Heart Failure Care Group, Royal Brompton and Harefield NHS Foundation Trust, Harefield Hospital, Harefield, Middlesex UB9 6JH, UK.
Eur J Heart Fail. 2012 Jun;14(6):613-20. doi: 10.1093/eurjhf/hfs042. Epub 2012 Apr 14.
Patients treated with a Thoratec HeartMate II left ventricular assist device (LVAD) are supported at a fixed pump speed. It is uncertain whether pump speed has a significant effect on exercise capacity. We investigated the relationship between pump speed and exercise capacity and the influence of residual LV function
We exercised 30 patients 6 months after HeartMate II implantation at clinical pump speed (typically 9000 r.p.m.) and again at the lowest speed available (6000 r.p.m.). Overall, peak oxygen uptake (pkVO(2)) positively correlated with LV ejection fraction (LVEF) both at the clinical pump speed (r = 0.41, P = 0.03) and after pump speed reduction (r = 0.50, P = 0.01). We divided the patients into two groups; those with higher LVEF (LVEF ≥40%) and those with lower LVEF (LVEF <40%) at the time of exercise testing. The response to speed change was different between the two groups. In the higher LVEF group, the impact of LVAD pump speed reduction was minimal (pkVO(2) 21.4 ± 4.8 mL/kg/min vs. 20.8 ± 5.5 mL/kg/min, P = 0.38). In the lower LVEF group, the pkVO(2) was lower at both speeds; 17.2 ± 5.3 and 14.7 ± 5.9 mL/kg/min, respectively. In the lower LVEF group, the pkVO(2) decreased by 2.5 mL/kg/min (P = 0.02) with speed reduction.
HeartMate II patients with lower residual LV function had a lower pkVO(2) and were more sensitive to pump speed reduction. This suggests that modulation of LVAD speed during exercise could be of benefit to this group of patients.
接受 Thoratec HeartMate II 左心室辅助装置（LVAD）治疗的患者以固定的泵速接受支持。目前尚不确定泵速是否对运动能力有显著影响。我们研究了泵速与运动能力之间的关系以及残余左心室功能的影响。
我们在植入 HeartMate II 后 6 个月以临床泵速（通常为 9000 r.p.m.）对 30 例患者进行运动，并再次以最低可用速度（6000 r.p.m.）进行运动。总的来说，峰值摄氧量（pkVO₂）与左心室射血分数（LVEF）呈正相关，无论是在临床泵速（r = 0.41，P = 0.03）还是在降低泵速后（r = 0.50，P = 0.01）。我们将患者分为两组：在运动测试时 LVEF 较高（LVEF ≥40%）和 LVEF 较低（LVEF <40%）的患者。两组对速度变化的反应不同。在 LVEF 较高的组中，LVAD 泵速降低的影响最小（pkVO₂ 21.4 ± 4.8 mL/kg/min 与 20.8 ± 5.5 mL/kg/min，P = 0.38）。在 LVEF 较低的组中，两种速度下的 pkVO₂均较低，分别为 17.2 ± 5.3 和 14.7 ± 5.9 mL/kg/min。在 LVEF 较低的组中，随着速度降低，pkVO₂ 降低了 2.5 mL/kg/min（P = 0.02）。
残余左心室功能较低的 HeartMate II 患者的 pkVO₂ 较低，对泵速降低更为敏感。这表明在运动期间调节 LVAD 速度可能对这组患者有益。
