Axial reciprocation of rotating impeller: a new concept of antithrombogenecity in centrifugal pump

For long-term application, rotary pump shave to solve the problems of beari ng wear and thrombosis along the bearing. Most investigators choose the mag netic bearing to realize zero-friction and no contact between the rotor and stator; the former avoids the mechanical wear and the latter eliminates th e possibility of thrombus formation. The authors have tried and found, howe ver, that it is difficult to apply a magnetic bearing to the rotary pump wi thout disturbing its simplicity, reliability and implantability, and have t herefore developed a much simpler and much more creative approach to achiev e the same results. Instead of using a sliding bearing, an rolling bearing has been devised for the pump, and its friction is about 1/15 of the slidin g bearing. Furthermore, an wear-proof material of ultra-high-molecular weig ht polythene has been adopted to make the rollers, and its anti-wear proper ty is 8 times better than metal. Thereby the service life of the bearing ha s been prolonged to ten years according to the documents provided by the pr oducer. In order to prevent the thrombus formation along the bearing, the i mpeller reciprocates axially as the impeller changes its rotating speed per iodically to produce a pulsatile flow. The reciprocation is the result of t he effects of a magnetic force between the motor rotor and stator, and a hy draulic force between the blood flow an the impeller. Similar to a piston p ump, the oscillating impeller can make the blood flow in and out of the bea ring, resulting in wash-out once a circle. This obviously helps to prevent thrombosis along the bearing and in the pump. The endurance tests with sali ne of this novel pump demonstrated the durability of the device. It promise s to be able to assist the circulation of patients permanently, and to be a ble to replace heart transplantation in the future.