kabel, Lars

    2016-01-01

    News and other kinds of journalistic stories, 16-17 hours a day, all year round, on all platforms, also the moderated social media. The key research thesis behind this article is that the continuous and speedy stream of news stories and media content now is becoming the centre of the production...... processes and the value creation in converged multimedia newsrooms. The article identify new methods and discuss editorial challenges in handling media flow....

  7. 17 CFR 229.1202 - (Item 1202) Disclosure of reserves.

    Science.gov (United States)

    2010-04-01

    ..., including standardized futures prices or management's own forecasts. (3) If the registrant provides...) Preparation of reserves estimates or reserves audit. Disclose and describe the internal controls...

  8. THE EPISTEMOLOGICAL PERSPECTIVE OF FRACTIONAL RESERVE BANKING AND FULL RESERVE BANKING: WHERE ISLAMIC BANKING SHOULD STAND?

    National Research Council Canada - National Science Library

    Yaser Taufik Syamlan

    2017-01-01

    Objectives – this research is aimed to compare those epistemological bases to the mindset of Islamic Bank and try to drive the philosophy in practical operation whether based on the Fractional Reserve Banking Sytem (RBS) or 100...

  9. Ready, Reliable, and Relevant: The Army Reserve Component as an Operational Reserve

    Science.gov (United States)

    2015-05-21

    33 Stephen Everett and L. Martin Kaplan, Department of the Army Historical Summary: Fiscal Year 1993, Center of...1992 and 1993, Public Law 102- 190, 102nd Cong. (December 5, 1991): 1352-1353. 35 Dennis Chapman , “Planning for Employment of the Reserve...not acronyms. These terms are referenced in Chapman , “Planning for Employment of the Reserve Components,” 1-4; 6-9; 11-12. 40 Chapman , “Planning

  10. Reserve Component Programs. Fiscal Year 1999 Report of the Reserve Forces Policy Board

    Science.gov (United States)

    2000-03-01

    border with Mexico in southern San Diego county as part of project Task Force Grizzly Border Road. In New York’s Operation Straight Shoot, the...1992, which was signed by six states: Arizona, California, Colorado, New Mexico , Nevada, and Utah. The third such compact was the Southern Regional...Reserve par- ticipated in the 1999 Copa Telemundo, a youth soccer tournament and fiesta for boys age 15 to 19. The Naval Reserve is actively

  11. Assessing reserve-building pursuits and person characteristics: psychometric validation of the Reserve-Building Measure.

    Science.gov (United States)

    Schwartz, Carolyn E; Michael, Wesley; Zhang, Jie; Rapkin, Bruce D; Sprangers, Mirjam A G

    2017-09-06

    A growing body of research suggests that regularly engaging in stimulating activities across multiple domains-physical, cultural, intellectual, communal, and spiritual-builds resilience. This project investigated the psychometric characteristics of the DeltaQuest Reserve-Building Measure for use in prospective research. The study included Rare Patient Voice panel participants. The web-based survey included the Reserve-Building Measure with one-week re-test, measures of quality of life (QOL) and well-being (PROMIS General Health; NeuroQOL Cognitive Function and Positive Affect & Well-Being short-forms; Ryff Environmental Mastery subscale); and the Big Five Inventory-10 personality measure. Classical test theory and item response theory (IRT) analyses investigated psychometric characteristics of the Reserve-Building Measure. This North American sample (n = 592) included both patients and caregivers [mean age = 44, SD 19)]. Psychometric analyses revealed distinct subscales measuring current reserve-building activities (Active in the World, Games, Outdoors, Creative, Religious/Spiritual, Exercise, Inner Life, Shopping/Cooking, Passive Media Consumption,), past reserve-building activities (Childhood Activities, Achievement), and reserve-related person-factors (Perseverance, Current and Past Social Support, and Work Value). Test-retest stability (n = 101) was moderately high for 11 of 15 subscales (ICC range 0.78-0.99); four were below 0.59 indicating a need for further refinement. IRT analyses supported the item functioning of all subscales. Correlational analyses suggest the measure's subscales tap distinct constructs (range r = 0.11-0.46) which are not redundant with QOL, well-being, or personality (range r = 0.11-0.48). The Reserve-Building Measure provides a measure of activities and person-factors related to reserve that may potentially be useful in prospective research.

  12. Reserve Officer Commissioning Program (ROCP) Officer andReserve Personnel Readiness

    Science.gov (United States)

    2017-04-07

    Cleared for Public Release DISTRIBUTION STATEMENT A. Approved for public release: distribution unlimited. Reserve Officer...Commissioning Program (ROCP) Officer and Reserve Personnel Readiness Jennifer Griffin and Michelle Dolfini-Reed April 2017 This work was...performed under Federal Government Contract No. N00014-16-D-5003. Copyright © 2017 CNA This document contains the best opinion of CNA at the time of

  13. Root carbon reserve dynamics in aspen seedlings: does simulated drought induce reserve limitation?

    Science.gov (United States)

    Galvez, David A; Landhäusser, S M; Tyree, M T

    2011-03-01

    In a greenhouse study we quantified the gradual change of gas exchange, water relations and root reserves of aspen (Populus tremuloides Michx.) seedlings growing over a 3-month period of severe water stress. The aim of the study was to quantify the complex interrelationship between growth, water and gas exchange, and root carbon (C) dynamics. Various growth, gas exchange and water relations variables in combination with root reserves were measured periodically on seedlings that had been exposed to a continuous drought treatment over a 12-week period and compared with well-watered seedlings. Although gas exchange and water relations parameters significantly decreased over the drought period in aspen seedlings, root reserves did not mirror this trend. During the course of the experiment roots of aspen seedlings growing under severe water stress showed a two orders of magnitude increase in sugar and starch content, and roots of these seedlings contained more starch relative to sugar than those in non-droughted seedlings. Drought resulted in a switch from growth to root reserves storage which indicates a close interrelationship between growth and physiological variables and the accumulation of root carbohydrate reserves. Although a severe 3-month drought period created physiological symptoms of C limitation, there was no indication of a depletion of root C reserve in aspen seedlings.

  14. Myocardial perfusion reserve compared with peripheral perfusion reserve : A [13N]ammonia PET study

    NARCIS (Netherlands)

    Scholtens, A. M.; Tio, R. A.; Willemsen, A.; Dierckx, R. A. J. O.; Boersma, Hendrikus; Zeebregts, C. J.; Glaudemans, A. W. J. M.; Slart, R. H. J. A.

    2011-01-01

    INTRODUCTION: [13N]ammonia PET allows quantification of myocardial perfusion. The similarity between peripheral flow and myocardial perfusion is unclear. We compared perfusion flow in the myocardium with the upper limb during rest and adenosine stress [13N]ammonia PET to establish whether peripheral

  15. Are Private Reserves Effective for Jaguar Conservation?

    Science.gov (United States)

    Gutiérrez-González, Carmina E; Gómez-Ramírez, Miguel A; López-González, Carlos A; Doherty, Paul F

    2015-01-01

    We present the first study of density and apparent survival for a jaguar (Panthera onca) population in northern Mexico using 13 years of camera trap data from 2000 to 2012. We used the Barker robust design model which combines data from closed sampling periods and resight data between these periods to estimate apparent survival and abundance. We identified 467 jaguar pictures that corresponded to 48 jaguar individuals. We included camera type and field technician as covariates for detection probabilities. We used three covariates to evaluate the effect of reserve on jaguar apparent survival: i) private reserve creation ii) later reserve expansions, and iii) cattle ranches' conservation activities. We found that the use of digital cameras in addition to film cameras increased detection probability by a factor of 6x compared with the use of only film cameras (p = 0.34 ± 0.05 and p = 0.05 ± 0.02 respectively) in the closed period and more than three times in the open period (R = 0.91 ± 0.08 and R = 0.30 ± 0.13 mixed and film cameras respectively). Our availability estimates showed no temporary emigration and a fidelity probability of 1. Despite an increase of apparent survival probability from 0.47 ± 0.15 to 0.56 ± 0.11 after 2007, no single covariate explained the change in these point estimates. Mean jaguar density was 1.87 ± 0.47 jaguars/100 km2. We found that 13 years of jaguar population monitoring with our sampling size were not enough for detecting changes in survival or density. Our results provide a baseline for studies evaluating the effectiveness of protected areas and the inclusion of ranch owners in jaguar conservation programs and long-term population viability.

