The morphological applicability of a novel endovascular aneurysm sealing (EVAS) system (Nellix) in patients with abdominal aortic aneurysms

A Meta-Analysis of Mid-Term Outcomes of Endovascular Aneurysm Sealing

BACKGROUND-AIM

Several studies have been published showing conflicting results on the outcome after endovascular aneurysm sealing (EVAS). The aim of the present study is to conduct a systematic review and meta-analysis of published evidence to assess the efficacy of EVAS in the management of patients with abdominal aortic aneurysm (AAA).

METHODS

An electronic search of the English medical literature, from 2010 to March 2021, was conducted using MEDLINE, EMBASE, and Cochrane databases to find studies relevant to outcome after EVAS.

RESULTS

The final analysis included 12 articles published between 2011 and 2021, including 1440 patients. In total, 79.3% of the included patients underwent aneurysm treatment according to the instructions for use. Technical success was 98.8%. Overall, 30-day mortality was 1.3%. Procedure-related complications were reported in 4% of the cohort. During median follow-up of 28.1 months (range 9-72 months), the pooled estimate of endoleak type I, migration and reinterventions was 16% (95% confidence interval [CI]=7-25), 16% (95% CI=9-23), and 19% (95% CI=11-28), respectively. In a sub-analysis, 7 studies (703 patients) reported outcome with a mean follow-up of more than 2 years (range 24-72 months). In these studies, the pooled estimate of endoleak type I, migration, and reinterventions was 25% (95% CI=13-38), 22% (95% CI=19-26), and 27% (95% CI=21-33), respectively.

CONCLUSION

Patients who have been treated with EVAS are in high risk for reintervention especially beyond 2 years following implantation. Close surveillance for patients treated with EVAS is mandatory.

The Altura endograft system for endovascular aneurysm repair: presentation of its unique design with clinical implications

INTRODUCTION

The Altura aortic endograft for the treatment of abdominal aortic aneurysms (AAA) consists of two separate components with a proximal double D-shaped design. The braided endoskeleton of the endograft is attached only at the proximal and distal ends of the inner surface of the fabric resulting in adjustable length of the Altura components. To ensure optimal orientation and sealing, the design of Altura permits collapse, readjustment, and deployment of the repositioned D-shaped endografts.

AREAS COVERED

Since this new endograft design by Lombard presents unique characteristics, the aim of this article is to present its unique structure and deployment method and discuss its applicability, indications and associated concerns.

EXPERT OPINION

The Altura endograft revolutionizes the mechanism of infrarenal sealing by containing no main body at all. This feature allows ideal treatment of AAA with considerable offset of the renal arteries and permits also relining in cases of failing endografts or in cases where the short length of existing structures precludes deployment of conventional bifurcated endografts.

Endovascular Aortic Aneurysm Repair: A Narrative Review

Endovascular aortic aneurysm repair (EVAR) has evolved as minimally invasive method of treating infrarenal abdominal aortic aneurysms (AAA) with perioperatively mortality of less than 1% compared with 5% with open AAA repair as suggested by many randomized control trials. Computed tomography angiography is the imaging of choice for appropriate selection of a patient with EVAR. For patients with unsuitable anatomy, advanced EVARs techniques, such as fenestrated, branch, and chimney EVARs, are also increasingly being offered to patients with equal success. Patients with ruptured AAA are treated with this minimally invasive procedure. Percutaneous EVAR emerged with less of wound-related complications. Endoleaks are the most common complications peculiar to this procedure, and most are preventable by preoperative planning. They are detected on completion angiogram or on the surveillance imaging. This review discusses indications of EVAR, its selection criteria, procedural steps, and common complications associated with this procedure and advanced EVARs.

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.

Morphological applicability of currently available stent grafts in the endovascular repair of asymptomatic abdominal aortic aneurysm in East-Central European patients

Introduction

Currently, there is a wide range of commercially available devices for endovascular aneurysm repair (EVAR) that differ in terms of both anatomical requirements and the technology and technique of deployment.

Aim

To assess the applicability of currently commercially available devices for EVAR in the treatment of an asymptomatic abdominal aneurysm (AAA).

Material and methods

The study group included 100 patients with infrarenal AAA with a maximum diameter ≥ 50 mm, qualified for invasive treatment at the University Hospital in 2013–2014. The aortoiliac morphological characteristics of the AAA were evaluated on preoperative computed tomography angiograms using the OsiriX DICOM viewer in the 3D-MPR mode. The morphological applicability of 14 types of CE-marked and FDA-approved stent grafts was determined based on their instructions for use (IFU).

Results

EVAR was feasible with at least one of the analysed devices in 68% of patients. The morphological applicability was as follows: Excluder Conformable (65%), Ovation iX (51%), Endurant II (47%), Treo (45%), Excluder C3 (45%), AFX 2 (45%), Incraft (44%), E-tegra (44%), Zenith Alfa (41%), Zenith Flex (40%), Anaconda (39%) Aorfix (37%), Altura (34%), and E-vita (20%). The differences in the stent graft applicability were statistically significant (p < 0.001). A wide diameter of the common iliac artery, angulated proximal neck, and diameter of proximal neck out of range constituted the most frequent causes of EVAR inapplicability.

