In vitro hemodynamic characterization of HeartMate II at 6000 rpm: Implications for weaning and recovery
In vitro hemodynamic characterization of HeartMate II at 6000 rpm: Implications for weaning and recovery
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DOI：
10.1016/j.jtcvs.2015.04.015
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发表时间：
2015-08-01
影响因子：
6
通讯作者：
Fukamachi, Kiyotaka
中科院分区：
文献类型：
--
作者：
Sunagawa, Gengo;Byram, Nicole;Fukamachi, Kiyotaka
目的：除非采取措施防止泵返流，否则停泵试验评估左心室恢复不是连续血流左心室辅助装置的选择。本实验研究的目的是表征HeartMate II （Thoratec Corp, Pleasanton, california）左心室辅助装置在6000 rpm时的血流动力学和泵流量，这是临床上常用的左心室恢复速度。方法：HeartMate II装置在模拟循环中以3种转速（6000、8000和10,000 rpm）操作。我们得到了每个稳态下的压力-流量曲线。在启动气动心室（心脏模拟器）的脉动模式下，在模拟正常心功能或心力衰竭的情况下，获得泵流量、总流量和主动脉压数据。结果：在心脏功能正常的6000 rpm支持下，舒张期有较大的反流；然而，净流量为零，在6000 RPM支持和没有左心室辅助装置支持之间，平均主动脉压没有差异。相比之下，在心力衰竭情况下，由于反流较少，6000 rpm的左心室辅助装置流量对平均主动脉压和总流量有显著贡献。结论：HeartMate II装置在6000 rpm时产生的净泵流量取决于剩余左心室功能的程度。在改善左心室功能的情况下，在6000 rpm时，我们注意到大量的反流重新加载左心室。虽然这个“标记”可以作为左心室恢复的有用指标，但除非采取措施防止反流，否则以这种速度评估左心室恢复是有缺陷的。
Objectives: Pump-off testing to assess left ventricular recovery is not an option for continuous-flow left ventricular assist devices unless measures are taken to prevent pump regurgitation. The purpose of this bench study was to characterize the hemodynamics and pump flow of the HeartMate II (Thoratec Corp, Pleasanton, Calif) left ventricular assist device at 6000 rpm, the speed commonly used clinically to determine left ventricular recovery.Methods: The HeartMate II device was operated in a mock loop at 3 speeds (6000, 8000, and 10,000 rpm). We acquired pressure-flow curves in each steady state. In pulsatile mode with the pneumatic ventricle (heart simulator) activated, pump flow, total flow, and aortic pressure data were obtained under conditions simulating normal heart function or heart failure.Results: A large regurgitant flow during diastole was confirmed in normal heart function at 6000 rpm support; however, the net flow was zero, and there were no differences in the mean aortic pressure between 6000 rpm support and no left ventricular assist device support. In contrast, in the heart failure condition, left ventricular assist device flow at 6000 rpm significantly contributed to the mean aortic pressure and total flow because there was less regurgitant flow.Conclusions: The net pump flow generated by the HeartMate II device at 6000 rpm depends on the degree of residual left ventricular function. In the setting of improved left ventricular function, at 6000 rpm, we noted a large regurgitant flow that reloaded the left ventricle. Although this "marker'' can serve as a useful indicator for left ventricular recovery, assessing left ventricular recovery at this speed is flawed unless measures are taken to prevent regurgitant flow.