A Computational Fluid Dynamics Approach to Investigate the Development of Mural Thrombus in Microvessels with Stenotic and Poststenotic Dilatation Zones

Abstract

Vascular stenosis is the narrowing of blood vessels due to plaque buildup within the vessel walls. It disturbs the blood flow dynamics in microvessels, leading to platelet activation and aggregation downstream of the stenosed region, resulting in a mural thrombus. In this study, we performed extensive numerical simulations to investigate the effect of hemodynamic parameters and stenosed geometries on the development of a mural thrombus. The methodology of the numerical simulation is experimentally validated. We performed simulations on bulk shear rates ranging from 100 s–1to 30,000 s–1, corresponding to various inlet flow rates. As flow progresses in the stenosed microvessels, the velocity at the stenosed region increases several-fold to the inlet flow velocity. At the downstream end, in the expansion zone, velocity abruptly decreases, creating flow separation and recirculation zones, further leading to the reattachment zone. It is observed from the numerical simulations that as platelets enter the stenosed region, they experience an 8-fold increase in wall shear stress as compared to the inlet. The exposure to high shear stress enhances the platelet activation level and hydrodynamic collision frequency of platelets with walls and platelets. Subsequently, they experience low shear stress (14-fold decrement as in the throat region) downstream of the throat, where platelets recirculate in vortices. A cumulative effect of high shear stress exposure in the throat and low shear stress in the recirculation zone allows platelets to get activated and have prolonged contact with the walls, which results in platelet deposition at the walls, in turn developing a mural thrombus. In addition, the effect of other parameters, such as elongation stresses, velocity distribution, and the strength of the recirculation zone on the platelet activation level and deposition, is studied in detail. Moreover, a detailed analysis of microvessels with poststenotic dilatation (PSD) and multiple stenosed regions is also reported. © 2025 American Chemical Society