Novel heart valve leaflet designs with stiff polymeric materials and biomimetic kinematics

Abstract

Despite continuous efforts to improve the robustness of cardiac valve implants, neither bioprosthetic nor mechanical valves fulfill both hemodynamic and durability requirements. This study discussed novel flexible leaflet designs, focusing on polymeric materials with proven hemocompatibility, such as polyether ether ketone, of much higher stiffness than native tissue, aiming at optimal valve implants. A biomimetic valve with a single-curvature belly-curve (B-C) was used as a reference for new design variants with a double-curvature B-C with varying radii. Soft (13.2 MPa) and stiff (2.4 GPa) leaflet materials and different thicknesses were studied using lean simulations and in vitro experiments under physiologic hemodynamic conditions. The performance was assessed using opening pressure (OP) and orifice area (OA). The latter was determined by a newly developed automatized image processing tool. Experimental trends are in agreement with simulations and demonstrated that a buckling-inspired double-curvature leaflet design significantly enhances the trileaflet valve opening behavior, which is particularly advantageous for stiffer leaflet materials. Compared to the reference, the best-performing variant showed an OP improvement of 47% and 44% based on simulations and experiments, respectively. In contrast, the achieved mean pressure differential was directly comparable to state-of-the-art bioprosthetic valves. The OA was slightly reduced for new variants but still in the satisfying range. Graphic abstract