Lei M, Kleinstreuer C, Archie J P
Department of Mechanical & Aerospace Engineering, North Carolina State University, Raleigh 27695-7910, USA.
J Biomech Eng. 1997 Aug;119(3):343-8. doi: 10.1115/1.2796099.
Severe occlusion of graft-artery junctions due to restenosis, e.g., excessive tissue overgrowth and renewed plaque formation, may occur within a few months or years after bypass surgery. Our hypothesis is that nonuniform hemodynamics, represented by large sustained wall shear stress gradients, trigger abnormal biological processes leading to rapid restenosis and hence early graft failure. In turn, this problem may be significantly mitigated by designing graft-artery bypass configurations for which the wall shear stress gradient (WSSG) is approximately zero and hence nearly uniform hemodynamics are achieved. Focusing on the distal end of several femoral artery bypass junctions, a validated finite volume code has been used to compute the transient three-dimensional velocity vector fields and its first and second surface derivatives in order to test the idea. Specifically, it is shown that the Taylor patch, which generates higher patency rates than standard end-to-side anastomoses, exhibits lower WSSG levels than standard configurations, and that further geometric design improvements reduce the WSSG in magnitude and local extent even more.
由于再狭窄，例如过度的组织过度生长和新的斑块形成，移植物 - 动脉连接处可能会在搭桥手术后数月或数年出现严重闭塞。我们的假设是，以持续的大壁面剪应力梯度为代表的不均匀血流动力学，会引发异常生物学过程，导致快速再狭窄，进而导致早期移植物失败。反过来，通过设计壁面剪应力梯度（WSSG）近似为零从而实现近乎均匀血流动力学的移植物 - 动脉搭桥构型，这个问题可能会得到显著缓解。为了验证这一想法，针对几条股动脉搭桥连接处的远端，使用经过验证的有限体积代码来计算瞬态三维速度矢量场及其一阶和二阶表面导数。具体而言，结果表明，与标准端侧吻合术相比具有更高通畅率的泰勒补片，其WSSG水平低于标准构型，并且进一步的几何设计改进会使WSSG在大小和局部范围上进一步降低。
