Structural study of a polymeric aortic valve prosthesis. Analysis for a hyperelastic material

Abstract

This work presents a structural computational simulation of a polymeric aortic valve prosthesis, made with a hyperelastic material (Styrene-Ethylene/Propylene-Styrene). The valve has a suture ring, three pillars placed at 120° and three leaflets. The analysis is based on a modification over previous designs consisting in a fillet concave surface to avoid stress concentration at the junctions between leaflets and pillars. Three shapes were simulated. The first one was used to validate the computational method by comparison of the results with a recent paper. The second shape was designed to show that a fillet or "rounding" can be beneficial to the stress leaflet reduction. The third shape was also designed to show that the reduction of leaflet thickness and intercommissural distance between leaflets at the pillar junctions improves the valve opening and closure. The use of fillet with a 0.5 mm radius, reduced 26.5% the maximum Von Mises stresses for the second shape and 33.9% for the third shape. Additionally, for the latter, the opening area was not affected for the high stiffness due to fillet. The results -mainly for the third shape-are promising and give rise to future studies: further shape optimization, analysis for other materials and valve simulation under pathological loads.

Keywords: Aortic valve; Finite element method; Stress concentration; Styrene-Ethylene/Propylene-Styrene; Valve prosthesis.