Conclusions

The IFU-based applicability of currently available AAA stent graft systems differs significantly. Despite the constant evolution of EVAR technology, at least 32% of AAA will require a different therapeutic approach.

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.

Nellix endovascular aneurysm-sealing system: a single-center experience and review of current evidence

Aims: We report the 6-year results of our use of the Nellix^® endovascular aneurysm sealing system. Materials & methods: This is a retrospective review of patients we treated from 2013 to 2019. The outcomes described include technical success rate, mortality, all procedure-related complications, reinterventions, open surgical conversion and secondary sac rupture. Results & conclusions: A total of 68 patients were treated. Mortality was 2.9%. Secondary interventions were carried out for distal embolization (3), stent occlusion (1), pseudoaneurysm (1) and endoleak (5). Open surgical conversion was required in 6.4% of cases. Medium- and long-term complications of EVAS occurred more frequently than expected. Because the durability of endovascular aneurysm sealing is questionable, strict postoperative surveillance of Nellix is crucial to identify features of failure.

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.

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.

Mid-Term Results of Endovascular Aneurysm Sealing in the Treatment of Abdominal Aortic Aneurysm With Unfavorable Morphology

PURPOSE

To report mid-term results of endovascular aneurysm sealing (EVAS) of abdominal aortic aneurysms (AAA) deemed unsuitable for a standard endovascular aneurysm repair (EVAR).

METHODS

A prospectively maintained database of 42 patients with EVAR-unfavorable anatomy treated by EVAS combined with chimney grafts in case of the proximal AAA neck shorter than 5 mm was analyzed. Early outcomes included final angiographic result, intra- and early post-operative deaths, and complications. Mid-term outcomes included all-cause mortality (ACM), aneurysm-related mortality (ARM), patency of the stents, occurrence of endoleaks, serious complications and graft failures defined as the AAA growth of more than 5 mm, type I endoleak, occlusion of the stent-graft or chimney graft, aorto-duodenal fistula, or aneurysm rupture.

RESULTS

The procedure was completed in all patients. Twenty-eight chimney grafts were implanted in 19 patients. Patients were followed for a median of 24 months (range 12-34 months). There were 2 intraoperative ruptures and 1 patient died in an early postoperative period. The cumulative ACM was 15, 21, and 36% at 12, 24, and 36 months, respectively, and the cumulative ARM was 8, 11, and 27% at 12, 24, and 36 months, respectively. Three out of 5 aneurysm-related deaths were due to a secondary aorto-duodenal fistula. The cumulative incidence of graft failure was 20, 27, and 42% at 12, 24, and 36 months, respectively. The cumulative incidence of an endoleak was 5, 9, and 23% at 12, 24, and 36 months, respectively. The graft failure increased significantly both ACM (p = .012) and ARM (p = .00003). The implantation of chimney grafts at the initial procedure increased ARM significantly (p = .008). The presence of an endoleak did not have any significant influence on ACM and ARM.

CONCLUSION

Patients treated with EVAS for AAAs with EVAR-unfavorable anatomy, especially those with chimney grafts, exhibit a high risk of graft failure and subsequent death.

Editor's Choice - Mid-term Migration and Device Failure Following Endovascular Aneurysm Sealing with the Nellix Stent Graft System - a Single Centre Experience

OBJECTIVE

Endovascular aneurysm sealing (EVAS) with the Nellix stent graft system is a novel concept in the management of abdominal aortic aneurysm (AAA) that aims to reduce the prevalence of all endoleaks following endovascular repair. There are few data describing the longer-term durability of this approach. The aim was to report the longer-term outcomes following EVAS in a single centre.

METHODS

This is a retrospective review of all patients that underwent Nellix at Cambridge University Hospitals Foundation Trust. Factors that are described as device failure include secondary sac rupture, graft explantation, further surgical procedures for Type 1 endoleak, or major migration of the stent grafts with pressurisation of the aortic sac.

RESULTS

A total of 161 patients have been treated with Nellix. The indications included primary AAA (n = 115), ruptured AAA (n = 4), salvage of other aortic grafts (n = 18), primary iliac aneurysm (n = 6), and chimney EVAS (ChEVAS) for pararenal AAA (n = 18). In total there have been 42 graft failures in patients treated with EVAS for primary AAA. The 4 year freedom from graft failure was 42% in patients treated for primary AAA. Failures mostly occurred more than 2 years post-Nellix implant. There were eight secondary sac ruptures (incidence 2.4 per 100 person years) and there have been 14 graft explants.

