Nellix Device Research Articles

Nellix Device Failure Mechanisms Analysis on Explanted Grafts.

To understand possible reasons for poor durability of the Nellix (Endologix Inc., Irvine, USA) endovascular aneurysm sealing (EVAS) device. 21 Nellix endoprostheses explanted for endoleaks and migration underwent visual examinations of stent structures and instrumental examinations of the polymer endobags on 4 devices. We harvested 2.0-gram polymer slices out of each of them and tested the samples in an in vitro implantation replication that included wet and dry exposures. During the wet phase, we placed samples in a beaker with saline, mimicking the filling of the endobags during implantation. An exposure to a 37°C environment with 60% humidity during the dry phase replicated the postimplantation conditions inside the aneurysmal sac. Iatrogenic defects affected 16 (76%) metal stents and 20 (95%) endobags. The polymer was disintegrated owing to degradation in 15 (71%) cases. The polymer could lose more than 70% of its initial weight when partially dehydrated and regain 80% when placed in saline. We observed volume decrease and polymer fragmentation during these study phases. The polymer can lose weight and volume while it dehydrates. This structural degradation of the polymer could lead to the development of endoleaks and/or migration of the device. Based on the results of previous investigations, due to possible endovascular device degradation, patients with endografts should be offered life-long surveillance, and the Nellix device is no exception. Herein we suggest polymer degradation as one of the possible reasons for the device failure. Although Nellix has been withdrawn from the market, there are numerous patients with this type of endograft. Due to its unpredictable performance in the medium and long term, these patients should be recommended enhanced life-long surveillance every 6 months. Any suspicious conditions during the follow-up must be taken seriously and explantation should be considered.

Endovascular Conversion of a Failed Nellix AAA-Repair by a Custom-Made Branched Device.

This technical note presents a case of a patient with a failed Nellix device (Endologix, Irvine, Calif) who was not deemed fit for open conversion. Our planned approach for repair involved an endovascular procedure utilizing a custom-made branched device. An endovascular repair was performed via a custom-made four outer branched device in conjunction with a custom-made bifurcated graft featuring inverted limbs (Cook Inc., Bloomington, Ind). All branches were connected to the target vessel with Gore Viabahn VBX balloon-expandable covered stents (Gore & Associates Inc.). Endovascular conversion with branched endovascular repair in a patient not deemed fit for open surgery was successfully performed, thereby reducing the risk of a high morbid and mortal procedure. Novel useful treatment solution of failed EVAR with Nellix device.

A Single Centre Long Term Follow Up of the Nellix Endovascular Aneurysm Sealing System

To evaluate the clinical performance at long term follow up of endovascular aneurysm sealing (EVAS, Endologix Inc. Nellix, Irvine, CA, USA) in the treatment of abdominal aortic aneurysm (AAA). Observational, prospective, single centre study of primary AAA interventions with EVAS (n= 117) from November 2013 to November 2016. Endpoints were primary technical success, Nellix device failure, freedom from open surgical conversion (OSC), freedom from secondary intervention, sac rupture, total mortality, and aneurysm related mortality at long term follow up. The median age was 75 years (interquartile range [IQR] 70, 81 years) and 83% were male. The median AAA diameter was 58 mm (IQR 54, 60 mm). The median length of follow up was 6.2 years (IQR 5.6, 6.8 years). Primary technical success was 100%. Median time to Nellix failure was 5.6 years (IQR 3.3, 7.4 years). Freedom from Nellix failure at five and seven years was 54% (95% confidence interval [CI] 54.2 - 63.8%) and 36% (95% CI 22.3 - 49.7%), respectively. Freedom from OSC at five and seven years was 63% (95% CI 53.2 - 72.8%) and 59% (95% CI 47 - 71%), respectively. The secondary intervention rate was 11.4/100 person years. Freedom from secondary intervention at five and seven years was 52% (95% CI 42.2 - 61.8%) and 51% (95% CI 41.2 - 60.8%), respectively. The cumulative mortality rate at five and seven years was 36% and 54%, respectively. Secondary sac rupture occurred in 9.4% (11/117) with a rate of 2/100 person years. Aneurysm related mortality was 12% (14/117) with a rate of 2.5/100 person years. The median survival was four years (IQR 3, 5.6 years). Thirty day mortality for acute OSC was 67% (n= 3) and 17.1% (6/35) for elective OSC. Long term follow up showed an increased failure rate. Diligent surveillance after endovascular AAA treatment is mandatory, especially when promising new devices are put into clinical use.

