Measurement of the closing behavior of the björk-shiley monoleaflet mechanical heart valve with an electrohydraulic total artificial heart.

When cavitation occurs near a material surface of a mechanical heart valve (MHV), pits on the surface of the MHV and hemolysis are caused. Therefore, it is very important to investigate the possibility of the occurrence of cavitation in an MHV. To study the possibility of cavitation occurrence in a 25 mm Björk-Shiley monoleaflet, we analyzed the closing behavior of these valves. The closing event of these valves in the mitral and aortic positions was simulated in an electrohydraulic total artificial heart with a stroke volume of 100 ml. 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 8.1 l/min, respectively. The disk-closing behavior was measured by a laser displacement sensor. The closing behaviors were investigated with various cardiac outputs and gravity direction. The maximum velocities of the aortic valve ranged from 0.8 to 0.9 m/s, and for the mitral valve ranged from 1.48 to 1.6 m/s. In aortic position valves, the maximum closing velocities were less than the reported cavitation thresholds, but the maximum closing velocities of the mitral valve were similar to the cavitation threshold. Therefore, we suggest that there should be the possibility of cavitation occurrence in the mitral valve of an electrohydraulic total artificial heart.