Editor's Choice - Occurrence and Classification of Proximal Type I Endoleaks After EndoVascular Aneurysm Sealing Using the Nellix™ Device

ALTURA™ Stent Graft Shortening and Its Implications After EVAR

Objectives: The ALTURA™ stent graft system is designed for the treatment of abdominal aortic and/or aorto-iliac aneurysms. This study evaluates the performance of the ALTURA™ stent graft, focusing on AAA diameter, landing zones, stent graft length, and migration following endovascular aortic repair (EVAR). Methods: This is a retrospective analysis of computed tomography (CT) images focuses on patients with infrarenal abdominal aortic aneurysm (AAA) treated with the ALTURA™ stent graft system (Lombard, Ltd., Didcot, UK) at Pauls Stradins Clinical University Hospital in Riga, Latvia, and University Hospital Düsseldorf in Düsseldorf, Germany. The study population consisted of patients with asymptomatic AAAs who underwent elective treatment between January 2014 and June 2017. Follow-up CT scans were performed at one month, six months, one, two, and three years after implantation. Changes in stent graft length, aneurysm sac diameter, and the proximal and distal sealing zones were evaluated. Results: A retrospective analysis was conducted on computed tomography (CT) images from 40 patients (mean age 70.4 ± 8.5 years, 34 males, 6 females) who were treated with the ALTURA™ stent graft system for infrarenal abdominal aortic aneurysms (mean aneurysm diameter 5.6 ± 1.0 cm). The mean follow-up duration was 24.2 ± 10.6 months, with CT scans completed for all patients at one month and for 80% at one year. The mean total shortening of the stent graft one year after EVAR was 4 ± 3 mm (p < 0.001), 7 ± 5 mm after two years (p < 0.001), and 9 ± 6 mm after three years (p < 0.001). The iliac extensions shortened by 4 ± 3 mm after one year (p < 0.001), 6 ± 4 mm after two years (p < 0.001), and 8 ± 4 mm after three years (p < 0.001). Significant shortening was observed in the iliac extension, while changes in the aortic stent graft were not statistically significant. The reduction in the distal sealing zone and upward migration of the stent graft were 3 ± 3 mm after one year (p < 0.001), 5 ± 5 mm after two years (p < 0.001), and 7 ± 7 mm after three years (p < 0.001). Over the follow-up period, significant stent graft shortening and loss of the distal sealing zone were observed. However, these changes remained within a clinically acceptable range and did not lead to type I endoleak. Aneurysm sac shrinkage greater than 10 mm one year after treatment was observed in 25% of patients (p < 0.001). No aneurysm ruptures or AAA-related deaths were reported. Conclusions: Significant shortening of ALTURA™ stent graft, migration, and sealing zone reduction were observed without clinical impact after three years. However, in patients with short distal sealing zones, these changes could increase the risk of type Ib endoleak. Longer follow-up is needed to assess long-term durability.

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

OBJECTIVE

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).

METHODS

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.

RESULTS

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.

CONCLUSION

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.

First Case of Nellix Stent Rupture in a Huge Symptomatic Abdominal Aortic Aneurysm Who Underwent Endovascular Aneurysm Sealing 7 Years Before

PURPOSE

Despite encouraging early results, mid- and long-term follow-up of endovascular aneurysm sealing (EVAS) has shown increased rates of failure mainly associated with endoleak detection and progressive bag separation with aneurysm reperfusion.

CASE REPORT

We present the first case of a Nellix endograft stent fracture detected in a 91-year-old male patient, presenting with widespread abdominal pain, 7 years after elective treatment of an abdominal aortic aneurysm by EVAS. Considering the sudden and unexpected nature of the event, an in-depth analysis of the possible causes of this structural failure has been performed.

CONCLUSION

Material fatigue could be another significant cause of late EVAS failure and should be carefully assessed in addition to endoleak detection during follow-up.

CLINICAL IMPACT

The case presented in this article further underlines the importance of a strict long term follow-up protocol in every patients who underwent EVAS.

