基于VLBM的髂外动脉血流动力学分析

Hemodynamic analysis of external iliac artery based on VLBM

为探索无创测量在狭窄髂外动脉血流动力学中的应用,使用自编的基于图形处理器(graphics processing unit,GPU)并行架构的体积格子玻尔兹曼方法(volumetric lattice Boltzmann method,VLBM)对狭窄髂外动脉进行模拟。首先从计算机断层扫描血管造影(computed tomography angiography,CTA)中提取髂外动脉模型;其次设定边界条件,其中入口为多普勒超声检测的脉动流,出口为基于三元windkessel模型的压力出口;最后将模拟结果与有创动脉血压(invasive blood pressure,IBP)直接测得的结果进行对比,发现二者吻合度较高,血压的相对误差在1%左右,从而验证了VLBM应用于狭窄髂外动脉模拟的可行性。在此基础上,根据血流动力学分析狭窄和还原的髂外动脉的血流速度、血压和壁面切应力(wall shear stress,WSS)可得到以下结论:1)血流流经狭窄处后,流速增大并向动脉中心处汇聚,且髂外动脉狭窄对髂内动脉血流速度的影响可忽略不计;2)狭窄处的WSS更高,且高WSS分布区域的大小随血压变化而变化;3)狭窄处有明显的压降,压降会随着血流速度的增大而增大。髂外动脉的血流动力学分析可为相关髂外动脉疾病的临床无创计算辅助决策提供数据支持和理论依据。

In order to explore application of non-invasive measurements to hemodynamics of the stenotic external iliac artery,a self-designed volumetric lattice Boltzmann method(VLBM) based on graphics processing unit(GPU) parallel architecture was used to simulate the stenotic external iliac artery.Firstly,the external iliac artery model was extracted from computed tomography angiography(CTA);secondly,the boundary conditions were set,in which the inlet was the pulsating flow detected by Doppler ultrasound and the outlet was the pressure outlet based on the three-element windkessel model;finally,comparing the simulation results with the measured resultsof invasive blood pressure(IBP),the two results were found to have high degree of coincidence,with the relative error of the blood pressure about 1%,which has verified feasibility of VLBM in simulation of the stenotic external iliac artery.On this basis,according to the hemodynamic analysis,including blood flow velocity,blood pressure,and wall shear stress(WSS) of the stenotic and restored external iliac artery,the following conclusions can be drawn:1) the flow velocity increases and converges to the center of the artery after the blood flowing through the stenosis,when the external iliac artery stenosishas anegligible impact on the blood flow velocity of the internal iliac artery;2) the WSS in the stenosis is higher,and the size of the high WSS distribution area varies with the change of blood pressure;3) there’s a significant pressure drop in the stenosis,which increases with the rise of the blood flow velocity.The hemodynamic analysis of the external iliac artery can provide data support and theoretical basis for clinical non-invasive calculation-assisted decision-making of related external iliac artery disease.