Background

While rates of stroke have declined with the HeartMate3 (HM3) continuous- flow (CF) left ventricular assist device (LVAD), the impact of non-pulsatile flow and artificial pulse physiology on cerebrovascular function is not known. We hypothesized that improved hemodynamics and artificial pulse physiology of HM3 patients would augment cerebrovascular metabolic reactivity (CVR) compared with HeartMate II (HMII) CF-LVAD and heart failure (HF) patients.

Methods

Mean, peak systolic and diastolic flow velocities (MFV, PSV, MinFV, respectively) and cerebral pulsatility index were determined in the middle cerebral artery (MCA) before and after a 30 sec breath-hold challenge in 90 participants: 24 healthy controls; 30 HF, 15 HMII, and 21 HM3 patients.

Results

In HM3 patients, breath-holding increased MFV (Δ8 ± 10 cm/sec, p < .0001 vs baseline) to levels similar to HF patients (Δ9 ± 8 cm/sec, p > .05), higher than HMII patients (Δ2 ± 8 cm/sec, p < .01) but lower than healthy controls (Δ13 ± 7 cm/sec, p < .05). CF-LVAD altered the proportion of systolic and diastolic flow responses as reflected by a differential cerebral pulsatility index (p = .03). Baseline MFV was not related to CVR (r² = 0.0008, p = .81). However, CF-LVAD pump speed was strongly inversely associated with CVR in HM II (r² = 0.51, p = .003) but not HM3 patients (r² = 0.01, p = .65).

Conclusions

Compared with HMII, HM3 patients have a significantly improved CVR. However, CVR remains lower in HM3 and HF patients than in healthy controls, therefore suggesting that changes in cerebral hemodynamics are not reversed by CF-LVAD therapy. Further research on the mechanisms and the long-term impact of altered cerebral hemodynamics in this unique patient population are warranted.

中文翻译：

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HeartMate 3 患者的脑血管反应性

背景

虽然 HeartMate3 (HM3) 连续血流 (CF) 左心室辅助装置 (LVAD) 的卒中发生率有所下降，但非脉动血流和人工脉搏生理学对脑血管功能的影响尚不清楚。我们假设与 HeartMate II (HMII) CF-LVAD 和心力衰竭 (HF) 患者相比，HM3 患者的血液动力学和人工脉冲生理学改善会增加脑血管代谢反应性 (CVR)。

方法

在 90 名参与者进行 30 秒屏气挑战之前和之后，测定大脑中动脉 (MCA) 的平均收缩期和舒张期流速（分别为 MFV、PSV、MinFV）和脑搏动指数：24 名健康对照；30 名 HF、15 名 HMII 和 21 名 HM3 患者。

结果

在 HM3 患者中，屏气使 MFV (Δ8 ± 10 cm/sec, p < .0001 vs基线) ​​增加到与 HF 患者相似的水平 (Δ9 ± 8 cm/sec, p > .05)，高于 HMII 患者 (Δ2 ± 8 cm/sec, p < .01) 但低于健康对照组 (Δ13 ± 7 cm/sec, p < .05)。CF-LVAD 改变了收缩期和舒张期血流反应的比例，反映在不同的脑搏动指数 ( p  = .03)。基线 MFV 与 CVR 无关 (r ²  = 0.0008, p  = .81)。然而，CF-LVAD 泵速与 HM II 患者的 CVR 呈强烈负相关（r ⁼  0.51，p  = .003），但与 HM3 患者无关（r²  = 0.01，p  = .65）。

结论

与HMII相比，HM3患者的CVR显着提高。然而，HM3 和 HF 患者的 CVR 仍然低于健康对照组，因此表明 CF-LVAD 治疗不能逆转脑血流动力学的变化。有必要进一步研究这一独特患者群体中脑血流动力学改变的机制和长期影响。