  16. Are Private Reserves Effective for Jaguar Conservation?

    Directory of Open Access Journals (Sweden)

    Carmina E Gutiérrez-González

    Full Text Available We present the first study of density and apparent survival for a jaguar (Panthera onca population in northern Mexico using 13 years of camera trap data from 2000 to 2012. We used the Barker robust design model which combines data from closed sampling periods and resight data between these periods to estimate apparent survival and abundance. We identified 467 jaguar pictures that corresponded to 48 jaguar individuals. We included camera type and field technician as covariates for detection probabilities. We used three covariates to evaluate the effect of reserve on jaguar apparent survival: i private reserve creation ii later reserve expansions, and iii cattle ranches' conservation activities. We found that the use of digital cameras in addition to film cameras increased detection probability by a factor of 6x compared with the use of only film cameras (p = 0.34 ± 0.05 and p = 0.05 ± 0.02 respectively in the closed period and more than three times in the open period (R = 0.91 ± 0.08 and R = 0.30 ± 0.13 mixed and film cameras respectively. Our availability estimates showed no temporary emigration and a fidelity probability of 1. Despite an increase of apparent survival probability from 0.47 ± 0.15 to 0.56 ± 0.11 after 2007, no single covariate explained the change in these point estimates. Mean jaguar density was 1.87 ± 0.47 jaguars/100 km2. We found that 13 years of jaguar population monitoring with our sampling size were not enough for detecting changes in survival or density. Our results provide a baseline for studies evaluating the effectiveness of protected areas and the inclusion of ranch owners in jaguar conservation programs and long-term population viability.

  17. Demand as Frequency-controlled Reserve

    DEFF Research Database (Denmark)

    Bang, Christian; Rasmussen, Christian Brandt; Østergaard, Jacob

    with great enthusiasm from all DFR project members who have shown a memorable dedication to their work. Active control of electricity demand is a key technology when creating a more dynamic, wind power friendly energy system. In this demonstration project, we have developed and tested devices, which use...... electric loads to provide frequency controlled primary reserves. The devices collected data from domestic households and industrial loads covering i.e. circulation pumps, electrical domestic heating, bottle coolers, a wastewater treatment plant etc., that have been analysed and used for the papers...

  18. Aksu-Zhabagly Nature Reserve's 90-anniversary

    OpenAIRE

    Anatoliy F. Kovshar

    2016-01-01

    The Aksu-Zhabagly nature reserve is located in West Tien Shan in Kazakhstan, on the border of three countries – Kazakhstan, Kyrgyzstan and Uzbekistan (70°18'-57' E and 42°08'-30' N), with an area of 1281 km2; its length is 53 km from the most western to the most eastern point and 41 km from the most southern to the most northern point. It occupies the western limit of the Talasskiy Alatau ridge and its north-western spurs: Zhabaglytau mountains, Alatau, Bugultor, Aksutau and Ugam ridges. In t...

  19. Essays in the California electricity reserves markets

    Science.gov (United States)

    Metaxoglou, Konstantinos

    This dissertation examines inefficiencies in the California electricity reserves markets. In Chapter 1, I use the information released during the investigation of the state's electricity crisis of 2000 and 2001 by the Federal Energy Regulatory Commission to diagnose allocative inefficiencies. Building upon the work of Wolak (2000), I calculate a lower bound for the sellers' price-cost margins using the inverse elasticities of their residual demand curves. The downward bias in my estimates stems from the fact that I don't account for the hierarchical substitutability of the reserve types. The margins averaged at least 20 percent for the two highest quality types of reserves, regulation and spinning, generating millions of dollars in transfers to a handful of sellers. I provide evidence that the deviations from marginal cost pricing were due to the markets' high concentration and a principal-agent relationship that emerged from their design. In Chapter 2, I document systematic differences between the markets' day- and hour-ahead prices. I use a high-dimensional vector moving average model to estimate the premia and conduct correct inferences. To obtain exact maximum likelihood estimates of the model, I employ the EM algorithm that I develop in Chapter 3. I uncover significant day-ahead premia, which I attribute to market design characteristics too. On the demand side, the market design established a principal-agent relationship between the markets' buyers (principal) and their supervisory authority (agent). The agent had very limited incentives to shift reserve purchases to the lower priced hour-ahead markets. On the supply side, the market design raised substantial entry barriers by precluding purely speculative trading and by introducing a complicated code of conduct that induced uncertainty about which actions were subject to regulatory scrutiny. In Chapter 3, I introduce a state-space representation for vector autoregressive moving average models that enables

  20. Forty Defective Criticisms of Full Reserve Banking

    OpenAIRE

    Musgrave, Ralph S.

    2016-01-01

    Abstract. The basics of full reserve banking (FR) are set out below, followed by forty defective criticisms of FR. Each of those forty sections has: 1. A heading. 2. Where the heading does not adequately capture the nature of the criticism, there is a paragraph below the heading starting “I.e…”, which expands on the heading. 3. There are references to one or more economists who have put the relevant criticism. 4. The answer to each criticism which starts with a paragraph beginning with the wo...

  1. Flexible reserve markets for wind integration

    Science.gov (United States)

    Fernandez, Alisha R.

    The increased interconnection of variable generation has motivated the use of improved forecasting to more accurately predict future production with the purpose to lower total system costs for balancing when the expected output exceeds or falls short of the actual output. Forecasts are imperfect, and the forecast errors associated with utility-scale generation from variable generators need new balancing capabilities that cannot be handled by existing ancillary services. Our work focuses on strategies for integrating large amounts of wind generation under the flex reserve market, a market that would called upon for short-term energy services during an under or oversupply of wind generation to maintain electric grid reliability. The flex reserve market would be utilized for time intervals that fall in-between the current ancillary services markets that would be longer than second-to-second energy services for maintaining system frequency and shorter than reserve capacity services that are called upon for several minutes up to an hour during an unexpected contingency on the grid. In our work, the wind operator would access the flex reserve market as an energy service to correct for unanticipated forecast errors, akin to paying the generators participating in the market to increase generation during a shortfall or paying the other generators to decrease generation during an excess of wind generation. Such a market does not currently exist in the Mid-Atlantic United States. The Pennsylvania-New Jersey-Maryland Interconnection (PJM) is the Mid-Atlantic electric grid case study that was used to examine if a flex reserve market can be utilized for integrating large capacities of wind generation in a lowcost manner for those providing, purchasing and dispatching these short-term balancing services. The following work consists of three studies. The first examines the ability of a hydroelectric facility to provide short-term forecast error balancing services via a flex

  2. Changing stakeholder relationships in nature reserve management: a case study on Snake Island-Laotie Mountain National Nature Reserve, Liaoning, China.

    Science.gov (United States)

    Zhou, Dan; Wang, Ziyan; Lassoie, James; Wang, Xiaoping; Sun, Lixin

    2014-12-15

    The number and total area of nature reserves in China has increased rapidly over the past couple of decades; however, the ability to effectively manage these reserves has not kept pace and conflicts between conservation efforts and economic development have emerged. The Snake Island-Laotie Mountain National Nature Reserve (SILMNNR) currently is experiencing the challenges of balancing conservation with local community development. This paper uses components analysis of human ecosystems (HEC) to examine conflicts arising from the management of the nature reserve and uses a stakeholder analysis to identify and better understand stakeholder inter-relationships in the SILMNNR-HEC. The goal of this study is to identify critical factors influencing stakeholder relationships in order to find ways of relieving conflicts between the reserve management and development. The stakeholder analysis revealed that the key stakeholders in the SILMNNR-HEC are natural resources, the Liaoning SILMNNR Authority, local residents, and enterprise developers; however, there was unequal power among stakeholders in the decision making process affecting the nature reserve. The paper evaluated the conditions and processes of SILMNNR-HEC through a framework of stakeholder relationships where critical factors, such as policy, finance, technology, and labor, and their respective strengths and feedbacks among stakeholders, were assessed and showed unequal flows of power among stakeholders. Two approaches are provided for transforming the unbalanced relationships into a stable and sustainable framework to sustainably manage the nature reserve: the first is by changing stakeholder relationships from opposition to cooperation; and the second by enhancing feedbacks and dynamics among stakeholders. The analysis used in this paper can be used as a model to assess conflicts around other protected areas in China and elsewhere.

  3. Sessile and mobile components of a benthic ecosystem display mixed trends within a temperate marine reserve.

    Science.gov (United States)

    Howarth, Leigh M; Pickup, Sarah E; Evans, Lowri E; Cross, Tim J; Hawkins, Julie P; Roberts, Callum M; Stewart, Bryce D

    2015-06-01

    Despite recent efforts to increase the global coverage of marine protected areas (MPAs), studies investigating the effectiveness of marine protected areas within temperate waters remain scarce. Furthermore, out of the few studies published on MPAs in temperate waters, the majority focus on specific ecological or fishery components rather than investigating the ecosystem as a whole. This study therefore investigated the dynamics of both benthic communities and fish populations within a recently established, fully protected marine reserve in Lamlash Bay, Isle of Arran, United Kingdom, over a four year period. A combination of photo and diver surveys revealed live maerl (Phymatolithon calcareum), macroalgae, sponges, hydroids, feather stars and eyelash worms (Myxicola infundibulum) to be significantly more abundant within the marine reserve than on surrounding fishing grounds. Likewise, the overall composition of epifaunal communities in and outside the reserve was significantly different. Both results are consistent with the hypothesis that protecting areas from fishing can encourage seafloor habitats to recover. In addition, the greater abundance of complex habitats within the reserve appeared to providing nursery habitat for juvenile cod (Gadus morhua) and scallops (Pecten maximus and Aequipecten opercularis). In contrast, there was little difference in the abundance of mobile benthic fauna, such as crabs and starfish, between the reserve and outside. Similarly, the use of baited underwater video cameras revealed no difference in the abundance and size of fish between the reserve and outside. Limited recovery of these ecosystem components may be due to the relatively small size (2.67 km(2)) and young age of the reserve (marine reserves can encourage seafloor habitats to recover, which in turn, can create a number of benefits that flow back to other species, including those of commercial importance. Copyright © 2015 Elsevier Ltd. All rights reserved.

