The Experts below are selected from a list of 102096 Experts worldwide ranked by ideXlab platform
Eric Dumont - One of the best experts on this subject based on the ideXlab platform.
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transcatheter aortic valve implantation in patients with severe aortic stenosis and small aortic Annulus
Journal of the American College of Cardiology, 2011Co-Authors: Dimitri Kalavrouziotis, Josep Rodescabau, Rodrigo Bagur, Daniel Doyle, Robert De Larochelliere, Philippe Pibarot, Eric DumontAbstract:Objectives Valve hemodynamics and clinical outcomes among patients with a small aortic Annulus who underwent transcatheter aortic valve implantation (TAVI) were examined. Background The presence of a small aortic Annulus may complicate the surgical management of patients with severe aortic stenosis (AS). TAVI is an alternative to aortic valve replacement (AVR) in high-risk patients, but few data exist on the results of TAVI in patients with a small aortic Annulus. Methods Between 2007 and 2010, 35 patients (mean age 79.2 ± 9.4 years) with severe AS and an aortic Annulus diameter Results Procedural success was achieved in 34 patients (97.1%). There was 1 in-hospital death. Peak and mean transaortic gradients decreased from 76.3 ± 33.0 mm Hg and 45.2 ± 20.6 mm Hg at baseline to 21.8 ± 8.4 mm Hg and 11.7 ± 4.8 mm Hg post-procedure, respectively, both p Conclusions In high-risk patients with severe AS and a small aortic Annulus, TAVI is associated with good post-procedural valve hemodynamics and clinical outcomes. TAVI may provide a reasonable alternative to conventional AVR in elderly patients with a small aortic Annulus.
Yunshik Choi - One of the best experts on this subject based on the ideXlab platform.
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assessment of mitral Annulus velocity by doppler tissue imaging in the evaluation of left ventricular diastolic function
Journal of the American College of Cardiology, 1997Co-Authors: Daewon Sohn, Inho Chai, Byunghee Oh, Youngbae Park, Yunshik ChoiAbstract:Objectives. This study assessed the clinical utility of mitral Annulus velocity in the evaluation of left ventricular diastolic function. Background. Mitral inflow velocity recorded by Doppler echocardiography has been widely used to evaluate left ventricular diastolic function but is affected by other factors. The mitral Annulus velocity profile during diastole may provide additional information about left ventricular diastolic function. Methods. Mitral Annulus velocity during diastole was measured by Doppler tissue imaging (DTI) 1) in 59 normal volunteers (group 1); 2) in 20 patients with a relaxation abnormality as assessed by Doppler mitral inflow variables (group 2) at baseline and after saline loading; 3) in 11 patients (group 3) with normal diastolic function before and after intravenous nitroglycerin infusion; and 4) in 38 consecutive patients (group 4) undergoing cardiac catheterization in whom mitral inflow velocity and tau as well as mitral Annulus velocity were measured simultaneously. Results. In group 1, mean ± SD peak early and late diastolic mitral Annulus velocity was 10.0 ± 1.3 and 9.5 ± 1.5 cm/s, respectively. In group 2, mitral inflow velocity profile changed toward the pseudonormalization pattern with saline loading (deceleration time 311 ± 84 ms before to 216 ± 40 ms after intervention, p < 0.001), whereas peak early diastolic mitral Annulus velocity did not change significantly (5.3 ± 1.2 cm/s to 5.7 ± 1.4 cm/s, p = NS). In group 3, despite a significant change in mitral inflow velocity profile after nitroglycerin, peak early diastolic mitral Annulus velocity did not change significantly (9.5 ± 2.2 cm/s to 9.2 ± 1.7 cm/s, p = NS). In group 4, peak early diastolic mitral Annulus velocity (r = −0.56, p < 0.01) and the early/late ratio (r = −0.46, p < 0.01) correlated with tau. When the combination of normal mitral inflow variables with prolonged tau (≥50 ms) was classified as pseudonormalization, peak early diastolic mitral Annulus velocity <8.5 cm/s and the early/late ratio <1 could identify the pseudonormalization with a sensitivity of 88% and specificity of 67%. Conclusions. Mitral Annulus velocity determined by DTI is a relatively preload-independent variable in evaluating diastolic function.
