Abstract: A pump unit for assisting in the blood feeding operation of a heart includes a pair of pumps 7a, 7b connected in parallel with each other. When the pump 7a (or 7b) has reached its expanded position and the pump 7b (or 7a) has reached its contracted position, the operation is changed so that the pump 7a (or 7b) is set up for contraction while the pump 7b (or 7a) is set up for expansion. A time difference TCM between the time when the expanded position is reached and the time when the contracted position is reached is determined. If TCM>Tr, a driving pressure for contraction is changed to a higher value while if TCM<Tr, a driving pressure for contraction is changed to a lower value. Tr represents a non-responsive interval which can be adjusted by an operator. When Tr has a high value, the pump exhibits a low flow rate which serves as a drive to assist in the delivery of blood by the heart. In this manner, the operator is enabled to adjust the driving flow rate.

Abstract: A pumping unit is disclosed which alternately applies a positive and a negative pressure, both of given values, to aa drive chamber of an artificial heart. In a first and a second embodiment, air of an elevated pressure which is discharged by an air compressor is fed through a positive pressure accumulator and a positive pressure open/close valve to the drive chamber, and a negative pressure from an air decompressor is fed through a negative pressure accumulator and the negative pressure open/close valve to the drive chamber. Alternating open periods are assigned to the positive and the negative pressure open/close valve. During the open period, each valve is opened and closed in a manner corresponding to the prevailing pressure in the drive chamber so as to maintain the pressure at a constant value.

Abstract: An apparatus for driving a medical appliance has a sensor for sensing a driving pressure which is an output pressure of the apparatus. The apparatus measures the rising and falling characteristics of the driving pressure by signals from the sensor. The apparatus adjusts the pressures in accordance with the rising and falling characteristics.