基于计算流体力学技术的胸主动脉瘤血流动力学研究

目的 探讨基于计算流体力学技术的个体化胸主动脉瘤的血流动力学模型在胸主动脉瘤生长、破裂机制研究中的作用.方法 用Mimics软件读取患者CT血管造影医学数字成像和通讯标准(DICOM)数据,重建三维个体化胸主动脉瘤模型,假设动脉血流为层流、不可压缩、牛顿流体,入口血液流速随时间周期性变化,应用有限体积法FLUENT软件进行非定常血流数值模拟,分析与动脉瘤生长、破裂相关的血流动力学参数.结果 数值结果得到胸主动脉瘤在心动周期不同时刻的血流速度及壁切应力分布.收缩期近端瘤颈的血流速度显著高于扩张的动脉瘤体的血流速度,射血进入动脉瘤,冲击动脉瘤体近端的外侧壁.动脉瘤内的射血峰值瞬时流线显示血流冲击动脉瘤壁,瘤体内观察到呈右手螺旋的涡流.高切应力分布于近、远端瘤颈以及血流直接冲击动脉瘤壁的位置,瘤体呈大范围的的低切应力分布.结论 重建的个体化胸主动脉瘤模型,用于血流动力学数值模拟研究,可分析胸主动脉瘤生长、破裂机制.

Hemodynamic study of thoracic aortic aneurysm based on computational fluid dynamics technique

Objective To establish a patient-specific hemodynamics model of thoracic aortic aneurysm (TAA) based on computational fluid dynamics technique and investigate its role in the study of growth and rupture mechanism of TAA.Methods 3D realistic model of thoracic aortic aneurysm was reconstructed from DICOM format computed tomography angiography (CTA) images of a male patient.The geometry was reconstructed using medical image processing software Mimics.The blood flow in aorta was assumed to be laminar and incompressible and the blood Newtonian fluid.A time-dependent pulsatile boundary condition was deployed at inlet.Unsteady blood flow simulation was performed in real geometry of TAA with a finite volume method (FVM) code FLUENT.The hemodynamic parameters related with the growth and rupture of aneurysm were analyzed.Results Analysis of the distributions of hemodynamic variables during the cardiac cycle such as wall shear stress,streamlines and velocity profiles in TAA were carried out.The numerical simulation results demonstrated that the blood velocity of proximal neck was considerably faster than that of aneurysm body.The outerwall of proximal aneurysm body was hit by blood jet entering aneurysm.Instant streamlines at peak systole showed that the entering blood stream hit the aneurysm wall and right-hand helical vortex was observed in aneurysm body.The distributions of high wall shear stress were observed in the proximal and distal aneurysm neck and the area where the entering blood stream first hit the wall.Large regions of lower wall shear stress occurred in aneurysm body.Conclusion The growth and rupture mechanisms of TAA may be analyzed based on a constructed patient-specific model and hemodynamic simulation.