Characteristics of cavitation intensity in a mechanical heart valve using a pulsatile device: synchronized analysis between visual images and pressure signals.

To investigate the characteristics of cavitation intensity, we performed a synchronized analysis of the visual images of cavitation and the pressure signals using a pulsatile device. The pulsatile device employed was a pneumatic ventricular assist device (PVAD) that is currently being developed by our group. A 23-mm Medtronic Hall valve (M-H valve) and a 23-mm Sorin Bicarbon bileaflet valve (S-B valve) were mounted in the inlet port of the PVAD after the sewing ring had been removed. A function generator provided a square signal, which was used as the trigger signal, via Electrocardiogram R wave (ECG-R) mode, of the control - drive console for circulatory support. The square signal was also used, after a suitable delay, to synchronize operation of a pressure sensor and a high-speed video camera. The data were stored using a digital oscilloscope at a 1-MHz sampling rate, and then the pressure signal was band-pass filtered between 35 and 200 kHz using a digital filter. The valve-closing velocity, visual cavitation time, and root mean square (RMS) pressure of the M-H valve were greater than those of the S-B valve. Both the visual cavitation time and RMS pressure represent the cavitation intensity, and this is a very important factor when estimating mechanical heart valve cavitation intensity in an artificial heart.