Avco Corporation

Avco Everett Research Laboratory, Inc.

Armando Federico

Arthur R Kantrowitz

George A Herzlinger

Richard W Curless

A solenoid operated drive system or actuating unit for driving blood pumps such as intra-arterial 'balloon' pumps, implantable pulsatile pumps, external pumps and the like, wherein a shaft attached to the movable end of a bellows is caused to move back and forth by a pair of oppositely disposed solenoids. The extent of the excursion of the shaft and hence the movable end of the bellows is variably controlled by a first stopper fixedly attached to the frame and a second stopper fixedly attached to a carriage which is adjustably carried within the frame. The solenoids are alternately actuated and/or controlled by suitable control signals which are keyed to the heartbeat or R wave. At the beginning of each cycle for each solenoid and for a short time thereafter, depending on the cycle, a voltage is applied to provide maximum drive. At the end of the maximum drive portion, a reduced voltage is applied to provide a drive and/or holding force of lesser magnitude and is maintained until after the shaft has stopped moving. Thereafter, the reduced voltage is removed and/or current flow through the solenoid is prevented for a further period of time until the next cycle for this solenoid begins with the application of the high voltage. Adjustable noise reducing bumpers are provided to keep impact noises at a minimum and insure the maintenance of a fixed stopping point over extended periods of time.

Solenoid operated blood pump drive system

A cardiac output monitor. The monitor receives signals representing radial arterial pressure, balloon pressure, balloon drive and balloon volume from an intra-aortic balloon pumping system. These signals are processed to define balloon depletion pressure (P.sub.1), ventricle ejection pressure (P.sub.2), balloon volume (BV) and heart rate (HR). The monitor displays the cardiac output according to

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Needham, MA, United States of America

Armando Federico