CONCLUSIONS

Failure of aneurysm sealing following treatment with Nellix has been more common than anticipated and can cause aortic rupture. Post-operative surveillance of Nellix stent grafts is crucial to identify features of failure.

Screening women aged 65 years or over for abdominal aortic aneurysm: a modelling study and health economic evaluation

BACKGROUND

Abdominal aortic aneurysm (AAA) screening programmes have been established for men in the UK to reduce deaths from AAA rupture. Whether or not screening should be extended to women is uncertain.

OBJECTIVE

To evaluate the cost-effectiveness of population screening for AAAs in women and compare a range of screening options.

DESIGN

A discrete event simulation (DES) model was developed to provide a clinically realistic model of screening, surveillance, and elective and emergency AAA repair operations. Input parameters specifically for women were employed. The model was run for 10 million women, with parameter uncertainty addressed by probabilistic and deterministic sensitivity analyses.

SETTING

Population screening in the UK.

PARTICIPANTS

Women aged ≥ 65 years, followed up to the age of 95 years.

INTERVENTIONS

Invitation to ultrasound screening, followed by surveillance for small AAAs and elective surgical repair for large AAAs.

MAIN OUTCOME MEASURES

Number of operations undertaken, AAA-related mortality, quality-adjusted life-years (QALYs), NHS costs and cost-effectiveness with annual discounting.

DATA SOURCES

AAA surveillance data, National Vascular Registry, Hospital Episode Statistics, trials of elective and emergency AAA surgery, and the NHS Abdominal Aortic Aneurysm Screening Programme (NAAASP).

REVIEW METHODS

Systematic reviews of AAA prevalence and, for elective operations, suitability for endovascular aneurysm repair, non-intervention rates, operative mortality and literature reviews for other parameters.

RESULTS

The prevalence of AAAs (aortic diameter of ≥ 3.0 cm) was estimated as 0.43% in women aged 65 years and 1.15% at age 75 years. The corresponding attendance rates following invitation to screening were estimated as 73% and 62%, respectively. The base-case model adopted the same age at screening (65 years), definition of an AAA (diameter of ≥ 3.0 cm), surveillance intervals (1 year for AAAs with diameter of 3.0-4.4 cm, 3 months for AAAs with diameter of 4.5-5.4 cm) and AAA diameter for consideration of surgery (5.5 cm) as in NAAASP for men. Per woman invited to screening, the estimated gain in QALYs was 0.00110, and the incremental cost was £33.99. This gave an incremental cost-effectiveness ratio (ICER) of £31,000 per QALY gained. The corresponding incremental net monetary benefit at a threshold of £20,000 per QALY gained was -£12.03 (95% uncertainty interval -£27.88 to £22.12). Almost no sensitivity analyses brought the ICER below £20,000 per QALY gained; an exception was doubling the AAA prevalence to 0.86%, which resulted in an ICER of £13,000. Alternative screening options (increasing the screening age to 70 years, lowering the threshold for considering surgery to diameters of 5.0 cm or 4.5 cm, lowering the diameter defining an AAA in women to 2.5 cm and lengthening the surveillance intervals for the smallest AAAs) did not bring the ICER below £20,000 per QALY gained when considered either singly or in combination.

LIMITATIONS

The model for women was not directly validated against empirical data. Some parameters were poorly estimated, potentially lacking relevance or unavailable for women.

CONCLUSION

The accepted criteria for a population-based AAA screening programme in women are not currently met.

FUTURE WORK

A large-scale study is needed of the exact aortic size distribution for women screened at relevant ages. The DES model can be adapted to evaluate screening options in men.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42015020444 and CRD42016043227.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Anatomical Predictors of Endoleaks or Migration After Endovascular Aneurysm Sealing

Purpose: To identify preoperative anatomical aortic characteristics that predict seal failures after endovascular aneurysm sealing (EVAS) and compare the incidence of events experienced by patients treated within vs outside the instructions for use (IFU). Methods: Of 355 patients treated with the Nellix EndoVascular Aneurysm Sealing System (generation 3SQ+) at 3 high-volume centers from March 2013 to December 2015, 94 patients were excluded, leaving 261 patients (mean age 76±8 years; 229 men) for regression analysis. Of these, 83 (31.8%) suffered one or more of the following events: distal migration ⩾5 mm of one or both stent frames, any endoleak, and/or aneurysm growth >5 mm. Anatomical characteristics were determined on preoperative computed tomography (CT) scans. Patients were divided into 3 groups: treated within the original IFU (n=166), outside the original IFU (n=95), and within the 2016 revised IFU (n=46). Categorical data are presented as the median (interquartile range Q1, Q3). Results: Neck diameter was significantly larger in the any-event cohort vs the control cohort [23.7 mm (21.7, 26.3) vs 23.0 mm (20.9, 25.2) mm, p=0.022]. Neck length was significantly shorter in the any-event cohort [15.0 mm (10.0, 22.5) vs 19.0 mm (10.0, 21.8), p=0.006]. Maximum abdominal aortic aneurysm (AAA) diameter and the ratio between the maximum AAA diameter and lumen diameter in the any-event group were significantly larger than the control group (p=0.041 and p=0.002, respectively). Regression analysis showed aortic neck diameter (p=0.006), neck length (p=0.001), and the diameter ratio (p=0.011) as significant predictors of any event. In the comparison of events to IFU status, 52 (31.3%) of 166 patients in the inside the original IFU group suffered an event compared to 13 (28.3%) of 46 patients inside the 2016 IFU group (p=0.690). Conclusion: Large neck diameter, short aortic neck length, and the ratio between the maximum AAA and lumen diameters are preoperative anatomical predictors of the occurrence of migration (⩾5 mm), any endoleak, and/or aneurysm growth (>5 mm) after EVAS. Even under the refined 2016 IFU, more than a quarter of patients suffered from an event. Improvements in the device seem to be necessary before this technique can be implemented on a large scale in endovascular AAA repair.

