A Relation Between Near-Wall Particle-Hemodynamics and Onset of Thrombus Formation in Abdominal Aortic Aneurysms

Abstract

A novel computational particle-hemodynamics analysis of key criteria for the onset of an intraluminal thrombus (ILT) in a patient-specific abdominal aortic aneurysm (AAA) is presented. The focus is on enhanced platelet and white blood cell residence times as well as their elevated surface-shear loads in near-wall regions of the AAA sac. The generalized results support the hypothesis that a patient's AAA geometry and associated particle-hemodynamics have the potential to entrap activated blood particles, which will play a role in the onset of ILT. Although the ILT history of only a single patient was considered, the modeling and simulation methodology provided allow for the development of an efficient computational tool to predict the onset of ILT formation in complex patient-specific cases.

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

“…In addition, Basciano et al [45] assessed the residence times and surface-shear loads of platelets and white bloods cells in a patient-specific AAA sac using Eulerian-Lagrangian CFD simulation methodology to investigate the onset of ILT, supporting Biasetti's work and the generalised view that aneurysms entrap blood particles. The one-way Lagrangian methodology used by Basciano [45] implements a particle drag force, pressure gradient force and gravity force, to calculate the particle trajectories in the arterial flow field, as these forces are thought to provide a reasonable prediction of cell transport.…”

“…By using a non-Newtonian model, as opposed Newtonian, we can capture the macro-scale shear-thinning of the blood, allowing a one-way Lagrangian particle transport model to provide a good prediction of individual blood-cell trajectories within the continuous phase (blood). This methodology follows that of Basciano et al where the particleparticle and particle-fluid interactions are ignored [45] and is discussed further in section 2.5.…”

“…We injected platelets and monocytes into the flow field on a transverse-plane within the IR aorta, well upstream of the common iliac arteries (see Figure 5). We assumed these particles to be spherical with diameters of 2 and 16 µm, and densities of 1040 kg/m 3 and 1070 kg/m 3 for the platelets [45] and monocytes [47], respectively. The particles were injected individually in parcels at randomly chosen spatial points (on the plane) with the same velocity as the continuous phase.…”

“…The one-way Lagrangian methodology used by Basciano [45] implements a particle drag force, pressure gradient force and gravity force, to calculate the particle trajectories in the arterial flow field, as these forces are thought to provide a reasonable prediction of cell transport.…”

Wall Shear Stress Prediction Using Computational Simulation on Patient Specific Artery with Aneurysm

“…The mortality rate is almost 57% [1] for rupture occuring at a medical facility. Aneurysms can be hereditary or caused by disease, both of which cause the wall of the blood vessel to weaken [2]. Wall shear stress (WSS) has been proposed as a key parameter to characterize aneurysm [3].…”