Geometrical Changes of the Aorta as Predictors for Thromboembolic Events After EVAR With the Anaconda Stent-Graft

PURPOSE

Thromboembolic events (TE), including limb graft occlusion (LGO) and distal limb embolization (DLE), are common complications after endovascular aneurysm repair (EVAR). The aim of this study was to find predictors for TE in patients treated with the Anaconda stent-graft for infrarenal aneurysms.

MATERIALS AND METHODS

Geometrical and anatomical variables were retrospectively analyzed in a consecutive Anaconda cohort. Pre- and postoperative CT scans were used to derive geometrical parameters length, curvature, torsion, and tortuosity index (TI) from the center lumen lines (CLLs). Limb characteristics, pre-to-post EVAR and mid-term-follow-up changes in the parameters were evaluated for their predictive value for TE.

RESULTS

Eighty-four patients (mean age 74±8.3 years, 74 men) were enrolled. The risk of TE was lowered with pre-to-post implant decreasing TI (steps of 0.05: OR: 1.30, 95% CI: 1.01-1.66, p=0.04), pre-to-post implant decreasing mean curvature (OR: 1.08, 95% CI: 1.01-1.16, p=0.03), and a larger degree of circumferential common iliac artery (CIA) calcification (OR: 0.98, 95% CI: 0.97-1.00, p=0.03). The only LGO predictor was the caudal relocation of maximal curvature after EVAR (OR: 1.01, 95% CI: 1.00-1.01, p=0.04). Preventors of DLE were CIA diameter (OR: 0.87, 95% CI: 0.76-0.99, p=0.04), circumferential CIA calcification (OR: 0.97, 95% CI: 0.95-1.00, p=0.03), mean and maximal curvature of the preoperative aortoiliac trajectory (OR: 0.86, 95% CI: 0.79-0.94, p<0.01 and OR: 0.97, 95% CI: 0.95-1.00, p=0.03, respectively) and pre-to-postoperative decrease in mean curvature (OR: 1.11, 95% CI: 1.02-1.21, p=0.02). Midterm TE predictors were length (OR: 0.95, 95% CI: 0.89-1.01, p=0.08) and torsion maximum location (OR: 1.01, 95% CI: 0.99-1.01, p=0.10).

CONCLUSION

The present study confirms that treatment of infrarenal AAA with an Anaconda stent-graft is related to a relatively high TE rate which decreases with a pre-to-postoperative reduction in curvature and TI, and a larger degree of circumferential CIA calcification. In other words, more aortoiliac straightening and more circumferential CIA calcification may prevent TE development after EVAR with this stent-graft.

Efficiently Simulating an Endograft Deployment: A Methodology for Detailed CFD Analyses

Numerical models of endografts for the simulation of endovascular aneurysm repair are increasingly important in the improvement of device designs and patient outcomes. Nevertheless, current finite element analysis (FEA) models of complete endograft devices come at a high computational cost, requiring days of runtime, therefore restricting their applicability. In the current study, an efficient FEA model of the Anaconda™ endograft (Terumo Aortic, UK) was developed, able to yield results in just over 4 h, an order of magnitude less than similar models found in the literature. The model was used to replicate a physical device that was deployed in a 3D printed aorta and comparison of the two shapes illustrated a less than 5 mm placement error of the model in the regions of interest, consistent with other more computationally intensive models in the literature. Furthermore, the final goal of the study was to utilize the deployed fabric model in a hemodynamic analysis that would incorporate realistic fabric folds, a feature that is almost always omitted in similar simulations. By successfully exporting the deployed graft geometry into a flow analysis, it was illustrated that the inclusion of fabric wrinkles enabled clinically significant flow patterns such as flow stagnation and recirculation to be detected, paving the way for this modelling methodology to be used in future for stent design optimisation.

Global Post-Market Clinical Follow-up of the Treovance Stent-Graft for Endovascular Aneurysm Repair: One-Year Results From the RATIONALE Registry

PURPOSE:

To evaluate the safety and performance of the Treovance stent-graft.

METHODS:

The global, multicenter RATIONALE registry ( ClinicalTrials.gov; identifier NCT03449875) prospectively enrolled 202 patients (mean age 73.0±7.8 years; 187 men) with abdominal aortic aneurysms (AAA) suitable for endovascular aneurysm repair (EVAR) using the Treovance. The composite primary safety endpoint was site-reported all-cause mortality and major morbidity. The primary efficacy outcome was clinical success. Further outcomes evaluated included technical success; stent-graft migration, patency, and integrity; endoleak; and aneurysm size changes.

RESULTS:

Technical success was 96% (194/202); 8 patients had unresolved type I endoleaks at the end of the procedure. There was no 30-day mortality and 1% major morbidity (1 myocardial infarction and 1 bowel ischemia). Clinical success at 1 year was confirmed in 194 (96%) patients; 6 of 8 patients had new/persistent endoleaks and 2 had aneurysm expansion without identified endoleak. A total of 8 (4%) reinterventions were required during the mean 13.7±3.1 months of follow-up (median 12.8). At 1 year, the Kaplan-Meier estimate for freedom from reintervention was 95.6% (95% CI 91.4% to 97.8%). Other estimates were 95.5% (95% CI 91.7% to 97.6%) for freedom from endoleak type I/III and 97.4% (95% CI 94.2% to 98.9%) for freedom from aneurysm expansion. Thirteen (6.4%) patients died; no death was aneurysm related.

CONCLUSION:

The RATIONALE registry showed favorable safety and clinical performance of the Treovance stent-graft for the treatment of infrarenal AAAs in a real-world setting.