DETECTION OF TOTAL ASSIST AND SUCKING POINTS BASED ON PULSATILITY OF A CONTINUOUS-FLOW ARTIFICIAL-HEART - IN-VITRO EVALUATION

We investigated the basic characteristics of the pulsatility of motor current with an in vitro mock circuit that consists of a sac-type puls atile pump (simulating the natural left ventricle), three reservoirs, and our mixed flow pump (MFP). There are three alternatives at the inl et of the MFP: 1) the left atrium (LA), 2) the left ventricle (LV), an d 3) both (LALV). The motor current waveform was monitored. The pump s peed of the MFP was changed from 0 to 7,000 rpm. We calculated the ind ex of motor current amplitude (ICA), which was obtained from the ampli tude of the motor current waveform divided by the simultaneous mean va lue. The ICA plotted against the pump speed had a peak point (t-point) that highly corresponded with the turning point from partial to total left heart assistance. The ICA also had a second specific point (s-po int) that corresponded with the beginning of severe sucking. In LV and LALV aortic bypass, t- and s-points could clearly be detected. In LA aortic bypass, however, early and severe sucking occurred, and t- and s-points were not manifest. These data suggest that the assist status of continuous flow artificial heart can be estimated by detecting the t- and s-points.