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Hartford, CT, United States

Wang Q.,Georgia Institute of Technology | Primiano C.,The Hartford Hospital | Sun W.,Georgia Institute of Technology
Journal of Biomechanics | Year: 2014

This study was to investigate the mechanisms of ischemic mitral regurgitation (IMR) by using a finite element (FE) approach. IMR is a common complication of coronary artery disease; and it usually occurs due to myocardial infarction. The pathophysiological mechanisms of IMR have not been fully understood, much debate remains about the exact contribution of each mechanism to IMR. Two patient-specific FE models of normal mitral valves (MV) were reconstructed from multi-slice computed tomography scans. Different grades of IMR during its pathogenesis were created by perturbation of the normal MV geometry. Effects of annular dilatation and papillary muscle (PM) displacement (both isolated and combined) on the severity of IMR were examined. We observed greater increase in IMR (in terms of regurgitant area and coaptation length) in response to isolated annular dilatation than that caused by isolated PM displacement, while a larger PM displacement resulted in higher PM forces. Annular dilation, combined with PM displacement, was able to significantly increase the severity of IMR and PM forces. Our simulations demonstrated that isolated annular dilatation might be a more important determinant of IMR than isolated PM displacement, which could help explain the clinical observation that annular size reduction by restrictive annuloplasty is generally effective in treating IMR. © 2014 Elsevier Ltd. Source

Wang Q.,Georgia Institute of Technology | Kodali S.,Columbia University | Primiano C.,The Hartford Hospital | Sun W.,Georgia Institute of Technology
Biomechanics and Modeling in Mechanobiology | Year: 2015

Aortic root rupture is one of the most severe complications of transcatheter aortic valve implantation (TAVI). The mechanism of this adverse event remains mostly unknown. The purpose of this study was to obtain a better understanding of the biomechanical interaction between the tissue and stent for patients with a high risk of aortic rupture. We simulated the stent deployment process of three TAVI patients with high aortic rupture risk using finite element method. The first case was a retrospective analysis of an aortic rupture case, while the other two cases were prospective studies, which ended with one canceled procedure and one successful TAVI. Simulation results were evaluated for the risk of aortic root rupture, as well as coronary artery occlusion, and paravalvular leak. For Case 1, the simulated aortic rupture location was the same as clinical observations. From the simulation results, it can be seen that the large calcified spot on the interior of the left coronary sinus between coronary ostium and the aortic annulus was pushed by the stent, causing the aortic rupture. For Case 2 and Case 3, predicated results from the simulations were presented to the clinicians at multidisciplinary pre-procedure meetings; and they were in agreement with clinician’s observations and decisions. Our results indicated that the engineering analysis could provide additional information to help clinicians evaluate complicated, high-risk aortic rupture cases. Since a systematic study of a large patient cohort of aortic rupture is currently not available (due to the low occurrence rate) to clearly understand underlying rupture mechanisms, case-by-case engineering analysis is recommended for evaluating patient-specific aortic rupture risk. © 2014, Springer-Verlag Berlin Heidelberg. Source

Wang Q.,University of Connecticut | Book G.,University of Connecticut | Book G.,Institute of Living | Ortiz S.H.C.,University of Connecticut | And 4 more authors.
Cardiovascular Engineering and Technology | Year: 2011

Accurate measurement of anatomical characteristics of the aortic root is needed for pre-procedural planning of many valve procedures and development of novel valve intervention devices. Dimensional measurement of the aortic root is currently performed on 2-dimensional (2D) images, rather than on a full 3-dimensional (3D) geometric model. In this study, full 3D aortic root geometric models, reconstructed from clinical multi-slice computed tomography (MSCT) scans during diastole, were used to perform dimensional analysis of the aortic root geometry of 94 patients. Thirty-two landmark points were placed on anatomic feature locations of each aortic root model for the measurement of aortic root dimensions. Diameters of the annulus, sinus of Valsalva (SOV), sino-tubular junction, and ascending aorta were compared with measurements obtained from 2D MSCT images in short axes. Additionally, the spatial distribution of the left coronary ostium (CO) within the left coronary sinus (LCS) was determined due to its significance in transcatheter aortic valve implantation. Aortic root dimensions measured by 3D models had good correlations with those measured by 2D MSCT images. The 3D perimeter-derived annulus and SOV diameters were larger than the direct measured diameters on short axis views. Additionally, this study indicated that the left CO is predominantly located in the upper right region of the LCS. Similar results could be obtained using the 3D models compared to 2D MSCT images. Since anatomical features of the aortic root can be easily identified on a full 3D geometric model, more complete information could be obtained. © 2011 Biomedical Engineering Society. Source

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