Patient-specific simulation of stent-graft deployment within an abdominal aortic aneurysm

In this study, finite element analysis is used to simulate the surgical deployment procedure of a bifurcated stent-graft on a real patient's arterial geometry. The stent-graft is modeled using realistic constitutive properties for both the stent and most importantly for the graft. The arterial geometry is obtained from pre-operative imaging exam. The obtained results are in good agreement with the post-operative imaging data. As the whole computational time was reduced to less than 2 hours, this study constitutes an essential step towards predictive planning simulations of aneurysmal endovascular surger

Simulation du déploiement d'endoprothèses dans des anévrismes iliaques tortueux

National audienceLe traitement des anévrismes par voie endovasculaire avec pose d'une endoprothèse (EP) est une technique de choix face à la chirurgie ouverte conventionnelle, mais elle reste à fiabiliser. Dans cette étude, une simulation complète par éléments finis de la pose d'EP est proposée afin d'évaluer et comparer les performances mécaniques de cinq dispositifs du marché. Les résultats confirment l'importance de la flexibilité des EPs et offrent une avancée notable dans la simulation de la chirurgie endovasculaire

Finite Element Analysis of the Mechanical Performances of 8 Marketed Aortic Stent-Grafts

International audiencePurpose: To assess numerically the flexibility and mechanical stresses undergone by stents and fabric of currently manufactured stent-grafts. Methods: Eight marketed stent-graft limbs (Aorfix, Anaconda, Endurant, Excluder, Talent, Zenith Flex, Zenith LP, and Zenith Spiral-Z) were modeled using finite element analysis. A numerical benchmark combining bending up to 180° and pressurization at 150 mmHg of the stent-grafts was performed. Stent-graft flexibility, assessed by the calculation of the luminal reduction rate, maximal stresses in stents, and maximal strains in fabric were assessed. Results: The luminal reduction rate at 90° was ‹<20% except for the Talent stent-graft. The rate at 180° was higher for Z-stented models (Talent, Endurant, Zenith, and Zenith LP; range 39%-78%) than spiral (Aorfix, Excluder, and Zenith Spiral-Z) or circular-stented (Anaconda) devices (range 14%-26%). At 180°, maximal stress was higher for Z-stented stent-grafts (range 370-622 MPa) than spiral or circular-stented endografts (range 177-368 MPa). At 90° and 180°, strains in fabric were low and did not differ significantly among the polyester stent-grafts (range 0.5%-7%), while the expanded polytetrafluoroethylene fabric of the Excluder stent-graft underwent higher strains (range 11%-18%). Conclusion: Stent design strongly influences mechanical performances of aortic stentgrafts. Spiral and circular stents provide greater flexibility, as well as lower stress values than Z-stents, and thus better durability

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

International audienceEndovascular 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

Etude de la morbi-mortalité en chirurgie vasculaire de reperméabilisation des membres inférieurs dans le service du professeur Clement. (A propos de 58 cas)

REIMS-BU Santé (514542104) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

Finite-Element Based Image Registration for Endovascular Aortic Aneurysm Repair

In this paper we introduce a new method for the registration between preoperative and intraoperative computerized tomography (CT) images used in endovascular interventions for aortic aneurysm repair. The method relies on a 3D finite-element model (FEM) of the aortic centerline reconstructed from preoperative CT scans. Intraoperative 2D fluoroscopic images are used to deform the 3D FEM and align it onto the current aortic geometry. The method was evaluated on clinical datasets for which a reference CT scan was available to evaluate the registration errors made by our method and to compare them with other registration methods based on rigid transformations. Errors were estimated based on the predicted locations of landmarks positioned at different branch ostia. It appeared that our method always reduced the registration errors of at least 20% compared to gold standard 3D rigid registration and permitted to reach a global precision of 3.8 mm and a renal precision of 2.6 mm, which is a significant improvement compatible with surgical specifications. Finally, the major asset of our method is that it only requires one fluoroscopic intraoperative 2D image to perform the 3D non-rigid registration. This would reduce patient irradiation and cut the costs compared to traditional methods

Endovascular treatment for carotid artery stenosis after neck irradiation.

International audienceBACKGROUND: To lower the risk of complications, carotid angioplasty and stenting (CAS) has been proposed as an alternative to open surgery for carotid artery stenosis after neck irradiation. However, there are little postoperative data to support the benefits of this strategy. This study evaluated the outcome of CAS in patients who had undergone neck irradiation. METHODS: This retrospective study was conducted at 15 vascular surgery or interventional radiology centers in France between January 1998 and July 2006. A total of 135 patients (115 men) with a mean age of 67 +/- 8 years (range, 43-88) underwent CAS for 149 irradiation-induced lesions. The interval between irradiation and discovery of the lesions was 12 +/- 8 years. Mean diameter reduction was 81% (range, 50%-95%), and stenosis was symptomatic in 34%. Contralateral carotid lesions were observed in 48% of patients, including thrombosis in 18 and stenosis >50% in 53. RESULTS: Technical failure occurred during CAS in three cases. The overall technical success rate was 98%. A cerebral protection device was used in 59%. No death, one transient ischemic attack, and two strokes occurred during the first postoperative month. Mean follow-up was 30 months. Six patients were lost to follow-up. Survival rates were 93.9% at 1 year and 75.3% at 3 years. Complications after the first postoperative month included neurologic events in six, carotid thrombosis in nine, and restenosis in 18. The rates of freedom from neurologic and anatomic events were, respectively, 96.2% and 93.2% at 1 year and 93.1% and 85.9% at 3 years. CONCLUSION: The immediate outcome of CAS for irradiation-induced carotid artery stenosis was satisfactory. Medium-term neurologic outcome was acceptable, but the incidence of anatomic events such as thrombosis and restenosis was high. A randomized study is needed to confirm that the outcome of the endovascular and surgical therapy is comparable in this indication

Mechanical performances of stent-grafts within tortuous abdominal aortic aneurysms

International audiencePas de résum

Computational comparison of stent-grafts: Mechanical performances within a tortuous abdominal aortic aneurysm

International audiencePas de résum

Computational comparison of stent-grafts: Mechanical performances within a tortuous abdominal aortic aneurysm

International audiencePas de résum