University Department of Radiology, Cambridge University Hospitals National Health Service Foundation Trust, United Kingdom.
J Stroke Cerebrovasc Dis. 2010 Mar;19(2):138-45. doi: 10.1016/j.jstrokecerebrovasdis.2009.03.014.
It remains controversial whether patients with severe disease of the internal carotid artery and a coexisting stenotic lesion downstream would benefit from a carotid endarterectomy (CEA) of the proximal lesion. The aim of this study was to simulate the hemodynamic and wall shear effects of in-tandem internal carotid artery stenosis using a computational fluid dynamic (CFD) idealized model to give insight into the possible consequences of CEA on these lesions.
A CFD model of steady viscous flow in a rigid tube with two asymmetric stenoses was introduced to simulate blood flow in arteries with multiple constrictions. The effect of varying the distance between the two stenoses, and the severity of the upstream stenosis on the pressure and wall shear stress (WSS) distributions on the second plaque, was investigated. The influence of the relative positions of the two stenoses was also assessed.
The distance between the plaques was found to have minimal influence on the overall hemodynamic effect except for the presence of a zone of low WSS (range -20 to 30 dyne/cm2) adjacent to both lesions when the two stenoses were sufficiently close (<4 times the arterial diameter). The upstream stenosis was protective if it was larger than the downstream stenosis. The relative positions of the stenoses were found to influence the WSS but not the pressure distribution.
The geometry and positions of the lesions need to be considered when considering the hemodynamic effects of an in-tandem stenosis. Low WSS is thought to cause endothelial dysfunction and initiate atheroma formation. The fact that there was a flow recirculation zone with low WSS in between the two stenoses may demonstrate how two closely positioned plaques may merge into one larger lesion. Decision making for CEA may need to take into account the hemodynamic situation when an in-tandem stenosis is found. CFD may aid in the risk stratification of patients with this problem.
严重的颈内动脉疾病患者和并存的下游狭窄病变是否受益于颈动脉内膜切除术（CEA）近端病变仍然存在争议。本研究旨在使用计算流体动力学（CFD）理想化模型模拟串联颈内动脉狭窄的血流动力学和壁面剪切效应，深入了解 CEA 对这些病变可能产生的影响。
引入了一个刚性管中具有两个不对称狭窄的稳态粘性流 CFD 模型，以模拟具有多个狭窄的动脉中的血流。研究了改变两个狭窄之间的距离以及上游狭窄的严重程度对第二个斑块上的压力和壁面剪切应力（WSS）分布的影响。还评估了两个狭窄的相对位置的影响。
发现斑块之间的距离除了在两个狭窄相邻处存在低 WSS 区（范围为 -20 至 30 达因/平方厘米）时对整体血流动力学效应的影响最小，当两个狭窄足够接近（<4 倍动脉直径）时。如果上游狭窄大于下游狭窄，则上游狭窄具有保护作用。狭窄的相对位置被发现会影响 WSS，但不会影响压力分布。
在考虑串联狭窄的血流动力学效应时，需要考虑病变的几何形状和位置。低 WSS 被认为会导致内皮功能障碍并引发动脉粥样硬化形成。两个狭窄之间存在低 WSS 的再循环流区可能表明两个紧密定位的斑块如何融合成一个更大的病变。在发现串联狭窄时，CEA 的决策可能需要考虑血流动力学情况。CFD 可能有助于对此类问题患者的风险分层。
