Studying the Interaction of Stent-Grafts and Treated Abdominal Aortic Aneurysms

Abstract

Since the advent of endovascular repair of aortic aneurysms (EVAR), clinical focus has been on preventing loss of sealing at the level of the infrarenal neck, which leads to type I endoleak and repressurization of the aneurysm sac. Enhanced mechanisms for central fixation and seal have consequently lowered the incidence of migration and endoleaks. However, endograft limb thrombosis and its causal mechanisms have not been addressed adequately in the literature. This article reviews the pathophysiological mechanisms associated with limb thrombosis in order to facilitate better clinical judgment to prevent iliac adverse effects.

Factors associated with elimination of type II endoleak during the first year after endovascular aneurysm repair

“…Angulations and aortoiliac tortuosity have certain hemodynamic consequences on the pressure and shear stress distribution in the iliac limbs over the cardiac cycle. 13,14,18 Iliac tortuosity has been associated with EVAR outcome. 13,14,18 Kumar et al 19 suggested that the right iliac tortuosity significantly increased the risk of ET II.…”

“…13,14,18 Iliac tortuosity has been associated with EVAR outcome. 13,14,18 Kumar et al 19 suggested that the right iliac tortuosity significantly increased the risk of ET II. However, in this study, iliac tortuosity was defined as the extent of tortuosity of the common iliac arteries according to the clinician's judgment using the categories of none (ie, straight), mild, moderate, or severe, which obviously is an arbitrary scoring system.…”

Computational Comparison Between a Classic Bifurcated Endograft and a Customized Model With “Dog Bone”–Shaped Limbs

“…Technical reasons refer to the use of unsupported graft limbs, extension of the distal landing zone to the external iliac artery, and excessive oversizing of the endograft. 23 It has been recently suggested that the geometry of iliac limbs can influence the magnitude or the direction of displacement forces acting on the entire endograft, predisposing to migration. 24 Nowadays, more and more companies provide custommade, patient-specific designs for challenging anatomies, such as the "dog bone"-shaped design with narrowed middle iliac limbs for accommodating significantly narrow refers to the late diastole, t2 to the accelerating phase, t3 depicts the peak systolic phase, t4 the late deceleration, t5 describes endsystole, and t6 the early diastolic phase.…”

“…Technical reasons refer to the use of unsupported graft limbs, extension of the distal landing zone to the external iliac artery, and excessive oversizing of the endograft. 23 It has been recently suggested that the geometry of iliac limbs can influence the magnitude or the direction of displacement forces acting on the entire endograft, predisposing to migration. 24…”

Numerical, simulations of blood flow effects under the presence of abdominal aortic aneurysm

“…The impact of EG implantation on blood flow can be studied by computational means. [87][88][89][90] To this end, researchers have managed to quantify post-EVAR effects harnessing the power of computational methods. 91 The migration of an EG and the occlusion of its limbs are multifactorial events, with unambiguous biomechanical aspects.…”