Endovascular aneurysm sealing with the Nellix endograft in hemodynamically-unstable ruptured abdominal aortic aneurysm with challenging anatomy

BACKGROUND

To assess immediate and midterm outcomes of hemodynamically-unstable patients with ruptured abdominal aortic aneurysm (rAAA) treated with the Nellix endovascular sealing system (EVAS).

METHODS

From June 2014 to June 2017, 21 hemodynamically-unstable rAAA patients with challenging anatomies were treated with EVAS. The mean AAA diameter and neck length measured 73±15 mm and 14±10 mm, respectively. All the patients presented an advance trauma life support (ATLS) hemorrhage class ≥1 confirming a compromised hemodynamic status. Primary endpoints include technical success, treatment success, primary safety and 30-day survival. Secondary endpoints include re-intervention rate and time free-from-reintervention.

RESULTS

Technical success was achieved in 95% (N.=20/21); one patient was converted intraoperatively to open surgery due to ongoing hemorrhage. Seven re-interventions were performed within 30-days and one during the follow-up; treatment success rate of 67% and re-intervention rate of 33%. Early endoleaks were diagnosed in 5 patients (24%). Primary safety was 52%. After a mean follow-up of 11±10 months, survival rates were 81%, 62% and 57% at 1, 6 and 12 months, respectively. Time free-from-reintervention was 15±11 months.

CONCLUSIONS

Emergency-EVAS (eEVAS) appeared feasible and useful, especially in hemodynamically-unstable patients with challenging anatomies. There are some limitations in this cohort study and larger, prospective and comparative studies are required to confirm eEVAS as part of an emergency treatment protocol for rAAA.

Influence of the Revised Nellix Instructions for Use on Outcomes After Endovascular Aneurysm Sealing

Purpose: To evaluate the impact of the revised Nellix instructions for use (IFU) from 2016 on clinical outcomes and anatomic applicability by retrospectively applying them to a cohort treated with endovascular aneurysm sealing according to the original IFU 2013. Methods: A single-center study was conducted of 100 consecutive patients (mean age 72±8 years, range 46–91; 89 men) treated electively with standard bilateral EVAS from July 2013 to August 2015 and followed through December 2017. Procedures previously classified within and outside the original IFU from 2013 (75 and 25, respectively) were reclassified according to the revised IFU 2016 (34 and 66, respectively). Stepwise backward logistic regression analysis was performed to evaluate the prognostic value of specific anatomic features for the development of endoleak and/or migration. Results: The single most important morphologic feature disqualifying patients from being within IFU 2016 was a thrombus ratio >1.4 (36 of 41 reclassified patients). Overall technical success was 98% (100% within vs 97% outside IFU 2016, p=0.323) and 30-day mortality was 3% (0% within vs 5% outside IFU 2016, p=0.251). During a median follow-up of 31 months (range 0–53), overall mortality was 21% (15% within vs 24% outside IFU 2016, p=0.469); aneurysm-related mortality was 8% (3% within vs 11% outside IFU 2016, p=0.533). Twenty-six patients developed an endoleak (6 within vs 20 outside IFU 2016, p=0.172) and 23 had migration (4 within vs 19 outside IFU 2016, p=0.088). Both proximal neck length <10 mm and neck angulation >60° were positive predictors for the development of endoleak and/or migration. A reintervention was performed in 26 patients (7 within vs 19 outside IFU 2016, p=0.376). While a significant difference was found between the within vs outside IFU 2016 groups with regard to freedom from migration (p=0.026) and the composite freedom from endoleak and/or migration (p=0.021), there were no significant differences in survival (p=0.201) or freedom from reintervention (p=0.505), suggesting a limited effectiveness of the new IFU 2016. Conclusion: The IFU 2016 reduced the anatomic applicability to 34% from 75% for the original IFU 2013. The lack of significant intergroup differences in terms of survival and reinterventions suggests a limited effectiveness of the new IFU 2016.