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

BackgroundDespite promising early results, midterm 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. MethodsWe 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. ResultsWe 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. ConclusionsThe 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.

Endovascular Aneurysm Sealing Therapy with the Nellix System in Patients Not Suitable for Conventional EVAR – A Single Centre Experience

Objective: Endovascular aneurysm sealing (EVAS) therapy with the Nellix system was introduced in 2013. In January 2019, the Medicines and Healthcare Regulatory Authority issued a Field Safety Notice to desist use. The aim was to review experience in the use of the Nellix device in a specific cohort of patients. Methods: A prospective study of 27 patients who underwent EVAS with the Nellix system in the Belfast Trust between December 2013 and January 2016. Use of the Nellix system was approved by the Trust Standards and Guidelines Committee. All cases were deemed not suitable for conventional endovascular aneurysm repair and judged suitable for EVAS by the product specialists as per the 2013 instructions for use criteria. Results: Up to April 2019, 17/27 patients had died. Three with confirmed ruptured AAA within an average of 1.8 years. The others were non-AAA related deaths. Four of 27 (14.8%) patients had a type I endoleak on first surveillance imaging, increasing to 10/27(37%) patients on follow up imaging. One out of 27 (3.7%) developed sac expansion. Of the 10 surviving patients, seven have an aneurysm related complication (six endoleaks and one sac expansion). One patient went on to rupture with successful conversion to open repair. Three patients were deemed not suitable or declined further intervention. The remainder of surviving patients will continue on yearly surveillance or await clinical review. Conclusion: The Nellix system is associated with unacceptably high morbidity and mortality rates in this specific cohort. While new technology is essential to progressing healthcare, specialised consent and stringent surveillance strategies are required when adopting new techniques.

The Safety of EVAS Surgical Conversion in a Comparative Monocentric Analysis

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. 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. 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 12months 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 16days 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. 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.

Three-Year Results of the Nellix Endovascular Aneurysm Sealing System for Treatment of Abdominal Aortic Aneurysms in Frail Patients with Poor Anatomical Features.

Endovascular aneurysm sealing represents an alternative to advanced technology devices for compromised patients with abdominal aortic aneurysms. We report our results of 15 fragile patients with very low-quality infrarenal necks treated with endovascular aneurysm sealing. All patients treated with Nellix device in our hospital between June 2015 and October 2016 were retrospectively reviewed. The primary endpoints are the following: overall survival and freedom from reintervention rates. The secondary endpoints are the following: technical success; 30-day mortality; abdominal aortic aneurysm-related mortality; and freedom from endoleak rate, complications, and surgical conversion rate. Nellix was used in 15 patients, median age 75.5 years, of which 67% were unfit for open surgery. Mean aneurysm diameter was 60 mm. One-third (5/15) of the patients were inside the Nellix instructions for use. Technical success rate was 93.3%. No perioperative complications existed, and 30-day mortality was 0%. Median follow-up was 35 (interquartile range: 11-37) months. Survival rates at 1 and 3 years were 80% and 59.3%. Abdominal aortic aneurysm-related mortality occurred in 3 of 15 cases. Freedom from rupture rates at 1 and 3 years were 92.9% and 66%. Freedom from endoleak rates at 1 and 3 years were 92.9% and 74.5%. Freedom from reintervention rates at 1 and 3 years were 86.7% and 70.6%, with a dramatic drop to 37.1% at 4 years of follow-up. Three open surgery conversions were needed. There were no statistically significant differences in results between patients treated inside and outside instructions for use. The endovascular aneurysm sealing has shown encouraging short-term results, but its safety and effectiveness during time is questionable, because this system still carries high rates of reintervention, conversions for type IA endoleaks, and secondary aneurysm ruptures.

