Purpose

Existing hemodynamic studies on aortic dissection after thoracic endovascular aortic repair (TEVAR) apply geometric simplifications. This study aims to evaluate the necessity of more accurate geometries at the proximal landing zone in computational fluid dynamic (CFD) studies.

Methods

Three patient-specific 3D aortic dissection models with different geometric accuracies at the proximal landing zone were manually fabricated for CFD simulations: (i) model 1 without the stent graft (SG), (ii) model 2 with the metal stent, and (iii) model 3 with the SG. The flow distribution, flow pattern, and wall shear stress (WSS)-related indicators in these three models were compared.

Results

The flow distributions were quite similar for the three models, with a maximum absolute difference of 0.27% at the left suclavian artery (LSA) between models 1 and 3 because of partial coverage. A more chaotic flow pattern was observed at the proximal landing zone in model 3, with significant regional differences in the WSS-related indicator distributions. The upstream and downstream WSS-related indicator distributions were quite similar for the three models.

Conclusions

The flow pattern and hemodynamic parameter distributions were affected by the geometric accuracy only in a small region near the proximal landing zone. The flow split was hardly affected by the LSA partial coverage, indicating that the coverage may have slight effects on short-term blood perfusion. However, this conclusion needs to be verified in future studies with larger sample sizes.

中文翻译：

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近端着陆区的几何精度对胸腔血管内修复患者模拟结果的影响

目的

现有的关于胸主动脉腔内修复术 (TEVAR) 后主动脉夹层的血流动力学研究应用了几何简化。本研究旨在评估计算流体动力学 (CFD) 研究中近端着陆区更精确几何形状的必要性。

方法

为 CFD 模拟手动制作了三个在近端着陆区具有不同几何精度的患者特定 3D 主动脉夹层模型：（i）没有覆膜支架（SG）的模型 1，（ii）具有金属支架的模型 2，以及（iii） ) 带 SG 的模型 3。比较了这三种模型中的流动分布、流型和壁面剪应力（WSS）相关指标。

结果

三个模型的流量分布非常相似，由于部分覆盖，模型 1 和模型 3 之间的左下锁骨动脉 (LSA) 的最大绝对差异为 0.27%。在模型 3 的近端着陆区观察到更混乱的流动模式，WSS 相关指标分布具有显着的区域差异。三个模型的上游和下游 WSS 相关指标分布非常相似。

结论

流动模式和血液动力学参数分布仅在近端着陆区附近的小区域中受几何精度的影响。LSA部分覆盖几乎不影响分流，表明覆盖可能对短期血液灌注有轻微影响。然而，这一结论需要在未来更大样本量的研究中得到验证。