Ojha M, Johnston K W, Cobbold R S
Institute of Biomedical Engineering, University of Toronto, Ontario, Canada.
J Vasc Surg. 1990 Jan;11(1):127-33; discussion 133-5.
The effects of an axisymmetric 65% area reduction stenosis on a pulsatile flow were investigated by use of an in vitro model that permits simultaneous visualization of the flow velocity profiles at seven sites. By use of seven lenses to focus the ultraviolet light from a nitrogen laser, seven thin blue lines were produced in the photochromic solution flowing through the tube. The displacement profiles of the dye traces were photographed, resulting in the acquisition of the velocity profiles. From these traces, the flow pattern was determined, and the wall shear stresses were measured. Turbulence was generated 3.3 to 6.5 tube diameters downstream from the edge of the stenosis, depending on the time in the pulsatile flow cycle. Maximum wall shear stress fluctuations between positive and negative values appeared to lie within 1.6 to 3.3 tube diameters downstream of the stenosis. In several illustrative clinical cases of thoracic outlet arterial compression, the poststenotic dilation was maximum at 2.0 +/- 0.3 vessel diameters downstream. Based on these observations, it is postulated that wall shear stress fluctuations may be important in the development of poststenotic dilation.
利用一个体外模型研究了轴对称65%面积减小狭窄对脉动血流的影响，该模型能够同时可视化七个部位的流速剖面。通过使用七个透镜聚焦来自氮激光的紫外光，在流经管道的光致变色溶液中产生了七条细蓝线。拍摄染料痕迹的位移剖面，从而获得流速剖面。根据这些痕迹确定了流动模式，并测量了壁面剪应力。根据脉动血流周期中的时间不同，在狭窄边缘下游3.3至6.5个管径处产生湍流。正负值之间的最大壁面剪应力波动似乎出现在狭窄下游1.6至3.3个管径范围内。在几例说明性的胸廓出口动脉压迫临床病例中，狭窄后扩张在下游2.0±0.3个血管管径处最大。基于这些观察结果，推测壁面剪应力波动可能在狭窄后扩张的发展中起重要作用。
