To test the hypothesis that intentionally inducing swirling blood flow in a small-caliber arterial graft can suppress acute thrombus formation by affecting the adhesion of platelets to the internal surface of the graft, an experimental comparative study was designed to investigate the effect of swirling flow on the adhesion and activation of platelets in a straight glass tube coated with calf skin type I collagen. The experimental results showed that when compared with the normal flow, the swirling flow generated in the test tube significantly reduced the platelet adhesion to the surface of the test tube. Different from normal flow condition under which platelet adhesion increased simply with decreasing wall shear stress, the platelet adhesion density under swirling flow condition remained almost unchanged along the first 5 mm section of the tube in which the flow had relatively high rotation strength, even though the wall shear stress in this section of the tube dropped drastically. This suggests that when the swirling flow in the tube was strong enough, platelet adhesion was dominantly affected by the swirling flow itself, wall shear stress was secondary. The results also showed that there was no significant difference in the activation of platelets between the spiral flow group and the normal flow group. The present study therefore suggests that intentionally introducing swirling flow in small-caliber arterial grafts has no adverse effect on platelet activation and may indeed be a solution to improving the patency of the grafts by suppressing acute thrombus formation.
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