Midterm results of endovascular aneurysm sealing to treat abdominal aortic aneurysm

BACKGROUND

Endovascular aneurysm sealing (EVAS) represents a novel approach to the treatment of abdominal aortic aneurysms. It uses polymer technology to achieve an anatomic seal within the sac of the aneurysm. This cohort study reports the early clinical outcomes, technical refinements, and learning curve during the initial EVAS experience at a single institution.

METHODS

Results from 150 consecutive EVAS cases for intact, infrarenal abdominal aortic aneurysms are reported here. These cases were undertaken between March 2013 and July 2015. Preoperative, perioperative, and postoperative data were collected for each patient prospectively.

RESULTS

The median age of the cohort was 76.6 years (interquartile range, 70.2-80.9 years), and 87.3% were male. Median aneurysm diameter was 62.0 mm (IQR, 58.0-69.0 mm). Adverse neck morphology was seen in 69 (46.0%) patients, including aneurysm neck length <10 mm (17.3%), neck diameter >32 mm or <18 mm (8.7%), and neck angulation >60 degrees (15.3%). Median follow-up was 687 days (IQR, 463-897 days); 37 patients (24.7%) underwent reintervention. The rates of unresolved endoleak are 1.3% type IA, 0.7% type IB, and 2.7% type I. There were no type III endoleaks. There have been seven secondary ruptures in this cohort; all but one of these patients survived after reintervention. Only one rupture occurred in an aneurysm that had been treated within the manufacturer's instructions for use (IFU).

CONCLUSIONS

The rate of unresolved endoleaks is satisfactorily low. The incidence of secondary rupture is of concern; however, when the IFU are adhered to, the rate is very low. The results of this study suggest that working within the IFU yields better clinical results.

Two-Year Outcomes of the Nellix EndoVascular Aneurysm Sealing System for Treatment of Abdominal Aortic Aneurysms

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.

Evolution of Computed Tomography Imaging the First Year after Endovascular Sealing of Infrarenal Aortic Aneurysms Using the Nellix Device

BACKGROUND

The Nellix endovascular aneurysm sealing (EVAS) system is an alternative endovascular treatment option for infrarenal aortic aneurysms (AAAs), with a unique appearance on computed tomography angiography (CTA). Normal evolution of post-EVAS CTA appearance follow-up is still largely unknown and important to timely detect eventual complications. The objective is to assess the normal appearance of CTA images 30 days and 1 year after EVAS in 50 consecutive patients.

METHODS

Fifty patients treated with Nellix EVAS for an infrarenal AAA were included from 3 hospitals. Using dedicated software, a total of 150 CTA scans were analyzed by predetermined variables per anatomical segment.

RESULTS

Thirty days post-EVAS, there was a slight, but not statistically significant, increase in AAA diameter that returned to the preoperative value after 1 year. A shift in total aortic volume distribution was observed without changing aortic diameter, including a trend toward a decreased thrombus volume (85.6 ± 49.1 mL and 78.8 ± 35.5 mL at 30 days and 1 year, respectively, P < 0.242) and a slight, but statistically significant, increase in polymer volume (68.2 ± 34.1 mL and 71.9 ± 35.2 mL at 30 days and 1 year, respectively, P < 0.001). The β-angle (P = 0.06) and iliac artery angulation (P < 0.001) decreased after implant. The latter returned to its original state after 1 year, whereas the neck straightening remained. Over time, there was a significant decrease in radiodensity in the middle of the polymer-filled endobags with an increase at its edges (P < 0.05). Thrombus radiodensity significantly increased over the first year (P < 0.05). Diameters of the infrarenal neck and common iliac arteries remained unchanged, no endoleaks were observed, and the position of the device was stable.

CONCLUSIONS

Change of CT appearance after EVAS is unique, and as such, the judgment of these images requires experience. The appearance of the endobags in respect to volume and radiodensity differ from classic EVAR. Normal changes over time are observed in aortoiliac angulation, volumes, and radiodensities.

Morphological suitability for endovascular repair, non-intervention rates, and operative mortality in women and men assessed for intact abdominal aortic aneurysm repair: systematic reviews with meta-analysis

BACKGROUND

Prognosis for women with abdominal aortic aneurysm might be worse than the prognosis for men. We aimed to systematically quantify the differences in outcomes between men and women being assessed for repair of intact abdominal aortic aneurysm using data from study periods after the year 2000.

