Fontan术血流动力学非牛顿特性研究

Hemodynamic Study on Non-Newtonian Properties of Fontan Procedure

目的分析计算模拟中血液非牛顿特性对Fontan术后血流动力学的影响。方法基于Fontan术后患者个体化三维血管模型,临床超声实测数据作为边界条件,分别选取常用的牛顿流体模型、非牛顿流体模型中的Casson模型与Carreau模型进行血流动力学模拟,计算血流分配比、能量损失、壁面切应力、非牛顿重要性系数等血流动力学参数,比较不同流体模型之间血流动力学参数差异。结果流体模型对血流分配比影响小,非牛顿流体模型的能量损失较牛顿流体模型高,其中Casson模型最高。在下腔静脉中有明显回流、血流扰乱区域,并伴有低壁面切应力分布。在低流速时,牛顿流体模型下腔静脉血流扰乱更明显。非牛顿重要性系数显示在下腔静脉的非牛顿特性显著。结论非牛顿特性在下腔静脉的低速回流区域影响显著,模拟患者个体化的Fontan血流动力学时应考虑血液的非牛顿特性。

Objective To investigate the effects of non-Newtonian properties on hemodynamic characteristics of Fontan procedure in computational simulation.Methods A Fontan vascular model was reconstructed based on patient-specific medical images.The boundary conditions were set according to velocity profiles measured by real-time echocardiography.The Newtonian model and two non-Newtonian(Casson and Carreau)models were applied to analyze the hemodynamic parameters,including flow ratio(FR),energy loss(EL),wall shear stress(WSS)as well as non-Newtonian importance factor,so as to compare flow differences between the Newtonian model and non-Newtonian models.Results The rheological models had small effects on the FR.The EL of non-Newtonian models was higher than that of the Newtonian model,and the EL of Casson model was the highest.Flow recirculation and flow disturbance accompanied with low WSS were observed in inferior vena cava(IVC).At low inflow velocity,flow disturbance in IVC of Newtonian model was more obvious.The calculations of non-Newtonian importance factor suggested significant non-Newtonian viscosity in IVC.Conclusions Non-Newtonian viscosity is significant in IVC where low velocity and flow recirculation are observed.Non-Newtonian properties of the blood should be considered in patient-specific hemodynamic simulation of Fontan procedure.