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Assessment of Mitral Annulus Velocity by Doppler Tissue Imaging in the Evaluation of Left Ventricular Diastolic Function
Journal of the American College of Cardiology, 1997Co-Authors: Daewon Sohn, Inho Chai, Byunghee Oh, Youngbae Park, Yunshik ChoiAbstract:Objectives. This study assessed the clinical utility of mitral Annulus velocity in the evaluation of left ventricular diastolic function. Background. Mitral inflow velocity recorded by Doppler echocardiography has been widely used to evaluate left ventricular diastolic function but is affected by other factors. The mitral Annulus velocity profile during diastole may provide additional information about left ventricular diastolic function. Methods. Mitral Annulus velocity during diastole was measured by Doppler tissue imaging (DTI) 1) in 59 normal volunteers (group 1); 2) in 20 patients with a relaxation abnormality as assessed by Doppler mitral inflow variables (group 2) at baseline and after saline loading; 3) in 11 patients (group 3) with normal diastolic function before and after intravenous nitroglycerin infusion; and 4) in 38 consecutive patients (group 4) undergoing cardiac catheterization in whom mitral inflow velocity and tau as well as mitral Annulus velocity were measured simultaneously. Results. In group 1, mean ± SD peak early and late diastolic mitral Annulus velocity was 10.0 ± 1.3 and 9.5 ± 1.5 cm/s, respectively. In group 2, mitral inflow velocity profile changed toward the pseudonormalization pattern with saline loading (deceleration time 311 ± 84 ms before to 216 ± 40 ms after intervention, p < 0.001), whereas peak early diastolic mitral Annulus velocity did not change significantly (5.3 ± 1.2 cm/s to 5.7 ± 1.4 cm/s, p = NS). In group 3, despite a significant change in mitral inflow velocity profile after nitroglycerin, peak early diastolic mitral Annulus velocity did not change significantly (9.5 ± 2.2 cm/s to 9.2 ± 1.7 cm/s, p = NS). In group 4, peak early diastolic mitral Annulus velocity (r = −0.56, p < 0.01) and the early/late ratio (r = −0.46, p < 0.01) correlated with tau. When the combination of normal mitral inflow variables with prolonged tau (≥50 ms) was classified as pseudonormalization, peak early diastolic mitral Annulus velocity
Morteza Gharib - One of the best experts on this subject based on the ideXlab platform.
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influence of ventricular pressure drop on mitral Annulus dynamics through the process of vortex ring formation
Annals of Biomedical Engineering, 2007Co-Authors: Arash Kheradvar, Morteza GharibAbstract:Several studies have suggested that the mitral Annulus displacement and velocity in early diastole can be used as indicators of diastolic performance. The peak velocity of the mitral Annulus away from the LV apex during early diastole, which indicates the rate of longitudinal expansion of the LV, is reduced in patients with impaired diastolic relaxation. With the intention of relating the trans-mitral flow to mitral Annulus plane dynamics, we measured mitral Annulus recoil force for different valve sizes, while applying an exponential pressure drop in a simplified model of the ventricle. The temporal changes in diameter of the valve during rapid filling phase were also considered. The process of ventricular vortex formation was studied together with the measurement of mitral Annulus recoil force within different pressure drop conditions. Matching the vorticity contour plots with the recoil force measurements resulted in the fact that the magnitude of recoil is maximal once the vortex ring is about to pinch off, regardless of the valve size or the characteristics of ventricular pressure drop. This study showed that the mitral Annulus recoil is maximal once occurs at the vortex formation time ranging from 3.5 to 4.5. It was also shown that the presence of leaflets would dissipate the Annulus recoil force.
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correlation between vortex ring formation and mitral Annulus dynamics during ventricular rapid filling
Asaio Journal, 2007Co-Authors: Arash Kheradvar, Michele Milano, Morteza GharibAbstract:One of the most important fluid phenomena observed in the left ventricle during diastole is the presence of vortex rings that develop with a strong jet entering through the mitral valve. The present study is focused on the rapid filling phase of diastole, during which the left ventricle expands and receives blood through the fully open mitral valve. The atrio-ventricular system during the rapid filling phase was emulated experimentally with a simplified mechanical model in which the relevant pressure decay and the dimension of mitral Annulus approximate the physiologic and pathologic values. Digital particle image velocimetry measurements were correlated with the force measurements on the mitral Annulus plane to analyze the relation between flow and the mitral Annulus motion. The recoil force on the displaced Annulus plane was computed on the basis of plane acceleration and plane velocity and correlated with the inflow jet. Measurements of the recoil force for different values of the mitral Annulus diameter showed that the recoil force was generated during fluid propulsion and that it is maximal for an Annulus diameter close to the normal adult value in a healthy left ventricle. We also tested Annulus diameters smaller and larger than the normal one. The smaller Annulus corresponds to the stenotic valves and the larger Annulus exists in dilated cardiomyopathy cases. In both conditions, the recoil force was found to be smaller than in the normal case. These observations are consistent with the previously reported results for dilated cardiomyopathy and mitral stenosis clinical conditions.
