Can vortices in the flow across mechanical heart valves contribute to cavitation?

Cavitation in mechanical heart valves is traditionally attributed to the ha mmer effect and to squeeze and clearance flow occurring at the moment of va lve closure. In the present study, an additional factor is considered-the c ontribution of vortex flow. Using a computational fluid dynamics analysis o f a 2D model of a tilting disk mitral valve, we demonstrate that vortices m ay form in the vicinity of the inflow side of the valve. These vortices rol l up from shear layers emanating from the valve tips during regurgitation. A significant decrease in the pressure at the centre of the vortices is fou nd. The contribution of the vortex to the total pressure drop at the instan t of closure is of the order of 70 mmHg. Adding this figure to the other pr essure drop sources that reach 670 mmHg, it might be that this is the decid ing factor that causes the drop in blood pressure below vapour pressure. Th e total pressure drop near the upper tip (750 mmHg) is larger than near the lower tip (670 mmHg), indicating a preferential location for cavitation in ception, in agreement with existing experimental findings.