Preliminary outcome of Nellix-in-Nellix extensions in patients treated with failed endovascular aneurysm sealing

Endovascular Repair of a Failed Nellix Endograft Proximal Sealing Zone Using the Altura Stent-Graft: A Case Report and Literature Review

Endovascular aortic aneurysm sealing (EVAS) with the Nellix endograft was initially considered a groundbreaking and acceptable alternative to conventional endovascular aortic aneurysm repair, with encouraging initial results. However, long-term follow-up has revealed a high incidence of endograft-related complications, such as caudal migration and type Ia endoleaks, indicating the need for reintervention. Managing failed EVAS remains challenging and is an ongoing topic of discussion, especially for high-risk patients. We describe a 70-year-old female who initially underwent EVAS with a Nellix endograft and presented after 5 years of follow-up with caudal endograft migration and a type Ia endoleak. The patient was treated with endovascular implantation of an Altura stent-graft, a relatively new low-profile device with a similar double stent configuration. Device migration and endoleaks were undetectable at 12 months of follow-up, suggesting that the Altura might offer a safe and efficient approach in cases of Nellix proximal failure.

Combining Endovascular Aneurysm Sealing with Chimney Grafts - 5 Year Follow-Up after 47 Procedures

BACKGROUND

To evaluate longer-term results of a cohort treated with primary chimney endovascular aneurysm sealing (ChEVAS) for complex abdominal aortic aneurysms or secondary ChEVAS after failed endovascular aneurysm repair/endovascular aneurysm sealing.

METHODS

A single-center study was conducted of 47 consecutive patients (mean age 72 ± 8 years, range 50-91; 38 men) treated with ChEVAS from February 2014 to November 2016 and followed through December 2021. The main outcome measures were all-cause mortality (ACM), aneurysm-related mortality, occurrence of secondary complications and conversion to open surgery. Data are presented as the median (interquartile range [IQR]) and absolute range.

RESULTS

35 patients received a primary ChEVAS (=group I) and 12 patients a secondary ChEVAS (=group II). Technical success was 97% (group I) and 92% (group II); 30-day mortality was 3% and 8%, respectively. The median proximal sealing zone length was 20.5 mm (IQR 16, 24; range 10-48) in group I and 26 mm (IQR 17.5, 30; range 8-45) in group II, respectively. During a median time of follow-up of 62 months (range 0-88), ACM amounted to 60% (group I) and 58% (group II); aneurysm mortality was 29% and 8%, respectively. An endoleak was seen in 57% (group I: 15 type Ia endoleaks, four isolated type Ib, and 1 endoleak type V) and 25% (group II: 1 endoleak type Ia, one type II, and 2 type V), aneurysm growth in 40% and 17%, migration in 40% and 17%, resulting in 20% and 25% conversions in group I and II, respectively. Overall a secondary intervention was performed in 51% (group I) and 25% (group II), respectively. The occurrence of complications did not significantly differ between the 2 groups. Neither the number of chimney grafts, nor the thrombus ratio significantly affected the occurrence of abovementioned complications.

CONCLUSIONS

While initially delivering a high technical success rate, ChEVAS fails to provide acceptable longer-term results both in primary and secondary ChEVAS, resulting in high rates of complications, secondary interventions and open conversions.

Editor's Choice - Focused Update on Patients Treated with the Nellix EndoVascular Aneurysm Sealing (EVAS) System from the European Society for Vascular Surgery (ESVS) Abdominal Aortic Aneurysm Clinical Practice Guidelines

OBJECTIVE

After alerts on EndoVascular Aneurysm Seal (EVAS) failure were raised, the European Society for Vascular Surgery (ESVS) Abdominal Aortic Aneurysm (AAA) Clinical Practice Guidelines Writing Committee (WC) initiated a task force with the aim to provide guidance on surveillance and management of patients with implanted EVAS devices.

METHODS

Based on a scoping review of risk for late serious aortic-related adverse events in patients treated with EVAS for AAA, the ESVS AAA Guidelines WC agreed on recommendations graded according to the European Society of Cardiology (ESC) grading system.

RESULTS

EVAS has a very high incidence of late endograft migration resulting in proximal type 1 endoleak with risk of rupture, requiring open conversion with device explantation. The reported mortality rate for elective explantation varies between 0% and 14%, while acute conversion for rupture has a very dismal prognosis with a 67 - 75% mortality rate.

