Bartoli Carlo R, Kang Jooeun, Motomura Tadashi
Division of Cardiovascular Surgery, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania.
MD-PhD Program, Vanderbilt University, Nashville, Tennessee.
J Card Surg. 2020 Jul;35(7):1477-1483. doi: 10.1111/jocs.14620.
Continuous-flow left ventricular assist devices (LVADs) produces supraphysiologic shear stress that causes von Willebrand factor (VWF) degradation and a bleeding diathesis. Reduction of revolutions per minute (RPM) with axial-flow LVADs does not decrease shear stress enough to reduce VWF degradation and bleeding. However, it is unknown if RPM reduction with centrifugal flow LVADs may minimize VWF degradation. We tested the hypothesis that RPM reduction preserves VWF multimers in the centrifugal-flow EVAHEART left ventricular assist system (LVAS), which is designed to minimize shear stress and blood trauma.
Whole blood samples were collected from humans (n = 28). Blood was circulated in ex vivo mock circulatory loops for 6 hours with an EVAHEART LVAS at 2300 (n = 12), 2100 (n = 8), or 1800 RPM (n = 8). Immunoblotting was used to resolve and quantify VWF multimers and degradation fragments.
RPM reduction from 2300 to 2100 to 1800 RPM significantly decreased EVAHEART blood flow from 5.8 ± 0.4 to 4.3 ± 0.6 to 4.1 ± 0.5 L/min (analysis of variance [ANOVA], P = .03). RPM reduction protected VWF from pathologic degradation. At lower RPMs, significantly greater levels of VWF multimers were observed (ANOVA, P = .001). Similarly, at lower RPMs, significantly fewer VWF fragments, a product of VWF degradation, were observed (ANOVA, P = .007).
RPM reduction significantly reduced VWF degradation with the centrifugal-flow EVAHEART LVAS, an LVAD specifically designed with low shear stress. Different LVADs have unique hematologic footprints and should be managed with device-specific protocols. Adjustment of RPM to minimize blood trauma while still maintaining physiologic hemodynamics has the potential to decrease complications related to LVAD-associated von Willebrand's disease, such as gastrointestinal bleeding and hemorrhagic stroke.
连续流左心室辅助装置（LVADs）会产生超生理剪切应力，导致血管性血友病因子（VWF）降解和出血素质。使用轴流LVADs降低每分钟转速（RPM）并不能充分降低剪切应力以减少VWF降解和出血。然而，尚不清楚使用离心流LVADs降低RPM是否可以使VWF降解最小化。我们检验了这样一个假设，即降低RPM可保留离心流EVAHEART左心室辅助系统（LVAS）中的VWF多聚体，该系统旨在使剪切应力和血液损伤最小化。
从28名人类受试者采集全血样本。血液在体外模拟循环回路中使用EVAHEART LVAS以2300转/分钟（n = 12）、2100转/分钟（n = 8）或1800转/分钟（n = 8）循环6小时。采用免疫印迹法解析和定量VWF多聚体及降解片段。
将RPM从2300降至2100再降至1800转/分钟，显著降低了EVAHEART的血流量，从5.8±0.4降至4.3±0.6再降至4.1±0.5升/分钟（方差分析[ANOVA]，P = 0.03）。降低RPM可保护VWF免于病理性降解。在较低RPM时，观察到VWF多聚体水平显著更高（ANOVA，P = 0.001）。同样，在较低RPM时，观察到VWF降解产物VWF片段显著更少（ANOVA，P = 0.007）。
降低RPM可显著减少离心流EVAHEART LVAS导致的VWF降解，EVAHEART LVAS是一种专门设计用于产生低剪切应力的LVAD。不同的LVAD具有独特的血液学特征，应采用特定于设备的方案进行管理。调整RPM以最小化血液损伤，同时仍维持生理血流动力学，有可能减少与LVAD相关的血管性血友病相关并发症，如胃肠道出血和出血性中风。
