From the Meinig School of Biomedical Engineering, Cornell University, Ithaca, New York.
Michigan Medicine, University of Michigan, Ann Arbor, Michigan.
ASAIO J. 2020 Sep/Oct;66(9):992-999. doi: 10.1097/MAT.0000000000001151.
Computational fluid dynamics has become a dynamic tool in the development of ventricular assist devices (VADs) and as a predictor of thrombosis within these pumps. The genesis of thrombi could be in loco, due to deposition within the VAD, or upstream such as the left atrial appendage or inside the left ventricle. To calibrate our group's computational model, a retrospective analysis of 29 explanted HeartMate II (HMII) VADs due to suspected pump thrombosis (PT) from the University of Michigan was conducted. Thrombi in these pumps were characterized by their frequency, composition, severity, and physical distribution in five regions of the blood flow pathway. The outlet bearing/stator region had the highest frequency of deposition (≈72%), and the preponderance of thrombi appeared white and unlaminated in their microstructure. Conversely, 41.3% of VADs showed thrombus on the fore bearing of the HMII, and these formations tended to be red and laminated, indicating they formed in layers over time. Furthermore, the majority of clots observed in the fore bearing and outlet bearing/stator regions were partially occlusive in nature. Fourteen VADs presented PT in multiple regions and analysis of the data showed a statistically significant correlation (p < 0.01) between deposition in the fore bearing and subsequent thrombosis in the outlet bearing/stator; however, no other regions exhibited statistically significant correlations. This gives credence to the hypothesis that thrombi do not occur independently in multiple regions of the blood flow pathway in the HMII but may propagate downstream.
计算流体动力学已成为心室辅助装置（VAD）开发的有力工具，并且可预测这些泵中的血栓形成。血栓的形成可能发生在局部，由于 VAD 内的沉积，或者发生在上游，如左心耳或左心室内部。为了校准我们团队的计算模型，对密歇根大学因疑似泵血栓形成（PT）而从 29 例植入的 HeartMate II（HMII）VAD 中进行了回顾性分析。这些泵中的血栓根据其在五个血流途径区域中的频率、组成、严重程度和物理分布进行了特征描述。出口轴承/定子区域的沉积频率最高（≈72%），血栓的优势表现为其微观结构中的白色和无分层。相反，41.3%的 HMII 前轴承上有血栓，这些形成物往往是红色且分层的，表明它们随着时间的推移分层形成。此外，在前轴承和出口轴承/定子区域观察到的大多数血栓基本上是部分阻塞的。14 例 VAD 在多个区域出现了 PT，数据分析显示前轴承沉积与随后的出口轴承/定子血栓形成之间存在统计学显著相关性（p<0.01）；然而，其他区域没有显示出统计学上显著的相关性。这一结果支持了这样的假设，即在 HMII 的血流途径的多个区域中，血栓不会独立发生，而是可能向下游传播。
