A model of platelet concentration sampling in arterial flow

Platelet aggregation and accumulation are two major components of blood clotting: the normal hemostasis that maintains vascular integrity, and the pathological thrombosis that is the cause of heart attacks and strokes. The main goal of the research is to develop a computational model of platelet accumulation, with which we can predict the thrombus growth, reduce the vascular graft failure and control the thrombosis risk in patients. Platelet margination, which is defined as the enrichment at the near-wall region, is measured using local sampling experiments. A 3D computational fluid dynamics (CFD) model based on the fluid mechanics is developed to design the experiment for medium size artery at physiological conditions. The model predicts the sample velocity required to sample platelet concentration from the near-wall zone, as the function of the bifurcation geometry and main tube flow conditions. The experiments verify the published Laser Doppler measurements of platelet margination in long 3 mm tubes at the normal shear rate. At normal arterial length, margination exists but is reduced. When pulsatility is included, the effect is reduced further. The near wall platelet count was a factor of 1.28 to 1.9 times the average platelet count.