Magnetic Bearings for Mechanical Cardiac Assist Devices
1 Magnetic Bearings for Assist Devices
Magnetic bearings produce contact-free electromagnetic force to stably support rotors or other loads. Compared to traditional bearings, magnetic bearings offer the advantages of no friction, low heat generation, no required lubrication, quiet operation, and fast and stable rotation. Because of these reasons, magnetic bearings have been used in rotary ventricular assist devices (VADs) in order to increase design life, reduce or eliminate material wear and bearing maintenance, as well as to increase biocompatibility by eliminating high fluid stresses and heat generation, both of which have been associated with hemolysis, platelet activation, and thrombus growth. Magnetic bearings have been used in several of the most recently developed mechanical circulatory assist devices as a means to extend pump life. This includes extending the mechanical life of the pump by eliminating material wear, but also minimizing damage of red blood cells and other blood factors and the formation of blood clots, both of which are physiological phenomena associated with elevated fluid shear stress and heat generation.