The hemodynamics of thrombus formation in arteries

Alterations in arterial blood flow are thought to predispose to thrombus formation, but the exact relationships have not been fully elucidated. The effect of varying blood flows on the accumulation of thrombotic material within arteries was investigated, with use of shear rate as an index of flow across the luminal surface. Partially denuded rabbit aortas were perfused with fresh nonanticoagulated human blood for 3 minutes, with an in vitro recirculating apparatus, Indium 111-labeled platelets, and fibrinogen I 125. Shear rates ranged from zero to 1500 sec-1, correlating with the hemodynamics of various segments of the human arterial tree. A significant correlation was observed between shear rate and platelet deposition, ranging from 5.2 +/- 2.8 x 10(6) platelets/cm2 of vessel surface area at zero shear to a maximum of 64.7 +/- 8.3 x 10(6) platelets/cm2 at a shear rate of 1500 sec-1 (F = 5.01, p less than 0.05). Fibrin deposition paralleled that of platelets, ranging from 28.2 +/- 7.6 micrograms/cm2 at zero shear to 354.1 +/- 62.7 micrograms/cm2 at a shear rate of 1500 sec-1 (F = 5.91, p less than 0.05). These results suggest that shear rate is a most important determinant of platelet and fibrin deposition on altered arterial surfaces.