内管道Fontan术虚拟手术的血流动力学研究

A computational study for the surgical design of intra-atrial conduit Fontan procedure

目的研究内管道Fontan手术中上腔静脉中线与心内管道中线之间(定义为Offset)的最佳距离并比较不同Offeet对血流动力学的影响。方法收集心内管道Fontan患儿术后心脏磁共振影像资料,通过三维立体建模、虚拟手术技术以及血流动力学模拟,探究不同Offset距离(相当于下腔静脉直径的0、33%、 67%和100%)对血管壁剪切力、血流分布、肝血流分配比以及能量损失等血流动力学参数的影响。结果 Offset为0时,患儿左肺动脉起始段存在异常高剪切力区域;同时,在上腔静脉、心内管道连接肺动脉处存在螺旋状涡流。Offset从0至100%相对应的能量损失分别为69.96 mW,50.52 mW,58.00 mW和62.94 mW;肝血流分配(左肺动脉/右肺动脉)分别为65%: 35%、60%: 40%、55%: 45%、55%: 45%。结论不同Offset对心内管道Fontan手术血流动力学有显著的影响。综合血管壁剪切力、血流分布、肝血流分配比以及能量损失等指标,Offset 33%为该患儿最佳Offset距离。

Objective To identify the desirable distance, defined as the Offset, between the central line of the superior vena cava (SVC) and the conduit using virtual surgery after an intraatrial conduit (IAC) Fontan procedure. Methods Three-dimensional model of IAC Fontan was reconstructed according to the MRI of one patient. Then three models with different Offsets relative to the SVC, equaling to 100%, 67%, 33% and 0 of the diameter of the IVC were reconstructed. Computational fluid dynamics (CFD) were performed in each model to predict the best hemodynamic performance, including streamlines of blood flow, wall shear stress (WSS), energy loss (EL) and the hepatic flow distribution ratio(HFD). Results High WSS was detected with an Offset 0 at the start of the left pulmonary artery;low speed swirls were observed near the anastomosis site of the SVC-PA and the conduit-PA. From Offset 0 to 100%, the EL was 69.96 mW, 50.52 mW, 58.00 mW and 62.94 mW respectively;HFD (LPA/RPA) was 65%: 35%, 60%: 40%, 55%: 45%, 55%: 45%, respectively. Conclusion The Offset distance influences hemodynamic performance after an IAC Fontan procedure. Considering several hemodynamic parameters, the best trade-off between velocity profile, pulmonary perfusion and energy efficiency was achieved at an Offset of 33%.