The Roles of Leaflet Geometry in the Structural Deterioration of Bioprosthetic Aortic Valves

Objectives: Our goal was to assess the role of leaflet geometry on the structural deterioration of bioprosthetic aortic valves (BAVs) in a closed configuration. Methods: With a Fung-type orthotropic model, finite element modeling was used to create ten cases with parabolic, circular and spline leaflet curvatures and six leaflet angles. Results: A circular circumferential curvature led to lower von Mises and compressive stresses in both the coaptation and load-bearing areas, reduced tensile stresses in the coaptation regions, and increased tensile stresses in the load-bearing areas. A parabolic radial curvature reduced von Mises stresses in the coaptation, as well as the load-bearing regions, reduced compressive stresses in the coaptation, and reduced tensile stresses in the load-bearing regions, leading to a slight increase in the minimized tensile stress in the coaptation regions (1.794 vs. 1.765 MPa) and the minimized compressive stress in the load-bearing regions (0.772 vs. 0.768 MPa). Within a range of downward inclination of the leaflets, all stresses in the coaptation regions decreased. A parabolic circumferential curvature, a linear radial curvature, and, for most cases, upward leaflet inclinations were associated with larger contact pressures between the leaflets. Conclusions: A parabolic radial curvature and downward leaflet inclination likely lead to the longer durability of BAVs.