From the Department of Mechanical Engineering, University of Washington, Seattle, WA.
Division of Cardiology, University of Washington, Seattle, WA.
ASAIO J. 2020 Jul;66(7):766-773. doi: 10.1097/MAT.0000000000001068.
Left ventricular assist device (LVAD) use has continued to grow. Despite recent advances in technology, LVAD patients continue to suffer from devastating complications, including stroke and device thrombosis. Among several variables affecting thrombogenicity, we hypothesize that insertion depth of the inflow cannula into the left ventricle (LV) influences hemodynamics and thrombosis risk. Blood flow patterns were studied in a patient-derived computational model of the LV, mitral valve (MV), and LVAD inflow cannula using unsteady computational fluid dynamics (CFD). Hundreds of thousands of platelets were tracked individually, for two inflow cannula insertion depth configurations (12 mm-reduced and 27 mm-conventional) using platelet-level (Lagrangian) metrics to quantify thrombogenicity. Particularly in patients with small LV dimensions, the deeper inflow cannula insertion resulted in much higher platelet shear stress histories (SH), consistent with markedly abnormal intraventricular hemodynamics. A larger proportion of platelets in this deeper insertion configuration was found to linger in the domain for long residence times (RT) and also accumulated much higher SH. The reduced inflow depth configuration promoted LV washout and reduced platelet SH. The increase of both SH and RT in the LV demonstrates the impact of inflow cannula depth on platelet activation and increased stroke risk in these patients. Inflow cannula depth of insertion should be considered as an opportunity to optimize surgical planning of LVAD therapy.
左心室辅助装置（LVAD）的使用持续增长。尽管最近在技术上取得了进步，但 LVAD 患者仍继续遭受破坏性并发症的困扰，包括中风和设备血栓形成。在影响血栓形成的几个变量中，我们假设流入套管插入左心室（LV）的深度会影响血液动力学和血栓形成风险。使用非定常计算流体动力学（CFD）在患者来源的 LV、二尖瓣（MV）和 LVAD 流入套管的计算模型中研究了血流模式。使用血小板级（拉格朗日）指标跟踪了数十万个体血小板，用于两种流入套管插入深度配置（12 毫米-减少和 27 毫米-常规），以量化血栓形成性。特别是在 LV 尺寸较小的患者中，更深的流入套管插入导致更高的血小板剪切应力史（SH），与明显异常的室内血液动力学一致。在这种更深的插入配置中，发现更大比例的血小板在较长的停留时间（RT）内徘徊，并且还积累了更高的 SH。减少的流入深度配置促进了 LV 的冲洗并降低了血小板 SH。LV 中 SH 和 RT 的增加表明流入套管深度对血小板激活和这些患者中风风险增加的影响。套管的插入深度应被视为优化 LVAD 治疗手术计划的机会。