CONCLUSION

It is recommended that all patients in whom a Nellix device has been implanted should be identified, properly informed, and enrolled in enhanced surveillance. If device failure is detected, early elective device explantation should be considered in surgically fit patients.

Innovative solutions for endovascular aneurysm sealing-delayed Nellix type 1a endoleak

A delayed Nellix (Endologix, Irvine, Calif) type 1a endoleak from endovascular aneurysm sealing (EVAS) is particularly challenging to treat owing to the restrictions and scarcity of the technical options available. We have described two viable endovascular solutions, with and without the availability of the Nellix endograft inventory. A Nellix-in-Nellix apparatus with multivisceral chimney, covered stent extensions and internal reinforcements can be used if Nellix endografts are available (patient 1). In the absence of Nellix endografts, we used a Viabahn-in-Nellix apparatus, also with multiple chimney stents, as an alternative and timely treatment for patient 2. Our patients remained well and free of endoleaks at 19 and 11 months after treatment.

An International, Multicenter Retrospective Observational Study to Assess Technical Success and Clinical Outcomes of Patients Treated with an Endovascular Aneurysm Sealing Device for Type III Endoleak

INTRODUCTION

Type III endoleaks post-endovascular aortic aneurysm repair (EVAR) warrant treatment because they increase pressure within the aneurysm sac leading to increased rupture risk. The treatment may be difficult with regular endovascular devices. Endovascular aneurysm sealing (EVAS) might provide a treatment option for type III endoleaks, especially if located near the flow divider. This study aims to analyze clinical outcomes of EVAS for type III endoleaks after EVAR.

METHODS

This is an international, retrospective, observational cohort study including data from 8 European institutions.

RESULTS

A total of 20 patients were identified of which 80% had a type IIIb endoleak and the remainder (20%) a type IIIa endoleak. The median time between EVAR and EVAS was 49.5 months (28.5-89). Mean AAA diameter prior to EVAS revision was 76.6±19.9 mm. Technical success was achieved in 95%, 1 patient had technical failure due to a postoperative myocardial infarction resulting in death. Mean follow-up was 22.8±15.2 months. During follow-up 1 patient had a type Ia endoleak, and 1 patient had a new type IIIa endoleak at an untreated location. There were 5 patients with aneurysm growth. Five patients underwent AAA-related reinterventions indications being: growth with type II endoleak (n=3), type Ia endoleak (n=1), and iliac aneurysm (n=1). At 1-year follow-up, the freedom from clinical failure was 77.5%, freedom from all-cause mortality 94.7%, freedom from aneurysm-related mortality 95%, and freedom from aneurysm-related reinterventions 93.8%.

CONCLUSION

The EVAS relining can be safely performed to treat type III endoleaks with an acceptable technical success rate, a low 30-day mortality rate and no secondary ruptures at short-term follow-up. The relatively low clinical success rates, related to reinterventions and AAA enlargement, highlight the need for prolonged follow-up.

The Polymer-Based Technology in the Endovascular Treatment of Abdominal Aortic Aneurysms

An abdominal aortic aneurysm (AAA) is a dilatation of the abdominal aorta that progressively grows until it ruptures. Treatment is typically recommended when the diameter is more than 5 cm. The EVAR (Endovascular aneurysm repair) is a minimally invasive procedure that involves the placement of an expandable stent graft within the aorta to treat aortic disease without operating directly on the aorta. For years, stent grafts' essential design was based on metallic stent frames to support the fabric. More recently, a polymer-based technology has been proposed as an alternative method to seal AAA. This review underlines the two platforms that are based on a polymer technology: (1) the polymer-filled endobags, also known as Endovascular Aneurysm Sealing (EVAS) with Nellix stent graft; and (2) the O-ring EVAR polymer-based proximal neck sealing device, also known as an Ovation stent graft. Polymer characteristics for this particular aim, clinical applications, and durability results are hereby summarized and commented critically. The technique of inflating endobags filled with polymer to exclude the aneurysmal sac was not successful due to the lack of an adequate proximal fixation. The platform that used polymer to create a circumferential sealing of the aneurysmal neck has proven safe and effective.

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.

Midterm single-center results after endovascular aneurysm sealing reveal a high rate of stent graft migration, secondary aneurysm ruptures, and device-related reinterventions

OBJECTIVE

To report procedural results and mid-term follow-up outcomes of patients treated with endovascular aneurysm sealing (EVAS) for abdominal aortic disease.

