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

The goal was to asses roles of leaflets geometry on the structural deterioration of bioprosthetic aortic valves (BAVs) in closed configuration. 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. 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 load bearing regions, reduced compressive stresses in the coaptation and tensile stresses in the load bearing regions, led 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. A parabolic radial curvature and downward leaflet inclination likely lead to longer durability of BAVs.