  4. Oak Ridge Reservation environmental report for 1989

    Energy Technology Data Exchange (ETDEWEB)

    Jacobs, V.A.; Wilson, A.R. (eds.)

    1990-10-01

    This two-volume report, the Oak Ridge Reservation Environmental Report for 1989, is the nineteenth in an annual series that began in 1971. It reports the results of a comprehensive, year-round program to monitor the impact of operations at the three major US Department of Energy (DOE) production and research installations in Oak Ridge on the immediate areas' and surrounding region's groundwater and surface waters, soil, air quality, vegetation and wildlife, and through these multiple and varied pathways, the resident human population. Information is presented for the environmental monitoring Quality Assurance (QA) Program, audits and reviews, waste management activities, land special environmental studies. Data are included for the Oak Ridge Y-12 Plant, Oak Ridge National Laboratory (ORNL), and Oak Ridge Gaseous Diffusion Plant (ORGDP). Volume 1 presents narratives, summaries, and conclusions based on environmental monitoring at the three DOE installations and in the surrounding environs during calendar year (CY) 1989. Volume 1 is intended to be a stand-alone'' report about the Oak Ridge Reservation (ORR) for the reader who does not want an in-depth review of 1989 data. Volume 2 presents the detailed data from which these conclusions have been drawn and should be used in conjunction with Volume 1.

  5. Extended-reach wells tap outlying reserves

    Energy Technology Data Exchange (ETDEWEB)

    Nazzal, G. (Eastman Teleco, Houston, TX (United States))

    1993-03-01

    Extended-reach drilling (ERD) is being used to exploit fields and reserves that are located far from existing platforms. Effective wellbore placement from fewer platforms can reduce development costs, maximize production and increase reserve recovery. Six wells drilled offshore in the US, North Sea and Australia illustrate how to get the most economic benefit from available infrastructure. These wells are divided into three categories by depth (shallow, medium and deep). Vertical depth of these wells range from 963 to 12,791 ft TVD and displacements range from 4,871 to 23,917 ft. Important factors for successful extended-reach drilling included: careful, comprehensive pre-planning; adequate cuttings removal in all sections; hole stability in long, exposed intervals; torque and drag modeling of drilling BHAs, casing and liners; buoyancy-assisted casing techniques where appropriate; critical modifications to drilling rig and top drive, for medium and deep ERD; modified power swivels for shallow operations; drill pipe rubbers or other casing protection during extended periods of drill string rotation; heavy-wall casting across anticipated high-wear areas; survey accuracy and frequency; sound drilling practices and creativity to accomplish goals and objectives. This paper reviews the case history of these sites and records planning and design procedures.

  6. Engineering, geology hike Black Bayou reserves

    Energy Technology Data Exchange (ETDEWEB)

    Bleakley, W.B.

    1971-01-04

    New wells drilled in strategic locations, combined with well-engineered attic-oil recovery projects, have added more than 20 million bbl of recoverable oil to Shell Oil Co's reserves in Black Bayou field, Cameron Parish, Louisiana. Development wells discover the small reservoirs in the highly faulted field and up dig gas injection assures Shell of getting all the oil possible. A continuous review of the field's geology, constantly updated with information from each new well, contributes to the program's sucess. In the last 10 yr, the combination of reservoir engineering and geology came up with 71 new wells, added 20 million bbl to the field's reserves, and increased production rate from 1,000 to 9,000 bpd. All this from a field that is celebrating its forty-first anniversary. Black Bayou is the oldest Shell-discovered field in Louisiana. It is a piercement-type salt dome with production confined to narrow bands around the periphery of the salt. The dome is bisected by a major NW.-dipping fault, and is further complicated by at least 30 radial faults. There are 26 productive oil sands of sands of Miocene and Oligocene age. Cumulative production from the field as of Nov. 1, 1970, is approx. 34 million bbl oil. Ultimate recovery for the field is estimated at 50 million bbl oil.

  7. Flow and Flow Decay of Refractory Castables

    Institute of Scientific and Technical Information of China (English)

    CHEN Zhiqiang; Bjom Myhre; Bjorn Sandberg

    2003-01-01

    Installation of refractoty castables depend not only on flow, but also on how soon the flow is lost because of setting. The loss of flow (flow decay) has always been one of the main problems of refractory castable manufacturers,a problem that has not been too well described in literature. The flow decay has been studied for a castable system based on alumina, pointing out some general trends. The flow decay was found very temperature sensitive, being strongly accelerated by termperature increases. To compensate for excessive flow loss, a retarder like citric acid may be used. Thus flow decay was measured as a function of citric acid (retarder) addition at 35 ℃ .

  8. 26 CFR 1.801-5 - Total reserves.

    Science.gov (United States)

    2010-04-01

    ... its highest aggregate reserve by taking State A's requirement of 10 against its life insurance business and adding it to State B's requirement of 7 against its annuity business. (b) Reserves required by...) The reasons for the change in basis of such reserve; and (6) Whether such change in the reserve has...

  9. 12 CFR 204.6 - Charges for reserve deficiencies.

    Science.gov (United States)

    2010-01-01

    ... waives the penalty for failing to satisfy a liquidity requirement, the Reserve Bank in the District where... 12 Banks and Banking 2 2010-01-01 2010-01-01 false Charges for reserve deficiencies. 204.6 Section 204.6 Banks and Banking FEDERAL RESERVE SYSTEM BOARD OF GOVERNORS OF THE FEDERAL RESERVE...

  10. 24 CFR 81.95 - Authority of Federal Reserve Banks.

    Science.gov (United States)

    2010-04-01

    ... 24 Housing and Urban Development 1 2010-04-01 2010-04-01 false Authority of Federal Reserve Banks... Authority of Federal Reserve Banks. (a) Each Federal Reserve Bank is hereby authorized as fiscal agent of..., Federal Reserve Bank Operating Circulars, this subpart H, and procedures established by the...

  11. 31 CFR 210.7 - Federal Reserve Banks.

    Science.gov (United States)

    2010-07-01

    ... 31 Money and Finance: Treasury 2 2010-07-01 2010-07-01 false Federal Reserve Banks. 210.7 Section... CLEARING HOUSE General § 210.7 Federal Reserve Banks. (a) Fiscal Agents. Each Federal Reserve Bank serves... under this part. As Fiscal Agent, each Federal Reserve Bank shall be responsible only to the...

  12. 7 CFR 1467.9 - Wetlands Reserve Enhancement Program.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 10 2010-01-01 2010-01-01 false Wetlands Reserve Enhancement Program. 1467.9 Section... CORPORATION, DEPARTMENT OF AGRICULTURE LOANS, PURCHASES, AND OTHER OPERATIONS WETLANDS RESERVE PROGRAM § 1467.9 Wetlands Reserve Enhancement Program. (a) Wetlands Reserve Enhancement Program (WREP). (1) The...

  13. 7 CFR 981.51 - Requirements for reserve.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 8 2010-01-01 2010-01-01 false Requirements for reserve. 981.51 Section 981.51... Regulating Handling Volume Regulation § 981.51 Requirements for reserve. Each handler may satisfy his reserve... include grade requirements for reserve almonds delivered to human consumption outlets....

  14. 12 CFR 204.9 - Emergency reserve requirement.

    Science.gov (United States)

    2010-01-01

    ... 12 Banks and Banking 2 2010-01-01 2010-01-01 false Emergency reserve requirement. 204.9 Section... RESERVE REQUIREMENTS OF DEPOSITORY INSTITUTIONS (REGULATION D) § 204.9 Emergency reserve requirement. (a..., additional reserve requirements on depository institutions at any ratio on any liability upon a finding by...

  15. 5 CFR 842.210 - Military reserve technicians.

    Science.gov (United States)

    2010-01-01

    ... 5 Administrative Personnel 2 2010-01-01 2010-01-01 false Military reserve technicians. 842.210... reserve technicians. (a) A military reserve technician as defined in 5 U.S.C. 8401(30) who is separated from civilian service because of ceasing to qualify as a member of a military reserve component...

  16. Habitat Quality and Anadromous Fish Production on the Warm Springs Reservation. Final Report.

    Energy Technology Data Exchange (ETDEWEB)

    Fritsch, Mark A.

