Problem and Solution on Clinical Application of Magnetically Suspended Centrifugal Blood Pump as Implanted Assist Heart

1)研究1本研究旨在探讨离心泵左心室辅助系统（LVAS）的流入道插管位置对心力衰竭模型心功能的影响。在10只绵羊中，通过在左心房（LA）和左心室（LV）中的两个流入插管并将这些插管连接到磁悬浮离心泵来建立LVAS。左心室插管的泵流量在收缩期增加，在舒张期减少，而左心房插管的泵流量不变。左心房插管的射血分数随着辅助率的增加而降低，而左心室插管的射血分数维持在75%辅助。随着辅助率的增加，左心房插管的外功逐渐减少，而左心室插管的外功直到辅助率达到75%才减少。两种插管的心肌耗氧量均随辅助频率的增加而成比例下降，且与对照组相比， 关于我们 辅助率为100%的左心室插管比左心房插管更有效。2）研究2设计了一套能满足机体需要的离心泵控制系统。在P-Q曲线（压头与流量的关系）上设置一个拐点。我们设置了两种泵控制模式：一种是泵流量小于拐点的陡坡疾病模式，另一种是泵流量大于拐点的缓坡健康模式。疾病模式运行良好，以保持最小泵流量。3）研究3仅通过泵参数评估心脏从衰竭中恢复的估计。同时记录LV压力和电流。随着LV压力增加，泵流量增加，但延迟一定时间。电流与泵流量的变化存在相位差。因此，我们需要校正公式来估计LV压力。少

1) Study 1This study was designed to investigate how the inflow cannulation site of the left ventricular assist system (LVAS) with centrifugal pump would influence cardiac function on failing heart models. In 10 sheep, LVAS was instituted by two inflow cannulae in the left atrium (LA) and the left ventricle (LV), and connecting those cannulae to a magnetically suspended centrifugal pump. The pump flow with LV cannulation increased during the systolic phase and decreased during the diastolic phase, while it was constant with LA cannulation. Ejection fraction with LA cannulation decreased as the assist rate increased, while that with LV cannulation was maintained up to 75% assist. The external work with LA cannulation decreased gradually as the assist rate increased, while the EW with LV cannulation did not decrease until the assist rate reached 75%. The myocardial oxygen consumption of both cannulation decreased proportionally as the assist rate increased, and were significantly less wi … More th LV cannulation at the 100% assist rate than with LA cannulation. The LV cannulation during LVAS maintains EF, and provides effective reduction in oxygen consumption.2) Study 2Control system of centrifugal pump in response to necessary demanding of body was devised. An inflection point was set on P-Q curve (Relationship between pressure head and flow). We set two modes of pump control: one is the disease mode with steep slope where the pump flow is less than the inflection point, and the other is the healthy mode with mild slope where the pump flow is more than the inflection point. The disease mode was well operated to keep the minimal pump flow rate. However, the healthy mode did not work well.3) Study 3Estimation of the heart recovering from failing was assessed by only pump parameters. The LV pressure and electricity current were recorded simultaneously. The pump flow increased as the LV pressure increased with some delay. The change between electricity-current and pump flow had phase difference. Therefore, we needed correction formula to estimate LV pressure. Less