Ojha M, Cobbold R S, Johnston K W
Institute of Biomedical Engineering, University of Toronto, Ontario, Canada.
J Vasc Surg. 1993 Apr;17(4):646-55.
The purpose of this article was to analyze the fluid mechanical effects of a side-to-end proximal anastomosis and to compare the results with those from our earlier study on the end-to-side distal anastomosis.
The photochromic tracer technique was used to determine the instantaneous wall shear stress and to visualize the overall flow field under pulsatile flow conditions. The flow consisted of a sinusoid plus a steady component with mean and modulation Reynolds numbers of 355 and 565, respectively, and a Womersley number of 7.9.
At the toe and heel of the junction, very high and positive wall shear stresses were seen together with substantial nonperiodic fluctuations. The peak wall shear stress was about four times higher at the toe and about seven times higher at the heel than the maximum values observed at about four tube diameters upstream from the junction. On the bed of the host vessel, nonperiodic fluctuations were also observed, but the shear stresses were mainly negative with magnitudes comparable to those seen upstream. With leakages of 11% and 28% of the mean flow through the blocked end of the host vessel, the shear stress pattern seemed to be significantly affected only at the toe for the higher leakage. Further, when the mean Reynolds number was reduced to 320, the magnitudes of the variations in the wall shear stress were reduced proportionately, except at the heel, where the reduction was much larger than expected.
It appears that the preferential development of intimal hyperplasia at the distal end-to-side anastomosis may be promoted by low wall shear stress at the toe and heel, and probably by high shear stresses or shear stress gradients on the bed.
本文旨在分析端侧近端吻合术的流体力学效应，并将结果与我们早期关于端端远端吻合术的研究结果进行比较。
采用光致变色示踪技术来确定瞬时壁面剪应力，并在脉动流条件下可视化整体流场。流动由正弦波加稳定分量组成，平均雷诺数和调制雷诺数分别为355和565，沃默斯利数为7.9。
在吻合口的趾端和跟端，观察到非常高的正壁面剪应力以及大量的非周期性波动。吻合口趾端的壁面剪应力峰值约为吻合口上游约四个管径处观察到的最大值的四倍，跟端约为七倍。在宿主血管的血管床处，也观察到了非周期性波动，但剪应力主要为负，其大小与上游观察到的相当。当有11%和28%的平均流量通过宿主血管阻塞端泄漏时，仅在较高泄漏率的情况下，剪应力模式似乎在趾端受到显著影响。此外，当平均雷诺数降至320时，壁面剪应力变化的幅度成比例降低，但跟端除外，其降低幅度远大于预期。
似乎远端端端吻合处内膜增生的优先发展可能是由趾端和跟端的低壁面剪应力以及可能由血管床处的高剪应力或剪应力梯度所促进的。