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

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

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Mortality analysis of endovascular aneurysm sealing versus endovascular aneurysm repair

BACKGROUND

Endovascular aneurysm sealing (EVAS), using the Nellix endovascular aneurysm sealing system, has been associated with high reintervention and migration rates. However, prior reports have suggested that EVAS might be related to a lower all-cause mortality compared with endovascular aneurysm repair (EVAR). In the present study, we examined the 5-year all-cause mortality trends after EVAS and EVAR.

METHODS

We compared the 333 EVAS patients in the EVAS-1 Nellix U.S. investigational device exemption trial with 16,497 infrarenal EVAR controls from the Vascular Quality Initiative, treated between 2014 and 2016, after applying the exclusion criteria from the investigational device exemption trial (ie, hemodialysis, creatinine >2.0 mg/dL, rupture). As a secondary analysis, we stratified the patients by aneurysm diameter (<5.5 cm and ≥5.5 cm). We calculated propensity scores after adjusting for demographics, comorbidities, and anatomic characteristics and applied inverse probability weighting to compare the risk-adjusted long-term mortality using Kaplan-Meier and Cox regression analyses.

RESULTS

After weighting, the EVAS group had experienced similar 5-year mortality compared with the controls from the Vascular Quality Initiative (EVAS vs EVAR, 18% vs 14%; hazard ratio [HR], 1.1; 95% confidence interval [CI], 0.71-1.7; P = .70). The subgroup analysis demonstrated that for patients with an aneurysm diameter of <5.5 cm, EVAS was associated with higher 5-year mortality compared with EVAR (19% vs 11%; HR, 2.4; 95% CI, 1.7-4.7; P = .013). In patients with an aneurysm diameter of ≥5.5 cm, EVAS was associated with lower mortality within the first 2 years (2-year mortality: HR, 0.29; 95% CI, 0.13-0.62; P = .002). However, compared with EVAR, EVAS was associated with higher mortality between 2 and 5 years (HR, 1.9; 95% CI, 1.2-3.0; P = .005), with no mortality difference at 5 years (18% vs 17%; HR, 0.82; 95% CI, 0.4-1.4; P = .46).

CONCLUSIONS

Within the overall population, EVAS was associated with similar 5-year mortality compared with EVAR. EVAS was associated with higher mortality for those with small aneurysms (<5.5 cm). For those with larger aneurysms (≥5.5 cm), EVAS was initially associated with lower mortality within the first 2 years, although this advantage was lost thereafter, with higher mortality after 2 years. Future studies are required to evaluate the specific causes of death and to elucidate the potential beneficial mechanism behind sac obliteration that leads to this potential initial survival benefit. This could help guide the development of future grafts with better proximal fixation and sealing that also incorporate sac obliteration.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Tailor-Made Tapering Grafts for Large-Neck Aorta

Patients having a large aortic neck poses a challenge in abdominal aortic aneurysm surgery both in endovascular and open aneurysm repair, sometimes necessitating paravisceral or thoracoabdominal aneurysm repair which carries considerable perioperative risk. Here, we describe techniques of using a tailor-made tapering graft in open surgery that can be adjusted for large neck morphology. This technique helps avoid discrepancies between the proximal aorta and graft, and postoperative acute kidney injury by clamping at lower levels. The conscientious use of this technique in selected patients realizes satisfactory outcomes both in the short term and midterm in the demanding anatomy of large aortic necks.

A Case of Late Type Ia Endoleak After Endovascular Aneurysm Sealing Using the Nellix System: Proximal Extension with Triple Chimney and Gutter Endoleak Embolization

An 87-year-old man, who submitted to endovascular aneurysm sealing (EVAS) on 2017, presented a type Ia endoleak 2 years later, with enlargement of the aneurysmal sac. We planned an endovascular procedure of correction consisting of a proximal extension through two covered stent grafts deployed into the previous Nellix stent grafts, with associated triple chimney. However, 3 months later, he had a further 5 mm aneurysmal sac enlargement. He was submitted to angiography with coil embolization of gutters, obtaining a successfully result. At 1 and 3 months, he is free from endoleak, with a stable aneurysmal diameter.

