Restenosis typically occurs in regions of low and oscillating wall shear stress, which also favor the accumulation of atherogenic macromolecules such as low-density lipoprotein (LDL). This study aims to evaluate LDL transport and accumulation at the carotid artery bifurcation following carotid artery stenting (CAS) by means of computational simulation. The computational model consists of coupled blood flow and LDL transport, with the latter being modeled as a dilute substance dissolved in the blood and transported by the flow through a convection-diffusion transport equation. The endothelial layer was assumed to be permeable to LDL, and the hydraulic conductivity of LDL was shear-dependent. Anatomically realistic geometric models of the carotid bifurcation were built based on pre- and post-stent computed tomography (CT) scans. The influence of stent design was investigated by virtually deploying two different types of stents (open- and closed-cell stents) into the same carotid bifurcation model. Predicted LDL concentrations were compared between the post-stent carotid models and the relatively normal contralateral model reconstructed from patient-specific CT images. Our results show elevated LDL concentration in the distal section of the stent in all post-stent models, where LDL concentration is 20 times higher than that in the contralateral carotid. Compared with the open-cell stents, the closed-cell stents have larger areas exposed to high LDL concentration, suggesting an increased risk of stent restenosis. This computational approach is readily applicable to multiple patient studies and, once fully validated against follow-up data, it can help elucidate the role of stent strut design in the development of in-stent restenosis after CAS.

中文翻译：

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支架植入后颈动脉分叉处低密度脂蛋白积累的计算模型


再狭窄通常发生在壁剪切应力低且振荡的区域，这也有利于低密度脂蛋白（LDL）等致动脉粥样硬化大分子的积累。本研究旨在通过计算模拟评估颈动脉支架置入术 (CAS) 后颈动脉分叉处的 LDL 转运和积累。该计算模型由耦合的血流和低密度脂蛋白运输组成，后者被建模为溶解在血液中的稀释物质，并通过对流扩散运输方程由血流运输。假设内皮层可渗透 LDL，并且 LDL 的水力传导率与剪切力相关。根据支架植入前和植入后计算机断层扫描 (CT) 扫描，建立了颈动脉分叉的解剖学真实几何模型。通过将两种不同类型的支架（开孔和闭孔支架）虚拟部署到同一颈动脉分叉模型中，研究了支架设计的影响。将支架后颈动脉模型与根据患者特异性 CT 图像重建的相对正常对侧模型之间的预测 LDL 浓度进行比较。我们的结果显示，在所有支架植入后模型中，支架远端部分的 LDL 浓度均升高，其中 LDL 浓度比对侧颈动脉高 20 倍。与开孔支架相比，闭孔支架暴露于高LDL浓度的面积更大，表明支架再狭窄的风险增加。这种计算方法很容易适用于多个患者的研究，一旦根据随访数据得到充分验证，它可以帮助阐明支架支柱设计在 CAS 后支架内再狭窄发展中的作用。