Tagusari O, Yamazaki K, Litwak P, Antaki J F, Watach M, Gordon L M, Kono K, Mori T, Koyanagi H, Griffith B P, Kormos R L
Department of Surgery, University of Pittsburgh Medical Center, Pennsylvania 15219, USA.
Artif Organs. 1998 May;22(5):399-404. doi: 10.1046/j.1525-1594.1998.06157.x.
We have been developing centrifugal pumps for an implantable left ventricular assist device. We manufactured 2 prototype centrifugal pumps (PI, PII). These two have similar designs except for the PII having a volute casing and a large output port. To determine the differences in the hydraulic characteristics between the PI and PII, we carried out in vitro and in vivo experiments. In vitro study showed that the PII had a shallower H-Q curve than that of the PI, and the PII required a pump speed faster than the PI for the same flow rate and pressure head. On the other hand, in vivo study showed that the PII demonstrated a flow pulsatility greater than that of the PI at 1,900 rpm and 8 L/min although no significant change was observed at low pump speeds (< or = 1,500 rpm). This greater pulsatility consisted of a large discharge according to the small differential pressure during the systolic phase and a small discharge according to the large differential pressure during the diastolic phase. In contrast, the PI, having the steeper H-Q curve, showed a small discharge in the systolic phase and a large discharge in the diastolic phase. These results showed that pulsatility synchronized with the native heart beating depended on the slope of the H-Q curve. As a result, the slope of the H-Q curve is important to determine the component of pulsatility synchronized with native cardiac output. Regarding the slope of the H-Q curve, a pump having a volute casing and a large outlet port demonstrates a shallow slope in the H-Q curve. In conclusion, we suggest that a centrifugal pump for use in left ventricular aortic bypass should be designed considering the effect on the native heart pulsatility.
我们一直在研发用于植入式左心室辅助装置的离心泵。我们制造了2台离心式泵原型（PI、PII）。这两台泵的设计相似，只是PII有一个蜗壳式泵壳和一个大输出端口。为了确定PI和PII之间的水力特性差异，我们进行了体外和体内实验。体外研究表明，PII的H-Q曲线比PI的更平缓，并且在相同流量和压头下，PII所需的泵速比PI更快。另一方面，体内研究表明，在1900转/分钟和8升/分钟时，PII的流量脉动性大于PI，尽管在低泵速（≤1500转/分钟）时未观察到显著变化。这种更大的脉动性包括收缩期小压差时的大流量和舒张期大压差时的小流量。相比之下，具有更陡H-Q曲线的PI在收缩期流量小，在舒张期流量大。这些结果表明，与天然心脏跳动同步的脉动性取决于H-Q曲线的斜率。因此，H-Q曲线的斜率对于确定与天然心输出量同步的脉动性成分很重要。关于H-Q曲线的斜率，具有蜗壳式泵壳和大出口端口的泵在H-Q曲线中显示出较平缓的斜率。总之，我们建议在设计用于左心室主动脉旁路的离心泵时应考虑对天然心脏脉动性的影响。