METHODS

In these systematic reviews and meta-analysis, we identified studies (randomised, cohort, or cross-sectional) by searching MEDLINE, Embase, CENTRAL, and grey literature published between Jan 1, 2005, and Sept 2, 2016, for two systematic reviews and Jan 1, 2009, and Sept 2, 2016, for one systematic review. Studies were included if they were of both men and women, with data presented for each sex separately, with abdominal aortic aneurysms being assessed for aneurysm repair by either endovascular repair (EVAR) or open repair. We conducted three reviews based on whether studies reported the proportion morphologically suitable (within manufacturers' instructions for use) for EVAR (EVAR suitability review), non-intervention rates (non-intervention review), and 30-day mortality (operative mortality review) after intact aneurysm repair. Studies had to include at least 20 women (for the EVAR suitability review), 20 women (for the non-intervention review), and 50 women (for the operative mortality review). Studies were excluded if they were review articles, editorials, letters, or case reports. For the operative review, studies were also excluded if they only provided hazard ratios or only reported in-hospital mortality. We assessed the quality of the studies using the Newcastle-Ottawa scoring system, and contacted authors for the provision of additional data if needed. We combined results across studies by random-effects meta-analysis. This study is registered with PROSPERO, number CRD42016043227.

FINDINGS

Five studies assessed the morphological eligibility for EVAR (1507 men, 400 women). The overall pooled proportion of women eligible (34%) for EVAR was lower than it was in men (54%; odds ratio [OR] 0·44, 95% CI 0·32-0·62). Four single-centre studies reported non-intervention rates (1365 men, 247 women). The overall pooled non-intervention rates were higher in women (34%) than men (19%; OR 2·27, 95% CI 1·21-4·23). The review of 30-day mortality included nine studies (52 018 men, 11 076 women). The overall pooled estimate for EVAR was higher in women (2·3%) than in men (1·4%; OR 1·67, 95% CI 1·38-2·04). The overall estimate for open repair also was higher in women (5·4%) than in men (2·8%; OR 1·76, 95% CI 1·35-2·30).

INTERPRETATION

Compared with men, a smaller proportion of women are eligible for EVAR, a higher proportion of women are not offered intervention, and operative mortality is much higher in women for both EVAR and open repair. The management of abdominal aortic aneurysm in women needs improvement.

FUNDING

National Institute for Health Research (UK).

Aneurysm sealing

Compulsory registration needed

Patient selection for endovascular sac sealing of abdominal aortic aneurysm

Endovascular sealing is a developing technique for treatment of abdominal aortic aneurysm that draws on novel concepts utilizing polymer filling of endobags within the aorto-iliac lumen. The morphologic indications and patient selection, while similar to those of endovascular aneurysm repair, differ in some regards. The Instructions for Use for the Nellix sealing device may expand the indications for aneurysm treatment and are closely scrutinized in this article. The authors draw on current evidence and their own experience and opinion in the discussion around appropriate patient selection and its influence on outcomes after endovascular aneurysm sealing. A recommendation for stricter adherence to Instructions for Use in the early phase of clinical experience is made, with acknowledgement that the natural evolution of endovascular aneurysm sealing may involve more challenging cases.

Clinical outcomes after Nellix Endovascular Aneurysm Sealing

The published evidence on clinical outcomes of Nellix Endovascular Aneurysm Sealing for elective abdominal aortic aneurysm repair has confirmed low procedural morbidity and reintervention rate. This early clinical experience with Nellix is encouraging, despite the device and procedural steps being in evolution, and patients being treated outside of the recommended instructions for use. The long-term follow-up of a treated patient cohort is now available and demonstrates low aneurysm-related mortality and morbidity. The initial experience with the commercially available Nellix device was captured in a multicenter report involving 171 patients and two independently monitored, company-sponsored device registries (EVAS Forward Global Trial and Forward US Investigational Device Exemption Trial). All three clinical studies report a 99% procedural technical success, low mortality, and persistent endoleak rate with re-intervention rates comparable to conventional EVR device registries. Nellix EVAS is applicable to a range of aneurysm anatomies, including patients with isolated of concomitant iliac artery aneurysms. The post-procedural imaging appearances after Nellix EVAS are unique due to the AAA sac polymer, change with time, but are now well understood.

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.

Extended use of endovascular aneurysm sealing for ruptured abdominal aortic aneurysms

Endovascular repair of abdominal aortic aneurysms (EVAR) is now an established treatment modality for suitable patients presenting with aneurysm rupture. EVAR for ruptured aneurysms reduces transfusion, mechanical ventilation, intensive care. and hospital stay when compared with open surgery. In the emergency setting, however, EVAR is limited by low applicability due to adverse clinical or anatomical characteristics and increased need for reintervention. In addition, ongoing bleeding from aortic side branches post-EVAR can cause hemodynamic instability, larger hematomas, and abdominal compartment syndrome. Endovascular aneurysm sealing, based on polymer filling of the aneurysm, has the potential to overcome some of the limitations of EVAR for ruptured aneurysms and to improve outcomes. Recent literature suggests that endovascular aneurysm sealing can be performed with early mortality similar to that of EVAR for ruptured aortic aneurysms, but experience is limited to a few centers and a small number of patients. The addition of chimney grafts can increase the applicability of endovascular aneurysm sealing in order to treat short-neck and juxtarenal aneurysms as an alternative to fenestrated endografts. Further evaluation of the technique, with larger longitudinal studies, is necessary before advocating wider implementation of endovascular aneurysm sealing in the emergency setting.

