針對單一心室心臟缺陷(Single Ventricle Heart Defects, SVHD)病患，可採取適當地階段性緩解(Palliative)手術來改善其血流動力學，其中最後階段的全腔靜脈肺動脈吻合術(Total Cavopulmonary Connection, TCPC)能重建動、靜脈血流的分流，達到體、肺循環分離及減少心室負擔的目的。但重建後的生理循環可能引起靜脈回流壓力(Venous Return Pressure)升高或左心前負荷(Preload)減少的問題，長此以往，可能造成蛋白質流失性腸病(Protein Losing Enteropathy)、肝水腫(Hepatic Congestion)、血栓栓塞(Thromboembolism)與運動能力降低(Diminished Exercise Capacity)等術後遠期併發症。本研究旨在發展包含三維TCPC血管模型與描述體肺循環之區塊參數模型(Lumped-Parameter Model)的混合式循環模型(Hybrid Circulation Model)，並進行 TCPC血流動力特徵之探討。其中，三維流場模擬是採用 Ansys Fluent的隱式SIMPLE演算法來進行求解，並透過使用者自定義函數(User-Defined Function, UDF)來和區塊參數模型作結合，而區塊參數模型則是以顯式的四階 Runge-Kutta 法來進行時間步進(Time Stepping)。本研究成功驗證了混合式循環模型於TCPC三維血流動力模擬的收斂性，並探討在不同TCPC的吻合方式上對於流場功率損失的影響，由模擬結果得到因為腔靜脈的回流速度較小，因此對於TCPC流場的功率損失並無明顯的差異。

Hemodynamics improvement in patients with single ventricle heart defects could be accomplished by palliative surgical procedure. The purpose of the final stage surgery in total cavopulmonary connection is to reconstruct the arteriovenous shunt, as well as to separating systemic and pulmonary circulation and reduce ventricular loading. However, the increase in venous return pressure or decrease in left ventricular preload are common in these physiological circulation reconstruction, and ultimately lead to protein losing enteropathy, hepatic congestion, thromboembolism and diminished exercise capacity. It is important to optimize the TCPC flow to mitigate the abovementioned complications. Computational Fluid Dynamics has been adopted as the major analysis tool, in which both flow model and boundary condition specification are crucial. The present research proposed a hybrid circulation simulation model consisting of a continuous three-dimensional flow model and a lumped-parameter model. Three-dimensional flow field simulation uses Ansys Fluent with implicit SIMPLE algorithms in conjunction with a user-defined function to combine lumped-parameter model as the terminal boundary conditions. The lumped-parameter model is solved based on explicit fourth-order Runge-Kutta method for time stepping. A special iterative procedure connecting the Fluent solver and the lumped-parameter system is developed. The hybrid circulation model in three-dimensional hemodynamic simulation was successfully validated. The simulation results show that, for the studied cases, there is no significant difference in power loss for TCPC flow field due to velocity of venous return is too small.

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