Deployment of stent grafts in curved aneurysmal arteries: toward a predictive numerical tool

Abstract

The mechanical behavior of aortic stent grafts plays an important role in the success of endovascular surgery for aneurysms. In this study, finite element analysis was carried out to simulate the expansion of five marketed stent graft iliac limbs and to evaluate quantitatively their mechanical performances. The deployment was modeled in a simplified manner according to the following steps: (i) stent graft crimping and insertion in the delivery sheath, (ii) removal of the sheath and stent graft deployment in the aneurysm, and (iii) application of arterial pressure. In the most curved aneurysm and for some devices, a decrease of stent graft cross-sectional area up to 57% was found at the location of some kinks. Apposition defects onto the arterial wall were also clearly evidenced and quantified. Aneurysm inner curve presented significantly more apposition defects than outer curve. The feasibility of finite element analysis to simulate deployment of marketed stent grafts in curved aneurysm models was demonstrated. The study of the influence of aneurysm tortuosity on stent graft mechanical behavior shows that increasing vessel curvature leads to stent graft kinks and inadequate apposition against the arterial wall. Such simulation approach opens a very promising way toward surgical planning tools able to predict intra and/or post-operative short-term stent graft complications.

Patient-specific simulation of endovascular repair surgery with tortuous aneurysms requiring flexible stent-grafts

“…At the moment, simulation results could be post-processed to estimate luminal areas along the vessel centreline (De Bock et al, 2012;Demanget et al, 2013) and stents apposition defects (De Bock et al, 2014;Perrin et al, 2015b). These estimates could point out possible SG kink, gap between SG and arterial wall or collateral artery coverage, and thus potential risk of thrombosis, endoleak or artery occlusion.…”

“…Afterwards, these models were used to feed FE simulations of SG deployment. About SG deployment, we can cite limb deployment in idealised vessels (Perrin et al, 2015b), simulation of in vitro SG main body deployment (De Bock et al, 2012) and patientspecific aortic endografting (Auricchio et al, 2013). Our group also recently managed to simulate the deployment of aorto-bi-iliac SGs in patient-specific AAAs (Perrin et al, 2015a).…”

Predictive Numerical Simulations of Double Branch Stent-Graft Deployment in an Aortic Arch Aneurysm

“…A linear elastic material behavior was used, reproducing the Nitinol behavior in its austenitic phase. Nitinol remained in its austenitic phase during SG deployment as the full crimping in its delivery sheath was not considered, as previously validated on different types of SGs 12,34 . An accurate geometry of the graft was created using FreeCAD ® and meshed with linear 4-node elements in Abaqus ® (S4R and 0.5 mean edge length).…”

Feasibility of using bulk metallic glass for self-expandable stent applications

“…66,67 In this technique, the aneurysm sac is excluded from the main stream circulation by the endovascular insertion of a stent-graft (SG) via the femoral arteries. 68 A typical SG is a combination of a metallic stent stitched to a polymeric fabric 69,70 with the metallic stent typically fabricated with nitinol or self-expanding 316 L stainless steel. 71 Here, we considered the Zenith TX2 TAA Endovascular Graft 72 with Pro-Form which is a two-piece cylindrical endovascular graft consisting of proximal and distal components.…”