Chimney with the Use of Nellix Device: An Alternative Solution for Type I Endoleak Treatment

Introduction - Endovascular aortic repair with chimney technique (Ch-EVAR) is commonly used in the treatment of type I endoleak when the patient is unsuitable for conversion to open surgery or custom made endograft implantation. Main issue with chimney technique is related to gutter endoleak; this risk may be reduced with the use of a Nellix device (Ch-EVAS), that could fill the gutter and reduce the incidence of type I endoleak. Methods - Sixteen consecutive patients (mean age 80.7 ± 7.0 years; 94% men) with prior EVAR were treated with ChEVAS between August 2015 and March 2018 in a single center. Indication for treatment was proximal type I endoleak in all patients, with associated neck dilation in 5 patients and migration in 5. The median diameter of residual aneurismal sac was 79.1 ± 2.4 mm The median time between original procedure and ChEVAS was 92.7±5.3 (range 1-148) months. Prior EVARs included different endografts (5 Zenith, 3 Endurant, 4 Talent, 1 Anaconda, 1 Fortron and 2 Nellix). In 12 patients (75%) preoperative CT scan showed the presence of suprarenal stent at the level of the visceral vessels. Two patients needed one chimney, ten patients needed double chimney and four patients needed three chimneys for a total of 34 target vessel overstented. In 30 visceral vessels a balloon expandable stent (Advanta atrium or Bentley BeGraft) was implanted, in the remaining 4 vessels a self-expandable stent (Viabahn Gore) was delivered. The Nellix endograft was implanted by bilateral percutaneous femoral approach in 11 patients Results - Technical success was achieved in 100% of the patients by completion angiography at the end of the procedure. No perioperative mortality was observed, one patient experienced non disabling posterior stroke at the end of the procedure. CT scan performed 1 month after the procedure showed sealing of 15/16 (94%) of type I endoleak , the remaining patient with residual proximal endoleak underwent a successful Onyx embolization one month later. At median follow-up of 13 months no recurrent endoleaks were recorded. All target vessel stented were patent with no need of reintervention. Conclusion - ChEVAS may serve as alternative treatment option in patients with type I endoleak where the implantation of fEVAR/brEVAR is hampered by the presence of previous endograt in site. Further follow-up and a multicenter study are needed to corroborate these preliminary results

Migration and sac expansion as modes of midterm therapeutic failure after endovascular aneurysm sealing

BackgroundEndovascular aneurysm sealing (EVAS) is a disruptive technology to treat abdominal aortic aneurysm (AAA). The use of sac filling rather than endograft fixation was designed to treat aortic aneurysms in a wide range of morphologic appearances and to reduce endoleaks. There are few data reporting outcomes beyond postoperative follow-up. This study reports outcomes up to 5 years for Nellix (Endologix, Irvine, Calif) EVAS. MethodsData were prospectively collected for EVAS patients from the time of adoption of EVAS in 2013. All patients treated with the Nellix device are included in this study, and as such, it reports on infrarenal, ruptured, and iliac aneurysms as well as the Nellix-in-Nellix application. Juxtarenal and suprarenal aneurysms were treated using the EVAS system with parallel grafts into the visceral vessels and are included. Therapeutic failure, a composite outcome of migration, sac expansion >5 mm, type Ia and type Ib endoleak, and secondary aortic rupture, was the primary outcome along with all-cause mortality, aneurysm-related mortality, and reintervention rates. ResultsThere were 295 EVAS cases undertaken between March 2013 and July 2018. Indications for treatment were infrarenal (n = 185), juxtarenal and suprarenal (n = 73), ruptured (n = 18), and iliac (n = 13) aneurysms. There were 15 reinterventions using the Nellix-in-Nellix application. In some cases, EVAS was used to salvage failing endovascular or open aneurysm repairs. Median follow-up was 2.42 years (interquartile range, 1.07-3.57 years).Therapeutic failure was observed in 98 of the 295 cases (33.2%) overall and exceeded 50% in some subgroups. In 71 cases (24.1%), reintervention was performed, with reasons for no reintervention being mainly physiologic. Complications leading to therapeutic failure were most commonly seen beyond 2 years of follow-up. There were 15 secondary ruptures (5.36%), and 9 EVAS devices required explantation either electively or for aortic rupture. ConclusionsEVAS with the Nellix device has not met expectations, and early encouraging results have been eroded. The incidence of therapeutic failure has been high, occurring 2 years and beyond after implantation. The Nellix system has been voluntarily recalled by Endologix, and the CE mark has subsequently been suspended. The adoption of EVAS as a disruptive technology highlights the need for cautious adoption of novel technologies and the strict governance around such arrangements.

