叶轮式心脏泵内防止血栓形成的新方法

叶轮血泵在解决血液相容性、可植入性及搏动流等一系列问题后，正面临使用耐久性的技术要求，即轴承的耐磨性及轴承处的抗血栓形成性能。为此，一种全新的方法应运而生。与过去采用滑动轴承不同，这次设计了一种滚动轴承，其摩擦约为滑动轴承的1／15。同时，滚子材料采用超高分子量聚乙烯，耐磨性是金属的8倍。根据相关技术资料，这种滚动轴承的寿命可达数年以上。为了防止轴承处形成血栓，血泵叶轮不仅周期性改变转速产生搏动流，同时作轴向往复运动。转子轴向运动是电机定子、转子间的电磁力和血流、叶轮间的液力相互作用的结果。与活塞泵相似，转子的轴向运动能使血液进入、排出轴承，每个周期可洗刷轴承一次，从而有利于防止在轴承和血泵中生成血栓．采用生理盐水进行寿命试验表明该新颖装置具有耐久性，有望能够永久性辅助病人的血液循环，并在不久的将来替代心脏移植。

A New Approach for Improving Antithrombogenicity in Centrifugal Pump

For long-term application of the rotary pumps, it is necessary to solve the problems of bearing wear and thrombosis along the bearing. Currently, many investigators choose the magnetic bearing to realize zero-friction and no contact between the rotor and stator; the former avoids the mechanical wear and the latter eliminates the possibility of thrombus formation. We tried and found that it is difficult to apply a magnetic bearing to rotary pump without disturbing its simplicity, reliability and implantability; therefore, we have developed a much simpler and much more creative approach to achieving the same results.Instead of the sliding bearing, a rolling bearing has been devised for the pump; its friction is about 1/15 of the sliding bearing. Furthermore, a wear-proof material of ultra-high-molecular weight polythene has been adopted in making the rollers, their anti-wear property is 8 times better than that of metal. Thereby, the service life of the bearing has extended to several years. For preventing the thrombus formation along the bearing, the impeller reciprocates axially as the impeller changes its rotating speed periodically to produce a pulsatile flow. The reciprocation is a result of the effects of a magnetic force between the motor rotor and stator, and a hydraulic force between the blood flow and the impeller. Similar to piston pump, the oscillating impeller can make the blood in and out of the bearing, resulting in wash-out once a circle. This is obviously beneficial to preventing thrombosis along the bearing and in the pump.The endurance tests with saline of this novel pump demonstrated a durability of the device. It promises to be able to assist the circulation of the patients permanently and to be able to replace the heart transplantation in the future.