Computational simulation of flow in the end-to-end anastomosis of a rigid graft and a compliant artery
Computational simulation of flow in the end-to-end anastomosis of a rigid graft and a compliant artery
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DOI：
10.1097/00002480-199609000-00078
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发表时间：
1996-09-01
期刊：
影响因子：
4.2
通讯作者：
Tarbell, JM
中科院分区：
文献类型：
--
作者：
Qiu, YC;Tarbell, JM
植入式血管移植物由于吻合区内膜增生而经常失败，而宿主动脉与移植物之间的顺应性不匹配加剧了这一问题。本研究的重点是桡动脉壁运动和压力波与流波之间的相位角（阻抗相位角[IPA]）对连接刚性移植物和柔顺动脉的端到端血管移植吻合模型的管壁剪切速率（WSR）行为的影响。建立了具有瞬态流动和移动边界的有限元模型，通过16%的小尺寸（平均）接枝模型来模拟振荡流动。在模拟过程中，在振荡血流（平均Re = 150，峰值Re = 300，非稳态参数alpha = 3.9）的生理范围内，模拟了一个周期内不同动脉直径的变化（DV）和IPAs。结果表明，在正常生理条件下（DV = 6%, IPA = -45度），在16%的小尺寸移植物中，与平均Re下的稳定流量相比，最小远端平均WSR降低了60%；当IPA从-5°变化到-85°时，最小远端波幅增加50%，当DV从2%变化到10%时，最小远端波幅增加60%。这表明顺应性错配导致吻合远端区平均WSR降低，振荡WSR增加，这可能导致内膜增生。此外，16%小尺寸移植物模型的会聚-发散几何形状可以通过改变血流诱导的切向力（与WSR同步）与桡动脉扩张诱导的环向应变（与DV同步）之间的局部相位角，显著影响作用于吻合口附近局部内皮细胞层的受力模式。该局部相位角在远端发散几何中减少65度，而在近端收敛几何中增加15度。
Implanted vascular grafts often fail because of the development of intimal hyperplasia in the anastomotic region, and compliance mismatch between the host artery and graft exacerbates the problem. This study focused on the effects of radial artery wall motion and phase angle between pressure and flow waves (impedance phase angle [IPA]) on the wall shear rate (WSR) behavior near end-to-end vascular graft anastomoses models connecting rigid grafts and compliant arteries. A finite element model with transient flow and moving boundaries was set up to simulate oscillatory flow through a 16% undersized (mean) diameter graft model. During the simulations, different artery diameter variations (DVs) over a cycle (DV) and IPAs were simulated in the physiologic range for an oscillatory flow (mean Re = 150, peak Re = 300, unsteadiness parameter alpha = 3.9). The results show that for normal physiologic conditions (DV = 6%, IPA = -45 degrees) in a 16% undersized graft, the minimum distal mean WSR is reduced by 60% compared to steady flow at the mean Re; the minimum distal WSR amplitude increases 50% when IPA changes from -5 degrees to -85 degrees, and increases 60% when DV changes from 2% to 10%. This indicates that compliance mismatch induces lower mean WSR and more oscillatory WSR in the distal anastomotic region, which may contribute to intimal hyperplasia. In addition, the convergent-divergent geometry of the 16% undersized graft model can significantly affect the force pattern applied to the local endothelial cell layer near the anastomosis by altering the local phase angle between the flow induced tangential force (synchronous with WSR) and the radial artery expansion induced cyclic hoop strain (synchronous with DV). This local phase angle is decreased by 65 degrees in the distal divergent geometry, while increased by 15 degrees in the proximal convergent geometry.