METHODS

In this retrospective observational study, all patients treated with EVAS between March 2013 and January 2018 for abdominal aortic aneurysm (AAA) or abdominal penetrating aortic ulcer were included. The datasets included demographics, aneurysm morphology, and procedural and clinical surveillance outcomes. Furthermore, patients treated within the original instructions for use (IFU-group) were compared with patients treated outside the IFU (non-IFU-group) with regard to survival, reintervention-free survival, freedom from type I endoleak, and freedom from stent graft migration.

RESULTS

Seventy patients were included (67 male; median age, 72.5 years). Sixty-five patients were treated for AAA and 5 patients for abdominal penetrating aortic ulcer. Sixty-nine cases were treated electively (98.6%). Technical success was achieved in 68 cases (97.1%). The median clinical follow-up was 50.5 months (interquartile range, 29.3-62.7 months) with a median computed tomography angiographic follow-up of 38.5 months (interquartile range, 17.1-60.2 months). There were five deaths during the study period (7.1%), four of which were aneurysm related (5.7%). Five secondary AAA ruptures were detected (7.1%). Overall, 25 of 70 patients (35.7%) underwent 35 reinterventions, mostly owing to thrombotic complications (18.6%), stent graft migration (17.1%), and type I endoleak (12.9%). Fifteen patients were treated outside of the IFU (non-IFU-group) (21.4%). The estimated reintervention-free survival for the entire cohort at 30 days and 1, 3, and 5 years was 94.3%, 88.5%, 72%, and 56.9%, respectively. Freedom from stent graft migration at 1, 3, and 5 years was 98.6%, 82.0%, and 47.3%, respectively. The estimated freedom from type I endoleak at 30 days and 1, 3, and 5 years in the IFU-group was 100%, 100%, 94.9% and, 91.1% and significantly different when compared with the non-IFU-group with 79.5%, 72.2%, 72.2%, and 72.2% (P = .012).

CONCLUSIONS

Although the technical and initial results were satisfying, the mid-term results were disappointing. The enforcement of a close follow-up protocol for all patients treated with EVAS, especially vigilant for stent graft migration to prevent secondary type I endoleak and rupture, is strongly recommended.

Progressive Device Failure at Long Term Follow Up of the Nellix EndoVascular Aneurysm Sealing (EVAS) System

OBJECTIVE

High rates of midterm failure of the Nellix EndoVascular Aneurysm Sealing (EVAS) System resulted in device withdrawal from the UK market. The study aim was to report long term Nellix EVAS outcomes and management of a failing device.

METHODS

A retrospective review of EVAS procedures at a tertiary unit was performed. Device failure was defined as a triad of stent migration, stent separation, and secondary sac expansion, or any intervention for type 1 endoleak, device rupture, or explant.

RESULTS

161 (male n = 140, female n = 21) patients with a median follow up of 6.0 (IQR 5.0-6.6) years were included. Freedom from all cause mortality estimate at six years was 41.5%. There were 70 (43.5%) device failures with a freedom from device failure estimate at six years of 32.3%. Failure was the result of sac expansion (n = 41), caudal stent migration (n = 36), stent separation (n = 26), and secondary AAA rupture (n = 15). A substantial number of type 1 endoleaks was present (1a n = 33, 1b n = 11), but the type 2 endoleak rate was low at 3.7%. Some 36 (22.4%) patients required re-intervention. Twenty-one patients underwent explant with no 30 day deaths. Six patients underwent Nellix-in-Nellix application (NINA) with one early death from bowel ischaemia and one patient who died later from non-aneurysm related cause. Two NINA patients have ongoing sac expansion and two have had thrombosis of a Nellix limb or visceral stent. Proximal embolisation was only successful in one of six cases.

CONCLUSION

The long term failure rate of Nellix EVAS is high. All patients with a device must be informed and be enrolled in enhanced surveillance. EVAS explant is an acceptable technique with favourable outcomes. Management by open explant, if the patient is fit, should be considered early and offered to those with device failure.

Open Conversion After Endovascular Aneurysm Sealing: Technical Features and Clinical Outcomes in 44 Patients

Purpose

To evaluate the technical features and clinical results after open conversion for complications following endovascular aneurysm sealing (EVAS).

Materials and Methods

From July 2013 to February 2020, 44 patients (mean age 72±8 years; 36 men) underwent an open conversion due to EVAS complications in a single center. Data were collected on patient characteristics, reasons for conversion, characteristics and duration of the procedure, condition of the polymer, blood loss, time in the intensive care unit (ICU), and intra/postoperative complications. The main outcome measure was mortality at 30 days and in follow-up. Data are presented as the median (IQR) and absolute range.

