Development project of ultra-mini centrifugal pumps as implantable heart assist device for infantsor neonate

自1998年以来，我们开发了超微型离心泵，作为婴儿或新生儿的植入式心脏辅助装置。1998年设计了一个带有三脚架轴承的原型模型，并于1999年建成。在2000年进行了模拟循环回路的水力性能试验和山羊血溶血试验，以评价其性能。试验结果表明，该装置在以下三个方面需要改进：1）驱动磁铁和耦合磁铁之间的长度; 2）叶轮下的枢轴轴承形状; 3）叶轮上的叶片形状。为了解决上述问题，我们研制了一种新型的单柱轴承。进行了三脚架模型和单脚架模型的水力性能试验。一种新的模型显示了更高的最大血流量，但在相同的血流量相同的头部压力。两种模型的压力-流量关系无差异。一个新的模型与单柱轴承表现出更高的效率比以前的模型与三脚架之一。monovpivot模型被认为是更可行的长期使用，但需要进一步发展，其植入试验。我们进行了急性动物实验与小猪，以评估该装置的植入能力。经左胸切口植入超微型离心泵，左心室心尖流出，降主动脉流入。泵在低转速时性能良好，但在高转速时出现左室收缩。我们研制了一种微型离心泵，并对该泵的工作性能进行了评价。本研究的下一个目标是评估长期性能的慢性动物经验。

We have developed ultra-mini centrifugal pumps as implantable heart assist device for infants or neonate since 1998. A prototype model with tripod bearing was designed in 1998 and build up in 1999. Hydrolic performance test with mock circulation loop and hemolytic test with goat blood have been performed to estimate its performance in 2000. These tests pointed out three points to be improved as the followings ; 1 ) length between driving magnet and coupling magnet, 2) shape of a pivot bearing under the impeller, 3) shape of vanes upper impeller. We made a new model with a monopivot bearing to resolve above problems. The hydrolic performance test was performed to compare the performance between a tripod and a monopivot model. A new model showed higher maximum blood flow but the same head pressure under the same blood flow. There were no differences between both models in pressure-flow relationship. A new model with monopivot bearing showed higher efficiency than did a previous model with tripod one. The monovpivot model is considered to be more feasible for long term use, however, there needs further developing for its implant trial.We performed acute animal experiences with piglets to estimate implantability of this device. An ultra-mini centrifugal pump was implanted via the left thoracotomy with the left ventricular apex outflow and descending aorta inflow. The pump revealed reasonable performance under low revolution level, however, sacking to the left ventricte was happened under high revolution level. We feel the necessity ofa computerized control system tor its device.We have developed a working model of an ultra-mini centrifugal pump for infants and have estimated its hydrolic performance since 1 998 to 2001. Chronic animal experience to estimate long term performance is the next target of this study.