The First Case of a Nellix Sac-Anchoring Endoprosthesis Removal for Aortoenteric Fistula

Difficult diagnosis and management of a complicated Nellix graft infection

An 81-year-old man, with a complex vascular surgical history, presents with sepsis from an infected Nellix stent-graft. He required an urgent laparotomy, explantation of the graft, and extra-anatomical repair. Although now widely used for this indication, the preoperative 18F-fluorodeoxyglucose positron emission tomography/computed tomography was nondiagnostic for his stent-graft infection. We describe our management of a complicated Nellix graft infection and discuss the utility of positron emission tomography/computed tomography for stent-graft infections.

Management of Nellix migration and type Ia endoleak from proximal endovascular aneurysm sealing relining to late open conversion

BACKGROUND

Despite promising early results, mid-term failures of the Nellix endovascular aneurysm sealing (EVAS) system (Endologix Inc, Irvine, Calif) have been reported at higher than expected rates. The management of proximal endoleaks and migration differs from those after conventional endovascular aortic aneurysm repair (EVAR) owing to the peculiar design of the Nellix device. In the present study, we report a monocentric experience in the management of EVAS complications using various techniques. We also performed a comprehensive review of the relevant literature on both open surgical and endovascular management of proximal failure of EVAS from the MEDLINE database.

METHODS

We retrospectively analyzed the reinterventions for type Ia endoleak and migration after elective infrarenal EVAS at our institution. We collected preoperative, intraoperative, and follow-up data. Open and endovascular techniques are described. Overall survival, aortic-related mortality, and the technical success rate (rate of exclusion of endoleaks) with endovascular techniques were the primary outcomes.

RESULTS

We performed 101 infrarenal elective EVAS procedures from 2013 to 2018. Of the 101 patients, 20 (19.8%) had required reintervention for proximal sealing failure. The indications were type Ia (Is2, Is3) endoleak, migration >5 mm, sac expansion >5 mm, and secondary rupture. Of the 20 patients, 6 (30%) were treated with endovascular techniques-2 with a chimney Nellix-in-Nellix application and 4 with proximal relining with a covered stent. The remaining 14 patients (70%) were treated with late open conversion (OC). The average time from EVAS to reintervention was 36.1 months (range, 3-65 months). Six patients (30%) had undergone OC in an emergent setting because of secondary rupture. The technical success rate for the patients treated with endovascular reinterventions was 100%. The 30-day mortality was 20% (4 of 20), all emergent cases (four of six emergent repairs; 67%). The overall survival for the 20 patients was 75% (n = 15) at a mean follow-up of 15.1 months (range, 2-47 months). One patient had died after 7 months of non-aortic-related causes.

CONCLUSIONS

The high reintervention rate of the Nellix graft mandates careful evaluation for its further use with the revised instructions for use, and it should not be used off-label. OC remains the strategy of choice when managing Nellix proximal sealing failures in fit patients. Chimney Nellix-in-Nellix application and transcatheter embolization are feasible alternative techniques. Proximal relining also appears to be an effective alternative to more complex interventions, although it requires further studies for validation.

Long-term failure after endovascular aneurysm sealing in a real-life, single-center experience with the Nellix endograft

BACKGROUND

Endovascular aneurysm sealing (EVAS) is an innovative alternative to conventional endovascular aneurysm repair (EVAR). EVAS relies on sac anchoring without proximal fixation to achieve sealing and should have allowed for the treatment of a broader range of anatomic features compared with standard EVAR. Despite the encouraging early reports, the mid- and long-term follow-up data have shown increased rates of failure. To address the issue, the manufacturer introduced revised instructions for use (IFU) in 2016. The present study reports the outcomes of this system after a median follow-up of 45 months.

METHODS

Data for all patients electively treated with EVAS at our institution were retrospectively collected. The patients were retrospectively reclassified according to the 2016 revised IFU of the device. All patients in the present series had undergone EVAS for the treatment of infrarenal abdominal aortic aneurysms (AAAs). The primary end point was therapeutic failure: graft migration >5 mm, sac expansion >5 mm, type IA endoleak (Is2 and Is3 using the Van den Ham classification), type Ib endoleak, and secondary rupture. The overall mortality, aortic-related mortality, and reintervention rates were also analyzed.

