Several factors such as peak dp/dt of ventricular pressure, maximum closing velocity of the leaflet and squeeze flow have been studied as indices for the cavitation threshold. To study the possibility of the occurrence of cavitation at a 25mm Björk-Shiley monoleaflet, we analyzed the closing behavior of the valves. The closing events of the valves in the mitral and aortic positions were simulated using a fully electro-hydraulic artificial heart. Tests were conducted under physiologic pressures at heart rates of 50, 60, 70 and 80 beats/min with cardiac outputs of 4.8, 5.9, 7.0 and 8.0L/min, respectively. The closing behavior of the valve was measured using a laser displacement sensor. The maximum velocity of the aortic valve ranged from 0.8 to 0.9m/s, and that of the mitral valve ranged from 1.48 to 1.6m/s. In aortic position valves, the maximum closing velocity was lower than the cavitation thresholds reported, but the maximum closing velocity of th mitral valve was similar to the cavitation threshold. Therefore, we suggest that it is possible for cavitation to occur in the mitral valuve of electro-hydraulic artificial hearts.
