A CONSTITUTIVE LAW FOR MITRAL-VALVE TISSUE

Biaxial mechanical testing and theoretical continuum mechanics analysi s are employed to formulate a constitutive law for cardiac mitral valv e anterior and posterior leaflets. A strain energy description is form ulated based on the fibrous architecture of the tissue, accurately des cribing the large deformation, highly nonlinear transversely isotropic material behavior. The results show that a simple three-coefficient e xponential constitutive law provides an accurate prediction of stress- stretch behavior over a wide range of deformations. Regional heterogen eity may, be accommodated by spatially varying a single coefficient an d incorporating collagen fiber angle. The application of this quantita tive information to mechanical models and bioprosthetic development co uld provide substantial improvement in the evaluation and treatment of valvular disease, surgery, and replacement.