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

BackgroundThe 1-year results of the use of the Nellix (Endologix Inc, Irvine, Calif) endovascular aneurysm sealing (EVAS) device were initially promising. However, midterm complications including migration and aneurysm growth occurred more frequently than expected, which provided an incentive to refine the instructions for use. Strategies for the management of complications arising after endovascular aneurysm repair are often not applicable for EVAS, given the unique configuration of the Nellix device, and new techniques are needed. This study analyzes the clinical outcomes of both elective and emergency deployment of a new Nellix device within a primarily placed device, for failure of EVAS, which we refer to as a Nellix-in-Nellix application (NINA). MethodsThis is a global, retrospective, observational cohort study focusing on the early outcome of NINA for failed EVAS, including data from 11 European institutions and 1 hospital in New Zealand. ResultsA total of 41 patients were identified who underwent a NINA procedure. Of these, 32 (78%) were placed electively and 9 (22%) were placed on an emergency basis. Seven patients were initially treated with chimney EVAS (n = 5 in the elective NINA group and n = 2 in the emergency NINA group). The average time between the primary EVAS procedure and NINA was 573 days (interquartile range, [IQR] 397-1078 days) and 478 days (IQR, 120-806) for the elective and emergency groups, respectively. The indication for elective NINA was endoleak with migration (50%), endoleak without migration (25%), migration without endoleak (16%), and other (9%). Chimney grafts were used in 21 of 32 patients in the elective group and 3 of 9 patients in the emergency group. Technical success was achieved in 94% of patients in the elective group and 100% of patients in the emergency group. At latest follow-up (median, 104 days; IQR, 49-328 days), there were three aneurysm-related deaths (9%), no ruptures, and five device-related reinterventions (16%) within the elective group. In the emergency group (median follow-up, 23 days; IQR, 7-61 days), there were four aneurysm-related deaths and three aneurysm-related reinterventions. ConclusionsIn conclusion, a NINA can be used to treat late failures of EVAS with an acceptable technical success rate and can be used when more established treatment options are unfeasible or contraindicated. The durability of this technique needs to be further reviewed.

The Nellix endovascular aneurysm sealing system: current perspectives.

BackgroundThe Nellix endovascular aneurysm sealing (EVAS) system is a novel approach for the treatment of abdominal aortic aneurysm (AAA). We aimed to evaluate the efficacy of EVAS in the management of patients with AAA.Materials and methodsWe searched PubMed/MEDLINE, CINAHL, and bibliographic reference lists to identify studies reporting clinical outcomes in patients with asymptomatic, non-ruptured AAA treated with EVAS with the Nellix device. We pooled dichotomous outcome data using random-effects models.ResultsWe identified 14 single-arm observational studies, reporting a total of 1,510 patients. The pooled estimate of technical success was 99% (95% CI =98–100; heterogeneity: P=0.869, I2=0%). Adjunctive procedures were carried out in 39% (95% CI =19–63; heterogeneity: P<0.0001, I2=88%). Two cases of aneurysm rupture were reported within 30 days of treatment (0.7%, 95% CI =0.3–1.6; heterogeneity: P=0.923, I2=0%) and another five cases of rupture occurred during follow-up (0.8%, 95% CI =0.4–1.6; heterogeneity: P=0.958, I2=0%). The pooled estimates of early (within 30 days) and late (during follow-up) type I endoleak were 2.8 % (95% CI =1.8–4.2; heterogeneity: P=0.254, I2=18%) and 1.9% (95% CI =1.3–2.8; heterogeneity: P=0.887, I2=0%), respectively. Sac enlargement was noted in 3.1% (95% CI =1.8–5.4; heterogeneity: P=0.419, I2=0%) and device migration in 2.1% (95% CI =0.8–5.3; heterogeneity: P=0.004, I2=65%). The early and late reintervention rates were 2.7% (95% CI =1.7–4.2; heterogeneity: P=0.183, I2=27%) and 3.5% (95% CI =2.3–5.5; heterogeneity: P=0.061, I2=42%), respectively. The pooled estimate of 30-day mortality was 1.5% (95% CI =0.9–2.6; heterogeneity: P=0.559, I2=0%) and the pooled estimate of aneurysm-related death during follow-up was 1.0% (95% CI =0.6–1.9; heterogeneity: P=0.872, I2=0%).ConclusionReported outcomes of EVAS are acceptable. Type I endoleak, sac enlargement, device migration, and aneurysm rupture are recognized complications. High-level research is required to investigate potential advantages of EVAS over conventional treatments.

