Dynamic simulation of bioprosthetic heart valves using a stress resultant shell model

It is a widely accepted axiom that localized concentration of mechanical stress and large flexural deformation is closely related to the calcification and tissue degeneration in bioprosthetic heart valves (BHV). In order to investigate the complex BHV deformations and stress distributions throughout the cardiac cycle, it is necessary to perform an accurate dynamic analysis with a morphologically and physiologically realistic material specification for the leaflets. We have developed a stress resultant shell model for BHV leaflets incorporating a Fung-elastic constitutive model for in-plane and bending responses separately. Validation studies were performed by comparing the finite element predicted displacement and strain measures with the experimentally measured data under physiological pressure loads. Computed regions of stress concentration and large flexural deformation during the opening and closing phases of the cardiac cycle correlated with previously reported regions of calcification and/or mechanical damage on BHV leaflets. It is expected that the developed experimental and computational methodology will aid in the understanding of the complex dynamic behavior of native and bioprosthetic valves and in the development of tissue engineered valve substitutes.