9407256 Kunzelman The objective of this Planning Grant is to allow for further study to characterize the biomechanical behavior of the mitral valve in health, disease, and after surgical repair. To meet this objective, the mechanical behavior of the tissue must be first determined based on its microstructure, and then integrated into a finite element model of the valve. The specific aims are to: (1) determine whether there is a difference between the biaxial mechanical properties of normal and diseased mitral valve tissue, (2) determine whether there is a difference in microstructurreal makeup between normal and diseased mitral valve tissue, (3) determine whether there is a relationship between biaxial mechanical properties and microstructural makeup, and (4) analyze the effect of diseased tissue properties on overall mitral valve function. ***