Midterm Outcomes of Nellix EVAS According to Revised Instructions for Use

To compare midterm outcomes of patients who were treated with the Nellix device for endovascular aneurysm sealing (EVAS) within the revised instructions for use (rIFU) to those who were treated outside the rIFU.

Invited commentary

Invited commentary

Midterm Single-Center Results of Endovascular Aneurysm Repair With Additional EndoAnchors

Purpose: To review midterm clinical outcomes of EndoAnchor placement during or after endovascular aneurysm repair (EVAR) or chimney EVAR (ch-EVAR). Materials and Methods: A retrospective analysis was conducted of 51 consecutive patients [median age 75 years; 38 men] who underwent EVAR/ch-EVAR with EndoAnchor placement between June 2010 and December 2016 to prevent seal failures (31, 61%) or to treat type Ia endoleak and/or migration (20, 39%). Median aortic neck diameter was 27.7 mm and median neck length was 9.0 mm. Thirty-three (65%) had a conical neck; 48 (94%) had at least 1 hostile neck characteristic. Thirty-two (63%) patients had severe comorbidities (ASA score ⩾III). Eight patients had a single ch-EVAR procedure. Baseline patient characteristics, anatomic variables, procedure details, early and late complications, reinterventions, and aneurysm-related and all-cause mortality rates were recorded. Follow-up imaging was performed with computed tomography angiography (CTA) or duplex ultrasonography. Results: Median procedure time was 100 minutes; a median of 6 EndoAnchors were implanted. There were 10 (10%) residual type Ia endoleaks at the end of the procedure; 9 had resolved by the first postoperative CTA. One residual and 2 new type Ia endoleaks were identified at the first postoperative imaging. Median follow-up for the entire cohort was 24.0 months, during which 3 new type Ia endoleaks were identified. Five of the 6 type Ia endoleaks were treated, 1 resolved spontaneously. There was 1 endograft limb occlusion without clinical consequences, 1 chimney graft occlusion without possibilities for a reintervention, 1 rupture after type IV endoleak (a Nellix device was successfully deployed within the main device), and 1 complete graft explantation for infection. There was no new-onset hemodialysis. Kaplan-Meier estimates of freedom from type Ia endoleak, proximal neck–related reinterventions, and aneurysm-related mortality at 2 years were 87.3%, 92.2%, and 94.0%, respectively. Conclusion: EndoAnchors are helpful in the endovascular treatment of unfavorable proximal aortic necks, with fair midterm results.

Nellix Endovascular Aneurysm Sealing System: Three Year Experience

The Nellix device (Endologix, Irvine, CA) provides a unique method of excluding and sealing abdominal aortic aneursyms (AAA) using a polymer-filled endobag surrounding dual aorto-iliac stent grafts. With this new technology comes hypothetical benefits in preventing endoleaks but also comes new potential failure modes. The Instructions For Use (IFU) was updated September 2017 with changes in aneurysm neck size and length, iliac landing zone diameter and length, and the ratio of maximum aneurysm diameter to the maximum flow lumen diameter.