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

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

The Dilemma after Sealing an Endovascular Aortic Aneurysm - Three Ways Out

INTRODUCTION

Endovascular aneurysm sealing (EVAS) was commercially introduced in 2013. The initial results of EVAS were positive, leading to its widespread use. The mid- and long-term reports showed greater than expected rates of migration, which led to a recall of the device. In the present article, we describe our experience in managing type Ia endoleaks and migration occurring with the Nellix system in three different ways: open repair with Nellix explantation, Nellix-in-Nellix application (NINA technique), and the use of the multibranched Colt device originally dedicated to the treatment of thoracoabdominal aneurysms.

MATERIALS AND METHODS

From February 2014 to June 2021, we performed 20 procedures for failed EVAS or ChEVAS (migration, type Ia endoleak, secondary aneurysm rupture). All patients treated for EVAS failure were male, aged 65 - 79.

RESULTS

Seven Nellix explantations were performed. Three patients were admitted to our hospital with ruptured aneurysms that occurred 3 weeks to 4 years (mean 124 weeks) after EVAS, and another four with type Ia endoleak. In all but one case, removal of the Nellix system was easy. In two patients, tube grafts were implanted and in the remaining five cases, bifurcated grafts were implanted. In four patients, graft legs were anastomosed with the internal iliac arteries. One patient with secondary aneurysm rupture died from multiorgan failure on the 4th postoperative day. In two cases, transient renal failure was noticed in the perioperative period. All patients were admitted to the intensive care unit for 1 to 4 days (mean 2 days). The mean hospital stay was 9 days. All patients stayed in follow-up (3 - 56 months), but no other complications occurred. Eight patients were treated with the NINA technique: five for distal migration of the Nellix and three for failed ChEVAS. Four patients had a NINA procedure performed with three chimneys, three with two and one with one chimney. In one case, two iliac limbs were implanted to avoid kinking of the external iliac arteries. The median hospitalization time after the procedure was 9 days (range 3 - 12). Four patients developed transient acute renal insufficiency in the perioperative period. The follow-up ranged between 4 and 72 months. In one patient, deterioration of preexisting chronic renal insufficiency developed 5 months after the procedure, but dialysis was not required. One patient died from exacerbation of heart failure 7 months after the NINA procedure. The Colt device was implanted in five patients for the treatment of distal migration with type Ia endoleaks. None of the patients developed any signs of spinal cord ischemia. All patients were admitted to the intensive care unit for 1 or 2 days. In two cases, transient acute renal failure was noticed in the perioperative period. The mean hospital stay was 9 days. All patients remained in follow-up (6 - 22 months). In one case, the occlusion of the celiac trunk branch was found in contrast computed tomography 1 month after implantation of the Colt device, but without any symptoms. No other complications occurred.

CONCLUSIONS

Normal strategies for the management of complications for late failure of EVAR, including stent-graft extensions, are not suitable after EVAS; therefore, alternatives are necessary. Conversion to open repair carries an extensive burden on the patient, so it is not recommended for patients with high surgical risk. The use of a Nellix-in-Nellix application to treat late failure of EVAS is not within the instructions for use but could be an effective strategy for a type Ia endoleak with or without migration. The use of this technique has been extremely limited since the Nellix system was recalled from the market. The use of the Colt multibranched device may be an alternative option, but due to the small number of patients, this method needs further evaluation.

Type 1A endoleak detachable coil embolization after endovascular aneurysm sealing: Case report

INTRODUCTION

Endovascular aneurysm sealing (EVAS) with the Nellix system was introduced to reduce endovascular aneurysm repair (EVAR) perioperative complications, especially endoleaks. Herein we report a case of successful type 1A endoleak managed with detachable coils embolization after EVAS.

PRESENTATION OF CASE

A 77-year-old male was referred for abdominal pain. The angio-CT scan confirmed the previous EVAS procedure and showed a type Is2 endoleak below the right renal artery resulting in a 2.5 cm aortic blister with contrast medium filling the space between the aortic wall and the endobags. The patient was considered unfit for conventional open surgery and an endovascular approach with coil embolization Concerto Helix Detachable Coil System was chosen under local anesthesia. After intervention, a complete abdominal pain regression was registered. The 12- month CT follow-up showed endoleak sealing and Nellix system stability.

