冠状动脉分叉病变单支架植入术后血流动力学分析

Hemodynamic analysis of coronary bifurcation lesion of single stent implantation

目的分叉病变在即刻手术成功率及远期心脏事件方面是最具有挑战的冠脉病变之一。血流动力学对动脉粥样硬化的形成有重要影响。对分叉病变单支架虚拟植入后的血流动力学参数分布进行分析,探讨其对支架后再狭窄的影响,可为临床治疗提供理论依据。方法本文选取一例冠状动脉分叉病变患者的冠状动脉血管造影(computed tomography angiography,CTA)图像,首先用Mimic软件对所获得冠脉CTA数据进行三维重建得到冠脉血流区域,然后运用类似虚拟去除斑块的方式建立不均匀壁厚血管壁模型,对所得模型在ABAQUS中进行单支架虚拟植入,最后根据虚拟植入前、后的冠脉模型分别生成支架前和真实变形后的血流域有限元模型,并利用ANSYS软件通过瞬态CFD分析模拟动脉血流的流动状态,获得目标血管段的血流动力学参数。结果支架植入后与支架植入前相比,目标血管段的血液流速、壁面剪切应力均降低;支架植入后主支血管远端有振荡的低剪切应力区域;支架边缘位置壁面剪切应力低于其他位置;分支血管直径变小;分支外侧壁壁面剪切应力低于内侧壁。结论分叉病变的单支架植入可改善冠脉主支的狭窄,但术后主支血管远端振荡的低剪切应力区域、支架边缘和边支外侧壁处的低壁面剪切应力,以及斑块和分叉嵴的移位有可能是分叉病变再狭窄的血流动力学机制。

Objective Bifurcation lesions are one of the most challenging coronary lesions in terms of immediate surgical success and long-term cardiac events.Hemodynamics has an important influence on the formation of atherosclerosis.The analysis of hemodynamic parameters can provide a theoretical basis for clinical treatment through the analysis of the distribution of hemodynamic parameters and the hemodynamic mechanism of coronary artery restenosis after single stenting.Methods A computed tomography angiography(CTA)image of a patient with coronary artery bifurcation lesions was performed.The coronary blood flow region was first reconstructed by using Mimic software.The model of uneven wall thickness was established by using similar methods to remove plaque,and then was virtually inserted into the ABAQUS.Finally,the finite element models of before and after virtual implantation were generated,and the hemodynamic parameters of the coronary bifurcation were simulated by transient CFD analysis with ANSYS software.Results Compared with before stent implantation,both of the blood flow velocity and wall shear stress of the coronary bifurcation periphery decreased.The distal end of the main branch vessel had an oscillating region of low shear stress.The shear stress of the bifurcated outer sidewall was lower than that of the inner sidewall.Furthermore the stent at the main branch vessel induced the displacements of plaque and bifurcation crest.Conclusions Stenting of bifurcation lesions can improve the main branch vessel lumen.However the low shear stress in the regions of the main branch distal end and the side branch,even the displacement of plaques and bifurcation crest may be the hemodynamic mechanism of restenosis in bifurcation lesions.