Hemodynamic effects of intraluminal thrombus burden in an idealized abdominal aortic aneurysm

Abdominal aortic aneurysm (AAA) is the dilatation of the abdominal aorta beyond 50% of its normal diameter and affects a wide range of society. If left untreated, AAA continues to grow and has a risk of rupture. The AAA rupture is an emergency condition and most of ruptured cases result in death. Understanding the AAA hemodynamics plays an important role for the accurate diagnosis and treatment methods. At this point, computational fluid dynamics (CFD) provide valuable information by simulating the flow in a virtual environment. In this study, AAA hemodynamics are investigated using CFD simulations by focusing on the effect of intraluminal thrombus (ILT) burden in an idealized AAA model. Different levels of ILT burden are virtually implemented in the AAA model, and the hemodynamic differences are analyzed by comparing the shear-related parameters such as wall shear stress (WSS), time-averaged WSS, oscillatory shear index, and endothelial cell activation potential. According to the results, the formation of ILT significantly changes the biomechanical environment in AAA. In the models with low ILT burden, a spatially heterogeneous WSS distribution is observed around the aneurysm. As the ILT burden increases, a relatively smooth and homogenous WSS distribution is obtained on the AAA wall. This shows that ILT acts as a mechanism which prevents the abnormal shear stresses around the aneurysmal enlargement.