title: A Parametric Computational Study of the Impact of Non-circular Configurations on Bioprosthetic Heart Valve Leaflet Deformations and Stresses: Possible Implications for Transcatheter Heart Valves.
abstract: Although generally manufactured as circular devices with symmetric leaflets, transcatheter heart valves can become non-circular post-implantation, the impact of which on the long-term durability of the device is unclear. We investigated the effects of five non-circular (EllipMajor, EllipMinor, D-Shape, TriVertex, TriSides) annular configurations on valve leaflet stresses and valve leaflet deformations through finite element analysis. The highest in-plane principal stresses and strains were observed under an elliptical configuration with an aspect ratio of 1.25 where one of the commissures was on the minor axis of the ellipse. In this elliptical configuration (EllipMinor), the maximum principal stress increased 218% and the maximum principal strain increased 80% as compared with those in the circular configuration, and occurred along the free edge of the leaflet whose commissures were not on the minor axis (i.e., the "stretched" leaflet). The D-Shape configuration was similar to this elliptical configuration, with the degree to which the leaflets were stretched or sagging being less than the EllipMinor configuration. The TriVertex and TriSides configurations had similar leaflet deformation patterns in all three leaflets and similar to the Circular configuration. In the D-Shape, TriVertex, and TriSides configurations, the maximum principal stress was located near the commissures similar to the Circular configuration. In the EllipMinor and EllipMajor configurations, the maximum principal stress occurred near the center of the free edge of the "stretched" leaflets. These results further affirm recommendations by the International Standards Organization (ISO) that pre-clinical testing should consider non-circular configurations for transcatheter valve durability testing.
authors: Office of Science and Engineering Laboratories (OSEL)/Division of Applied Mechanics (DAM), Center for Devices and Radiological Health (CDRH), U.S. Food and Drug Administration (FDA), Silver Spring, MD, 20993, USA. nandini.duraiswamy@fda.hhs.gov.
authors: Nandini
authors: N
authors: Duraiswamy
authors: Office of Science and Engineering Laboratories (OSEL)/Division of Applied Mechanics (DAM), Center for Devices and Radiological Health (CDRH), U.S. Food and Drug Administration (FDA), Silver Spring, MD, 20993, USA.
authors: Jason D
authors: JD
authors: Weaver
authors: Office of Science and Engineering Laboratories (OSEL)/Division of Applied Mechanics (DAM), Center for Devices and Radiological Health (CDRH), U.S. Food and Drug Administration (FDA), Silver Spring, MD, 20993, USA.
authors: Yasamin
authors: Y
authors: Ekrami
authors: Office of Science and Engineering Laboratories (OSEL)/Division of Applied Mechanics (DAM), Center for Devices and Radiological Health (CDRH), U.S. Food and Drug Administration (FDA), Silver Spring, MD, 20993, USA.
authors: Stephen M
authors: SM
authors: Retta
authors: Office of Device Evaluation (ODE)/Division of Cardiovascular Devices (DCD), Center for Devices and Radiological Health (CDRH), U.S. Food and Drug Administration (FDA), Silver Spring, MD, 20993, USA.
authors: Changfu
authors: C
authors: Wu
mesh_terms: D003198:Computer Simulation; D006350:Heart Valve Prosthesis; D006351:Heart Valves / Q000502:physiology*; D006801:Humans; D008955:Models, Cardiovascular; D013314:Stress, Mechanical; D065467:Transcatheter Aortic Valve Replacement / Q000295:instrumentation*
keywords: FEA; Leaflet durability; Non-circular deformation; TAVR; THV; Transcatheter heart valve