CONSTITUTIVE MODELING AND FINITE ELEMENT ANALYSIS OF MYXOMATOUS MITRAL LEAFLET TISSUE

Abstract

Although rarely discussed, material modeling of the myxomatous leaflet is considered as the cornerstone of mitral valve finite element analysis. The present study presents an incompressible, hyperelastic constitutive model to characterize myxoid mitral leaflet tissue mechanics. The model incorporates the transversely isotropic response and the layered structure of the tissue. First, an analytical constitutive model for the tissue is developed based on continuum mechanics and layered composites theory. Second, the material constants of the constitutive equation are determined by fitting the model to the experimental data. The analytical material model is then implemented using solid finite element methods by simulating a biaxial tensile test. A numerical simulation of the out-of-plane pressure loading is also conducted. Both the analytical outcomes and the simulated results agree well with experimental data and show good mutual agreement. The calculated strain distribution of the out-of-plane pressure loading simulation indicates myxoid leaflets exhibit enhanced extensibility and decreased stiffness compared to normal valves; the radial direction is more extensible than the circumferential direction. The presented material approximation is able to capture the myxomatous mitral leaflet mechanics. The results of the numerical simulation conform to those of the experimental tests.