On the characterization of local shear-induced activation versus transport of activated platelets in aortic artificial heart valves

A comprehensive analysis of local shear-induced platelet activation and the subsequent transport in artificial heart valves is essential to understand their coagulation dynamics, thereby reducing their (sub)clinical thrombosis. Here, the activation of platelets due to shear stresses and their transport is investigated in two designs of mechanical heart valves (MHVs), namely a trileaflet MHV (TMHV) and a bileaflet MHV (BMHV), and compared against a bioprosthetic heart valve (BHV) as a control. The shear-induced total platelet activation at the end of diastole, when cyclic state is reached, is 20.07% and 30.74% higher in BMHV while 5.78% and 10.21% higher in TMHV compared to BHV, based on Linear and Soares activation models, respectively. The MHVs show a higher washout than BHV, consistently being over 10.40 and 2.39 times higher in BMHV while 4.90 and 1.40 higher in TMHV compared to BHV in the aortic sinuses and central lumen, respectively. These findings indicate that the risk of clinical thrombosis in MHVs is mainly due to higher levels of shear-induced activation compared to BHV despite the lower residence time (better washout). Furthermore, the subclinical thrombosis in BHVs is probably due to higher residence times observed in BHVs relative to MHVs.