Potential Pathways for Platelet Activation

As platelets are transported they are continuously stretched, compressed and sheared by local gradients in the flow. Exposure to elevated gradients can cause platelets to actively react with conformational, chemical and enzymatic responses, i.e. becoming activated. Once switched to the activated state, platelets perform multifaceted roles to orchestrate clotting. Mechanically-induced platelet activation under pathological conditions has been studied since the late 1970s. This work builds on [1], which introduced a trajectory-based level of activation parameter for platelets, and [2] describing coherent structures in cardiovascular flow. We introduce a new direction-independent Lagrangian measure. This measure is introduced as an activation potential in two senses. First, it provides a measure of mechanical strain, which has been shown to have the potential to activate platelets. Second, it is plotted at the initial location of the platelets. This latter condition is subtle, but it enables us to uncover an interesting observation that locations of highest activation potential tend to occur along structures that have important implications to the transport topology.