Effect of Hemodynamic Forces on Platelet Aggregation Geometry

The shear rate dependence of platelet aggregation geometries is investigated using a combination of in vitro and numerical experiments. Changes in upstream shear rate, γ Pw , are found to cause systematic changes in mature platelet aggregation geometries. However, γ Pw is not the only factor determining the shear rate experienced by a platelet moving over, and adhering to, a platelet aggregation: flow simulations demonstrate that naturally occurring variations in platelet aggregation geometry cause the local shear rate on the surface of a mature platelet aggregation to vary between zero and up to eight times γ Pw . Additionally, as a platelet aggregation grows, systematic changes in geometry are found, indicating that the local shear field over a growing platelet aggregation will differ from that over mature platelet aggregations.