Endovascular Aneurysm Sealing: Early and Midterm Results From the EVAS FORWARD Global Registry

PURPOSE

To report the early and 12-month results of a global registry of patients treated with endovascular aneurysm sealing (EVAS) for abdominal aortic aneurysms (AAAs).

METHODS

The EVAS FORWARD Global Registry was a postmarket, multicenter, open-label, single-arm registry that enrolled 277 patients (mean age 75 years; 228 men) treated with the Nellix EVAS system for nonruptured AAAs at 18 sites over a 1-year period. The cohort had challenging aortic anatomy, with 17% having a proximal aortic neck length <10 mm, 8% a neck angulation >60°, and 20% an iliac diameter >25 mm. Baseline and follow-up computed tomography images were assessed by an independent core laboratory, and major adverse events were reviewed by an independent safety committee.

RESULTS

Three patients died within 30 days of the procedure (none device-related). There were 13 endoleaks recorded in this time frame: 8 type Ia, 1 type Ib, and 5 type II. Root cause analysis demonstrated that the majority of type Ia endoleaks were due to technical error (low device placement and underfilling of the endobags). Between 30 days and 1 year, there were 4 new type Ia endoleaks; all were treated. There was also 1 type III endoleak between a Nellix device and a distal extension limb. At 1 year, the persistent endoleak rate was 0.7% (1 type Ia and 1 type II). The Kaplan-Meier estimates of freedom from types I and II endoleak at 12-month follow-up were 96% and 98%, respectively. The estimate of freedom from open conversion (n=7) was 98% at 12 months and the rate of freedom from any reintervention was 92%. The need for secondary intervention was associated with aortic morphology; for patients meeting the requirements of the instructions for use (IFU), the freedom from reintervention at 12 months was 98% compared with 86% when the implant was outside the IFU (p=0.009). At 1 year, the estimates of freedom from aortic-related and all-cause mortality were 98% and 95%, respectively.

CONCLUSION

The EVAS FORWARD Global Registry documents the 12-month outcome of EVAS in an unselected group of patients with challenging aortic morphology. The results at present appear acceptable with regard to perioperative outcomes and complications. The type II endoleak rate is low. The place of EVAS in the armamentarium of techniques to treat AAAs will be defined by durability data in the longer term.

Early experience with the new endovascular aneurysm sealing system Nellix: First clinical results after 50 implantations

Objective

In the present study, 50 EVAS procedures were evaluated in regard to primary (survival and technical success) and secondary (device-related complications) events of interest.

Methods

The single center study was conducted from July 2013 to August 2014 with prospective collection of the clinical data. The clinical results were controlled by CT angiography and contrast-enhanced ultrasound .

Results

The technical success was 98% and the 30-day mortality 4%. One (2%) patient died from multisystem organ failure and another patient from an intracranial bleeding, respectively. One patient (2%) suffered from a device-related aneurysm rupture. During early follow-up, one (2%) patient developed an endoleak type II, while three (6%) patients suffered from a partial endograft limb thrombosis. Overall, a secondary intervention was necessary in six (12%) patients.

Conclusions

With the Nellix EVAS system, a high primary technical success of 98% was achieved; one (2%) patient developed an endoleak type II which did not require secondary intervention. Those promising results are contrasted by a substantial rate of endograft limb thromboses (8%) and one (2%) intraoperative aneurysm rupture. Further studies are needed to assess the durability of the Nellix stentgraft and the occurrence of device-related complications.

Endovascular repair of abdominal aortic aneurysms

Endovascular repair of abdominal aortic aneurysms is an important technique in the vascular surgeon's armamentarium, which has created a seismic shift in the management of aortic pathology over the past two decades. In comparison to traditional open repair, the endovascular approach is associated with significantly improved perioperative morbidity and mortality. The early survival benefit of endovascular abdominal aortic aneurysm repair is sustained up to 3 years postoperatively, but longer-term life expectancy remains poor regardless of operative modality. Nonetheless, most abdominal aortic aneurysms are now repaired using endovascular stent grafts. The technology is not perfect as several postoperative complications, namely endoleak, stent-graft migration, and graft limb thrombosis, can develop and therefore lifelong imaging surveillance is required. In addition, a postoperative inflammatory response has been documented after endovascular repair of aortic aneurysms; the clinical significance of this finding has yet to be determined. Subsequently, the safety and applicability of endovascular stent grafts are likely to improve and expand with the introduction of newer-generation devices and with the simplification of fenestrated systems.

