植入式叶轮全人工心脏的原型设计

PROTOTYPE DESIGN OF IMOLANTABLE IMPELLERTOTAL HEART

此装置具有一个两端均有输出轴的直流电机,左、右叶轮直接固定于输出轴上。有两个介于电机壳和泵壳之间的密封盒,每个密封盒内部都有磁铁——磁性流体结构,提供转子的非摩擦密封。由于不同的压力与流量比率,开式叶轮分别为混流型(左)和轴流型(右),两者都用新的三元理论的解析方法来设计,其扭曲的叶片形状由轴向螺旋线和径向对数螺旋线组合而成,以便减小血细胞的速度变化,降低泵中的雷诺切应力。随着电机周期性地改变转速,左泵和右泵同步地射血,产生符合生理条件的脉动流。泵输出通过改变电机平均电压来调节。两个泵的流量平衡是由叶轮泵的自动调节特性来实现的。根据叶轮辅助心脏的离体和在体试验结果,可知叶轮全人工心脏的溶血指标是可以接受的。

<ABSTRACT> Although advantages of impeller pump as assist device are well-known, yet associated problems have limited its application. Based on adva- nce in solving such problems as hemolysis, bearing and sealing, generation of pulsatile flow, and development of impeller assist heart, nonpulsatile as well as pulsatile pump,a prototype design of impeller total heart has been acomplished. The device possesses a DC motor with double output shafts, on which the left and right impellers are directly fixed. Each of the two sealing boxes between the motor and pump-housings has a magnet-ferrofluid cons- truction, providing a frictionless sealing of the roror. Because of different pressure/volume ratios, the open impellers are of mixed-flow type (left) and axial type (righy ) respectively, both being designed with a new analytical method according to 3-dimensional theory. Their twisted vanes have a form compacted by axial helical spiral and radial logarithmic spiral, so as to minimize velocity variations of blood cells, thus reducing Reynolds shear in the pump. As the motor changes its RPM periodically, the left and right pumps eject simultaneously, producing a physiological pulsatile flow. The volume is adjusted by changing motor voltage and eq- uilibrium of both pumps is achieved by self-modulation property of the impeller pump. with in-vitro and in-vivo experiences of pulsatile impeller pump, the index of hemolysis (IH ) of this device promises to be accepta- ble. The device weights 365g (incl. 290g motor ). For anatomical considera- tion, it is desirable to develop a disc form motor with larger diameter and shorter length.