In vivo evaluation of the national cardiovascular center electrohydraulic total artificial heart

We have been developing an electrohydraulic total artificial heart system. The system comprises an intrathoracic pumping unit composed of diaphragm ty pe ellipsoidal blood pumps and an energy converter in addition to an electr onics unit. The in vivo performance of the pumping unit was evaluated in a series of animal implantations with 3 calves weighing 62-85 kg. An interatr ial shunt 4.5 mm in diameter was made in the atrial septum to compensate le ft-right imbalance. Two calves died early postoperatively, one of external controller power failure and the other of interatrial shunt stenosis due to thrombus formation. One calf, however, survived over 10 days under stable circulatory conditions. No abnormality was found in the oxygen metabolic co ndition or in major organ functions. The generation and dissipation of heat from the device was acceptable. This animal died of device malfunction cau sed by energy converter bearing breakdown. The device demonstrated a good a natomic fit without compromising the great vessels and adjacent tissues. It is concluded that the pumping unit has a sufficient in vivo basic performa nce although appropriate countermeasures are to be implemented against the detected problems concerning mechanical durability and interatrial shunt pa tency.