From the Mechanical and Aerospace Engineering Department, University of California San Diego, La Jolla, California.
Division of Cardiovascular Medicine, University of California San Diego, La Jolla, California.
ASAIO J. 2021 Jan 1;67(1):74-83. doi: 10.1097/MAT.0000000000001158.
The success of left ventricular assist device (LVAD) therapy is hampered by complications such as thrombosis and bleeding. Understanding blood flow interactions between the heart and the LVAD might help optimize treatment and decrease complication rates. We hypothesized that LVADs modify shear stresses and blood transit in the left ventricle (LV) by changing flow patterns and that these changes can be characterized using 2D echo color Doppler velocimetry (echo-CDV). We used echo-CDV and custom postprocessing methods to map blood flow inside the LV in patients with ongoing LVAD support (Heartmate II, N = 7). We compared it to healthy controls (N = 20) and patients with dilated cardiomyopathy (DCM, N = 20). We also analyzed intraventricular flow changes during LVAD ramp tests (baseline ± 400 rpm). LVAD support reversed the increase in blood stasis associated with DCM, but it did not reduce intraventricular shear exposure. Within the narrow range studied, the ventricular flow was mostly insensitive to changes in pump speed. Patients with significant aortic insufficiency showed abnormalities in blood stasis and shear indices. Overall, this study suggests that noninvasive flow imaging could potentially be used in combination with standard clinical methods for adjusting LVAD settings to optimize flow transport and minimize stasis on an individual basis.
左心室辅助装置（LVAD）治疗的成功受到血栓形成和出血等并发症的阻碍。了解心脏和 LVAD 之间的血流相互作用可能有助于优化治疗并降低并发症发生率。我们假设 LVAD 通过改变血流模式来改变左心室（LV）中的剪切力和血液通过情况，并且可以使用 2D 超声彩色多普勒速度（echo-CDV）来描述这些变化。我们使用 echo-CDV 和定制的后处理方法来绘制正在接受 LVAD 支持的患者（Heartmate II，N=7）的 LV 内血流图。我们将其与健康对照组（N=20）和扩张型心肌病（DCM，N=20）患者进行了比较。我们还分析了 LVAD 斜坡试验期间（基线±400rpm）的室内血流变化。LVAD 支持逆转了与 DCM 相关的血液淤滞增加，但并未降低室内剪切暴露。在所研究的狭窄范围内，心室血流对泵速变化的敏感性较低。有明显主动脉瓣关闭不全的患者表现出血液淤滞和剪切指数异常。总的来说，这项研究表明，非侵入性血流成像可能与标准临床方法结合使用，用于调整 LVAD 设置，以优化个体的血流输送并最大程度地减少淤滞。
