A Computational Study on Deformed Bioprosthetic Valve Geometries: Clinically Relevant Valve Performance Metrics

Reza Jafar; Michel R Labrosse; Jason D Weaver; Stephen M Retta; Changfu Wu; Nandini Duraiswamy

doi:10.1115/1.4044235

A Computational Study on Deformed Bioprosthetic Valve Geometries: Clinically Relevant Valve Performance Metrics

J Biomech Eng. 2020 Jan 1;142(1):011003. doi: 10.1115/1.4044235.

Authors

Reza Jafar¹, Michel R Labrosse¹, Jason D Weaver², Stephen M Retta³, Changfu Wu³, Nandini Duraiswamy⁴

Affiliations

¹ Cardiovascular Mechanics Laboratory, Department of Mechanical Engineering, University of Ottawa, Ottawa, ON K1N 6N5, Canada.
² Division of Applied Mechanics (DAM), Office of Science and Engineering Laboratories (OSEL), Center for Devices and Radiological Health (CDRH), Food and Drug Administration (FDA), Silver Spring, MD 20993.
³ Office of Product Evaluation and Quality (OPEQ), Center for Devices and Radiological Health (CDRH), Food and Drug Administration (FDA), Silver Spring, MD 20993.
⁴ Division of Applied Mechanics (DAM), Office of Science and Engineering Laboratories (OSEL), Center for Devices and Radiological Health (CDRH), Food and Drug Administration (FDA), 10903 New Hampshire Avenue, WO62, #2206, Silver Spring, MD 20993.

Abstract

Transcatheter aortic valves (TAV) are symmetrically designed, but they are often not deployed inside cylindrical conduits with circular cross-sectional areas. Many TAV patients have heavily calcified aortic valves, which often result in deformed prosthesis geometries after deployment. We investigated the effects of deformed valve annulus configurations on a surgical bioprosthetic valve as a model for TAV. We studied valve leaflet motions, stresses and strains, and analog hydrodynamic measures (using geometric methods), via finite element (FE) modeling. Two categories of annular deformations were created to approximate clinical observations: (1) noncircular annulus with valve area conserved, and (2) under-expansion (reduced area) compared to circular annulus. We found that under-expansion had more impact on increasing stenosis (with geometric orifice area metrics) than noncircularity, and that noncircularity had more impact on increasing regurgitation (with regurgitation orifice area metrics) than under-expansion. We found durability predictors (stress/strain) to be the highest in the commissure regions of noncircular configurations such as EllipMajor (noncircular and under-expansion areas). Other clinically relevant performance aspects such as leaflet kinematics and coaptation were also investigated with the noncircular configurations. This study provides a framework for choosing the most challenging TAV deformations for acute and long-term valve performance in the design and testing phase of device development.

Keywords: finite element modeling; coaptation surface area; durability; geometric orifice area; hydrodynamics; noncircular; regurgitant orifice area; transcatheter aortic valve.

Publication types

Research Support, U.S. Gov't, P.H.S.

MeSH terms

Aortic Valve
Benchmarking
Heart Valve Prosthesis*
Humans

Grants and funding

FD999999/ImFDA/Intramural FDA HHS/United States