Status of Endovascular Aneurysm Sealing After 5 Years of Commercial Use

Endovascular aneurysm sealing (EVAS) using the Nellix Endovascular Sealing System was introduced commercially in 2013 with the aim of reducing the incidences of reintervention and late complications observed after conventional endovascular aneurysm repair (EVAR). In the 5 years since its commercial launch, the Nellix system has evolved in terms of its structure, instructions for use, and delivery technique. Complications, including migration and proximal endoleak, have been recognized and treatment strategies developed, although durability remains to be demonstrated. Prospective multicenter trials have shown a low incidence of type I endoleak and reintervention at 1-year follow-up, comparable to conventional EVAR with modern devices. Since the aneurysm sac is “actively managed” with EVAS, similar to open surgical repair, type II endoleaks are rare with the Nellix system. Unexpected benefits of active sac management with EVAS include reduced incidences of postimplantation syndrome and cardiac complications, with low all-cause mortality at 1 year. Less neck dilatation compared to EVAR has also been observed. The Nellix device and procedure continue to evolve, and further prospective studies are indicated. This article analyzes the current EVAS evidence to update our knowledge of this technique in the management of abdominal aortic aneurysm.

Temporal Changes in Intraluminal Thrombus Volume Within Abdominal Aortic Aneurysms: Implications for Planning Endovascular Aneurysm Sealing

Purpose: To explore whether or not there are temporal changes in the abdominal aortic aneurysm (AAA) and intraluminal thrombus (ILT) volumes between planning and implantation of the endovascular aneurysm sealing (EVAS) device and how these changes influence lumen volume. Methods: A retrospective review was conducted of 51 AAA patients (mean age 76±7.1 years; 36 men) in whom 2 serial preoperative computed tomography angiograms (CTAs) had been performed within 1 to 18 months before fenestrated endovascular repair. The 2 preoperative CTAs were analyzed to identify changes in total sac, ILT, and lumen volumes. Results: Over a median 7.0 months (interquartile range 4, 10), 46 (90%) of 51 AAAs increased in volume between the 2 CTAs. ILT volume increased in 44 aneurysms. In contrast, lumen volume increased in 31 and decreased in 20 AAAs. There was a strong correlation between changes in AAA volume and ILT volume (rs=0.859, p<0.001), which remained significant after adjustment for initial volumes (rs=0.815; p<0.001). There was no correlation between the time interval separating the 2 CTAs and changes in AAA volume (rs=0.115; p=0.421), changes in ILT volume (rs=0.084; p=0.599), or changes in lumen volume (rs=0.060; p=0.676). The AAA growth rate (defined as the change in AAA size/days between CTAs) showed a weak correlation with ILT volume (rs=0.272, p=0.054), which disappeared after adjustment for initial AAA size (rs=−0.002, p=0.991). Between the 2 CTAs, 12 aneurysms crossed the new <1.4 Nellix maximum aorta/lumen diameter ratio. Conclusion: As AAAs grow, the increase in aortic volume is largely occupied by additional ILT formation, with minimal change in lumen volume. These changes may alter the suitability of the aneurysm for the Nellix device and could have implications for EVAS planning and device deployment.

Preliminary results of endovascular aneurysm sealing from the multicenter Italian Research on Nellix Endoprosthesis (IRENE) study

