The effect of contact geometry and component compliance on the magnitude, distribution, and state of various types of stresses on a bileaflet mechanical heart valve prosthesis during valve closure was analyzed using an Edwards-Duromedics™ mitral valve as example. Static and dynamic stresses developing on both the leaflet and pivot ball during valve closure were modeled using finite element analysis (FEA). Uniform contact between the leaflet and housing as well as between the pivot ball and pivot slot can significantly reduce both static and dynamic stresses around the contact area. The level of the dynamic flexural stresses can be an order of magnitude higher than that of the static stresses. When both the radial and axial compliance of the housing are taken into consideration, peak dynamic stress was more than 40% less than that generated through the impact between a moving leaflet and a non-compliant rigid housing.
Clinical evaluation of the St. Jude Medical heart valve prosthesis