The Experts below are selected from a list of 240 Experts worldwide ranked by ideXlab platform
Olaf Reinhartz - One of the best experts on this subject based on the ideXlab platform.
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Imaging and surgical repair of a bifurcating aortico-Left Ventricle tunnel.
The Annals of thoracic surgery, 2011Co-Authors: Clayton A. Kaiser, Taylor Chung, Howard M. Rosenfeld, Olaf ReinhartzAbstract:Aortico-Left Ventricle tunnels are rare congenital anomalies with variable anatomy; however, by definition, they consist of an abnormal connection between the ascending aorta and the Left Ventricle. Diagnosis is usually by echocardiography, and treatment typically uses a two-patch surgical repair. Herein, we describe a case of an aortico-Left Ventricle tunnel, with the tunnel bifurcating before entering the Left Ventricle. Preoperative echocardiography and magnetic resonance imaging show the lesion in great detail. Two patches were required on the Left-ventricular side of the tunnel for closure. A bifurcating aortico-Left Ventricle tunnel has not yet been described in the literature. The preoperative imaging and surgical management are discussed.
Frederick Y. Chen - One of the best experts on this subject based on the ideXlab platform.
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Restraint to the Left Ventricle alone is superior to standard restraint.
The Journal of thoracic and cardiovascular surgery, 2012Co-Authors: Suyog A. Mokashi, Lawrence S. Lee, Jan D. Schmitto, Ravi K. Ghanta, Siobhan Mcgurk, Rita G. Laurence, R. Morton Bolman, Lawrence H. Cohn, Frederick Y. ChenAbstract:Objective In standard ventricular restraint therapy, a single level of restraint is applied to the entire ventricular surface. We showed previously that at high restraint levels, cardiac tamponade develops because of the thin-walled right Ventricle, even while the Left Ventricle remains unaffected. We now hypothesize that applying restraint exclusively to the Left Ventricle permits higher levels of restraint, resulting in increased benefit to the Left Ventricle. Methods The acute effect of restraint applied to the Left Ventricle alone was analyzed in healthy and cardiomyopathic sheep hearts. Restraint therapy was applied by fluid-filled epicardial balloons placed solely around the Left Ventricle. Restraint level was defined by the measured balloon luminal pressure at end diastole. At incrementally higher restraint levels (0, 3, 5, 8, 10, 12, and 14 mm Hg), transmural myocardial Left ventricular pressure (P tm = Left Ventricle pressure − Balloon pressure) and indices of myocardial oxygen consumption were measured in healthy sheep (n = 5) and in sheep with heart failure (n = 6). Results Increasing restraint from 0 to 14 mm Hg decreased transmural myocardial pressure by 48.8% ( P ≤ .02) and the Left Ventricle tension-time index by 39.1% ( P ≤ .01), and the pressure–volume area decreased by 58.4% ( P ≤ .01). Similarly, stroke work decreased by 57.9% ( P ≤ .03). Systemic hemodynamics were unchanged. There was no difference in the trend for all indices between animals that were healthy and those with heart failure. Conclusions We showed previously that, with standard restraint, right Ventricle tamponade develops at high restraint levels, limiting restraint therapy. We now show that restraint applied to the Left Ventricle alone permits increased restraint levels, without causing right Ventricle or Left Ventricle tamponade, for greater therapeutic benefit. We conclude that partial Left Ventricle restraint may be more effective than standard restraint.
Thomas S. Huang - One of the best experts on this subject based on the ideXlab platform.
