Evolution of the Proximal Sealing Rings of the Anaconda Stent-Graft After Endovascular Aneurysm Repair

Abstract

Purpose: To provide insight into the evolution of the saddle-shaped proximal sealing rings of the Anaconda stent-graft after endovascular aneurysm repair (EVAR). Methods: Eighteen abdominal aortic aneurysm patients were consecutively enrolled in a single-center, prospective, observational cohort study (LSPEAS; Trialregister.nl identifier NTR4276). The patients were treated electively using an Anaconda stent-graft with a mean 31% oversizing (range 17–47). According to protocol, participants were to be followed for 2 years, during which 5 noncontrast electrocardiogram-gated computed tomography scans would be conducted. Three patients were eliminated within 30 days (1 withdrew, 1 died, and a third was converted before stent-graft deployment), leaving 15 patients (mean age 72.8±3.7 years; 14 men) for this analysis. Evolution in size and shape (symmetry) of both proximal infrarenal sealing rings were assessed from discharge to 24 months using dedicated postprocessing algorithms. Results: At 24 months, the mean diameters of the first and second ring stents had increased significantly (first ring: 2.2±1.0 mm, p<0.001; second ring: 2.7±1.1 mm, p<0.001). At 6 months, the first and second rings had expanded to a mean 96.6%±2.1% and 94.8%±2.7%, respectively, of their nominal diameter, after which the rings expanded slowly; ring diameters stabilized to near nominal size (first ring, 98.3%±1.1%; second ring, 97.2%±1.4%) at 24 months irrespective of initial oversizing. No type I or III endoleaks or aneurysm-, device-, or procedure-related adverse events were noted in follow-up. The difference in the diametric distances between the peaks and valleys of the saddle-shaped rings was marked at discharge but became smaller after 24 months for both rings (first ring: median 2.0 vs 1.2 mm, p=0.191; second ring: median 2.8 vs 0.8 mm; p=0.013). Conclusion: Irrespective of initial oversizing, the Anaconda proximal sealing rings radially expanded to near nominal size within 6 months after EVAR. Initial oval-shaped rings conformed symmetrically and became nearly circular through 24 months. These findings should be taken into account in planning and follow-up.

Outcomes of Endovascular Aneurysm Repair Using the Anaconda Stent-Graft

“…23 Age, the number of patent collateral arteries, maximum aneurysm size, and smoking are main factors consistently associated with type II endoleak. 22,24 In our cohort, the small number of patent collateral branches might have contributed to the low rate of type II endoleak.…”

“…Factors influencing sealing and fixation consist of conformational changes of ring stents and aorta over time. Koenrades et al 22 evaluated the evolution of the saddle-shaped proximal sealing rings of the Anaconda stent-graft after EVAR. The initially oval-shaped ring conformed symmetrically and become nearly circular through 24 months.…”

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

“…Major wrinkles disturbed the flow pattern and caused recirculation and low wall shear stresses, effects that have been linked to thrombus formation. 26 It is interesting to note that after EVAR, endovascular devices continue to expand within the native artery to near nominal oversize, 14 meaning that the rigid geometry used in this study represents a worst case for fabric infolding. In the future, this CFD analysis capability will be validated against experimental data to strengthen its use as a tool in designing new stent grafts to promote smoother flow.…”

Geometric Remodeling of the Perirenal Aortic Neck at and Adjacent to the Double Sealing Ring of the Anaconda Stent-Graft After Endovascular Aneurysm Repair

“…Details of the patient sample, including preoperative anatomical characteristics by standard computed tomography angiography (CTA) imaging, and the image acquisition protocol were reported in a prior publication about the evolution of the Anaconda proximal sealing rings. 17 Sizes of the stent-graft body ranged from 25.5 to 34 mm. The device was oversized by 17% to 47% (mean 31%) based on inner wall diameters from static preoperative CTA scans.…”

“…In the present study, we continue analysis of a previously reported patient cohort 17 to seek full understanding of abdominal aortic neck remodeling after Anaconda stentgraft implantation by investigating the geometric evolution of the entire perirenal neck segment above, at, and below the 2 fixation and sealing rings.…”