Examination of Fluid-Structure Interaction in Stent Grafts and its Hemodynamic Implications

Abstract

Every year in the United States, 4,500 deaths occur from abdominal aortic aneurysm (AAA) rupture. Aneurysms develop when the arterial wall weakens. Many risk factors can contribute to aneurysm formation, including age, sex, ethnicity, smoking and hypertension [1]. AAAs are the most common form of aneurysm because the aorta experiences the highest wall shear stress (WSS) of any vessels in the human body. These aneurysms are 5–6% prevalent in men and 1–2% in women, both over 65 years of age [2]. In the aorta, high WSS causes plaque formation, but in peripheral arteries where the flow rate is lower, atherosclerosis can also trigger aneurysm formation.

Patient-specific computational flow simulation reveals significant differences in paravisceral aortic hemodynamics between fenestrated and branched endovascular aneurysm repair

“… 36 Other studies have also shown minimal differences between rigid vs deformable wall simulations on calculated hemodynamic parameters in the abdominal aorta. 37 Results from our study may also differ depending on overall graft designs using different manufacturers with varying graft geometry with respect to diameters and lengths of tapered segments or fenestration/branch portal diameters.…”

Patient-specific computational flow modelling for assessing hemodynamic changes following fenestrated endovascular aneurysm repair

“… 38 However, it has been shown that the differences between rigid wall and fluid-solid interaction deformable wall simulations have minimal impact on calculated hemodynamic parameters in the abdominal aorta, with tWSS and oscillatory shear index values differing only by approximately 5% between methods. 39 Nonetheless, hemodynamic analysis is not able to calculate force vectors affecting the stent structure from either pulsatile or respiratory-induced motion. These external forces are key factors as they pertain to mechanical methods of graft failure, such as material fatigue and stent fracture, and are better investigated using other analytical or bench models.…”

Retrograde branched extension limb assembling stent of pararenal abdominal aortic aneurysm: A longitudinal hemodynamic analysis for stent graft migration

“…The grid resolution varied from 2 564 019 to 4 178 775 cells with approximately 2 000 000 to 4 000 000 tetrahedral elements in the core region and five prismatic layers in the boundary layers near the wall. The arterial wall was assumed as the rigid wall with a non‐slip boundary condition, and it is shown that there is a negligible difference between rigid and compliant wall 29 . Blood was considered to be incompressible, and a Newtonian fluid with a density of 1050 kg/m 3 and a dynamic viscosity of 0.00365 kg m −1 s 30 .…”