The effects of non-physiological shear rate gradient, frequency, and amplitude on platelet aggregation.

Mechanical circulatory support devices (MCSDs), such as ventricular assist devices (VADs), are an important treatment option for providing perioperative or long-term circulatory support in patients with end-stage heart failure. However, the complex geometric structure and mechanical pumping mechanism of these devices can generate non-physiological flow fields, which are prone to causing clinical complications such as thrombosis. Previous studies have primarily focused on thrombus formation under conditions of constant shear stress and exposure time, but there is still a lack of research related to dynamic shear stress. This study systematically investigates the effects of dynamic shear parameters-shear rate gradient (SRG), shear frequency (SF), and shear amplitude (SA)-on platelet aggregation. To achieve this, three microfluidic chips (G-chip, F-chip, and A-chip) were designed and utilized in conjunction with Computational Fluid Dynamics (CFD) simulations and in vitro experiments. The results demonstrated that an increase in SRG promotes platelet aggregation, SF exhibits a positive correlation with the severity of aggregation, and an enhancement in SA may increase platelet aggregation, with particularly pronounced effects observed at high amplitudes. This study provides foundational insights into the mechanisms of thrombus formation in MCSDs and offers theoretical guidance for optimizing blood pump design to mitigate shear-induced complications.