Nellix EndoVascular Aneurysm Sealing System: Device description, technique of implantation, and literature review

Clinical outcome reports document that from 30% to 60% of endovascular aneurysm repair procedures are performed outside of US Food and Drug Administration-approved Instruction for Use, or "off label." Endovascular aneurysm repair performed outside of Instruction for Use has a significantly higher rate of device failure, potentially requiring device reintervention and even planned or emergent explant. The Nellix device has the potential to reduce the rate of aneurysm device failure through its novel design. The objective of this article was to introduce the Nellix EndoVascular Aneurysm Sealing System and indications for use and describe the technique of implantation. We describe various modes of endovascular aneurysm repair failure and how the Nellix system can reduce these unplanned adverse outcomes. Additional clinical applications and theoretical shortcomings of endovascular aneurysm sealing devices are detailed.

Global Experience With the Nellix Endosystem for Ruptured and Symptomatic Abdominal Aortic Aneurysms

Purpose: To assess the feasibility and safety of the endovascular aneurysm sealing (EVAS) technique in the treatment of acute abdominal aortic aneurysm (AAA). Methods: A retrospective, multicenter, observational study was conducted at 8 centers (7 European and 1 in New Zealand) experienced with EVAS in the elective setting. From February 2013 to April 2015, 58 patients (mean age 74±9 years; 46 men) with an acute AAA were treated (28 ruptured and 30 symptomatic). The primary endpoint of the study was 30-day mortality; secondary endpoints included endoleak, reinterventions, and 30-day morbidity. Results: The overall intensive care unit and hospital stays were 2.2±6.6 days and 9.7±11.4 days, respectively. Thirty-day mortality rates were 32% (9/28) for the ruptured group and 7% (2/30) for the symptomatic group, with morbidity rates of 57% and 17%, respectively. Early endoleak was present in only 2 (3%) patients, one in each group; both leaks were type Ia. Reinterventions within 30 days were performed in 8 patients in the ruptured group; in the symptomatic patients, the only perioperative reintervention was embolization a type Ia endoleak. The mean follow-up was 9.3±3.1 months in the ruptured group and 12.4±5.4 months in the symptomatic group. The mean aneurysm diameter at 30-day follow-up was 71.8±16.0 mm compared with 74.7±15.7 mm preoperatively in the ruptured group and 66.1±13.5 mm compared with 65.8±13.0 mm in the symptomatic group. Conclusion: EVAS in the acute setting appears safe and feasible and concordant with the literature for endovascular aneurysm repair. More robust prospective and comparative data are required to establish the position of the technique in the treatment algorithm of acute AAA.

Imaging After Nellix Endovascular Aneurysm Sealing

Endovascular aneurysm sealing (EVAS) using the Nellix system is a new and different method of abdominal aortic aneurysm repair. Normal postoperative imaging has unique appearances that change with time; complications also have different and specific appearances. This consensus document on the imaging findings after Nellix EVAS is based on the collective experience of the sites involved in the Nellix EVAS Global Forward Registry and the US Investigational Device Exemption Trial. The normal findings on computed tomography (CT), duplex ultrasound, magnetic resonance imaging, and plain radiography are described. With time, endobag appearances change on CT due to contrast migration to the margins of the hydrogel polymer within the endobag. Air within the endobag also has unique appearances that change over time. Among the complications after Nellix EVAS, type I endoleak usually presents as a curvilinear area of flow between the endobag and aortic wall, while type II endoleak is typically small and usually occurs where an aortic branch artery lies adjacent to an irregular aortic blood lumen that is not completely filled by the endobag. Procedural aortic injury is an uncommon but important complication that occurs as a result of overfilling of the endobags during Nellix EVAS. The optimum imaging surveillance algorithm after Nellix EVAS has yet to be defined but is largely CT-based, especially in the first year postprocedure. However, duplex ultrasound also appears to be a sensitive modality in identifying normal appearances and complications.

Aortic Dehiscence During Endovascular Sealing for Ruptured Abdominal Aortic Aneurysms

PURPOSE

To present a case of aneurysm disruption during endovascular sealing of a ruptured abdominal aortic aneurysm.

CASE REPORT

A 91-year-old woman presented with a ruptured abdominal aortic aneurysm. Her aneurysm morphology was unsuitable for standard or fenestrated endovascular repair, whereas open repair was considered to have an increased perioperative risk owing to multiple comorbidities. The Nellix endovascular sealing system was used. The balloon-expandable stent-grafts were deployed, but in the presence of aneurysm rupture, it was decided not to prefill the endobags with saline. The patient developed hypotension during endobag filling, which resolved once target pressure was reached. The procedure was completed uneventfully, and the completion angiogram revealed no endoleak. The time from guidewire insertion to completion angiogram was 24 minutes. Over the following days, she developed a gradual drop in hemoglobin, and computed tomographic angiography revealed an increased retroperitoneal hematoma and pronounced disruption of the calcified rim of the aortic sac compared to the preoperative imaging. She was managed with supportive treatment, demonstrating remarkable progress. She remains in good health 4 months later.

CONCLUSION

Endovascular sealing can be used in patients with ruptured abdominal aortic aneurysm. Intraoperative endobag saline prefill should be avoided to minimize the risk of aortic wall disruption.