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Modeling, analysis, and visualization of Left Ventricle shape and motion by hierarchical decomposition
IEEE Transactions on Pattern Analysis and Machine Intelligence, 1994Co-Authors: Chang Wen Chen, Thomas S. Huang, M. ArrottAbstract:This paper presents an approach to the modeling, analysis, and visualization of Left Ventricle motion and deformation. The authors' modeling of Left Ventricle shape and motion as a hierarchical representation enables them to develop a promising noninvasive technique for monitoring heart dynamics where both image analysis and image synthesis are involved. The proposed hierarchical motion model of Left Ventricle is constructed by combining several existing simple models and is able to capture major motion and deformation components of the Left Ventricle. The hierarchical decomposition characterizes the Left Ventricle motion and deformation in a coarse-to-fine fashion and leads to computationally efficient estimation algorithms. The authors estimate the global rigid motion of the Left Ventricle by establishing a time-varying object-centered coordinate system. The global deformations of the Left Ventricle are obtained by fitting the given data to superquadric modeling primitives. The local deformations are estimated by a tensor-description approach that is based on the locally deformable surface obtained by constructing spherical harmonic local surface from the residues of global shape estimation. The authors also describe in this paper methods of image synthesis and dynamic animation for visualizing the estimated results of the time-varying Left Ventricle shape, motion, and deformations. These animation results are consistent with the apparent motion pattern of the Left Ventricle and therefore show the success of the authors' hierarchical decomposition based approach. >
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ICASSP - Left Ventricle motion analysis by hierarchical decomposition
[Proceedings] ICASSP-92: 1992 IEEE International Conference on Acoustics Speech and Signal Processing, 1992Co-Authors: Chang Wen Chen, Thomas S. HuangAbstract:An approach to the modeling and analysis of Left Ventricle motion and deformation is presented. The hierarchical motion model of the Left Ventricle is constructed by combining several simple models and is able to capture major motion and deformation components that are already confirmed by medical observations. The hierarchical decomposition characterizes the Left Ventricle motion and deformation in a coarse-to-fine fashion and leads to computationally efficient estimation algorithms. The global rigid motion of the Left Ventricle is estimated by establishing a time-varying object-centered coordinate system. The global and local deformations of the Left Ventricle are obtained by fitting the given data to superquadric and spherical harmonic modeling primitives, respectively. The animation of estimation results is consistent with prior knowledge of the Left Ventricle and therefore shows the success of the hierarchical decomposition based approach. >
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ICASSP - Model based estimation of Left Ventricle motion
[Proceedings] ICASSP 91: 1991 International Conference on Acoustics Speech and Signal Processing, 1991Co-Authors: Chen Wen Chang, Thomas S. Huang, Yung-chang ChenAbstract:A model based estimation algorithm is presented for the analysis of Left Ventricle motion and deformation over a cardiac cycle. This model based approach allows the authors to decouple a nonlinear and complex estimation problem into simple and well structured sub-problems. They identify the global motion as the relative position and orientation change of the Left Ventricle as a whole and model its shape as a tapered ellipsoid. A recursive algorithm is developed by incorporating the modeling primitive into the estimation procedure. This recursive algorithm produces a good estimate of the global motion and Left Ventricle shape even when the given bifurcation points are unevenly distributed. Upon compensation for the global motion, a tensor analysis based approach is introduced to parameterize the localized deformation of Left Ventricle surface. >
Lauren Rispen - One of the best experts on this subject based on the ideXlab platform.
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DICTA - Left Ventricle Volume Measuring using Echocardiography Sequences
2018 Digital Image Computing: Techniques and Applications (DICTA), 2018Co-Authors: Yi Guo, Simon Green, Laurence A. F. Park, Lauren RispenAbstract:Measuring Left Ventricle (LV) volume is a challenging problem in physiological study. One of the non-intrusive methods that is possible for this task is echocardiography. By extracting Left Ventricle area from ultrasound images, the volume can be approximated by the size of the Left Ventricle area. The core of the problem becomes the identification of the Left Ventricle in noisy images considering spatial temporal information. We propose adaptive sparse smoothing for Left Ventricle segmentation for each frame in echocardiography video for the benefit of robustness against strong speckle noise in ultrasound imagery. Then we adjust the identified Left Ventricle areas (as curves in polar coordinate system) further by a fixed rank principal component analysis as post processing. This method is tested on two data sets with labelled Left Ventricle areas for some frames by expert physiologist and compared against active contour based method. The experimental results show clearly that the proposed method has better accuracy than that of the competitor.
William H. Spencer - One of the best experts on this subject based on the ideXlab platform.
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Malposition of transvenous pacing lead in the Left Ventricle.
Clinical cardiology, 1996Co-Authors: Chakravarthy Raghavan, W.richard Cashion, William H. SpencerAbstract:Transvenous pacemaker lead malposition in the Left Ventricle occurs rarely and requires a high index of suspicion for proper diagnosis. The case of a woman with unintentional lead placement in the Left Ventricle is presented. She had two episodes of transient neurologic deficits, possibly secondary to embolic events, and was started on oral anticoagulants. Chest x-ray and electrocardiogram (ECG) suggested pacemaker lead malposition and transesophageal echocardiography revealed sinus, venosus atrial septal defect. The lead was shown to cross the atrial septum and the mitral valve to the Left Ventricle. The malpositioned lead was successfully removed from the Left Ventricle at the time of surgical repair of the atrial septal defect. The potential value of 12-lead ECG, chest x-ray, posteroanterior and lateral views, and echocardiography in the diagnosis of pacemaker lead malposition are discussed and recommendations to avoid this complication at the time of pacemaker implant are outlined.
