Occluder dynamics and valve hemodynamics in mechanical heart valves (MHV's) are strongly coupled. We propose to develop a numerical fluid- structure interaction model for predicting leaflet dynamics as a function of the flow field at physiologic flow rates in-tilting disk mitral MHV's. The Influence-Coefficient method, which we earlier used to model flow- structure interactions in natural aortic valves, will be adapted for simulating mitral MHV dynamics. In Phase I, a two-dimensional computer model will be developed for a typical bi-leaflet valves. The model will be used to study valve hemodynamics and cavitation inception near the valve. Published in-vitro data on valve closure velocity and clinical data on the sites for cavitation damage in MHV explants will be used to assess and refine the model predictions. In Phase II, the model will be adapted for mono-leaflet tilting disk valves, and then extended for three-dimensional (3-D) simulations. The 3-D model will be validated in collaboration with a leading experimental research group. It will then be used to develop the design criteria for tilting disk mitral MHVs with improved hemodynamics in which cavitation is eliminated.
The developed model would be valuable design tools for companies designing and manufacturing mechanical heart valves. It would serve as a computational test chamber for current and future MHV designs. It would be of interest to manufacturers of left ventricular assist devices (LVAD's) and pulsatile blood pumps in which cavitation damage has been reported. The developed software will be suitable for running on workstations, which are within the financial budgets of LVAD and valve manufacturers.
