How T V, Marois Y, Guidoin R, Black R A
Department of Clinical Engineering, University of Liverpool, UK.
J Biomater Sci Polym Ed. 1994;6(2):111-22. doi: 10.1163/156856294x00248.
A common method of assessing the thrombogenicity of prosthetic arterial grafts is to determine the amount of platelets and fibrin that accumulates on their surfaces. This study was designed to compare thrombus formation in cylindrical and tapered vascular grafts (angle of taper 0.5 deg) made from the same biomaterial. Turbulence was generated upstream of the grafts by means of a 75% axi-symmetric stenosis. In general, turbulence is dissipated by the effect of blood viscosity, whereas in a tapered graft, there is an additional reduction in the intensity of turbulence owing to the effect of converging flow through the taper. The aim of this study was to assess the effect of turbulence on thrombus formation in cylindrical and tapered grafts. After blood had circulated for 2 and 4 h through the cylindrical and tapered grafts, which formed part of two parallel ex vivo circuits, platelet deposition and fibrinogen uptake were measured by means of a radioisotope technique. Although the flow disturbances were less in the tapered grafts, no significant difference in platelet and fibrin deposition in the two types of graft was observed at 2 h. For the longer perfusion time, however, increased platelet and fibrin activity was recorded in the annular vortex region in the tapered grafts. In general, neither platelets nor fibrin accumulated in areas of high turbulence intensity.
评估人工动脉移植物血栓形成倾向的一种常用方法是测定其表面聚集的血小板和纤维蛋白量。本研究旨在比较由相同生物材料制成的圆柱形和锥形（锥角0.5度）血管移植物中的血栓形成情况。通过75%的轴对称狭窄在移植物上游产生湍流。一般来说，湍流会因血液粘度的作用而消散，而在锥形移植物中，由于通过锥度的汇聚流的作用，湍流强度会进一步降低。本研究的目的是评估湍流对圆柱形和锥形移植物中血栓形成的影响。血液在构成两个平行体外循环一部分的圆柱形和锥形移植物中循环2小时和4小时后，采用放射性同位素技术测量血小板沉积和纤维蛋白原摄取。尽管锥形移植物中的流动干扰较小，但在2小时时，两种类型移植物中的血小板和纤维蛋白沉积未观察到显著差异。然而，对于较长的灌注时间，在锥形移植物的环形涡旋区域记录到血小板和纤维蛋白活性增加。一般来说，血小板和纤维蛋白都不会在高湍流强度区域积聚。