    1995-06-01

    The number of anadromous fish returning to the Columbia River and its tributaries has declined sharply in recent years. Changes in their freshwater, estuarine, and ocean environments and harvest have all contributed to declining runs of anadromous fish. Restoration of aquatic resources is of paramount importance to the Confederated Tribes of the Warm Springs (CTWS) Reservation of Oregon. Watersheds on the Warm Springs Reservation provide spawning and rearing habitat for several indigenous species of resident and anadromous fish. These streams are the only ones in the Deschutes River basin that still sustain runs of wild spring chinook salmon, Oncorhynchus, tshawytscha. Historically, reservation streams supplied over 169 km of anadromous fish habitat. Because of changes in flows, there are now only 128 km of habitat that can be used on the reservation. In 1981, the CTWS began a long-range, 3-phase study of existing and potential fish resources on the reservation. The project, consistent with the Northwest Power Planning Council`s Fish and Wildlife Program, was designed to increase the natural production of anadromous salmonids on the reservation.

  17. STEM Summer Academy on the Navajo Reservation

    Science.gov (United States)

    Alexander, C. J.

    2012-12-01

    The US Rosetta Project is the NASA contribution to the International Rosetta Mission, an ESA cornerstone mission to comet Churyumov-Gerasimenko. While the project's outreach efforts span multi-media, and a variety of age and ethnic groups, a special emphasis has been made to find a way to provide meaningful outreach to the reservation communities. Because language preservation is an issue of urgent concern to the reservation communities, and because Rosetta, uniquely among NASA missions, has been named after the notion that keys to missing understanding of elements of the ancient past were found in the language on the original Rosetta stone, the US Rosetta Project has embarked upon outreach with a focus on STEM vocabulary in ancient US languages of the Navajo, Hopi, Ojibwe, and other tribal communities as the project expands. NASA image and science are used and described in the native language, alongside lay English and scientific English curriculum elements. Additionally, science (geology/chemistry/botany/physics) elements drawn from the reservation environment, including geomorphology, geochemistry, soil physics, are included and discussed in the native language as much as possible — with their analogs in other planetary environments (such as Mars). In this paper we will report on the most recent Summer Science Academy [2012], a four week summer course for middle school children, created in collaboration with teachers and administrators in the Chinle Unified School District. The concept of the Academy was initiated in 2011, and the first Academy was conducted shortly thereafter, in June 2011 with 14 children, 3 instructors, and a NASA teacher workshop. The community requested three topics: geology, astronomy, and botany. The 2012 Academy built on the curriculum already developed with more robust field trips, addressed to specific science topics, additional quantitative measurements and activities, with more written material for the cultural components from

  18. A public finance analysis of multiple reserve requirements

    OpenAIRE

    Espinosa-Vega, Marco; Russell, Steven

    1999-01-01

    This paper analyzes multiple reserve requirements of the type that have been imposed by a number of developing countries. We show that previous theoretical work on this topic has not succeeded in providing a social welfare rationale for the existence of multiple reserve requirements: in the basic reserve requirements model, any allocation that can be supported by a multiple-reserves regime can also be supported by a single-bond reserve requirement. We go on to present extended versions of the...

  19. A public finance analysis of multiple reserve requirements

    OpenAIRE

    Espinosa-Vega, Marco; Russell, Steven

    1999-01-01

    This paper analyzes multiple reserve requirements of the type that have been imposed by a number of developing countries. We show that previous theoretical work on this topic has not succeeded in providing a social welfare rationale for the existence of multiple reserve requirements: in the basic reserve requirements model, any allocation that can be supported by a multiple-reserves regime can also be supported by a single-bond reserve requirement. We go on to present extended versions of the...

  20. Energy reserves. [Summary of reserve estimates and economic supply models for exhaustible resources

    Energy Technology Data Exchange (ETDEWEB)

    Tessmer, R.G. Jr.; Carhart, S.C.; Marcuse, W.

    1977-03-01

    There is an increasing concern about scarcity of the world's remaining natural energy resources and, in particular, the future supply of oil and natural gas. This paper summarizes recent estimates of energy reserves and economic supply models for exhaustible resources. The basic economic theory of resource exhaustion is reviewed, and recent estimates of both discovered and undiscovered energy resources are presented and compared. Domestic and world-wide reserve estimates are presented for crude oil and natural gas liquids, natural gas, coal, and uranium. Economic models projecting supply of these energy forms, given reserve estimates and other pertinent information, are discussed. Finally, a set of recent models which project world oil prices are summarized and their published results compared. The impact of energy conservation efforts on energy supply is also briefly discussed. 53 references.

  1. Aksu-Zhabagly Nature Reserve's 90-anniversary

    Directory of Open Access Journals (Sweden)

    Anatoliy F. Kovshar

    2016-05-01

    Full Text Available The Aksu-Zhabagly nature reserve is located in West Tien Shan in Kazakhstan, on the border of three countries – Kazakhstan, Kyrgyzstan and Uzbekistan (70°18'-57' E and 42°08'-30' N, with an area of 1281 km2; its length is 53 km from the most western to the most eastern point and 41 km from the most southern to the most northern point. It occupies the western limit of the Talasskiy Alatau ridge and its north-western spurs: Zhabaglytau mountains, Alatau, Bugultor, Aksutau and Ugam ridges. In the neighbouring Karatau ridge there is a palaeontological site with an area of 2.2 km2 with deposits of flora and fauna of the Jurassic period. The absolute heights above sea level are 1300–4200 m. The relief is alpine – deep canyons with steep slopes. The middle mountain zone (1300–2000 m is occupied by meadow-steppe formations with juniper sparse forests (Juniperus semiglobosa, J. seravschanica; subalpine meadows (2000–3000 m are alternated by creeping juniper thickets (Juniperus turkestanica and rocky outcrops; the alpine zone (higher than 3000 m is dominated by rocks and snowfields, and glaciers above 3500 m. The nature reserve's flora constitutes almost half of all West Tien Shan's flora and counts 1737 species, including: 235 species of fungi, 64 lichens, 63 species each of algae and mosses, as well as 1312 species of higher plants. Among those, 200 species are medicinal and 57 species are listed in the Red Data Books of Kazakhstan, Uzbekistan and Kyrgyzstan. The vertebrates fauna includes 320 species: mammals – 52 species, birds – 247 (130 of them are nesting, reptiles and amphibians – 14, fishes – 7 species. Animals inhabiting the territory include argali (Ovis ammon karelini, mountain goat (Capra sibirica, bear (Ursus arctos isabellinus, snow leopart (Uncia uncia, Turkestan lynx (Lynx lynx isabellinus; birds – bearded vulture (Gypaёtus barbatus, Himalayan snowcock (Tetraogallus himalayensis, chukar (Alectoris chukar, blue

  2. Beurteilungsmöglichkeiten der ovariellen Reserve

    Directory of Open Access Journals (Sweden)

    Shebl O

    2010-01-01

    Full Text Available Die Überprüfung der Funktionstüchtigkeit der Ovarien ist für die Beratung und Planung einer IVF-Behandlung von besonderer Bedeutung. Die Funktionstüchtigkeit wird im Allgemeinen als ovarielle Reserve bezeichnet. Diese setzt sich aus der Anzahl der im Rahmen einer kontrollierten ovariellen Stimulation gewonnenen Eizellen und der Qualität eben dieser zusammen. Es gibt verschiedene Möglichkeiten, diese zu bestimmen, jedoch keinen Parameter, der beide Kriterien optimal erfüllt. Auch zeigen sich viele Parameter als nicht unabhängig voneinander oder als zu aufwendig für die routinemäßige Verwendung bei Frauen mit Kinderwunsch. Die Kombination einzelner Parameter erlaubt jedoch eine gute Aussage über die zu erwartende Antwort der Ovarien auf eine kontrollierte ovarielle Stimulation und somit die Anpassung der Stimulation.

  3. Oak Ridge Reservation environmental report for 1989

    Energy Technology Data Exchange (ETDEWEB)

    Jacobs, V.A.; Wilson, A.R. (eds.)

    1990-10-01

    The first two volumes of this report are devoted to a presentation of environmental data and supporting narratives for the US Department of Energy's (DOE's) Oak Ridge Reservation (ORR) and surrounding environs during 1989. Volume 1 includes all narrative descriptions, summaries, and conclusions and is intended to be a stand-alone'' report for the ORR for the reader who does not want to review in detail all of the 1989 data. Volume 2 includes the detailed data summarized in a format to ensure that all environmental data are represented in the tables. Narratives are not included in Vol. 2. The tables in Vol. 2 are addressed in Vol. 1. For this reason, Vol. 2 cannot be considered a stand-alone report but is intended to be used in conjunction with Vol. 1. 16 figs., 194 tabs.

  4. Oak Ridge Reservation Environmental report for 1990

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, A.R. (ed.)

    1991-09-01

    The first two volumes of this report are devoted to a presentation of environmental data and supporting narratives for the US Department of Energy's (DOE's) Oak Ridge Reservation (ORR) and surrounding environs during 1990. Volume 1 includes all narrative descriptions, summaries, and conclusions and is intended to be a stand-alone'' report for the ORR for the reader who does not want to review in detail all of the 1990 data. Volume 2 includes the detailed data summarized in a format to ensure that all environmental data are represented in the tables. Narratives are not included in Vol. 2. The tables in Vol. 2 are addressed in Vol. 1. For this reason, Vol. 2 cannot be considered a stand-alone report but is intended to be used in conjunction with Vol. 1.