RESULTS

A total of 101 patients had undergone elective treatment by EVAS from 2013 to 2018 for infrarenal AAAs. The median follow-up was 3.75 years. Therapeutic failure was observed in 31 of the 101 patients (30.7%), with no significant difference between the in-IFU and off-IFU 2016 subgroups. Failure occurred at a median interval of 34 months from the index procedure. Of the 101 patients, 6.9% had presented with secondary rupture. Freedom from aneurysm-related mortality was 96.9% at 1 and 2 years and 89.9% at 5 years. Freedom from reintervention decreased over time: 94.7% at 1 year, 77% at 4 years, and 52.1% at 6 years. Of the 101 patients, 14 (13.9%) had undergone emergent or elective graft explantation.

CONCLUSIONS

EVAS performed worse than conventional endografts for several critical end points, regardless of any preoperative anatomic parameters. The incidence of therapeutic failures tended to increase over time, especially 4 years after the index procedure.

The Safety of EVAS Surgical Conversion in a Comparative Monocentric Analysis

BACKGROUND

Endovascular aneurysm sealing (EVAS) was a widespread technology to treat abdominal aortic aneurysm. However, the particular morphology and structure of this endoprosthesis predisposed to proximal sealing defects with a high rate of reintervention or conversion to open surgery treatments. The purpose of this article is to report our experience on late open conversion of Nellix device, compared with the previous reported experience.

MATERIALS AND METHODS

Between September 2013 and February 2020, eight late open surgical conversions for endoleak (EL) were performed in our center: four of these were for EVAR. Four of these were EVAS devices required explantation and were included in the study. All excisions of infected abdominal aortic endograft were excluded.

RESULTS

All patients were treated within the original instructions for use. Aorto-bi-iliac reconstruction was performed with a bifurcated Dacron graft in all the four cases. At 12 months Doppler ultrasonography follow-up, good results at short term with preserved primary patency and freedom of re-intervention in three cases were reported. Only one patient died 16 days after the procedure. Nevertheless, the endoprosthetic structure allows in three of our cases to clamp down the renal level, with a decrease of the time of lower limbs ischemia and greater safety of the open surgery repair procedure.

CONCLUSIONS

The EVAS conversion is common, and a closer follow-up is required. The most recurrent open surgery indication is its migration and the EL type 1. The procedure is influenced by multiple comorbidities; emergency graft excision appears to increase morbidity and mortality, compared with elective surgical setting.

Secondary interventions after endovascular aneurysm sac sealing: endoleak embolization and limb-related interventions

The Nellix endovascular aneurysm sealing system is a novel alternative to conventional endovascular aneurysm repair for aortic aneurysm management using paired balloon expandable endografts supported by polymer-filled endobags to achieve sealing and anatomic fixation. Part of the promise of endovascular aneurysm sealing is increased resistance to lateral and longitudinal forces and thus a potential for reduced rates of device-related failures, particularly endoleaks. Initial efficacy data on this device are encouraging, but our knowledge of its associated complications and their management is limited. Reported adverse events include Type 1 and 2 endoleaks, graft stenosis and occlusion. The aim of this article is to review the early experience of endovascular aneurysm sealing focusing on the incidence, significance, and management of device-related complications.

Midterm Outcomes of the Nellix Endovascular Aneurysm Sealing System: A Dual-Center Experience

PURPOSE

To report midterm outcomes of the Nellix Endovascular Aneurysm Sealing (EVAS) System in the treatment of abdominal aortic aneurysm (AAA).

METHODS

Between September 2013 and July 2014, 64 AAA patients (mean age 76.6±6.8 years; 61 men) were treated with the EVAS system at 2 centers (only procedures performed at least 12 months prior to the analysis were included). Most patients were treated for a stable AAA, while 1 patient was treated for a ruptured aneurysm. Mean aneurysm diameter was 57.3±9.3 mm. The proximal neck measured a mean 21.5±3.3 mm in diameter and 27.0±12.1 mm long; the neck angle was 16.9°±19.3°. Eleven (17.2%) patients were treated outside the instructions for use (IFU).

RESULTS

Technical success was achieved in 63 (98.4%) of 64 patients; 1 type Ia endoleak was treated intraoperatively. One (1.6%) aneurysm-related death occurred at 4 months due to a secondary aortoenteric fistula. Overall, endoleaks occurred in 3 (4.7%) patients (2 type Ia, 1 type II). The estimated rates for 18-month overall survival, freedom from aneurysm-related death, and freedom from secondary interventions were 92.7%, 98.4%, and 95.0%, respectively. Patients treated outside the IFU had a significantly higher incidence of device-related complications (p=0.03).

CONCLUSION

The use of the Nellix device in everyday clinical practice is safe and offers promising midterm results. The risk of secondary aortoenteric fistula requires further analysis. Longer follow-up is needed to assess the actual efficacy of the device, although the risk of migration with late endoleak seems low.