Sensorless controlling method for a continuous flow left ventricular assist device

We originated a novel control strategy for a continuous flow left ventricul ar assist device (LVAD). We examined our method by acute animal experiments to change the left ventricular (LV) contractility or LV end-diastolic pres sure (LVEDP). To estimate the pump pulsatility without any specific sensor, we calculated the index of current amplitude (ICA) from motor current wave form. The ICA had a peak point (t-i point) that corresponded closely with t he turning point from partial to total assistance, and a trough (s-i point) that corresponded with the beginning point of ventricular collapse. The pu mp flow at the t-i point (Qt-i) had no component of Row regurgitation. In t he evaluation of the effects of preload LVEDP, afterload (mAoP), and contra ctility (max LV dp/dt), we found that preload was the only parameter that s ignificantly influenced Qt-i, We concluded that our method could well contr ol continuous flow LVAD by preventing reversed flow and ventricular collaps e.