Department of Biomedical Engineering, University of Malaya, Kuala Lumpur, Malaysia.
Texas Heart Institute, Houston, Texas, United States of America.
PLoS One. 2018 Apr 20;13(4):e0195975. doi: 10.1371/journal.pone.0195975. eCollection 2018.
Despite the widespread acceptance of rotary blood pump (RBP) in clinical use over the past decades, the diminished flow pulsatility generated by a fixed speed RBP has been regarded as a potential factor that may lead to adverse events such as vasculature stiffening and hemorrhagic strokes. In this study, we investigate the feasibility of generating physiological pulse pressure in the pulmonary circulation by modulating the speed of a right ventricular assist device (RVAD) in a mock circulation loop. A rectangular pulse profile with predetermined pulse width has been implemented as the pump speed pattern with two different phase shifts (0% and 50%) with respect to the ventricular contraction. In addition, the performance of the speed modulation strategy has been assessed under different cardiovascular states, including variation in ventricular contractility and pulmonary arterial compliance. Our results indicated that the proposed pulse profile with optimised parameters (Apulse = 10000 rpm and ωmin = 3000 rpm) was able to generate pulmonary arterial pulse pressure within the physiological range (9-15 mmHg) while avoiding undesirable pump backflow under both co- and counter-pulsation modes. As compared to co-pulsation, stroke work was reduced by over 44% under counter-pulsation, suggesting that mechanical workload of the right ventricle can be efficiently mitigated through counter-pulsing the pump speed. Furthermore, our results showed that improved ventricular contractility could potentially lead to higher risk of ventricular suction and pump backflow, while stiffening of the pulmonary artery resulted in increased pulse pressure. In conclusion, the proposed speed modulation strategy produces pulsatile hemodynamics, which is more physiologic than continuous blood flow. The findings also provide valuable insight into the interaction between RVAD speed modulation and the pulmonary circulation under various cardiovascular states.
尽管旋转血泵 (RBP) 在过去几十年中在临床应用中得到了广泛认可，但固定转速 RBP 产生的流量脉动减弱已被认为是可能导致血管僵硬和出血性中风等不良事件的潜在因素。在这项研究中，我们通过在模拟循环回路中调节右心室辅助装置 (RVAD) 的速度来研究在肺循环中产生生理脉压的可行性。已经实现了具有预定脉冲宽度的矩形脉冲轮廓作为泵速模式，具有相对于心室收缩的两个不同的相移 (0%和 50%)。此外，还评估了速度调制策略在不同心血管状态下的性能，包括心室收缩力和肺动脉顺应性的变化。我们的结果表明，具有优化参数的建议脉冲轮廓 (Apulse = 10000 rpm 和 ωmin = 3000 rpm) 能够在生理范围内产生肺动脉脉压 (9-15 mmHg)，同时避免在共搏和反搏模式下出现不期望的泵回流。与共搏相比，反搏时的冲程工作减少了超过 44%，表明通过反搏泵速可以有效地减轻右心室的机械工作量。此外，我们的结果表明，改善的心室收缩力可能导致心室抽吸和泵回流的风险增加，而肺动脉僵硬导致脉压增加。总之，所提出的速度调制策略产生脉动血流动力学，比连续血流更符合生理。这些发现还为 RVAD 速度调制与各种心血管状态下的肺循环之间的相互作用提供了有价值的见解。