  5. Independents add gas reserves, forego romance

    Energy Technology Data Exchange (ETDEWEB)

    Gill, D.

    1981-08-01

    Incentive pricing for low-permeability reservoirs and tax advantages for drilling them are 2 big reasons why more independents may start making a special effort to add gas reserves to their inventories. If so, it will be a change from past practices, which saw independents build up big gas positions by circumstance rather than by intention. There are always major refiners ready and willing to buy whole crude oil reservoirs from small producers, but purchasers willing to take gas fields in a single investment are few and far between. Lower-than-normal return on equity during the first 20 years, plus the heavy front-end cost of a frac necessary to produce the tight gas might dissuade independents from drilling tight gas sands, but those liabilities are offset by the higher price tight gas gets and the peculiar tax advantages of exploring for it that make a nice fit with the small operator's way of doing business.

  6. Macrofungi of the Zasavica special nature reserve

    Directory of Open Access Journals (Sweden)

    Cvijanović Marko S.

    2009-01-01

    Full Text Available In the frame of biodiversity investigation of the Republic of Serbia, the investigation of the presence and the diversity of macrofungi of the Zasavica Special Nature Reserve (North Serbia has been undertaken. Relatively poor generic diversity of macrofungi was recorded with domination of ecological group of wood-decaying species. Even though being preliminary, our results point to the necessity of conservation and protection of recent fungal diversity but, in our opinion, not by making a so-called 'Red list of endangered species', which, due to the lack of information and very poor evidence on this group of organisms in our country, are extremely unreliable and therefore disputable, but rather through the very short list of a few not endangered species, conditionally called 'White list of not endangered fungal species', if such species recently exist et all.

  7. Tissue carnitine reserves of newborn infants.

    Science.gov (United States)

    Shenai, J P; Borum, P R

    1984-07-01

    This study assessed the tissue reserves of carnitine at birth in a group of neonates (n = 22) of varying gestational age dying within 24 h of birth, prior to possible changes in carnitine status induced by postnatal intervention. Tissue carnitine concentration was highest in the muscle in each infant. The mean (+/- SD) muscle carnitine concentration of 8.4 +/- 3.6 nmol/mg noncollagen protein (NCP) in very immature infants (less than or equal to 1000 g birth weight) was significantly lower than the corresponding mean (+/- SD) values of 14.0 +/- 3.2 nmol/mg NCP in larger preterm infants (1001-2500 g; P less than 0.01) and 19.4 +/- 2.6 nmol/mg NCP in term infants (greater than or equal to 2501 g; P less than 0.001). Muscle carnitine concentration correlated positively with gestational age (r = 0.832; P less than 0.001) and with body dimensions. Liver and heart carnitine concentrations did not correlate significantly with gestation or body dimensions. The mean (+/- SD) liver carnitine concentration for all the neonates as a group was 4.1 +/- 1.5 nmol/mg NCP. The mean (+/- SD) heart carnitine concentration was 4.7 +/- 1.3 nmol/mg NCP. In comparison to adult controls, tissue carnitine concentrations were markedly lower in neonates, particularly in immature newborns. These data suggest that newborn infants, especially premature babies, are born with limited tissue reserves of carnitine and are therefore at an increased risk for developing carnitine deficiency and its adverse effects in the postnatal period, particularly if maintained on carnitine-free intravenous nutrition for prolonged periods of time.

  8. Marine reserves as linked social-ecological systems.

    Science.gov (United States)

    Pollnac, Richard; Christie, Patrick; Cinner, Joshua E; Dalton, Tracey; Daw, Tim M; Forrester, Graham E; Graham, Nicholas A J; McClanahan, Timothy R

    2010-10-26

    Marine reserves are increasingly recognized as having linked social and ecological dynamics. This study investigates how the ecological performance of 56 marine reserves throughout the Philippines, Caribbean, and Western Indian Ocean (WIO) is related to both reserve design features and the socioeconomic characteristics in associated coastal communities. Ecological performance was measured as fish biomass in the reserve relative to nearby areas. Of the socioeconomic variables considered, human population density and compliance with reserve rules had the strongest effects on fish biomass, but the effects of these variables were region specific. Relationships between population density and the reserve effect on fish biomass were negative in the Caribbean, positive in the WIO, and not detectable in the Philippines. Differing associations between population density and reserve effectiveness defy simple explanation but may depend on human migration to effective reserves, depletion of fish stocks outside reserves, or other social factors that change with population density. Higher levels of compliance reported by resource users was related to higher fish biomass in reserves compared with outside, but this relationship was only statistically significant in the Caribbean. A heuristic model based on correlations between social, cultural, political, economic, and other contextual conditions in 127 marine reserves showed that high levels of compliance with reserve rules were related to complex social interactions rather than simply to enforcement of reserve rules. Comparative research of this type is important for uncovering the complexities surrounding human dimensions of marine reserves and improving reserve management.

  9. Estimation of in situ resources, recoverable reserves and marketable reserves from a coal quality perspective

    Energy Technology Data Exchange (ETDEWEB)

    Leach, B.; Whitby, K.; Meyers, A. [A & B Mylec Pty. Ltd., Rockhampton, Qld. (Australia)

    2000-10-01

    The competitive nature of the coal industry currently has meant that attention to detail in estimating coal resources, and recoverable and marketable reserves is of greater importance now than probably at any other time in the history of the Australian coal industry. This paper describes the mechanisms applied in deriving the best possible resource and reserve estimates in evaulating a coal lease, largely from the coal quality perspective. It attempts to show one way of uniting the geological model of a coal deposit to quality aspects such as in situ density and tonnage and ultimately to the anticipated product coal tonnes. 2 refs., 3 figs., 4 tabs.

  10. Establishment of nature reserves in administrative regions of mainland China.

    Directory of Open Access Journals (Sweden)

    Ziliang Guo

    Full Text Available Nature reserves are widely considered as one available strategy for protecting biodiversity, which is threatened by habitat fragmentation, and wildlife extinction. The Chinese government has established a goal of protecting 15% of its land area by 2015. We quantitated the characteristics and distribution of nature reserves in mainland China and evaluated the expansion process for national nature reserves. National nature reserves occupy 64.15% of the total area of nature reserves. Steppe and meadow ecosystem, ocean and seacoast ecosystem, and wild plant nature reserves represent lower percentages, particularly in national nature reserves, in which they comprised 0.76%, 0.54%, and 0.69%, respectively, of the area. Furthermore, medium and small nature reserves compose 92.32% of all nature reserves. The land area under any legal protection has reached 14.80%, although only 9.78% is strictly protected. However, if 9 super-large national nature reserves, located in Southwest and Northwest China were removed, the percentage of strictly protected area decreases to 2.66% of the land area of China. The areas contained in nature reserves in each province are not proportional to the areas of the provinces, particularly for national nature reserves, with higher protection rates in Southwest and Northwest China than in other regions. Of the 31 provinces, 22 provinces feature strict protection of less than 4% of their areas by national nature reserves; these provinces are mainly located in East, Central, South, and North China. Moreover, the unevenness indexes of the distribution of nature reserves and national nature reserves are 0.39 and 0.58, respectively. The construction of nature reserves has entered a steady development stage after a period of rapid expansion in mainland China. In recent years, the total area of national nature reserves has increased slowly, while the total area of nature reserves has not increased, although the number of nature

  11. Significance of microvascular remodelling for the vascular flow reserve in hypertension

    DEFF Research Database (Denmark)

    Jacobsen, Jens Christian Brings; Hornbech, Morten Sonne; von Holstein-Rathlou, Niels-Henrik

    2011-01-01

    responsible for the reduction in VFR is, however, not known. Here we present simulations performed on large microvascular networks to assess the VFR in various situations. Particular attention is paid to the VFR in networks in which the vessels have structurally adapted to a sustained increase in pressure...

  12. Standards for Teaching about the Federal Reserve System: An Initiative by Two Federal Reserve Banks

    Science.gov (United States)

    Bosshardt, William D.; Grimes, Paul W.; Suiter, Mary C.

    2011-01-01

    In the fall of 2008, the Federal Reserve Banks of Atlanta and St. Louis began a systematic evaluation of their economic and personal finance educational outreach programs. Both banks were interested in developing tools to assess the success of their existing economic and financial education programs. However, before any assessment could begin, a…

  13. Investigating Textbook Reserves: A Case Study of Two Models for Reserves Collections

    Science.gov (United States)

    Pitts-Noggle, Stephanie; Rafferty, Ryan

    2017-01-01

    This article examines the behaviors and preferences of medical and nursing students in relation to their required textbooks and library reserves. The findings are based on an April 2015 survey at the University of Illinois-Chicago satellite Library of the Health Sciences in Urbana, where the library provides access to textbooks through traditional…

  14. Estimation of the Functional Reserve of Human Liver

    Science.gov (United States)

    Moody, Frank G.; Rikkers, Layton F.; Aldrete, Joaquin S.