DISCUSSION

EVAS has been associated to a high endoleaks and complications incidence when compared to EVAR. The EVAS different device concept led to a different endoleak classification and management. Endoleak management main options include the Nellix system explantation or the Nellix in Nellix application, however these are nearly always not applicable, respectively, due to the high surgical risk condition and the Nellix system availability, especially in emergent setting. Despite the use of coil embolization is controversial, this tool is off-the-shelf and leads to a disease resolution in most of patients without other surgical options.

CONCLUSION

Proximal type Is2 embolization after EVAS is feasible with limited invasiveness.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

The Fluid-Dynamics of Endo Vascular Aneurysm Sealing (EVAS) System failure

Purpose

The main objective of this work is to investigate hemodynamics phenomena occurring in EVAS (Endo Vascular Aneurysm Sealing), to understand if and how they could lead to type 1a endoleaks and following re-intervention. To this aim, methods based on computational fluid mechanics are implemented as a tool for checking the behavior of a specific EVAS configuration, starting from the post-operative conditions. Pressure and velocity fields are detailed and compared, for two configurations of the Nellix, one as attained after correct implantation and the other in pathological conditions, as a consequence of migration or dislocation of endobags.

Methods

The computational fluid dynamics (CFD) approach is used to simulate the behavior of blood within a segment of the aorta, before and after the abdominal bifurcation. The adopted procedure allows reconstructing the detailed vascular geometry from high-resolution computerized tomography (CT scan) and generating the mesh on which the equations of fluid mechanics are discretized and solved, in order to derive pressure and velocity field during heartbeats.

Results

The main results are obtained in terms of local velocity fields and wall pressures. Within the endobags, velocities are usually quite regular during the whole cardiac cycle for the post-implanted condition, whereas they are more irregular for the migrated case. The largest differences among the two cases are observed in the shape and location of the recirculation region in the rear part of the aorta and the region between the endobags, with the formation of a gap due to the migration of one or both of the two. In this gap, the pressure fields are highly different among the two conditions, showing pressure peaks and pressure gradients at least four times larger for the migrated case in comparison to the post-implanted condition.

Conclusions

In this paper, the migration of one or both endobags is supposed to be related to the existing differential pressures acting in the gap formed between the two, which could go on pushing the two branches one away from the other, thus causing aneurysm re-activation and endoleaks. Regions of flow recirculation and low-pressure drops are revealed only in case of endobag migration and in presence of an aneurysm. These regions are supposed to lead to possible plaque formation and atherosclerosis.

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.

Secondary Endoleak Management Following TEVAR and EVAR

Endovascular abdominal and thoracic aortic aneurysm repair and are widely used to treat increasingly complex aneurysms. Secondary endoleaks, defined as those detected more than 30 days after the procedure and after previous negative imaging, remain a challenge for aortic specialists, conferring a need for long-term surveillance and reintervention. Endoleaks are classified on the basis of their anatomic site and aetiology. Type 1 and type 2 endoleaks (EL1 and EL2) are the most common endoleaks necessitating intervention. The management of these requires an understanding of their mechanics, and the risk of sac enlargement and rupture due to increased sac pressure. Endovascular techniques are the main treatment approach to manage secondary endoleaks. However, surgery should be considered where endovascular treatments fail to arrest aneurysm growth. This chapter reviews the aetiology, significance, management strategy and techniques for different endoleak types.

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.

Migration After Endovasclar Aneurysm Sealing in Conjunction With Chimney Grafts

Purpose

To assess the incidence of migration after endovascular aneurysm sealing (EVAS) in conjunction with chimney grafts (chEVAS) for repair of abdominal aortic aneurysms (AAAs).

Materials and Methods

A retrospective, observational cohort study was conducted of 31 patients (mean age 75.7 years; 27 men) treated for juxtarenal AAA between April 2013 and December 2018 at single centers in New Zealand and the Netherlands. The majority of patients received >1 chimney graft (13 single, 13 double, and 5 triple) during chEVAS. Six patients had only the first postoperative scan, so the migration analysis was based on 25 patients.

