反動脈式(Counter-Pulsatile)循環輔助器中，不論是以主動脈內(Intra-Aortic)或主動脈外(Extra-Aortic)泵浦作動其流場特徵都非常不一樣。本文目的在研究經由與血管彈性相符(Compliance-Matching)的T型歧管當與主動脈之側主動脈血泵(Para-Aortic Blood Pump, PABP)橋接並作動所形成的流場現象，並希望藉由這種設計來減少因側接主動脈形成之複雜紊流所造成的血液及血管併發症。本研究使用計算流體力學(Computational Fluid Dynamics)商業軟體FLUENT及使用者定義(User-Defined)動態網格系統做流固藕合(Fluid-Structure Interaction)計算，將主動脈內腔的彈性結構與流體方程式共同結合以進行流固藕合數值運算。此外，也將動物實驗中量測的脈動流流量及壓力作為計算邊界條件，並進行數值模擬驗證。本研究利用Lagrangian顆粒追蹤方式求得顆粒在流體中所經歷的非常態(Unsteady)雷諾剪應力(Reynolds Stress)並量化血球受剪應力破壞之溶血指數(Hemolysis Index)。從計算流體力學分析結果得知：1)在脈動流場中歧管內壁面並沒有持續性的停滯區存在；2)在血泵射血時所造成的高壁面剪應力(High Wall Shear Stress)區被良好的包覆在T型歧管內；3)在T型歧管的轉角以及與血管彈性不相符(Compliance Mismatching)的交接端處，都會形成高壁面剪應力梯度(Wall Shear Stress Gradient)；4)因剪應力而造成的血球破壞指數值皆落在無臨床症狀的範圍。從研究結果可知側主動脈血泵能抵抗血栓形成，同時與血管彈性相符的設計可以有效地減少植入後所引發的血管病變。

Counter-pulsatile circulation support realized by intra- or extra-aortic pumping means has very different flow characteristics. The objective of this research is to study the detail flow structure of a conduit-mediated para-aortic blood pump (PABP) which adopts a specially designed compliance-matching T-shaped conduit. This configuration is expected to mitigate the blood and vascular complications that might arise in this complex, turbulent end-to-side anastomotic flow. A fluid-structure interaction computational fluid dynamics (CFD) simulation was performed using a commercially available FLUENT code and a user-defined dynamic grid system. The aortic lumen was modeled flexible and the structural equation was solved together with the flow equations. Parallel animal studies were also conducted in which in-vivo pulsatile flowrate and pressure measurements were obtained. These in-vivo data were used for simulation validation and for numerical boundary condition specification. Unsteady, turbulent Reynolds stresses were evaluated for selected Lagrangian-tracked particles and blood cell damage was quantified using an empirical stress-time hemolysis index. The CFD analysis reveals that 1) there exists nowhere in the pulsatile juncture flow that is constantly stasis, 2) high wall shear stress occurs in the pump ejection phase and this high shear stress zone is well contained within the conduit, 3) wall shear stress gradient is found high around the salient corner of the conduit T-juncture and the two graft-aortic edges where compliance mismatching occurs, and 4) the stress-time blood trauma index is low in the subclinic range. It is suggested by the present analysis that the conduit-mediated PABP is thrombo-resistant and the vascular complication caused by the implant can be minimized by the compliance-matching design.

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