    1974-01-01

    Functional hepatic reserve was determined in 32 patients with known liver or biliary tract disease employing kinetic analysis of hepatic removal of indocyanine green (ICG). The initial removal rates of incremental doses of ICG (0.5, 1.0 and 5.0 mg/kg body weight) were plotted as a reciprocal against the inverse of dose (Lineweaver-Burk plot) to provide a means of determining maximal removal rate from submaximal doses (Rmax). This function equalled 3.40 mg/kg/min in ten patients with normal livers, but was only .24 mg/kg/min in eight patients with alcoholic cirrhosis. Portasystemic shunting did not further influence Rmax. Infiltrative liver disease had only a mild depressive effect on this function. The results show that hepatic function can be precisely quantitated by classical enzyme kinetics (Michaelis-Menten). If Rmax is an estimate of protein receptor mass for organic anions, then the technique may allow an indirect means for quantitating hepatocytes even in the presence of changes in blood flow or hepatic function. The profound depression in Rmax observed in patients with alcoholic cirrhosis is consistent with the progressive loss in hepatic mass associated with this disease. PMID:4413286

  15. The Global Societal Steel Scrap Reserves and Amounts of Losses

    Directory of Open Access Journals (Sweden)

    Alicia Gauffin

    2016-09-01

    Full Text Available In this study a newly developed method called the Progressing and Backcasting models were used to evaluate the annual resource utilizations of steel scrap in Sweden and globally. The model results show that it is possible to assess the amounts of steel scrap available for steelmaking at a given point in time, based on statistical dynamic material flow models. By a better mapping of the available amounts of steel scrap reserves on a country basis, it is possible to ease the trade of scrap across country boarders. This in turn can optimize the supply of recyclable metals as a raw material used in the industry. The results for Swedish steel consumption show that export bans used to secure the domestic market of steel scrap do damage the internal market due to increased amounts of losses. This suggests that export bans should be lifted to optimize recycling in countries. The model results also show that the global losses of steel are higher than for an industrialized country such as Sweden. Furthermore, the results show that the Backcasting and Progressing models can be used to calculate robust forecasts on the long term availability of steel scrap assets. This information could be used for future structural plans of scrap consuming steelmaking mills and waste management facilities. Hence, it is possible to contribute to a sustainable industrial development and a circular economy.

  16. Engineering geology studies in the National Petroleum Reserve in Alaska

    Energy Technology Data Exchange (ETDEWEB)

    Kachadoorian, R.; Crory, F.E.

    1989-01-01

    The U.S. Geological Survey (USGS) has been charged with the responsibility of evaluating the petroleum potential of the national Petroleum Reserve in Alaska (NPRA). To help fulfill its responsibility, the USGS in February 1977 started an engineering geology program to provide the geotechnical support necessary for the exploration program. The USGS requested the U.S. Army Waterways Experiment Station (WES) at Vicksburg, Mississippi, and the U.S. Army Cold Regions Research and Engineering Laboratory (CRREL) at Hanover, New Hampshire, to conduct studies to obtain the physical parameters required to evaluate and solve some of the geotechnical and engineering problems. All of the NPRA is underlain by permafrost, and thus virtually all of the engineering and geotechnical problems encountered during the construction of the well sites and subsequent drilling were associated with permafrost. The widespread occurrence of permafrost containing large amounts of near-surface ground ice in the form of wedges, masses, and intergranular ice required that construction activity not disturb the thermal regime of the ground surface, because such disturbance could lead to thawing of permafrost. Once the permafrost was thawed, ground subsidence, sediment flow, and impassable conditions would result. Construction problems were compounded by the necessity that all construction in the NPRA be done during the winter months to meet the environmental requirements. Therefore, the engineering geology program consistently addressed the impact of the environment on the facilities and the effect of the facilities on the environment.

  17. Disorders of lymph flow.

    Science.gov (United States)

    Witte, C L; Witte, M H

    1995-04-01

    Disturbances in blood capillary exchange of fluid, macromolecules, and cells across intact and abnormal microvessels and deranged lymphatic transport are integral, interacting components in disorders of tissue swelling. Lymphedema or low-output failure of the lymph circulation is often indolent for many years before lymphatic insufficiency (failure) and tissue swelling emerge and persist. Superimposed occult or overt infection (lymphangitis) are probably major contributors to progressive limb deformity (elephantiasis). Long-standing lymphedema is characterized by trapping in the skin and subcutaneous tissue of fluid, extravasated plasma proteins, and other macromolecules: impaired immune cell trafficking; abnormal processing of autologous and foreign antigens; heightened susceptibility to superimposed infection; local immunodysregulation; defective lymphatic (lymphangion) propulsion from an imbalance of mediators regulating vasomotion; soft-tissue overgrowth; scarring and hypertrophy; and exuberant angiogenesis occasionally culminating in vascular tumors (Fig. 8). In contrast to the blood circulation, where flow depends primarily on the propulsive force of the myocardium, lymph propulsion depends predominately on intrinsic truncal contraction, a phylogenetic vestige of amphibian lymph hearts. Whereas venous "plasma" flows rapidly (2-3 l/min) against low vascular resistance, lymph flows slowly (1-2 ml/min) against high vascular resistance. On occasion, impaired transport of intestinal lymph may be associated with reflux and accumulation and leakage of intestinal chyle in a swollen leg. Although the term "lymphedema" is usually reserved for extremity swelling, the pathogenesis of a wide variety of visceral disorders also may be traceable to defective tissue fluid and macromolecular circulation and impaired cell trafficking of lymphocytes and macrophages. Thus, lymph stasis, with impaired tissue fluid flow, underlies or complicates an indolent subclinical course with

  18. Marginal reserves of energy and environmental problems

    Energy Technology Data Exchange (ETDEWEB)

    Raveloson, E.A.; Rakotomaria, E. [Universite d`Antananarivo (Madagascar); Gazerian, J.P. [Universite d`Aix-Marseille (France)] [and others

    1995-12-31

    Madagascar is a country which has a variety of energy fields that present limited reserves in quantity and quality. Up till now, these fields were not economically viable. When and how to change this situation? In the classical project management approach, there will not be any chance to drive up the development of these energy fields. Nowadays, the economical crisis is general at a world-wide level, but for each developing country it appears that poverty is closely linked to environmental problems. Drought, starvation, deforestation, intensive migration of population without taking into account the standard constraints of under-development, non existence of roads or of modern agriculture and industry, limitation of financing availability, etc. The preliminary conditions to answer efficiently the common problems of development and of environment should be the reduction of the project size to a reasonable investment, the splitting of the field to a small zones of {open_quotes}development and environment,{close_quotes} identifying the economic potential (agriculture, industry, tourism, trade, and consumer centers), then determining the model of energy production adapted to the in situ available raw material. Project management methods and competitive intelligence methods should be combined to find the right solution in due time for the southern part of Madagascar. From the logical framework method, the Logiframe software has been designed to be an efficient tool for developing countries project managers and decision makers to solve the projects integratability problems on behalf of a regional development program.

  19. Measures of cognitive reserve in Alzheimer's disease

    Directory of Open Access Journals (Sweden)

    Margarida Sobral

    2014-09-01

    Full Text Available INTRODUCTION: Cognitive reserve (CR, a hypothetical construct used to obtain information about cognitive aging, describes the capacity of the adult brain to cope with the effects of neurodegenerative processes. This study evaluated CR using a CR questionnaire (CRQ and a set of variables (education, leisure activities, lifelong occupation that inform CR. It also developed a CR index, validated the CRQ, and examined the correlation between the different CR measures.METHODS: Functional and neuropsychological capacities of 75 outpatients (mean age: 80.2 years with a probable AD diagnosis were evaluated. Socio-demographic data and clinical variables were collected. Patients completed two questionnaires: the Participation in Leisure Activities throughout Life questionnaire, and the CRQ.RESULTS: Participants with a greater CR had higher scores in cognitive tests than the elderly with a lower CR. A CR index was developed. CRQ reliability was 0.795 (Cronbach's alpha. There was a close association between the CR Index and the CRQ.CONCLUSIONS: This study found an association between CR measures and education, occupation and participation in leisure activities. The CRQ seems to be a suitable instrument to measure CR in Portuguese populations.

  20. Oak Ridge Reservation environmental report for 1990

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, A.R. (ed.)

    1991-09-01

    The purpose of this report is to provide information to the public about the impact of the US Department of Energy's (DOE's) facilities located on the Oak Ridge Reservation (ORR) on the public and the environment. It describes the environmental surveillance and monitoring activities conducted at and around the DOE facilities operated by Martin Marietta Energy Systems, Inc. Preparation and publication of this report is in accordance with DOE Order 5400.1. The order specifies a publication deadline of June of the following year for each calendar year of data. The primary objective of this report is to summarize all information collected for the previous calendar year regarding effluent monitoring, environmental surveillance, and estimates of radiation and chemical dose to the surrounding population. When multiple years of information are available for a program, trends are also evaluated. The first seven sections of Volume 1 of this report address this objective. The last three sections of Volume 1 provide information on solid waste management, special environmental studies, and quality assurance programs.

