Using a total artificial heart with accessory chamber, the authors newly developed an automatic drive control unit which would respond very sensitively to venous return and would provide a corresponding stroke volume. With this artificial pump the accessory chamber membrane responds to the change in venous return, that is the capacity of the accessory chamber is changed. In order to determine the diastolic time the movement of the accessory chamber membrane is detected. When the venous return becomes poor, the capacity of the accessory chamber increases and when it again becomes small, this triggers the automation. As for systolic time, when the diaphragm comes to the full systole position by the wave pattern of the positive drive pressure, the ceiling is reached. This is utilized as the trigger. As a result,
1. A stroke volume curve which responded very well to venous return volume was obtained.
2. Regardless of the inlet pressure the maximum stroke volume was always attained.
3. Within the inlet pressure range of 5-20cmH2O, the heart rate was 70-90 per minute and % systole was 30-35% and automatic drive control was possible.