Robert D Howe - One of the best experts on this subject based on the ideXlab platform.
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mitral Annulus segmentation from four dimensional ultrasound using a valve state predictor and constrained optical flow
Medical Image Analysis, 2012Co-Authors: Robert J Schneider, Douglas P Perrin, Gerald R. Marx, Nikolay V. Vasilyev, Pedro J. Del Nido, Robert D HoweAbstract:Measurement of the shape and motion of the mitral valve Annulus has proven useful in a number of applications, including pathology diagnosis and mitral valve modeling. Current methods to delineate the Annulus from four-dimensional (4D) ultrasound, however, either require extensive overhead or user-interaction, become inaccurate as they accumulate tracking error, or they do not account for annular shape or motion. This paper presents a new 4D Annulus segmentation method to account for these deficiencies. The method builds on a previously published three-dimensional (3D) Annulus segmentation algorithm that accurately and robustly segments the mitral Annulus in a frame with a closed valve. In the 4D method, a valve state predictor determines when the valve is closed. Subsequently, the 3D Annulus segmentation algorithm finds the Annulus in those frames. For frames with an open valve, a constrained optical flow algorithm is used to the track the Annulus. The only inputs to the algorithm are the selection of one frame with a closed valve and one user-specified point near the valve, neither of which needs to be precise. The accuracy of the tracking method is shown by comparing the tracking results to manual segmentations made by a group of experts, where an average RMS difference of 1.67 ± 0.63 mm was found across 30 tracked frames.
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Mitral Annulus Segmentation From 3D Ultrasound Using Graph Cuts
IEEE Transactions on Medical Imaging, 2010Co-Authors: Robert J Schneider, Douglas P Perrin, Gerald R. Marx, Nikolay V. Vasilyev, Pedro J. Del Nido, Robert D HoweAbstract:The shape of the mitral valve Annulus is used in diagnostic and modeling applications, yet methods to accurately and reproducibly delineate the Annulus are limited. This paper presents a mitral Annulus segmentation algorithm designed for closed mitral valves which locates the Annulus in three-dimensional ultrasound using only a single user-specified point near the center of the valve. The algorithm first constructs a surface at the location of the thin leaflets, and then locates the Annulus by finding where the thin leaflet tissue meets the thicker heart wall. The algorithm iterates until convergence metrics are satisfied, resulting in an operator-independent mitral Annulus segmentation. The accuracy of the algorithm was assessed from both a diagnostic and surgical standpoint by comparing the algorithm's results to delineations made by a group of experts on clinical ultrasound images of the mitral valve, and to delineations made by an expert with a surgical view of the mitral Annulus on excised porcine hearts using an electromagnetically tracked pointer. In the former study, the algorithm was statistically indistinguishable from the best performing expert (p = 0.85 ) and had an average RMS difference of 1.81±0.78 mm to the expert average. In the latter, the average RMS difference between the algorithm's Annulus and the electromagnetically tracked points across six hearts was 1.19±0.17 mm .
Dimitri Kalavrouziotis - One of the best experts on this subject based on the ideXlab platform.
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transcatheter aortic valve implantation in patients with severe aortic stenosis and small aortic Annulus
Journal of the American College of Cardiology, 2011Co-Authors: Dimitri Kalavrouziotis, Josep Rodescabau, Rodrigo Bagur, Daniel Doyle, Robert De Larochelliere, Philippe Pibarot, Eric DumontAbstract:Objectives Valve hemodynamics and clinical outcomes among patients with a small aortic Annulus who underwent transcatheter aortic valve implantation (TAVI) were examined. Background The presence of a small aortic Annulus may complicate the surgical management of patients with severe aortic stenosis (AS). TAVI is an alternative to aortic valve replacement (AVR) in high-risk patients, but few data exist on the results of TAVI in patients with a small aortic Annulus. Methods Between 2007 and 2010, 35 patients (mean age 79.2 ± 9.4 years) with severe AS and an aortic Annulus diameter Results Procedural success was achieved in 34 patients (97.1%). There was 1 in-hospital death. Peak and mean transaortic gradients decreased from 76.3 ± 33.0 mm Hg and 45.2 ± 20.6 mm Hg at baseline to 21.8 ± 8.4 mm Hg and 11.7 ± 4.8 mm Hg post-procedure, respectively, both p Conclusions In high-risk patients with severe AS and a small aortic Annulus, TAVI is associated with good post-procedural valve hemodynamics and clinical outcomes. TAVI may provide a reasonable alternative to conventional AVR in elderly patients with a small aortic Annulus.
