Department of Cardiovascular and Thoracic Surgery, University of Louisville, Louisville, Kentucky; Department of Bioengineering, University of Louisville, Louisville, Kentucky.
Department of Bioengineering, University of Louisville, Louisville, Kentucky.
J Heart Lung Transplant. 2015 Jan;34(1):122-131. doi: 10.1016/j.healun.2014.09.017. Epub 2014 Sep 28.
Rotary blood pumps operate at a constant speed (rpm) that diminishes vascular pulsatility and variation in ventricular end-systolic and end-diastolic volumes, which may contribute to adverse events, including aortic insufficiency and gastrointestinal bleeding. In this study, pump speed modulation algorithms for generating pulsatility and variation in ventricular end-systolic and end-diastolic volumes were investigated in an ischemic heart failure (IHF) bovine model (n = 10) using a clinically implanted centrifugal-flow left ventricular assist device (LVAD).
Hemodynamic and hematologic measurements were recorded during IHF baseline, constant pumps speeds, and asynchronous (19-60 cycles/min) and synchronous (copulse and counterpulse) pump speed modulation profiles using low relative pulse speed (±25%) of 3,200 ± 800 rpm and high relative pulse speed (±38%) of 2,900 ± 1,100 rpm. End-organ perfusion, hemodynamics, and pump parameters were measured to characterize pulsatility, myocardial workload, and LVAD performance for each speed modulation profile.
Speed modulation profiles augmented aortic pulse pressure, surplus hemodynamic energy, and end-organ perfusion (p < 0.01) compared with operation at constant speed. Left ventricular external work and myocardial oxygen consumption were significantly reduced compared with IHF baseline (p < 0.01) but at the expense of higher LVAD power consumption.
Pump speed modulation increases pulsatility and improves cardiac function and end-organ perfusion, but the asynchronous mode provides the technologic advantage of sensorless control. Investigation of asynchronous pump speed modulation during long-term support is warranted to test the hypothesis that operating an LVAD with speed modulation will minimize adverse events in patients supported by an LVAD that may be associated with long-term operation at a constant pump speed.
旋转血泵以恒定速度（rpm）运行，这会降低血管脉动性和心室收缩末期及舒张末期容积的变化，这可能导致不良事件，包括主动脉瓣关闭不全和胃肠道出血。在这项研究中，使用临床植入的离心流左心室辅助装置（LVAD）在缺血性心力衰竭（IHF）牛模型（n=10）中研究了产生心室收缩末期和舒张末期容积脉动性和变化的泵速调制算法。
在 IHF 基线、恒定泵速以及异步（19-60 次/分钟）和同步（copulse 和 counterpulse）泵速调制谱下记录血液动力学和血液学测量，使用相对较低的脉冲速度（±25%）3000 ± 800 rpm 和相对较高的脉冲速度（±38%）2900 ± 1100 rpm。测量终末器官灌注、血液动力学和泵参数，以表征每种速度调制谱的脉动性、心肌工作量和 LVAD 性能。
与恒速运行相比，速度调制谱增加了主动脉脉搏压、剩余血液动力学能量和终末器官灌注（p < 0.01）。与 IHF 基线相比，左心室外部工作和心肌耗氧量显著降低（p < 0.01），但代价是更高的 LVAD 功率消耗。
泵速调制增加脉动性并改善心功能和终末器官灌注，但异步模式提供了无传感器控制的技术优势。需要对长期支持期间的异步泵速调制进行研究，以检验假设，即通过调制速度操作 LVAD 将最大限度地减少与长期恒速泵运行相关的不良事件，从而支持 LVAD 患者。