Results

On average, the open conversion took place 3 years after the initial EVAS implantation [median 37 months (IQR 23, 50); range 0–64]. Most patients were converted due migration (82%), aneurysm growth (77%), and/or endoleak (75%), with 21 patients (48%) having all 3 events. Less frequent diagnoses were aneurysm rupture (n=7), aortic infection (n=3), technical failure during implantation (n=2), and graft thrombosis (n=1). The majority of patients (n=26) were asymptomatic and converted electively, but 9 were operated on urgently and 9 emergently (7 late rupture and 2 due to technical failure). The median procedure duration was 178 minutes (IQR 149, 223; range 87–417), the median blood loss was 1100 mL (IQR 600, 2600; range 300–5000). Polymer degradation was mentioned in the operative reports of 18 cases (41%). Patients stayed a median of 3 days (IQR 2, 7; range 1–35) in the ICU, while the median length of stay in the hospital was 14 days (IQR 10, 20; range 0–93). The 30-day mortality was 23% (n=10). During a median follow-up of 3 months (IQR 0, 11; range 0–38), no additional deaths occurred, but 12 patients suffered from an adverse event. There were 3 cases of wound dehiscence after laparotomy, 2 cases of leg ischemia, 2 cases of renal failure, and individual cases of urinary obstruction, urinoma, paralytic ileus, gastrointestinal bleeding, and postoperative delirium. A non-elective setting was associated with a significantly increased mortality of 33% in urgent cases and 56% in emergent cases (p=0.007). Based on these results an algorithm for the management of EVAS complications was developed.

Conclusion

The significantly increased mortality associated with nonelective conversions highlights the need for active surveillance. The presented algorithm offers a structured tool to avoid emergency conversions.

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.

Electrocardiography-gated computed tomography angiography analysis of cardiac pulsatility-induced motion and deformation after endovascular aneurysm sealing with chimney grafts

OBJECTIVE

To evaluate the proximal stability of the chimney endovascular aneurysm sealing configuration (chEVAS) during the cardiac cycle by investigating the cardiac pulsatility-induced movement and deformation.

METHODS

We retrospectively analyzed postoperative electrocardiogram-gated computed tomography angiography scans of 11 chEVAS cases (9 primary chEVAS plus 2 chEVAS-in-chEVAS). ChEVAS procedures were conducted between September 2013 and June 2016. Motion and deformation of the EVAS stents, the chimney grafts, and the stented branch vessels were evaluated during the cardiac cycle using an established combination of image registration and segmentation techniques.

RESULTS

Electrocardiogram-gated computed tomography angiography scans of 11 chEVAS configurations including 22 EVAS stents and 20 chimney grafts were analyzed. The three-dimensional displacement was at most 1.7 mm for both the EVAS stents and the chimney grafts. The maximum change in distance between components was no more than 0.4 mm and did not differ between EVAS-to-EVAS stent and EVAS stent-to-chimney stent (0.2 ± 0.1 mm vs 0.2 ± 0.1 mm; P = .823). The mean change in chimney deflection angle was 1.2 ± 0.7°; the maximum change was greatest for the superior mesenteric artery (SMA) (2.6°). The EVAS stent-to-chimney angles for the left renal artery, right renal artery, and SMA varied on average by 0.7 ± 0.3° (range, 0.4°-1.3°), 1.0 ± 0.3° (range, 0.5°-1.7°), and 0.8 ± 0.4° (range, 0.3°-1.3°), respectively, during the cardiac cycle. The end-stent angles for the left renal artery, right renal artery, and SMA varied on average by 1.7 ± 0.9° (range, 0.5°-3.3°), 1.9 ± 0.8° (range, 0.7°-3.3°), and 1.3 ± 0.4° (range, 0.7°-1.6°), respectively, during the cardiac cycle. Overall, the end-stent angles varied on average by 1.7 ± 0.8° (range, 0.5°-3.3°).

CONCLUSIONS

The chEVAS configuration proved to be stable during the cardiac cycle, as demonstrated by minimal cyclical changes in distance between device components and angulation between the EVAS stents and the chimney grafts. The limited deflection angles of the chimney grafts decrease the risk of bending fatigue, but the more apparent change in end-stent angle distal to the chimney graft may raise concerns regarding late branch occlusion or stenosis.