  1. Amyloid positron emission tomography and cognitive reserve

    Institute of Scientific and Technical Information of China (English)

    Matteo Bauckneht; Agnese Picco; Flavio Nobili; Silvia Morbelli

    2015-01-01

    Alzheimer’s disease(AD) is characterized by a nonlinear progressive course and several aspects influence the relationship between cerebral amount of AD pathology and the clinical expression of the disease. Brain cognitive reserve(CR) refers to the hypothesized capacity of an adult brain to cope with brain damage in order to minimize symptomatology. CR phenomenon contributed to explain the disjunction between the degree of neurodegeneration and the clinical phenotype of AD. The possibility to track brain amyloidosis(Aβ) in vivo has huge relevance for AD diagnosis and new therapeutic approaches. The clinical repercussions of positron emission tomography(PET)-assessed Aβ load are certainly mediated by CR thus potentially hampering the prognostic meaning of amyloid PET in selected groups of patients. Similarly, amyloid PET and cerebrospinal fluid amyloidosis biomarkers have recently provided new evidence for CR. The present review discusses the concept of CR in the framework of available neuroimaging studies and specifically deals with the reciprocal influences between amyloid PET and CR in AD patients and with the potential consequent interventional strategies for AD.

  2. Drillers' logs of wells in the Hanford reservation. Volume I

    Energy Technology Data Exchange (ETDEWEB)

    Summers, W.K.; Schwab, G.

    1977-01-01

    More than 3000 wells and test holes have been drilled within the Hanford Reservation. Information on these wells range from complete sample suites complemented by bore hole geophysical studies to no record at all. Often the driller's log is the only record available for a well. This report is a product of the continuing project aimed at quantifying the hydraulic parameters of the synthetic flow system of the Hanford Reservation. The subsurface geology of the Hanford Reservation must be understood before the hydrologic parameters of the rocks can be estimated with any accuracy. To refine the state of our knowledge of the hydrologic regime all available data concerning the reservation geology must be considered and evaluated. Transcriptions are presented of 417 drillers' logs. This compilation includes every original driller's report we could obtain for the 600, 1100, and 3000 areas of the Hanford Reservation, but only a few logs from each of the 100, 200, and 300 areas where holes are very close together. The standard format consists of two parts: a heading that gives the general information for the well, and the description of the material penetrated.

  3. Marine ecological reserves research program: research results 1996-2001

    National Research Council Canada - National Science Library

    2002-01-01

    This is a collection of results of research done through the Marine Ecological Reserves Research Program, a competitive, peer-review research program focusing on the four new marine ecological reserves...

  4. 12 CFR 204.7 - Supplemental reserve requirement.

    Science.gov (United States)

    2010-01-01

    ... to increase the amount of reserves maintained to a level essential for the conduct of monetary policy... reserve ratios established by the Monetary Control Act of 1980 (Pub. L. 96-221) in effect on September 1...

  5. Relaxed resource advance reservation policy in grid computing

    Institute of Scientific and Technical Information of China (English)

    XIAO Peng; HU Zhi-gang

    2009-01-01

    The advance reservation technique has been widely applied in many grid systems to provide end-to-end quality of service (QoS). However, it will result in low resource utilization rate and high rejection rate when the reservation rate is high. To mitigate these negative effects brought about by advance reservation, a relaxed advance reservation policy is proposed, which allows accepting new reservation requests that overlap the existing reservations under certain conditions. Both the benefits and the risks of the proposed policy are presented theoretically. The experimental results show that the policy can achieve a higher resource utilization rate and lower rejection rate compared to the conventional reservation policy and backfilling technique. In addition, the policy shows better adaptation when the grid systems are in the presence of a high reservation rate.

  6. Marine ecology: reserves do have a key role in fisheries.

    Science.gov (United States)

    Roberts, Callum

    2012-06-05

    A new study of the Great Barrier Reef proves a 100-year old conjecture correct: marine reserves do replenish populations in surrounding fishing grounds, while modern reserve networking theory is validated by exchange of offspring of animals among protected areas.

  7. Marine Ecology: Reserve Networks Are Necessary, but Not Sufficient.

    Science.gov (United States)

    Almany, Glenn R

    2015-04-20

    New work reveals that the large network of no-take marine reserves on the Great Barrier Reef is working splendidly. However, bold, global action is needed to eliminate threats that reserves cannot guard against.

  8. 7 CFR 930.57 - Secondary inventory reserve.

    Science.gov (United States)

    2010-01-01

    ... Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Marketing... Handling Regulations § 930.57 Secondary inventory reserve. (a) In the event the inventory reserve... accordance with the annual marketing policy and with § 930.54....

  9. Water resources of the Menominee Indian Reservation of Wisconsin

    Science.gov (United States)

    Krohelski, J.T.; Kammerer, P.A.; Conlon, Terrence D.

    1994-01-01

    Water resources of the Menominee Indian Reservation, Wisconsin, were investigated during the period October 1981 through September 1987. The report presents baseline data and some interpretation of ground- and surface-water hydrology and quality of the Reservation.

  10. The petroleum reserves: a peak oil or a plate?; Les reserves de petrole: pic ou plateau?

    Energy Technology Data Exchange (ETDEWEB)

    Chevallier, B.

    2010-09-15

    With 1100 to 1200 Gbl of proved petroleum reserves, the world can still consume petroleum for 35 to 40 years; if we add 1000 to 1200 Gbl of reserves potentially recoverable and if the politico economical conditions allow it, it is 35 supplementary years that can be considered. In this context and while hydrocarbons will still represent 50% of the world 'energetic mixing' in 2030, the production capacity will reach its maximum at about 100 Mbl/day in 2020-2030 with a potential problem in 2015 due to the investment delays resulting of the crisis. Nevertheless, the detection, exploitation and disposal of these resources will imply non only gigantic investments (about 6000 milliards of dollars from now to 2030) but advanced experts and technologies too. (O.M.)

  11. Development and Status of Forestry Nature Reserves in China

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The primary conservation objective in China is to establish nature reserves to protect biological resources and natural heritage, protect ecosystems which are of global importance or have unique regional features, protect endangered and threatened species and their habitat, and safeguard the genetic resources. By 2000, the number of nature reserves increased to 1,276, while at the same time, the total area protected in nature reserves was up to 123 million ha. Of the total number of reserves, 908 sites ...

  12. Removing bank subsidies leads inexorably to full reserve banking

    OpenAIRE

    Musgrave, Ralph S.

    2013-01-01

    The recent banking crisis laid bare a long standing and inherent defect in fractional reserve banking: the fact that fractional reserve is unlikely to work for long without taxpayer backing. Changing bank regulations in such a way that banks are never a burden on taxpayers leads inexorably to full reserve banking. Full reserve involves splitting the banking industry into two halves. A safe half where depositors earn no interest, but they do have instant access to their money, and a second...

  13. Removing bank subsidies leads inexorably to full reserve banking

    OpenAIRE

    Musgrave, Ralph S.

    2013-01-01

    The recent banking crisis laid bare a long standing and inherent defect in fractional reserve banking: the fact that fractional reserve is unlikely to work for long without taxpayer backing. Changing bank regulations in such a way that banks are never a burden on taxpayers leads inexorably to full reserve banking. Full reserve involves splitting the banking industry into two halves. A safe half where depositors earn no interest, but they do have instant access to their money, and a second...

  14. International Reserve Holdings with Sovereign Risk and Costly Tax Collection

    OpenAIRE

    Aizenman, Joshua; Nancy P. Marion

    2003-01-01

    This paper analyzes the international reserve-holding behavior of developing countries. It shows that political-economy considerations modify the optimal reserve level determined by efficiency criteria. A country characterized by volatile output, inelastic demand for fiscal outlays, high tax collection costs and sovereign risk will want to accumulate international reserves as well as external debt. Efficiency considerations imply that reserves are optimal when the benefits they provide for in...

