Electrohydraulic Control Systems for Heart Assist Devices.

摘要

An implantable electrohydraulic energy system,consisting of a high-speed rotary pump,an immersed brushless dc motor, a magnetic coupling and the attending control system,has been developed. This system,using valving as the flow switching mechanism and unidirectional motor-pump rotation,delivers 10watts of hydraulic power to the circulatory assist device. Hydrostatic forces generated by this hydraulic flow apply a uniform squeeze to the blood bladder in 1:1correspondence between hydraulic fluid and blood flow rates and pressures. The energy system has been designed to operate either asynchronously or synchronously with the natural heart. Provision for manually adjustable beat rates over the range of 40to 150beats per minute was incorporated in the asynchronous mode. Four control logic methods initially were provided in the breadboard control electronics unit for synchronous system operation. In-vivo testing dictated final selection of detecting threshold flow from the blood pump to the energy system at the beginning of a beat. In-vivo test results also indicated that the integrated energy system and circulatory assist device is: (1) capable of being synchronized with the natural heart over an extended beat range; (2) capable of reducing the left ventricular pressure to 20/0mm Hg;and (3) capable of automatic operation during complete heart failure at a predetermined fixed rate.