A Prototype Left Ventricular Assist Artificial Heart Pump: An Integrated Permanent Magnet and Active Magnetic Bearing Suspension System

The progress in the development of ventricular assist artificial heart pumps is continuing. This paper describes the magnetic suspension for a unique prototype axial flow pump designed for approximately 6 L/min at 100 mm Hg performance with an operating speed of approximately 7,000 rpm. The integrated magnetic suspension design provides a direct non-contact blood flow path through the pump with no obstructions which might create low flow areas and thrombosis (blood clots). The magnetic suspension is a combination of permanent magnets (PMs) and active magnetic bearings (AMBs). There are two radial AMBs which support the four degrees of freedom at the ends of the axial pump impeller and an axial PM thrust bearing. The axial PM bearing supports the direction of the largest fluid force on the impeller. A major objective of artificial hearts is to have extremely low power consumption. Thus the integrated PM and AMB suspension system has an operating magnetic suspension power of approximately 2 watts. The design, numerical modeling, and testing of the magnetic suspension system to support the fluid loads and the g loads are described in the paper.