Purpose: To analyze the 2-year outcomes of endovascular aneurysm sealing (EVAS) according to 2 versions of the instructions for use (IFU). Methods: A retrospective study was conducted involving 355 consecutive patients treated with the first-generation EVAS device from April 2013 to December 31, 2015, at 3 high-volume centers. Out of 355 patients treated with EVAS, 264 were elective asymptomatic infrarenal EVAS procedures suitable for analysis. In this cohort, 168 (63.3%) patients were treated within the IFU 2013 criteria; of these 48 (18.2%) were in compliance with the revised IFU 2016 version. Results: Overall technical success was 98.2% (165/168) in the IFU 2013 group and 97.9% (47/48) in the IFU 2016 subgroup (p=0.428). The 2-year freedom from reintervention estimates were 89.7% (IFU 2013) and 95.7% (IFU 2016), with significantly more reinterventions in the first 45 cases (p=0.005). The stenosis/occlusion estimates were 6.5% (IFU 2013) and 4.2% (IFU 2016; p=0.705). Nine (5.4%) endoleaks (8 type Ia and 1 type Ib) were observed within the IFU 2013 cohort; 3 (2.1%) were in the IFU 2016 subgroup (p=0.583). Migration ≥10 mm or ≥5 mm requiring intervention was reported in 12 (7.1%) patients in the IFU 2013 cohort but none within the IFU 2016 subgroup. Ten (6.0%) patients demonstrated aneurysm growth in the IFU 2013 cohort, of which 2 (4.2%) were in the IFU 2016 subgroup. Overall survival and freedom from aneurysm-related death estimates at 2 years were 90.9% and 97.6% in the IFU 2013 cohort (IFU 2016: 95.5% and 100.0%). The prevalence of complications seemed lower within IFU 2016 without significant differences. Conclusion: This study shows acceptable 2-year results of EVAS used within the IFU, without significant differences between the 2 IFU versions, though longer follow-up is indicated. The refined IFU significantly reduced the applicability of the technique.

Purpose: To describe the feasibility and technical aspects of a proximal Nellix-in-Nellix extension to treat caudal stentgraft migration after endovascular aneurysm sealing (EVAS) in the in vitro and in vivo settings. Methods: In vitro studies were designed (1) to assess inner diameters of Nellix-in-Nellix extensions after postdilation with 12-mm balloons and (2) to test wall apposition in tubes with different diameters using a Nellix-in-Nellix stent-graft that extended out of the original Nellix stent-graft lumen by 10, 20, 30, and 40 mm. Simulated-use experiments were performed using silicone models in conjunction with a pulsatile flow pump. In the clinical setting, 5 patients (median age 74 years, range 73-83) presented at 2 centers with type Ia endoleak secondary to caudal Nellix stent-graft migration measuring a median 9 mm (range 7-15) on the left and 7 mm (range 0-11) on the right. Median polymer fill volume at the initial EVAS procedure was 42.5 mL (range 25-71). The median time to reintervention with a proximal Nellix extension was 15 months (range 13-32). Results: In vitro, the inner diameters of the Nellix-in-Nellix extensions were consistent after postdilation. Cases with 10 and 20 mm of exposed endobag resulted in a poor seal with endoleak, while cases with 30 and 40 mm of exposed endobag length exhibited angiographic seal. Fill line pressures of the second Nellix were higher than expected. In the 5 clinical cases, chimney grafts were required in each case to create an adequate proximal landing zone. The Nellix-in-Nellix procedure was successful in all patients. There were no procedure-related complications, and no endoleaks were observed during a median 12-month follow-up. Reinterventions were performed in 2 patients because of in-stent stenosis and chimney graft compression, respectively. Conclusion: Proximal Nellix-in-Nellix extension can be used to treat caudally migrated Nellix stent-grafts and to treat the consequent type Ia endoleak, but the technique differs from primary EVAS. The development of dedicated proximal extensions is desirable.