冠状动脉狭窄对血管血流动力学的影响

目的运用计算流体动力学技术,模拟冠状动脉不同狭窄程度的血流动力学变化,探索冠状动脉血流动力学变化和血流分布与冠状动脉不同狭窄病变的关系。方法以正常人右冠状动脉CT图像数据为基础,重建冠状动脉几何模型,人工建立狭窄程度分别为0%(正常)、30%(轻度狭窄)、60%(中度狭窄)和90%(重度狭窄)的4种血管模型,并分别构建血管血流动力学模型,最后分别进行数值模拟,分析比较4种血管模型血流动力学的差别。结果通过比较4种血管模型的血流动力学数值模拟可发现,随着冠状动脉狭窄程度增加,狭窄远心端血流涡旋愈加明显,狭窄处血流速度以及狭窄前血管壁面压力(WP)逐渐增加,而狭窄远心端WP逐渐下降;狭窄处壁面切应力(WSS)分布一直处于高值,并且当血管狭窄程度达到中重度狭窄,狭窄远心端血管可见明显的高WSS区域,而狭窄远心端血管其他区域呈现低WSS;狭窄前后血管血流速度以及血流分布也发生了改变。结论在CT图像上,可能能较准确重建出冠状动脉血流动力学模型,并模拟出不同狭窄程度冠状动脉模型。中重度冠状动脉狭窄远心端血流动力学表现为明显的血流涡旋以及高WSS区域,这种血流动力学变化可能会加重血管动脉粥样硬化,从而进一步加重血管狭窄。

Effect of different coronary artery stenosis on the hemodynamics

Aim The computational fluid dynamics (CFD) technique was used to simulate the changes of blood flow in different degrees of coronary artery stenosis, to explore the relationship between the change of coronary artery hemodynamics and different stenosis. Methods The right coronary arterial geometric model was reconstructed with CT images. The model of stenosis was defined as 0%(normal vascular), 30%(mildly stenosis), 60%( moderate stenosis) and 90%(severe stenosis), respectively. The model of vascular hemodynamics was established respectively. Numerical simulations were performed to compare the hemodynamics between the different vascular models. Results By comparing the hemodynamic numerical simulations of four kinds of stenosis, with the severe of the stenosis, the vortex flow becomes more obvious, the velocity of the flow showed faster in stenosis. In the proximal vascular region of stenosis, wall pressure (wall pressure, WP) was gradually increased; on the other hand, the WP showed lower in the region after the stenosis. The wall shear stress (WSS) distribution at the stenosis site always showed higher, and in the moderate and severe stenosis model, the high WSS region was found in the distal vascular region of stenosis, and the other distal vascular region of stenosis showed low WSS. Moreover, on the velocity and distribution of vascular blood flow, proximal and distal vascular region of the stenosis were also changed. Conclusion CFD based on CT images maybe reconstruct the coronary arterial hemodynamic model accurately, and the coronary arterial hemodynamic model with diverse stenosis may simulate coronary arterial stenosis. As hemodynamic risk factors, the vortex of stenosis posterior flow and the high WSS in the distal vascular region of stenosis which showed in moderate and sever stenosis model maybe aggravated atherosclerosis of coronary artery, and further aggravated the vascular stenosis.