Intimal hyperplasia and wall shear in arterial bypass graft distal anastomoses:: An in vivo model study
Intimal hyperplasia and wall shear in arterial bypass graft distal anastomoses:: An in vivo model study
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DOI：
10.1115/1.1389461
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发表时间：
2001-10-01
影响因子：
1.7
通讯作者：
Rittgers, SE
中科院分区：
文献类型：
--
作者：
Keynton, RS;Evancho, MM;Rittgers, SE
在旁路移植物动脉瘤中观察到的内膜增生表明局部血流动力学和血管壁反应之间存在潜在的相互作用。由于其对正常血管内皮的已知影响，壁剪切力特别受到牵连，因此，对其在动脉旁路移植物远端血管狭窄中内膜增生发展中的可能作用进行了检查，Tapered（4-7 min I.D.）将6 cm长的e-PTFE合成移植物作为双侧颈动脉旁路植入体重在25 - 30 kg之间的st. x成年杂种犬中，远端吻合移植物与动脉直径比（DR）为1.0或1.5。植入后立即在吻合平面内的脚趾和动脉底部区域以0.35分钟、0.70分钟和1.05分钟的径向增量使用专门设计的20 MHz三重晶体超声壁剪切率换能器进行同时轴向速度测量。平均、峰值和脉冲幅度壁剪切率（WSR），它们的绝对值，从这些速度测量值计算空间和时间壁剪切应力梯度（WSSG）和振荡剪切指数（OSI）。所有移植物在植入12周后收获，并沿着脚趾区域和宿主动脉的动脉底以1 mm增量测量内膜增生（IH）的程度。虽然一些IH发生沿着脚趾区域（8.35 +/- 23.1 μ m），并且在DR组之间存在显著差异（p < 0.003），但最大量发生沿着动脉底部（81.6 +/- 06.5 μ m，平均值+/-S.D.）。（p < 0.001），但DR组之间无显著差异。对配对的IH和平均值、峰值和脉冲幅度WSR数据以及所有移植物的绝对平均值、峰值和脉冲幅度WSR数据进行线性回归。平均和绝对平均WSRS显示与IH的适度相关性（分别为r =-0.406和-0.370），当使用空气指数关系时，观察到进一步改善（分别为r = -0.482和-0.445）。整体最佳相关性是相对于OSI的指数函数（r = 0.600）。虽然这些相关系数不高，但发现具有统计学显著性，如获得的大F统计量所证明的。最后，观察到超过75%的IH发生在等于或低于100 s（-1）的平均WSR值，而大约92%的IH发生在等于或低于等于自体动脉的一半的平均WSR值。（特别是，振荡壁剪切）似乎为吻合口内膜增生的发展提供刺激。
The observation of intimal hyperplasia at bypass graft anastomoses has suggested a potential interaction between local hemodynamics and vascular wall response. Wall shear has been particularly implicated because of its known effects upon the endothelium of normal vessels and, thus, was examined as to its possible role in the development of intimal hyperplasia in arterial bypass graft distal anastomoses, Tapered (4-7 min I.D.) e-PTFE synthetic grafts 6 cm long were placed as bilateral carotid artery, bypasses in st. x adult, mongrel dogs weighing between 25 and 30 kg with distal anastomotic graft-to-artery diameter ratios (DR) of either 1.0 or 1.5. immediately following implantation, simultaneous axial velocity measurements were made in the toe and artery floor regions in the plane of the anastomosis at radial increments of 0.35 min, 0.70 min, and 1.05 min using a specially designed 20 MHz triple crystal ultrasonic wall shear rate transducer Mean, peak, and pulse amplitude wall shear rates (WSRs), their absolute values, the spatial and temporal wall shear stress gradients (WSSG), and the, oscillatory shear index (OSI) were computed from these velocity, measurements. All grafts were harvested after 12 weeks implantation and measurements of the degree of intimal hyperplasia (IH) were made along the toe region and the artery floor of the host artery in I nun increments. While some IH occurred along the toe region (8.35 +/- 23.1 mum) and was significantly different between DR groups (p < 0.003), the greatest amount occurred along the artery floor (81.6 +/- 06.5 mum, mean +/-S.D.) (p < 0.001) although no significant differences were found between DR groups. Linear regressions were performed on the paired IH and mean, peak, and pulse amplitude WSR data as well as the absolute mean, peak, and pulse amplitude WSR data from all grafts. The mean and absolute mean WSRS showed a modest correlation with IH (r = - 0.406 and -0.370, respectively) with further improvements seen (r = -0.482 and -0.445, respectively) when using air exponential relationship. The overall best correlation it-as seen against an exponential function of the OSI (r = 0.600). Although these correlation coefficients were not high, the) were found to be statistically significant as evidenced by the large F-statistic obtained. Finally, it was observed that over 75 percent of the IH occurred at or below a mean WSR value of 100 s(-1) while approximately 92 percent of the IH occurred tit or below a mean WSR equal to one-half that of the native artery Therefore, while not being the only factor involved, wall shear (and in particular, oscillatory wall shear) appears to provide a stimulus for the development of anastomotic intimal hyperplasia.