Numerical Simulation On Hemodynamics Of Total Cavopulmonary Connection

Computational Fluid Dynamics?CFD?can be used to help predict the postoperative treatment effect,and the hemodynamic study of Total Cavopulmonary Connection?TCPC?can provide theoretical support for the optimal clinical surgical plan.In this study,CT image data of patients,CFD simulation and multi-scale coupling boundaries were used to study the hemodynamic differences between the extracardiac conduit?EC?technique and the direct cavopulmonary connection?DCPC?technique in TCPC,as well as the hemodynamic effects of the connection of extracardiac conduit and additional pulmonary blood flow?APBF?.Based on the surgical methods and the postoperative three-dimensional vascular model of patients,the differences of the postoperative vascular structure between EC and DCPC and the effect of these differences on hemodynamics were studied.The result showed that a single difference in vascular structure could lead to a maximum of 45.22%,0.34%and 69.61%change in the power loss of blood flow?PL?,the left pulmonary artery shunt ratio of pulmonary flow(PFD_LPA)and the left pulmonary artery shunt ratio of hepatic flow(HFD_LPA),respectively.However,the overall structural differences between EC and DCPC did not cause significant differences in PL,PFD_LPAand HFD_LPA.According to the CT image data of patients with double superior vena cava and the recommendations of clinical surgeons,different extracardiac conduit connections were virtually designed.Under different blood flow pulsation conditions,the hemodynamic differences of them and the main factors causing these differences were analyzed,combined with the influence of vascular structure on hemodynamics.The result showed that the offset connection between the superior and inferior vena cava is the main factor causing the hemodynamic differences.Connecting the extracardiac conduit between the left and right superior vena cava resulted in an optimal PL?38%less than the maximum?and HFD_LPA?the value is 48.2%and the ideal value is 50%?,but it will cause local flow velocity and wall shear stress to decrease.The hemodynamic effects of APBF on Glenn and Fontan circulation were studied for the vascular models with single superior vena cava and double superior vena cava,respectively.The result showed that APBF led to better power loss index of blood flow and systemic arterial oxygen saturation but worse superior vena cava pressure and heart load.The maximum decrease of power loss index of blood flow was 72%.The maximum increase of systemic arterial oxygen saturation,superior vena cava pressure and heart load was 15.2%,20%and 36%,respectively.The increase in APBF also effectively results in better flow pulsation,region velocity,wall shear stress and the residence time of fluid micelle,all of which have a protective effect against endothelial dysfunction and thrombosis.