Abstract
The flow rate patterns at the inlet and outlet cannulae of the ventricualr assist device (VAD) driven by the pneumatic drive unit have been analyzed. The results have shown that the condition which can avoid thrombosis and hemolysis is equal to the condition which can minimize the driving energy when the full-fill and full-ejection driving is not accomplished. These conditions can be considered as the optimal operating point on the function curve of the stroke volume versus the systolic duration. It has been revealed that the optimal operating point is the vertex of the triangular figure of the function curve, i. e., the point where the stroke volume becomes maximum. An automatic control algorithm for keeping the optimal operating point has been obtained by using the only information on the time when the flow rate becomes zero. The experiments using an adult goat has ascertained that the proposed algorithm can work successfully
