Effect of Shear Rate on Thrombus Growth

In this study micro and nano scale measurement techniques are applied to platelet studies and determination of factors in platelet aggregation and thrombus formation. Conventionally it has been assumed that platelets are stimulated by blood clotting factors and platelet activators to aggregate and form a thrombus at sites of vascular injury. We have recently shown that a primary factor in initiating platelet aggregation is hemodynamic shear. This paper presents the effect of shear rate on the time evolution of thrombus formation and the final geometry of a mature thrombus. A relationship between maximum mature thrombus height and local shear rate is formulated. We have shown that the shear rate is not only an important factor in initiating platelet aggregation but is also one of the main inhibitors of platelet aggregation and thrombus formation. We propose that when the platelets reach a critical height, they encounter a specific local hemodynamic range, which prevents further thrombus growth.