Simulated Transcatheter Aortic Valve Deformation: A Parametric Study on the Impact of Leaflet Geometry on Valve Peak Stress

• Type of Material: Article
• Authors: Kewei Li, University of Connecticut; Wei Sun, Emory University
• Language: English
• Date: 2017-03
• Publisher: Wiley: 12 months
• Publication Version: Author Accepted Manuscript (After Peer Review)
• Copyright Statement: © John Wiley & Sons Ltd
• Final Published Version (URL): http://dx.doi.org/10.1002/cnm.2814
• Title of Journal or Parent Work: International Journal for Numerical Methods in Biomedical Engineering
• ISSN: 2040-7939
• Volume: 33
• Issue: 3
• Start Page: e02814
• End Page: e02814
• Grant/Funding Information: This research was supported in part by the NIH grants HL104080 and HL108240.
• Keywords: Heart valve biomechanics; Optimization analysis; Finite element analysis; Aortic stenosis; Transcatheter aortic valve implantation
• Research Categories: Engineering, Biomedical

Abstract

In this study, we developed a computational framework to investigate the impact of leaflet geometry of a transcatheter aortic valve (TAV) on the leaflet stress distribution, aiming at optimizing TAV leaflet design to reduce its peak stress. Utilizing a generic TAV model developed previously [Li and Sun, Annals of Biomedical Engineering, 2010. 38(8): 2690-2701], we first parametrized the 2D leaflet geometry by mathematical equations, then by perturbing the parameters of the equations, we could automatically generate a new leaflet design, remesh the 2D leaflet model and generate a 3D leaflet model from the 2D design via a Python script. Approximately 500 different leaflet designs were investigated by simulating TAV closure under the nominal circular deployment and physiological loading conditions. From the simulation results, we identified a new leaflet design that could reduce the previously reported valve peak stress by about 5%. The parametric analysis also revealed that increasing the free edge width had the highest overall impact on decreasing the peak stress. A similar computational analysis was further performed for a TAV deployed in an abnormal, asymmetric elliptical configuration. We found that a minimal free edge height of 0.46 mm should be adopted to prevent central backflow leakage. This increase of the free edge height resulted in an increase of the leaflet peak stress. Furthermore, the parametric study revealed a complex response surface for the impact of the leaflet geometric parameters on the peak stress, underscoring the importance of performing a numerical optimization to obtain the optimal TAV leaflet design.