When Flow Goes Slow, von Willebrand Factor Can Bind Red Blood Cells

“Stasis, hypercoagulability, vessel wall injury”: If you repeat Virchow’s triad to yourself a few times, it almost sounds like the definition of clotting rather than the cause of clotting. Still, Virchow’s triad is a remarkable predictor of where clotting initiates, specifically during venous thrombosis in the valve pocket. In the body, blood is typically clotting under flow conditions unless it has pooled outside of a broken vessel. Within vessels, the prevailing flow dictates the cellular collision frequency, the collision interaction time, as well as the forces on adhering or aggregating cells. However, when venous flows becomes pathologically slow at <100 s−1 wall shear rate (or <1 dyne/cm2 wall shear stress), the collision rate …