Results

Median seal length assessed on the first postoperative computed tomography scan was 36.5 mm. The assisted technical success rate was 93.5% with 2 technical failures. Median time to final imaging follow-up was 17 months in 25 patients. At the latest follow-up, there were no cases of caudal migration >10 mm. Freedom from caudal movement of 5 to 9 mm was estimated as 86.1% at 1 year and 73.9% at 2 years; freedom from clinically relevant migration (movement requiring reintervention) was 100% at both time intervals. However, at 3 years there were 2 cases of caudal movement of 5 to 9 mm and a type Ia endoleak warranting reintervention. No correlation between migration and aneurysm growth (p=0.851), endoleak (p=0.562), or the number of chimney grafts (p=0.728) was found. During follow-up, 2 patients (7%) had aneurysm rupture and 10 (33%) had reinterventions. Eight patients (27%) died; 2 were aneurysm-related (7%) and due to the consequences of a reintervention.

Conclusion

In the 2 years following chEVAS, there was no caudal migration >10 mm, but nearly a quarter of patients had caudal movement of 5 to 9 mm. A trend was observed toward ongoing migration that required intervention at 3-year follow-up. chEVAS is technically challenging and should be considered only for patients with no viable alternative treatment option.

Current assessment and management of endoleaks after advanced EVAR: new devices, new endoleaks?

INTRODUCTION

In recent years there has been an increasing application of advanced EVAR techniques to tackle complex clinical and anatomical scenarios. In a bid to overcome the limitations of the traditional stent-grafts, newer EVAR endografts and techniques have been developed and introduced into clinical practice, permitting endovascular management of difficult infrarenal, juxta-renal and thoracoabdominal aneurysms for which previously there was no endovascular solution. As a consequence, we are now confronted with unique patterns of endoleak requiring customized clinical-radiological assessment and treatment. Despite the increasing body of evidence regarding new EVAR techniques and related endoleaks, current guidelines do not specifically address these issues.

OBJECTIVES

Our review aims to assess risk factors, development, and management strategies of these endoleaks, in the most recent infrarenal EVAR devices and in more complex fenestrated EVAR (FEVAR) and Chimney EVAR (Ch-EVAR).

EXPERT OPINION

Most new devices have demonstrated types of endoleaks that need specific imaging and treatment, as in EVAS, FEVAR, and ChEVAR. Knowledge of specific stent-graft characteristics and the nature of endoleaks associated with the various procedures facilitates the application of relevant useful imaging. In addition, it should aid development of a customized and practically relevant approach to patient management during intervention and follow-up.

Physiological Appearance of Hybrid FDG-Positron Emission Tomography/Computed Tomography Imaging Following Uncomplicated Endovascular Aneurysm Sealing Using the Nellix Endoprosthesis

Purpose: To investigate the physiological uptake of hybrid fluorine-18-fluorodeoxyglucose (FDG)-positron emission tomography/computed tomography (PET/CT) before and after an uncomplicated endovascular aneurysm sealing (EVAS) procedure as a possible tool to diagnose EVAS graft infection and differentiate from postimplantation syndrome. Materials and Methods: Eight consecutive male patients (median age 78 years) scheduled for elective EVAS were included in the prospective study (ClinicalTrials.gov identifier NCT02349100). FDG-PET/CT scans were performed in all patients before the procedure and 6 weeks after EVAS. The abdominal aorta was analyzed in 4 regions: suprarenal, infrarenal neck, aneurysm sac, and iliac. The following parameters were obtained for each region: standard uptake value (SUV), tissue to background ratio (TBR), and visual examination of FDG uptake to ascertain its distribution. Demographic data were obtained from medical files and scored based on reporting standards. Results: Visual examination showed no difference between pre- and postprocedure FDG uptake, which was homogenous. In the suprarenal region no significant pre- and postprocedure differences were observed for the SUV and TBR parameters. The infrarenal neck region showed a significant decrease in the SUV and no significant decrease in the TBR. The aneurysm sac and iliac regions both showed a significant decrease in SUV and TBR between the pre- and postprocedure scans. Conclusion: Physiological FDG uptake after EVAS was stable or decreased with regard to the preprocedure measurements. Future research is needed to assess the applicability and cutoff values of FDG-PET/CT scanning to detect endograft infection after EVAS.

