In vitro investigation of the effect of platelet aggregation ability on the adhesion of platelets to micro-structures

Thrombus formation on rough surfaces in cardiovascular devices implanted into patients with heart failure is a significant problem. It is, therefore, necessary to investigate the thrombus formation mechanism on rough surfaces. We have proposed a hypothesis that micro-secondary flows which are proportional to the size of micro-structure composing the rough surfaces contribute the platelet adhesion around micro-structure, that is, enhance possibility of thrombus formation. In this study, blood perfusion tests were conducted, using bovine blood with different platelet aggregation abilities, to evaluate platelet adhesion on a test piece with micro-cylinders on its surface. It was found that the platelet adhesion was sufficiently enhanced and the platelets exhibited high aggregation ability. This phenomenon depends on shear flow, and the platelets may selectively adhere to the perimeter of larger structures in the presence of microstructures of different sizes. Our results indicate that the platelet adhesion increases in proportion to size of microstructures when there is an average platelet aggregation per unit platelet (NL-PATI/PLT) ratio of over 0.002. These results can aid in designing the surface roughness of the blood contact material to help reduce the risk of thrombus formation.