目的 通过有限元仿真探索带有辅助搭桥血管模式的冠状动脉搭桥术中,辅助搭桥管吻合口与冠状动脉狭窄处之间的距离对该吻合口及其下游区域的血流动力学影响,为带有辅助搭桥管的新型冠状动脉搭桥术的临床应用提供理论指导.方法 利用有限元分析方法,假定血液为不可压缩牛顿流体,建立3种搭桥血管模型,其冠状动脉上吻合口和狭窄的距离分别为0.0045 m、0.006 m和0.009 m.通过仿真结果考察不同模型中的血流速度、壁面切应力等参数的变化.结果 吻合口与狭窄处之间的距离不同,冠状动脉血管内的血流动力学参数也不相同.速度方面,心动周期0.09 s时刻L1.5模型中吻合口足跟处轴向截面的最大速度约为0.54 m/s,同时刻L2和L3模型中其最大速度分别为0.45 m/s和0.37 m/s.壁丽切应力方面,0.09 s时刻,L1.5模型中吻合口对应面的血管壁上其流动停滞点距离吻合口足跟仅为0.0024 m,同时刻L2和L3模型中其流动停滞点距离足跟处分别为0.0039 m和0.0068 m,长度明显增加.其他时刻流动停滞点分布有相同趋势.结论 在实施冠状动脉搭桥术时,吻合口与狭窄处之间保持较大的距离,有利于改善吻合口处的血流动力学环境,降低吻合口处发生再狭窄的可能性.

Objective Modified B-T shunt(MBTS) and central shunt(CS) are two common surgical procedures for the treatment of tetralogy of fallot(TOF).The purpose is to analyze and compare the hemodynamic features of MBTS and CS.Methods 3D anatomy was reconstructed by medical images obtained from a patient with TOF,and two computational models were generated through virtual operations.A lumped parameter model was constructed to predict the post-operational boundary conditions.Computational fluid dynamics(CFD) was performed for the two models.Results A persistent pulmonary blood perfusion was observed in each model both during the systolic phase and diastolic phase,but the maximum velocities in the shunt were different for the two models.The pressure drop of the shunt in CS model was higher than that in MBTS model.The wall shear stress of the shunt in the MBTS model ranged unevenly from 0.025 to 340 Pa,while the wall shear stress in CS model ranged relatively evenly from 32.2 to 72.6 Pa.Conclusions Pulmonary artery blood was increased effectively for both options.The blood perfusion of right upper extremity was decreased in the MBTS model.More blood was directed into the pulmonary artery in CS model.Attention should be paid to the fact that the pressure gradient was large at the proximal anastomosis in both models in clinic.This study provides important theoretical references for surgeons to make choice from the surgery options in the treatment with TOF.