DPIV Prediction of Flow Induced Platelet Activation—Comparison to Numerical Predictions

Abstract

Abstract-Flow induced platelet activation (PA) can lead to platelet aggregation, deposition onto the blood vessel wall, and thrombus formation. PA was thoroughly studied under unidirectional flow conditions. However, in regions of complex flow, where the platelet is exposed to varying levels of shear stress for varying durations, the relationship between flow and PA is not well understood. Numerical models were developed for studying flow induced PA resulting from stress histories along Lagrangian trajectories in the flow field. However, experimental validation techniques such as Digital Particle Image Velocimetry (DPIV) were not extended to include such models. In this study, a general experimental tool for PA analysis by means of continuous DPIV was utilized and compared to numerical simulation in a model of coronary stenosis. A scaled up (5:1) 84% eccentric and axisymetric coronary stenosis model was used for analysis of shear stress and exposure time along particle trajectories. Flow induced PA was measured using the PA State (PAS) assay. An algorithm for computing the PA level in pertinent trajectories was developed as a tool for extracting information from DPIV measurements for predicting the flow induced thrombogenic potential. CFD, DPIV and PAS assay results agreed well in predicting the level of PA. In addition, the same trend predicted by the DPIV was measured in vitro using the Platelet Activity State (PAS) assay, namely, that the symmetric stenosis activated the platelets more as compared to the eccentric stenosis.

A comparison of hemodynamic metrics and intraluminal thrombus burden in a common iliac artery aneurysm

“…These observations are physically similar to the separation of the boundary-layer downstream of stenoses, where Raz et al [30] showed the direct relationship between platelet recirculation time and both platelet activation and acetylated thrombin generation. Furthermore, Rayz et al [31] observed thrombus deposition in certain regions of patient-specific intracranial geometries with an increase in residence time and low WSS.…”

Platelet Activation Due to Hemodynamic Shear Stresses: Damage Accumulation Model and Comparison to In Vitro Measurements

“…The PAS assay was successfully applied for measuring the procoagulant activity of devices, both in vitro and in an animal model, [23][24][25] and under various shear stress-exposure time combinations in flow loops and stenosis models. 22,26 PAS values were normalized against the average activity of fully activated platelets measured for each experiment, obtained by sonication (10 W for 10 seconds, Branson Sonifier 150 with microprobe, Branson, MO). PAS values are expressed as a fraction of maximal prothrombinase activity.…”

High-Resolution Measurement of the Unsteady Velocity Field to Evaluate Blood Damage Induced by a Mechanical Heart Valve

“…One study 42 These results suggest that in this region cells are exposed for hundreds of ms to shear stresses sustainedly larger than the normal physiological range (between 0.5 Pa and 1 Pa). The shear stresses we measured for cells travelling in the lateral orifice jet, farther from the leaflet tip, fall within the normal physiological range.…”