Shaik E, Hoffmann K A, Dietiker J F
Wichita State University, Wichita, KS, USA.
Mol Cell Biomech. 2007 Mar;4(1):41-53.
A potential interaction between the local hemodynamics and the artery wall response has been suggested for vascular graft failure by intimal hyperplasia (IH). Among the various hemodynamic factors, wall shear stress has been implicated as the primary factor responsible for the development of IH. In order to explore the role of hemodynamics in the formation of IH in end-to-side anastomosis, computational fluid dynamics is employed. To validate the numerical simulations, comparisons with existing experimental data are performed for both steady and pulsatile flows. Generally, good agreement is observed with the velocity profiles whereas some discrepancies are found in wall shear stress (WSS) distributions. Using the same end-to-side anastomosis geometry, numerical simulations are extended using a femoral artery waveform to identify the possible role of unsteady hemodynamics. In the current simulations, Carreau-Yasuda model is used to account for the non-Newtonian nature of blood. Computations indicated a disturbed flow field at the artery-graft junction leading to locally elevated shear stresses on the vascular wall. Furthermore, the shear stress distribution followed the same behavior with oscillating magnitude over the entire flow cycle. Thus, distal IH observed in end-to-side artery-graft models may be caused by the fluctuations in WSS's along the wall.
内膜增生（IH）导致的血管移植失败表明，局部血流动力学与动脉壁反应之间可能存在相互作用。在各种血流动力学因素中，壁面剪应力被认为是导致内膜增生的主要因素。为了探究血流动力学在端侧吻合术中内膜增生形成中的作用，采用了计算流体动力学方法。为了验证数值模拟结果，对稳定流和脉动流都与现有实验数据进行了比较。一般来说，速度剖面的结果吻合良好，而壁面剪应力（WSS）分布存在一些差异。使用相同的端侧吻合几何结构，利用股动脉波形扩展数值模拟，以确定非定常血流动力学的可能作用。在当前模拟中，使用卡罗厄-亚苏达模型来考虑血液的非牛顿特性。计算表明，动脉-移植物交界处的流场紊乱，导致血管壁上局部剪应力升高。此外，剪应力分布在整个流动周期内呈现出相同的振荡幅度变化规律。因此，端侧动脉-移植物模型中观察到的远端内膜增生可能是由沿壁面的壁面剪应力波动引起的。
