Patient-specific numerical simulation of stent-graft deployment: Validation on three clinical cases

Abstract

Endovascular repair of abdominal aortic aneurysms faces some adverse outcomes, such as kinks or endoleaks related to incomplete stent apposition, which are difficult to predict and which restrain its use although it is less invasive than open surgery. Finite element simulations could help to predict and anticipate possible complications biomechanically induced, thus enhancing practitioners' stent-graft sizing and surgery planning, and giving indications on patient eligibility to endovascular repair. The purpose of this work is therefore to develop a new numerical methodology to predict stent-graft final deployed shapes after surgery. The simulation process was applied on three clinical cases, using preoperative scans to generate patient-specific vessel models. The marketed devices deployed during the surgery, consisting of a main body and one or more iliac limbs or extensions, were modeled and their deployment inside the corresponding patient aneurysm was simulated. The numerical results were compared to the actual deployed geometry of the stent-grafts after surgery that was extracted from postoperative scans. We observed relevant matching between simulated and actual deployed stent-graft geometries, especially for proximal and distal stents outside the aneurysm sac which are particularly important for practitioners. Stent locations along the vessel centerlines in the three simulations were always within a few millimeters to actual stents locations. This good agreement between numerical results and clinical cases makes finite element simulation very promising for preoperative planning of endovascular repair.

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

“…The arterial lumen geometry was extracted with surgery oriented Endosize® software (Therenva, France) as shown in Figure 1A and meshed with triangular shell elements (1.5 mm mean edge length) as illustrated in Figure 1B, following the methodology detailed in (Perrin et al, 2015a). These elements were not assigned mechanical properties as they represented the inner surface of the rigid phantom made of a thermoset polymer, assumed to have negligible deformations induced by the SG.…”

“…The methodology proposed in (Perrin et al, 2015a) was used to generate the mesh and to model the mechanical behaviour of arterial walls. More specifically, they were modelled by triangular shell finiteelements (1.5 mm mean edge length), 1.5 mm or 1 mm thick in aortic or iliac areas.…”

“…Elements were assigned orthotropic linear elastic material properties. The constitutive parameters, computed by a linearization of the Holzapfel-Gasser-Ogden hyperelastic law (Gasser et al, 2006) in physiological conditions, as in (Perrin et al, 2015a), are reported in Table 3.…”

“…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). However, all the aforementioned studies only dealt with rather simple arterial geometries: idealised tubular shapes, idealised fusiform AAA, short patient-specific ascending aorta or rather straight patient-specific AAAs.…”

Computational Material Analysis of Structural and Hemodynamic Model of Coronary Stent by CFD/FEA in Computer Aided Mechanical Engineering Approach

“…The boundaries of the flow in the arteries are not rigid, and cannot be predicted using rigid wall, or predefined-boundarymotion calculations [2]. The methodology developed is to improve a commercially available computational fluid dynamics (CFD) method [3] to assess hemodynamic in ISO's 5840 [4]. The stress analysis by combining corresponding functions and the restenosis problem were studied by cardiovascular simulations as research concept shown in Fig.…”