Thrombogenicity of cardiovascular devices: mutual and relative effect of biomaterial and shear stress

Supra-physiologic levels of shear stress and blood contact with artificial material are considered the main causes of the thrombogenicity of cardiovascular devices, such as prosthetic heart valves and ventricular assist devices. To investigate the mutual and relative role of these factors in platelet activation a set of experiments was performed consisting in the evaluation of platelet activation in samples of isolated platelets exposed to different levels of shear stress and different materials. The results showed that 1) platelet activation by mechanical stimuli exhibits a dose-time-response, which depends on the material in contact with the platelets, 2) biomaterials have a different thrombogenic potential, being polyethylene the least thrombogenic among the ones investigated and 3) the contact with an artificial material and the mechanical stimulation have approximately the same effect on platelet activation.