Lei M, Kleinstreuer C, Archie J P
Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh 27695-7910, USA.
J Biomech. 1996 Dec;29(12):1605-14.
The present study is based on the hypothesis that nonuniform hemodynamics, represented by large time-averaged wall shear stress gradients, trigger abnormal biological processes leading to rapid restenosis, i.e. excessive tissue overgrowth and renewed plaque formation, and hence early graft failure. It implies that this problem may be significantly mitigated by finding graft-artery bypass configurations for which the wall shear stress gradient is approximately zero and hence nearly uniform hemodynamics is achieved. These fluid flow and geometric design considerations are applied to four different end-to-side anastomoses for the distal end of a femoral artery bypass with an appropriate test input pulse and a typical 20-80 flow division. A validated finite-volume code has been used to compute the transient three-dimensional velocity vector fields, wall shear stress distributions and surface contours of the wall shear stress gradients. It is shown that large anastomotic flow areas, small continuously changing bifurcation angles, and smooth junction wall curvatures reduce local time-averaged wall shear stress gradients significantly and hence should mitigate restenosis.
以较大的时间平均壁面剪应力梯度为代表的血流动力学不均匀性会引发异常生物学过程，导致快速再狭窄，即过度的组织过度生长和新的斑块形成，进而导致早期移植物失败。这意味着，通过找到壁面剪应力梯度近似为零从而实现近乎均匀血流动力学的移植物 - 动脉旁路构型，这个问题可能会得到显著缓解。这些流体流动和几何设计考量被应用于四种不同的端侧吻合术，用于股动脉旁路远端，采用适当的测试输入脉冲和典型的20 - 80分流。一个经过验证的有限体积代码已被用于计算瞬态三维速度矢量场、壁面剪应力分布以及壁面剪应力梯度的表面轮廓。结果表明，较大的吻合口血流面积、较小的连续变化的分叉角度以及平滑的连接壁曲率会显著降低局部时间平均壁面剪应力梯度，因此应该会减轻再狭窄。
