Abstract: Retroperfusion control apparatus for supplying arterial blood of a patient to the venous side of the patient's heart including a pump having an inlet and an outlet and a piston movable through a pump stroke for moving a liquid from the inlet to the outlet of the pump. A stepper motor is provided which drives the piston. Electronic circuitry is provided for driving the stepper motor and senses the presence of an R wave in a patient to operate the stepper motor in response to the sensed R wave.

Abstract: Disposable pump cassette for a liquid comprising a substantially rigid housing providing a chamber and having upper and lower portions. A flexible substantially cylindrical bladder is vertically disposed in the chamber and has an inlet adapted to receive the liquid and an outlet. The bladder has upper and lower wall portions. The lower wall portion is of a thinner cross section then the upper wall portion. An inlet valve is disposed in the inlet of the bladder and is mounted in the lower portion of the housing. An outlet valve is disposed in the outlet of the bladder and is mounted in the upper portion of the housing. The inlet and outlet valves are disposed in the liquid and provide unidirectional flow of the liquid through the bladder. A substantially incompressible driving liquid is disposed in the chamber and surrounds the bladder. A housing extension is mounted on said housing and is in communication with the driving liquid disposed in the chamber.

Abstract: Retroperfusion control apparatus for supplying arterial blood of a patient to the venous side of the patient's heart including a pump having an inlet and an outlet and a piston movable through a pump stroke for moving a liquid from the inlet to the outlet of the pump. A stepper motor is provided which drives the piston. Electronic circuitry is provided for driving the stepper motor and senses the presence of an R wave in a patient to operate the stepper motor in response to the sensed R wave.