ObjectiveBecause of advances in technology and experience of the operator, endovascular aneurysm repair (EVAR) has supplanted open repair to treat abdominal aortic aneurysm (AAA). The low 30-day mortality and morbidity of EVAR make the endovascular approach particularly suitable for patients at high surgical risk. However, endoleak or endograft migration requiring secondary intervention or open surgical conversion is a limitation of EVAR. The Nellix system (Endologix, Inc, Irvine, Calif) has been designed to seal the entire AAA to overcome these limitations with EVAR. We report the results of a retrospective, multicenter study with endovascular aneurysm sealing (EVAS) aimed to assess technical success, procedure-related mortality, complications, and reinterventions. MethodsThis study included patients selected for elective treatment with the Nellix device per the endovascular repair protocol at 16 Italian vascular centers. All patients were enrolled in a postoperative surveillance imaging program including duplex ultrasound investigations, computed tomography, and magnetic resonance controls following local standards of care. ResultsFrom 2013 to 2015, there were 335 patients (age, 75.5 ± 7.4 years; 316 men) who underwent elective EVAS. In 295 cases (88.0%), EVAS was performed under standard instructions for use of the Nellix system. Preoperative aneurysm diameter was 55.5 ± 9.4 mm (range, 46-65 mm). The inferior mesenteric artery and lumbar arteries emerging from the AAA were patent in 61.8% and 81.3% of cases, respectively. Chimney grafts were electively carried out in eight cases (2.4%). One (0.3%) intraprocedural type IB endoleak was observed and promptly corrected. Device deployment was successful in all patients, with no perioperative mortality. Early (≤30 days) complications included 1 (0.3%) type IA endoleak, 2 (0.6%) type II endoleaks (0.6%), 2 (0.6%) stent occlusions (0.6%), 3 (0.9%) distal embolizations, and 2 (0.2%) femoral artery dissections. Six (2.9%) patients underwent reinterventions. At 1-year follow-up, complications included 3 (1.1%) type II endoleaks, 4 (1.4%) type IA endoleaks, 1 (0.3%) type IB endoleak, 2 (0.7%) distal stent migrations, 5 (1.8%) distal embolizations, and 1 (0.3%) stent occlusion. Twelve patients (3.7%) underwent reinterventions, including four (1.4%) surgical conversions due to aortoduodenal fistula (1), endograft infection (1), and type IA endoleak that was unsuccessfully treated percutaneously (2). Two AAA-related deaths occurred. Freedom from aneurysm-related reintervention was 98.3% at 1-month and 94.7% at 12-month follow-up. ConclusionsThe preliminary results of this real-world multicenter study showed that EVAS with Nellix for the management of AAAs appears feasible. This device platform is associated with acceptable procedure-related mortality and low overall complication and reintervention rates. Definitive conclusions on the value of this novel device await long-term follow-up data.

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

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 30days and 1year after EVAS in 50 consecutive patients. 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. 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±49.1mL and 78.8±35.5mL at 30days and 1 year, respectively, P<0.242) and a slight, but statistically significant, increase in polymer volume (68.2±34.1mL and 71.9±35.2mL at 30days 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. 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.

Successful Use of Nellix and Endovascular Aortic Sealing Technology for Treatment of Aortic Rupture in a Porcine Model

Endovascular aortic sealing (EVAS) represents a recent transformation in approach for treatment of aortic aneurysms. Initial reporting has shown that EVAS using the Nellix device is safe with similar complication rates to standard endovascular aortic repair (EVAR). What remains unknown is how EVAS technology will behave in the ruptured setting. The purpose of this report is to discuss how EVAS system and endobag technology behave when deployed in a porcine model of aortic rupture. A controlled left retroperitoneal rupture was created in 20 large swine. Following rupture, an EVAS system was deployed across the rupture site to seal the area. The primary end point was seal from ongoing hemorrhage. Other parameters were examined to include endobag extravasation, aortic wall pressure measurements and device behavior in a live tissue model. Of the EVAS systems used, 15 Nellix (Endologix, Irvine, CA) devices and 5 novel EVAS systems were used. Of the correctly deployed devices, 100% sealed the rupture (n=19). One device was deployed above the rupture site, and seal was not achieved secondary to malpositioning. Endobag extravasation was seen with an average protrusion of 7.7mm. No other areas of aortic injury were noted secondary to endobag trauma. Pressure recording from behind the endobag indicates loss of pulsatile flow to the aortic wall with polymer curing. Endovascular aortic sealing for rupture is feasible and performs well in a porcine model of aortic rupture. Polymer extravasation is seen and may be controllable by the implanter. Once the polymer has cured, pulsatile aortic wall pressure is no longer present. EVAS represents an emerging technology for treatment of aortic rupture.