  15. The correlation between coronary flow reserve and clinical outcomes in patients with primary ;angioplasty for acute myocardial infarction with high baseline white blood cell count%基础白细胞计数增高的急性心肌梗死患者冠状动脉介入术后冠状动脉血流储备降低对远期预后的影响

    Institute of Scientific and Technical Information of China (English)

    郑振国; 周旭晨; 朱皓; 尹达; 张妍

    2014-01-01

    Objective Both abnormal coronary flow reserve (CFR) following percutaneous coronary intervention (PCI) and elevated white blood cell (WBC) count in acute myocardial infarction (AMI) are known as useful predictors for adverse outcomes. We evaluated the value of abnormal CFR for prediction of adverse outcomes in AMI patients with high baseline WBC count following primary PCI. Methods We studied 72 consecutive patients (mean age 56±12, male 55) presenting with AMI who were admitted to our institution. Analyze of CFR was performed following PCI by intra-coronary Doppler wire. All enroll patents’ baseline WBC count was obtained at admission and WBC count≥10.4×109/L. The occurrence of major adverse cardiac events (MACE) were analyzed during clinical follow up (12.7±7.1 months). According to the best cutoff value of CFR for predicting MACE, the patients were divided into 2 groups:group 1 with CFR<1.4, group 2 with CFR≥1.4. Results Baseline CK and CK-MB in group 1 were significantly higher than in group 2[(4 109±407)U/L vs. (2 685±562)U/L, P<0.05; (290.8± 26.6)ng/ml vs. (255.7±65.6)ng/ml, P<0.05 respectively]; Percent of post PCI MBG grade3 were more often in group 2 than in group 1(25.9%vs. 38.9%, P<0.05). MACE rate were significantly higher in group 1 than in group 2(40.7%vs. 27.8%, P<0.05), the mortality rate was significantly higher in group 1 than in group 2(13.0% vs. 0, P<0.05). Conclusions Abnormal CFR following PCI with high baseline WBC count in patients with AMI were associated with a higher incidence of adverse long-term clinical outcomes. This observation may provide a potential explanation that links of microvascular dysfunction and vascular inflammation in patients with AMI.%目的:急性心肌梗死(AMI)患者在接受了冠状动脉介入术(PCI)后,即刻冠状动脉血流储备(CFR)的降低,以及AMI急性期基础血液中白细胞计数的增加均被视为AMI患者远期预后不良的预测因子。我们现将这

  16. Naval Petroleum and Oil Shale Reserves. Annual report of operations, Fiscal year 1993

    Energy Technology Data Exchange (ETDEWEB)

    1993-12-31

    During fiscal year 1993, the reserves generated $440 million in revenues, a $33 million decrease from the fiscal year 1992 revenues, primarily due to significant decreases in oil and natural gas prices. Total costs were $207 million, resulting in net cash flow of $233 million, compared with $273 million in fiscal year 1992. From 1976 through fiscal year 1993, the Naval Petroleum and Oil Shale Reserves generated $15.7 billion in revenues for the US Treasury, with expenses of $2.9 billion. The net revenues of $12.8 billion represent a return on costs of 441 percent. See figures 2, 3, and 4. In fiscal year 1993, production at the Naval Petroleum and Oil Shale Reserves at maximum efficient rates yielded 25 million barrels of crude oil, 123 billion cubic feet of natural gas, and 158 million gallons of natural gas liquids. The Naval Petroleum and Oil Shale Reserves has embarked on an effort to identify additional hydrocarbon resources on the reserves for future production. In 1993, in cooperation with the US Geological Survey, the Department initiated a project to assess the oil and gas potential of the program`s oil shale reserves, which remain largely unexplored. These reserves, which total a land area of more than 145,000 acres and are located in Colorado and Utah, are favorably situated in oil and gas producing regions and are likely to contain significant hydrocarbon deposits. Alternatively the producing assets may be sold or leased if that will produce the most value. This task will continue through the first quarter of fiscal year 1994.

  17. Approaches to identifying reservoir heterogeneity and reserve growth opportunities from subsurface data: The Oficina Formation, Budare field, Venezuela

    Energy Technology Data Exchange (ETDEWEB)

    Hamilton, D.S.; Raeuchle, S.K.; Holtz, M.H. [Bureau of Economic Geology, Austin, TX (United States)] [and others

    1997-08-01

    We applied an integrated geologic, geophysical, and engineering approach devised to identify heterogeneities in the subsurface that might lead to reserve growth opportunities in our analysis of the Oficina Formation at Budare field, Venezuela. The approach involves 4 key steps: (1) Determine geologic reservoir architecture; (2) Investigate trends in reservoir fluid flow; (3) Integrate fluid flow trends with reservoir architecture; and (4) Estimate original oil-in-place, residual oil saturation, and remaining mobile oil, to identify opportunities for reserve growth. There are three main oil-producing reservoirs in the Oficina Formation that were deposited in a bed-load fluvial system, an incised valley-fill, and a barrier-strandplain system. Reservoir continuity is complex because, in addition to lateral facies variability, the major Oficina depositional systems were internally subdivided by high-frequency stratigraphic surfaces. These surfaces define times of intermittent lacustrine and marine flooding events that punctuated the fluvial and marginal marine sedimentation, respectively. Syn and post depositional faulting further disrupted reservoir continuity. Trends in fluid flow established from initial fluid levels, response to recompletion workovers, and pressure depletion data demonstrated barriers to lateral and vertical fluid flow caused by a combination of reservoir facies pinchout, flooding shale markers, and the faults. Considerable reserve growth potential exists at Budare field because the reservoir units are highly compartment by the depositional heterogeneity and structural complexity. Numerous reserve growth opportunities were identified in attics updip of existing production, in untapped or incompletely drained compartments, and in field extensions.

  18. VO2 Reserve vs. Heart Rate Reserve During Moderate Intensity Treadmill Exercise.

    Science.gov (United States)

    Solheim, Tanner J; Keller, Brad G; Fountaine, Charles J

    VO2 and heart rate (HR) are widely used when determining appropriate training intensities for clinical, healthy, and athletic populations. It has been shown that if the % reserve (%R) is used, rather than % of max, HR and VO2 can be used interchangeably to accurately prescribe exercise intensities. Thus, heart rate reserve (HRR) can be prescribed if VO2 reserve (VO2R) is known. Therefore, the purpose of this study was to compare VO2 R and HRR during moderate intensity exercise (50%R). Physically active college students performed a maximal treadmill test to exhaustion. During which VO2 and HR were monitored to determine max values. Upon completion of the maximal test, calculations were made to determine the % grade expected to yield approximately 50% of the subjects VO2R. Subjects then returned to complete the submaximal test (50%R) at least two days later. The %VO2R and %HRR were calculated and compared to the predicted value as well as to each other. Statistical analysis revealed that VO2 at 50%R was significantly greater than the actual VO2 achieved, p VO2 could be more accurately predicted than HR during moderate intensity exercise. The weak correlation between VO2R and HRR indicates that caution should be used when relying on a HR to determine VO2.

  19. Water Reserves Program. An adaptation strategy to balance water in nature

    Science.gov (United States)

    Lopez Perez, M.; Barrios, E.; Salinas-Rodriguez, S.; Wickel, B.; Villon, R. A.

    2013-05-01

    Freshwater ecosystems occupy approximately 1% of the earth's surface yet possess about 12% of all known animal species. By virtue of their position in the landscape they connect terrestrial and coastal marine biomes and provide and sustain ecosystem services vital to the health and persistence of human communities. These services include the supply of water for food production, urban and ind ustrial consumption, among others. Over the past century many freshwater ecosystems around the world have been heavily modified or lost due to the alteration of flow regimes (e.g. due to damming, canalization, diversion, over-abstraction). The synergistic impacts of land use change, changes in flows, chemical deterioration, and climate change have left many systems and their species very little room to adjust to change, while future projections indicate a steady increase in water demand for food and energy production and water supply to suit the needs of a growing world population. In Mexico, the focus has been to secure water for human development and maximize economic growth, which has resulted in allocation of water beyond available amounts. As a consequence episodic water scarcity severely constrains freshwater ecosystems and the services they provide. Climatic change and variability are presenting serious challenges to a country that already is experiencing serious strain on its water resources. However, freshwater ecosystems are recognized by law as legitimate user of water, and mandate a flow allocation for the environment ("water reserve" or "environmental flows"). Based on this legal provision the Mexican government through the National Water Commission (Conagua), with support of the Alliance WWF - Fundación Gonzalo Río Arronte, and the Interamerican Development Bank, has launched a national program to identify and implement "water reserves": basins where environmental flows will be secured and allocated and where the flow regime is then protected before over

  20. Water Reserves Program. An adaptation strategy to prevent imbalance of water in nature

    Science.gov (United States)

    Salinas-Rodriguez, S. A.; López Pérez, M.; Barrios Ordóñez, J.; Wickel, B.; Villón Bracamonte, R. A.

    2013-12-01

    Freshwater ecosystems occupy approximately 1% of the earth's surface yet possess about 12% of all known animal species. By virtue of their position in the landscape they connect terrestrial and coastal marine biomes and provide and sustain ecosystem services vital to the health and persistence of human communities. These services include the supply of water for food production, urban and industrial consumption, among others. Over the past century many freshwater ecosystems around the world have been heavily modified or lost due to the alteration of flow regimes (e.g. damming, canalization, diversion, over-abstraction). The synergistic impacts of land use change, changes in flows, chemical deterioration, and climate change have left many systems and their species very little room to adjust to change, while future projections indicate a steady increase imbalance in water demand for food and energy production and water supply to suit the needs of a growing world population. In Mexico, the focus has been to secure water for human development and maximize economic growth, which has resulted in allocation of water beyond available amounts, and that in many river basins has led imbalance of water in nature. As a consequence episodic water scarcity severely constrains freshwater ecosystems and the services they provide. Climatic change and variability are presenting serious challenges to a country that already is experiencing serious strain on its water resources. However, freshwater ecosystems are recognized by law as legitimate user of water, and mandate a flow allocation for the environment ('water reserve' or 'environmental flows'). Based on this legal provision the Mexican government through the National Water Commission (Conagua), with support of the Alliance WWF - Fundación Gonzalo Río Arronte, and the Interamerican Development Bank, has launched a national program to identify and implement 'water reserves': basins where environmental flows will be secured and