Department of Cardiothoracic Surgery, Stanford University School of Medicine, Stanford, Calif.
Department of Bioengineering, Stanford University, Stanford, Calif; Department of Pediatrics (Cardiology), Stanford University, Stanford, Calif.
J Thorac Cardiovasc Surg. 2021 Nov;162(5):1556-1563. doi: 10.1016/j.jtcvs.2020.04.164. Epub 2020 May 15.
Aortic incompetence (AI) is observed to be accelerated in the continuous-flow left ventricular assist device (LVAD) population and is related to increased mortality. Using computational fluid dynamics (CFD), we investigated the hemodynamic conditions related to the orientation of the LVAD outflow in these patients.
We identified 10 patients with new aortic regurgitation, and 20 who did not, after LVAD implantation between 2009 and 2018. Three-dimensional models of patients' aortas were created from their computed tomography scans. The geometry of the LVAD outflow graft in relation to the aorta was quantified using azimuth angles (AA), polar angles (PAs), and distance from aortic root. The models were used to run CFD simulations, which calculated the pressures and wall shear stress (rWSS) exerted on the aortic root.
The AA and PA were found to be similar. However, for combinations of high values of AA and low values of PA, there were no patients with AI. The distance from aortic root to the outflow graft was also smaller in patients who developed AI (3.39 ± 0.7 vs 4.07 ± 0.77 cm, P = .04). There was no significant difference in aortic root pressures in the 2 groups. The rWSS was greater in AI patients (4.60 ± 5.70 vs 2.37 ± 1.20 dyne/cm, P < .001). Qualitatively, we observed a trend of greater perturbations, regions of high rWSS, and flow eddies in the AI group.
Using CFD simulations, we demonstrated that patients who developed de novo AI have greater rWSS at the aortic root, and their outflow grafts were placed closer to the aortic roots than those patients without de novo AI.
在连续血流左心室辅助装置（LVAD）人群中观察到主动脉功能不全（AI）加速，并且与死亡率增加有关。我们使用计算流体动力学（CFD）研究了与这些患者 LVAD 流出方向相关的血液动力学条件。
我们从 2009 年至 2018 年接受 LVAD 植入的患者中确定了 10 例新出现主动脉瓣反流患者和 20 例无主动脉瓣反流患者。使用患者的 CT 扫描创建主动脉的三维模型。使用方位角（AA）、极角（PA）和距主动脉根部的距离来量化 LVAD 流出移植物相对于主动脉的几何形状。对模型进行 CFD 模拟，计算施加在主动脉根部的压力和壁面切应力（rWSS）。
AA 和 PA 发现相似。但是，对于 AA 值高而 PA 值低的组合，没有 AI 患者。AI 患者的主动脉根部至流出移植物的距离也较小（3.39 ± 0.7 比 4.07 ± 0.77 cm，P = 0.04）。两组主动脉根部压力无显著差异。AI 患者的 rWSS 更大（4.60 ± 5.70 比 2.37 ± 1.20 dyne/cm，P < 0.001）。定性地，我们观察到 AI 组的 rWSS 更大，存在更大的扰动、高 rWSS 区域和流动涡流。
使用 CFD 模拟，我们证明了新出现 AI 的患者主动脉根部的 rWSS 更大，并且他们的流出移植物放置得比没有新出现 AI 的患者更靠近主动脉根部。
