De Santis G, Conti M, Trachet B, De Schryver T, De Beule M, Degroote J, Vierendeels J, Auricchio F, Segers P, Verdonck P, Verhegghe B
BiTech-bioMMeda, Ghent University, Ghent, Belgium.
Comput Methods Biomech Biomed Engin. 2013;16(6):648-59. doi: 10.1080/10255842.2011.629997. Epub 2011 Dec 8.
Carotid artery stenting (CAS) has emerged as a minimally invasive alternative to endarterectomy but its use in clinical treatment is limited due to the post-stenting complications. Haemodynamic actors, related to blood flow in the stented vessel, have been suggested to play a role in the endothelium response to stenting, including adverse reactions such as in-stent restenosis and late thrombosis. Accessing the flow-related shear forces acting on the endothelium in vivo requires space and time resolutions which are currently not achievable with non-invasive clinical imaging techniques but can be obtained from image-based computational analysis. In this study, we present a framework for accurate determination of the wall shear stress (WSS) in a mildly stenosed carotid artery after the implantation of a stent, resembling the commercially available Acculink (Abbott Laboratories, Abbott Park, Illinois, USA). Starting from angiographic CT images of the vessel lumen and a micro-CT scan of the stent, a finite element analysis is carried out in order to deploy the stent in the vessel, reproducing CAS in silico. Then, based on the post-stenting anatomy, the vessel is perfused using a set of boundary conditions: total pressure is applied at the inlet, and impedances that are assumed to be insensitive to the presence of the stent are imposed at the outlets. Evaluation of the CAS outcome from a geometrical and haemodynamic perspective shows the presence of atheroprone regions (low time-average WSS, high relative residence time) colocalised with stent malapposition and stent strut interconnections. Stent struts remain unapposed in the ostium of the external carotid artery disturbing the flow and generating abnormal shear forces, which could trigger thromboembolic events.
颈动脉支架置入术（CAS）已成为一种替代动脉内膜切除术的微创方法，但由于支架置入术后的并发症，其在临床治疗中的应用受到限制。有研究表明，与支架置入血管内血流相关的血流动力学因素在支架置入后内皮反应中发挥作用，包括支架内再狭窄和晚期血栓形成等不良反应。在体内获取作用于内皮的与血流相关的剪切力需要空间和时间分辨率，目前非侵入性临床成像技术无法实现，但可通过基于图像的计算分析获得。在本研究中，我们提出了一个框架，用于精确测定植入类似市售Acculink（美国伊利诺伊州雅培公园雅培实验室）的支架后轻度狭窄颈动脉中的壁面剪切应力（WSS）。从血管腔的血管造影CT图像和支架的微型CT扫描开始，进行有限元分析，以便在血管中部署支架，在计算机模拟中再现CAS。然后，根据支架置入后的解剖结构，使用一组边界条件对血管进行灌注：在入口处施加总压力，在出口处施加假定对支架存在不敏感的阻抗。从几何和血流动力学角度对CAS结果的评估显示，易形成动脉粥样硬化的区域（低时间平均WSS、高相对停留时间）与支架贴壁不良和支架支柱互连部位共定位。支架支柱在颈外动脉开口处仍未贴壁，扰乱血流并产生异常剪切力，这可能引发血栓栓塞事件。
