Department of Epidemiology and Preventive Medicine, Monash University, Melbourne, Victoria, Australia.
Artif Organs. 2013 Aug;37(8):695-703. doi: 10.1111/aor.12070. Epub 2013 May 3.
This multicenter study examines in detail the spontaneous increase in pump flow at fixed speed that occurs in exercise. Eight patients implanted with the VentrAssist rotary blood pump were subjected to maximal and submaximal cycle ergometry studies, the latter being completed with patients supine and monitored with right heart catheter and echocardiography. Maximal exercise studies conducted in each patient at three different pump speeds on separate days established initially the magnitude and consistency of increases in pump flow that correlated well with changes in heart rate. However, there was considerable variation, coefficients of variation for mean heart rate and pump flow being 47.9 and 49.3%, respectively. Secondly, these studies indicated that increasing pump flows caused significant improvements in maximal exercise capacity. An increase of 2.1 L/min (35%) in maximum blood flow caused 12 W (16%) further increase in achievable work, 1.26 (9.3%) mL/kg/min in maximal oxygen uptake, and 2.3 (23%) mL/kg/min in anaerobic threshold. Mean increases in lactate were 0.85 mm (24%), but mean B-type natiuretic peptide fell by 126 mm, (-78%). From submaximal supine exercise studies, multiple linear regression of pump flow on factors thought to underlie the spontaneous increase in pump flow indicated that it was associated with increases in heart rate (P = 0.039), pressure gradient across the left ventricle (P = 0.032), and right atrial pressure (P = 0.003). These changes have implications for the recently reported Starling-like controller for pump flow based on pump pulsatility values, which emulates the Starling curve relating pump output to left ventricular preload. Unmodified, the controller would not permit the full benefits of this effect to be afforded to patients implanted with rotary blood pumps. A modification to the pump control algorithm is proposed to eliminate this problem.
这项多中心研究详细研究了在固定速度下运动时泵流量的自发增加。 8 名植入 VentrAssist 旋转血泵的患者接受了最大和次最大的循环运动研究，后者在仰卧位进行，并通过右心导管和超声心动图进行监测。 在每个患者的三种不同泵速下进行的最大运动研究，在不同的日子里建立了泵流量增加的幅度和一致性，这些增加与心率的变化密切相关。 然而，存在很大的变化，平均心率和泵流量的变异系数分别为 47.9%和 49.3%。 其次，这些研究表明，增加泵流量可显著改善最大运动能力。 最大血流量增加 2.1 L/min（35%）可使可实现的工作增加 12 W（16%），最大摄氧量增加 1.26（9.3%）mL/kg/min，无氧阈增加 2.3（23%）mL/kg/min。 乳酸的平均增加量为 0.85 mm（24%），但 B 型利钠肽平均下降 126 mm（-78%）。 从仰卧位次最大运动研究中，对泵流量与被认为是引起泵流量自发增加的因素进行多元线性回归分析表明，它与心率增加（P = 0.039）、左心室压力梯度（P = 0.032）和右心房压力（P = 0.003）相关。 这些变化对最近报道的基于泵脉动值的 Starling 样泵流量控制器有影响，该控制器模拟了泵输出与左心室前负荷之间的 Starling 曲线。 在不进行修改的情况下，该控制器将不允许旋转血泵植入患者充分受益于这种效果。 提出了一种泵控制算法的修改，以消除这个问题。
