DEVELOPMENT OF FULL-FILL TO FULL-EMPTY DRIVE CONTROL SYSTEM OF ARTIFICIAL HEARTS BY MEASURING ELECTRICAL IMPEDANCE IN A BLOOD CHAMBER WIYH AOUTOMATIC TRIGGER LEVEL ADJUSTMENT METHOD FOR EJECTING PHASE

Abstract

Continuous monitoring method of pump performance by measuring electrical impedance in a blood chamber was applied to the trigger system of full-fill to full-empty(F/E) drive control. An automatic trigger level adjustment method(ATAM) for settlement of a trigger level to change a phase from ejecting to filling was developed to maintain a definite stroke volume against changes of afterload or driving pressure. ATAM was an automatic searching algorism that can identfy the volume change of last ejection by impedance method and settle next trigger level to maintain a destination stroke volume. In a mock circuit and animal experiments, ATAM functioned satisfactorily to follow the changes of afterload and driving pressure and maintained definite stroke volume. In conclusion, this method was practical and useful in regulation of F/E driving.