Aghilinejad Arian, Wei Heng, Magee Gregory A, Pahlevan Niema M
Department of Aerospace and Mechanical Engineering, University of Southern California, Los Angeles, CA, United States.
Division of Vascular Surgery and Endovascular Therapy, Department of Surgery, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States.
Front Bioeng Biotechnol. 2022 Jun 23;10:825015. doi: 10.3389/fbioe.2022.825015. eCollection 2022.
Thoracic endovascular aortic repair (TEVAR) is a commonly performed operation for patients with type B aortic dissection (TBAD). The goal of TEVAR is to cover the proximal entry tear between the true lumen (TL) and the false lumen (FL) with an endograft to induce FL thrombosis, allow for aortic healing, and decrease the risk of aortic aneurysm and rupture. While TEVAR has shown promising outcomes, it can also result in devastating complications including stroke, spinal cord ischemia resulting in paralysis, as well as long-term heart failure, so treatment remains controversial. Similarly, the biomechanical impact of aortic endograft implantation and the hemodynamic impact of endograft design parameters such as length are not well-understood. In this study, a fluid-structure interaction (FSI) computational fluid dynamics (CFD) approach was used based on the immersed boundary and Lattice-Boltzmann method to investigate the association between the endograft length and hemodynamic variables inside the TL and FL. The physiological accuracy of the model was evaluated by comparing simulation results with the true pressure waveform measurements taken during a live TEVAR operation for TBAD. The results demonstrate a non-linear trend towards increased FL flow reversal as the endograft length increases but also increased left ventricular pulsatile workload. These findings suggest a medium-length endograft may be optimal by achieving FL flow reversal and thus FL thrombosis, while minimizing the extra load on the left ventricle. These results also verify that a reduction in heart rate with medical therapy contributes favorably to FL flow reversal.
胸主动脉腔内修复术（TEVAR）是治疗B型主动脉夹层（TBAD）患者的常用手术。TEVAR的目的是用血管内移植物覆盖真腔（TL）和假腔（FL）之间的近端入口撕裂，以诱导假腔血栓形成，促进主动脉愈合，并降低主动脉瘤和破裂的风险。虽然TEVAR已显示出良好的效果，但它也可能导致严重的并发症，包括中风、脊髓缺血导致的瘫痪以及长期心力衰竭，因此治疗仍存在争议。同样，主动脉内移植物植入的生物力学影响以及移植物设计参数（如长度）的血流动力学影响尚未得到充分理解。在本研究中，基于浸入边界和格子玻尔兹曼方法，采用流固耦合（FSI）计算流体动力学（CFD）方法来研究移植物长度与真腔和假腔内血流动力学变量之间的关系。通过将模拟结果与TBAD患者实时TEVAR手术期间采集的真实压力波形测量值进行比较，评估模型的生理准确性。结果表明，随着移植物长度的增加，假腔血流逆转呈非线性增加趋势，但左心室搏动负荷也增加。这些发现表明，中等长度的移植物可能是最佳选择，既能实现假腔血流逆转从而形成假腔血栓，又能将左心室的额外负荷降至最低。这些结果还证实，药物治疗降低心率有利于假腔血流逆转。
