The effect of graft caliber upon wall shear within in vivo distal vascular anastomoses.
The effect of graft caliber upon wall shear within in vivo distal vascular anastomoses.
复制标题
移植物口径对体内远端血管吻合内壁剪切的影响。
DOI：
10.1115/1.2798047
复制
发表时间：
1999
期刊：
影响因子：
--
通讯作者：
Rittgers,SE
中科院分区：
文献类型：
--
作者：
Keynton,RS;Evancho,MM;Sims,RL;Rittgers,SE
在慢性动脉旁路移植术后的动脉粥样硬化中，壁面剪切力被广泛认为是内膜增生的一个促成因素。早期的研究仅限于：（1）体外或计算机模拟模型，详细描述了吻合术内的复杂血液动力学，而没有相应的生物学反应，或（2）体内模型，仅记录了近似的壁剪切信息的生物学效应。最近，一个专门设计的脉冲超声多普勒壁剪切率（PUDWSR）测量装置，使人们有可能获得三个近壁速度测量非侵入性内1.05毫米的血管腔表面的壁剪切率（WSR）的衍生。本研究的目的是评价移植物口径（一种手术可控变量）对局部血流动力学的影响，而局部血流动力学反过来又在吻合口增生的最终发展中起重要作用。锥形（4-7 mm内径）将6cm长的移植物以端侧方式植入双侧，近端和远端均为30 °，以绕过16只犬的闭塞颈总动脉。旁路移植物在对侧血管中随机配对，并放置，使得远端吻合处的移植物-动脉直径比DR为1.0或1.5。对于所有移植物，平均Re为432 ± 112，基于动脉直径的平均Womersley参数α为3.59 ± 0.39。随着驻点的发展，血流向动脉底部急剧倾斜，驻点的位置随时间（最多两个动脉直径）和DR（DR = 1.0时通常更下游）而变化。DR = 1.0和1.5时，沿动脉底部的平均WSR沿着从中等到高逆行值（分别为589 s-1和1558 s-1）上游到高顺行值（分别为2704 s-1和2302 s-1）的范围急剧变化。虽然组间平均和峰值WSR没有总体差异，但组间振荡WSR以及绝对标准化平均和峰值WSR存在显著差异（p < 0.05）。两种DR病例沿着动脉底部轴向位置的平均和峰值WSR也存在显著差异（p < 0.05）。总之，在端侧远端移植物动脉瘤内，特别是沿着动脉底部，WSR变化范围很大（1558 s-1逆行至2704 s-1顺行），可能通过内皮内物质转运和机械信号转导的局部改变在内膜增生的发展中发挥作用。
Wall shear has been widely implicated as a contributing factor in the development of intimal hyperplasia in the anastomoses of chronic arterial bypass grafts. Earlier studies have been restricted to either: (1) in vitro or computer simulation models detailing the complex hemodynamics within an anastomosis without corresponding biological responses, or (2) in vivo models that document biological effects with only approximate wall shear information. Recently, a specially designed pulse ultrasonic Doppler wall shear rate (PUDWSR) measuring device has made it possible to obtain three near-wall velocity measurements nonintrusively within 1.05 mm of the vessel luminal surface from which wall shear rates (WSRs) were derived. It was the purpose of this study to evaluate the effect of graft caliber, a surgically controllable variable, upon local hemodynamics, which, in turn, play an important role in the eventual development of anastomotic hyperplasia. Tapered (4–7 mm I.D.) 6-cm-long grafts were implanted bilaterally in an end-to-side fashion with 30 deg proximal and distal anastomoses to bypass occluded common carotid arteries of 16 canines. The bypass grafts were randomly paired in contralateral vessels and placed such that the graft-to-artery diameter ratio, DR, at the distal anastomosis was either 1.0 or 1.5. For all grafts, the average Re was 432 ± 112 and the average Womersley parameter,α, was 3.59 ± 0.39 based on artery diameter. There was a sharp skewing of flow toward the artery floor with the development of a stagnation point whose position varied with time (up to two artery diameters) and DR (generally more downstream for DR = 1.0). Mean WSRs along the artery floor for DR = 1.0 and 1.5 were found to range sharply from moderate to high retrograde values (589 s−1and 1558 s−1, respectively) upstream to high antegrade values (2704 s−1and 2302 s−1, respectively) immediately downstream of the stagnation point. Although there were no overall differences in mean and peak WSRs between groups, there were significant differences (p < 0.05) in oscillatory WSRs as well as in the absolute normalized mean and peak WSRs between groups. There were also significant differences (p < 0.05) in mean and peak WSRs with respect to axial position along the artery floor for both DR cases. In conclusion, WSR varies widely (1558 s−1retrograde to 2704 s−1antegrade) within end-to-side distal graft anastomoses, particularly along the artery floor, and may play a role in the development of intimal hyperplasia through local alteration of mass transport and mechano-signal transduction within the endothelium.