Numerical Study On Hemodynamics Of Systemic-to-pulmonary Shunt Based On Multi-scale And Muti-dimension

With the continuous progress of computer technology,medical imaging technology and medical image processing software,the application of computational fluid dynamics（CFD）in cardiovascular system gradually accepted by clinical practice.The hemodynamic numerical simulation based on the patient-specific vascular anatomy and blood flow conditions can effectively improve the clinicial decision-making process.In this study,a multi-scale and multi-dimensional coupling method was used to study the effects of different shunt configurations,shunt diameters and pulmonary artery stenosis on hemodynamics,which provided a theoretical basis for surgical decision-making and disease prevention.Based on the preoperative CT of patients with pulmonary atresia,three different shunt configurations,CS,left mBT and right mBT,were constructed.The hemodynamic differences of three different shunt configurations in different shunt diameters,such as 3,3.5,4,4.5 and 5mm,were compared and analyzed.The results show that the left and right pulmonary artery blood flow of CS is more uniform,which is conducive to the balanced development of pulmonary artery.The CS model and Right mBT model have higher power conversion efficiency compared with Left mBT.When the shunt diameter is 5 mm,the power conversion efficiency of CS model and right mBT model were 73.2%and 72.9%respectively.When the shunt diameter increased from 3mm to 5mm,the range of oxygen delivery was 210.4 m L/min-180.1 m L/min.Increasing the shunt diameter is conducive to increasing pulmonary blood flow and promoting the development of pulmonary arteries.However,with the increase of the shunt diameter,the oxygen delivery of the three kinds of shunt configurations decreased gradually.On the premise of preserving the additional pulmonary blood flow,the degree of pulmonary artery stenosis was defined by the ratio of additional pulmonary blood flow to cardiac output.The effects of different shunt diameters（3,3.5,4,4.5 and 5 mm）and the degree of pulmonary artery stenosis（α=5%,10%,15%and 20%）on the hemodynamics of CS were studied.The results showed that with the increase ofα,the power loss decreased dramatically.Whenαwas increased from 5%to 20%,the power loss decreased more than 29%.Compared withα,the shunt diameter has no significant effect on the power loss,but the power conversion efficiency is significantly increased with the increase of shunt diameter.When the shunt diameter is 5mm,the power conversion efficiency is higher than 74.4%.The effects of different shunt diameters and pulmonary artery stenosis on hemodynamics of Left mBT and Right mBT configurations were studied.The results show that Left mBT model has a more uniform distribution of left and right pulmonary artery blood flow compared with the right mBT model.The ratio of Q_LPA/RPA is 0.95-1.07,which means that left mBT mode is condutive to the balanced development of pulmonary artery.Increasing the shunt diameter andαwill reduce the oxygen deliverey and improve power conversion efficiency.In general,the Left mBT model has higher oxygen delivery,while the Right mBT model has high power conversion efficiency.