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目的通过数值模拟仿真研究中央分流手术(central shunt,CS)的血流动力学环境,并分别研究弹性与刚性血管壁条件对其血管内血流动力学参数分布的影响。方法建立两个理想化的CS搭桥模型,其中一个假设为刚性血管壁,另一个为弹性血管壁。利用有限元方法进行数值计算,其中弹性血管壁模型采用流固耦合方法。结果两个模型中的流速和压力分布总体大致相同。刚性血管壁模型中大约有68.9%血液从主动脉分流进入肺动脉中,弹性血管壁模型中该值增加到了70%。弹性模型和刚性模型中搭桥血管两端的压降分别为7.668 8 kPa和7.222 3 kPa。弹性模型中搭桥管各处的横截面积有一定变化,最大变化率约为2.2%,出现在近心端吻合口处。提取两个模型中的5个关键区域进行壁面切应力比较,其数值差别最多约为16.1%。结论总体来说两个模型的血液流动形态没有大的改变;血管的弹性因素轻微影响了流量的分布和搭桥管两端的压降;搭桥管上血管的弹性对近心段吻合口处的影响高于对远心端吻合口处的影响。在CS术治疗法洛四联症的数值模拟仿真中血管壁为刚性这一假设是可以接受的,而流固耦合的数值模拟将得到更为可信的仿真结果。
Objective To study the hemodynamic environment of central shunt (CS) by numerical simulation and investigate the influence of elastic and rigid vascular wall conditions on the distribution of intravascular hemodynamic parameters. Methods Two idealized CS bypass models were established, one of which was assumed to be a rigid vessel wall and the other to a flexible vessel wall. The finite element method is used for numerical calculation, in which the elastic vascular wall model uses the fluid-structure coupling method. Results The flow and pressure distributions in both models are generally the same. Approximately 68.9% of the blood in the rigid vessel wall model shunts into the pulmonary artery from the aorta, an increase of 70% in the elastic vessel wall model. The pressure drop across the vessel in the elastic model and the rigid model are 7.668 8 kPa and 7.222 3 kPa, respectively. In the elastic model, the cross-sectional area of the bypass tube varies a little, and the maximum rate of change is about 2.2%, appearing at the anastomotic proximal end. Five critical sections of the two models were extracted for wall-shear stress comparison with a maximum of about 16.1% difference in value. CONCLUSIONS Overall, there was no major change in the blood flow patterns between the two models; the elastic properties of the blood vessels slightly affected the distribution of flow and the pressure drop across the bridge; the elasticity of the blood vessels in the bypass tube had a high effect on the proximal anastomosis Effect on distal anastomosis. It is acceptable to assume that the vascular wall is rigid in numerical simulation of tetralogy of Fallot (CS) surgery, and that the numerical simulation of fluid-structure interaction will yield more credible simulation results.