Revisiting the Relevance of Platelet Margination in Arteries: a Computational Investigation

Platelet margination (PM) refers to the migration of platelets toward the endothelial wall. Hence, it may influence platelet wall adhesion and thrombosis formation. PM has been experimentally observed in coronary-sized tubes (mm diameter) [1], [2] between 10 and 25 cm of tube length. These values surpass the typical axial locations of epicardial coronary arterial segments with atherosclerotic plaques [3]. This observation questions the need to consider PM in thrombosis simulations of the epicardial coronary arteries.

We investigated PM across vascular scales with 2D axisymmetric discrete particle transport (DPT) models: 1) A standard non-inertial drift-diffusion (DD) model [4], 2) a modified DD model accounting for shear and red blood cell concentration gradients [5], and 3) an inertial Maxey-Riley (MR) model [6]. Reynolds number (Re) and diameter ranged from 1 to 350 and 0.1 mm to 4 mm. We quantified PM as the percent displacement of particles from their initial radial position, as well as the normalized radial density of particles after 1 second of flow.

All models had PM < 2% when diameter > 2 mm and Re > 20. The modified DD model had normalized near-wall platelet density of 6 for 0.1 mm vessels when Re < 4, whereas the standard model was 1.25. At these scales, the MR model led to center-of-vessel migration. All models had continuous, uniform platelet distributions when diameter > 2 mm. Our DPT results imply that PM may be negligible in coronary arteries. Future work will validate these results in 3D.