The Safety of EVAS Surgical Conversion in a Comparative Monocentric Analysis

BACKGROUND

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSIONS

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

National Numbers of Secondary Aortic Reinterventions after Primary Abdominal Aortic Aneurysm Surgery from the Dutch Surgical Aneurysm Audit

BACKGROUND

Long-term secondary aortic reinterventions (SARs) can be a sign of (lack of) effectiveness of abdominal aortic aneurysm (AAA) surgery. This study provides insight into the national number of SARs after primary AAA repair by endovascular aneurysm repair (EVAR) or by open surgical repair in the Netherlands.

METHODS

Observational study included all patients undergoing SAR between 2016 and 2017, registered in the compulsory Dutch Surgical Aneurysm Audit (DSAA). The DSAA started in 2013, SARs are registered from 2016. Characteristics of SAR and postoperative outcomes (mortality/complications) were analyzed, stratified by urgency of SAR. Data of SARs were merged with data of their preceded primary AAA repair, registered in the DSAA after January 2013. In these patients undergoing SAR, treatment characteristics of the preceded primary AAA repair were additionally described, with focus on differences between stent grafts.

RESULTS

Between 2016 and 2017, 691 patients underwent SAR, this concerned 9.3% of all AAA procedures (infrarenal/juxtarenal/suprarenal) in the Netherlands (77% elective/11% acute symptomatic/12% ruptured). Endoleak (60%) was the most frequent indication for SAR. SARs were performed with EVAR in 66%. Postoperative mortalities after SAR were 3.4%, 11%, and 29% in elective, acute symptomatic, and ruptured patients, respectively. In 26% (n = 181) of the patients undergoing SAR their primary AAA repair was performed after January 2013 and data of primary and SAR procedures could be merged. In 93% (n = 136), primary AAA repair was EVAR. Endografts primarily used were nitinol/polyester (62%), nitinol/polytetrafluoroethylene (8%), endovascular sealing (21%), and others (9%), compared with their national market share of 76% (odds ratio [OR], 0.52; 95% confidence interval [CI], 0.38-0.71), 15% (OR, 0.50; CI, 0.29-0.89), 4.9% (OR, 5.04; CI, 3.44-7.38), and 4.1% (OR, 2.81; CI, 1.66-4.74), respectively.

CONCLUSIONS

In the Netherlands, about one-tenth of the annual AAA procedures concerns an SAR. A quarter of this cohort had an SAR within 1-5 years after their primary AAA repair. Most SARs followed after primary EVAR procedures, in which an overrepresentation of endovascular sealing grafts was seen. Postoperative mortality after SAR is comparable with primary AAA repair.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Endovascular Aneurysm Sealing is Associated with Higher Medium-Term Survival than Traditional EVAR

BACKGROUND

Endovascular aneurysm repair (EVAR) is the dominant treatment modality for abdominal aortic aneurysm (AAA). Periprocedural risks are low, and cardiovascular events are the principle determinants of long-term survival. Recently, the concept of endovascular aneurysm sealing (EVAS) has been introduced into clinical investigation. In previous cohort studies, EVAS has been associated with a lower all-cause mortality than expected despite device issues. We used a propensity weighted approach to investigate whether EVAS was associated with lower all-cause mortality after aneurysm repair.

METHODS

We compared 333 patients in the Nellix United States Investigational Device Exemption trial to 15,431 controls from the Vascular Quality Initiative between 2014 and 2016 after applying the exclusion criteria from the investigational device exemption (hemodialysis, creatinine > 2.0 mg/dL, or rupture). We calculated propensity scores and applied inverse probability weighting to compare risk adjusted medium-term survival using Kaplan-Meier and Cox regression.

RESULTS

After weighting, patients treated with the Nellix EVAS system experienced higher 3-year survival than controls from the Vascular Quality Initiative (93% vs. 88%, respectively). This corresponded to a 41% lower risk of mortality for EVAS compared with EVAR (HR 0.59 [0.38-0.92], P = 0.02). Subgroup analysis demonstrated that the association between EVAS and higher survival was strongest in the subgroup of patients with aneurysms over 5.5 cm (P for interaction < 0.001). In this subgroup, EVAS patients experienced half the rate of mortality as those patients treated with EVAR, with 3-year survival of 92% compared with 86% (HR 0.5 [0.3-0.9], P = 0.02).

CONCLUSIONS

In this select group of patients, EVAS was associated with higher medium-term survival than traditional EVAR. Although issues with the device have recently surfaced, this exploratory analysis shows that the concept of sac sealing may hold promise. Further study is needed to confirm this finding and determine whether EVAS is associated with lower rates of cardiovascular events.

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.

Stent Frame Movement Following Endovascular Aneurysm Sealing in the Abdominal Aorta

Purpose: To investigate the incidence and extent of stent frame movement after endovascular aneurysm sealing (EVAS) in the abdominal aorta and its relationships to aneurysm growth and the instructions for use (IFU) of the Nellix endograft. Methods: A retrospective single-center study was conducted to review the clinical data and computed tomography (CT) images of 75 patients (mean age 76±7.6 years; 57 men) who underwent infrarenal EVAS and had a minimum 1-year follow-up. The first postoperative CT scan at 1 month and the subsequent scans were used to measure the distances between the proximal end of the stent frames and a reference visceral vessel using a previously validated technique. Device migration was based on the Society of Vascular Surgery definition of >10-mm downward movement of either Nellix stent frame in the proximal landing zone; a more conservative proximal displacement measure (downward movement ⩾4 mm) was also recorded. Patients were categorized according to adherence to the old (2013) or new (2016) Nellix IFU. Aneurysm diameter was measured for each scan; a change ⩾5 mm was deemed indicative of aneurysm growth. Results: Over a median follow-up of 24 months (range 12–48), proximal displacement ⩾4 mm occurred in 42 (56%) patients and migration >10 mm in 16 (21%), with similar incidences in the right and left stent frames. Proximal displacement was significantly more frequent among patients whose anatomy did not conform to any IFU (p=0.025). Presence of aneurysm growth ⩾5 mm was observed in 14 (19%) patients and was significantly associated with proximal displacement ⩾4 mm (p=0.03). Conclusion: Infrarenal EVAS may be complicated by proximal displacement and migration, particularly when performed outside the IFU. The definition of migration used for endovascular aneurysm repair may be inappropriate for EVAS; a new consensus on definition and measurement technique is necessary.

Endovascular Treatment of Various Aortic Pathologies: Review of the Latest Data and Technologies

The technologies and innovations applicable to endovascular treatment for complex aortic pathologies have progressed rapidly over the last two decades. Although the initial outcomes of an endovascular aortic repair have been excellent, as long-term data became available, complications including endoleaks, endograft migration, and endograft infection have become apparent and are of concern. Previously, the indication for endovascular therapy was restricted to descending thoracic aortic aneurysms and abdominal aortic aneurysms. However, its indication has expanded along with the improvement of techniques and devices, and currently, it has become possible to treat pararenal aortic aneurysms and Crawford type 4 thoracoabdominal aortic aneurysm (TAAA) using the off-the-shelf devices. Additionally, custom-made devices allow for the treatment of arch or more extensive TAAAs. Endovascular treatment is applied not only to aneurysms but also to acute/chronic dissections. However, long-term outcomes are still unclear. This article provides an overview of available devices and the results of endovascular treatment for various aortic pathologies.

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.

Endobag separation - an ominous sign after endovascular aneurysm sealing with the Nellix device

Our report aims to alert physicians performing endovascular aneurysm sealing with the Nellix endoprosthesis to the risk of rupture when endobag separation is noticed on computed tomography. Endobag separation when observed with acute presentation of abdominal pain is an indicator of imminent rupture and prompt interventional treatment should be undertaken.