Endovascular aneurysm sealing as an alternative for the treatment of failed endovascular aneurysm repair

Abstract

Objective

The Nellix EndoVascular Aneurysm Sealing (EVAS) system has offered a novel approach in the treatment of abdominal aortic aneurysm (AAA). While it is currently indicated as a primary procedure in patients with infrarenal AAA with suitable anatomy according to the indications for use, a few studies aimed to address its potential interest in failed endovascular aneurysm repair (EVAR). The aim of this systematic review was to analyze the postoperative outcomes of patients with prior EVAR who underwent EVAS.

Design of the study

A literature search was performed according to Preferred Reporting Items for Systematic reviews and Meta-Analyses guidelines in May 2019 and included patients with prior EVAR who underwent EVAS. The publications had to report at least one of the basic postoperative outcomes (technical success rate, all-cause complications, mortality, length of in-hospital stay, length of stay in intensive care unit, the need of re-intervention).

Results

Eleven studies fulfilled the inclusion criteria, for a total of 46 patients. EVAS was used to treat endoleaks in 45 cases (97.8%): 29 type Ia endoleaks (63%), 6 type IIIa endoleaks (13%), and 10 type IIIb endoleaks (21.7%). Standard EVAS procedure was performed in 21 patients (45.7%), and 25 patients (54.3%) had chimney-EVAS. The technical success was achieved in all the studies. Two patients (4.9%) died during the 30-day postoperative period, but no aneurysm-related mortality was reported. The presence of endoleaks was reported in five patients (9.8%) during the follow-up.

Conclusion

The results suggest the safety and the efficiency of EVAS in the treatment of complications following EVAR including type Ia, type IIIa, and type IIIb endoleaks. Further studies on larger cohorts and longer follow-up periods are required to confirm the interest of EVAS in the endovascular management of failed EVAR.

Keywords

Endovascular aneurysm sealing Nellix device endovascular aneurysm repair endoleaks

Introduction

Endovascular aneurysm repair (EVAR) has become an alternative therapeutic option to open surgery which can be proposed in patients with challenging anatomy.^1–3 Even if EVAR has proven its safety and efficiency, some patients may develop postoperative complications such as endoleaks, endotension, stent-graft migration, stent-graft thrombosis or stenosis, subsequent iliac aneurysm formation, or aneurysm rupture.^4–6 Such complications may require a re-intervention using endovascular procedures or open surgery. The choice of the most appropriate approach mainly depends on the clinical characteristics of the patients, the anatomic configuration of the abdominal aortic aneurysm (AAA), and the pre-existing device, as well as the experience of the operators.^7,8 The Nellix EndoVascular Aneurysm Sealing (EVAS) system (Endologix, Inc., Irvine, CA) has offered a novel approach in the treatment of AAA.⁹ The technique consists in sealing the aneurysm sac, thanks to the use of balloon-expandable endoframes each surrounded by a polymer-filled endobags.¹⁰ By conforming to the anatomical and prosthetic structures, it may contribute to limit gutters and endoleaks formation.⁹ It is indicated in patients with infrarenal AAA with suitable anatomy for treatment within the indications for use (IFU).⁹ EVAS has recently been proposed in the treatment of complications following EVAR. The aim of this systematic review was to analyze the postoperative outcomes of patients with prior EVAR who underwent EVAS.

Material and methods

Literature search and eligibility criteria

Standard reporting guidelines set by the Preferred Reporting Items for Systematic reviews and Meta-Analyses Group¹¹ were followed to identify studies reporting the outcomes of patients with prior EVAR who underwent EVAS. Study titles and abstracts were searched using Medline in July 2018, with the most recent search carried out on May 2019. Only publications written in English were selected. The search strategy was unrestricted and used the following exploded MeSH (medical subject heading) terms: “Nellix,” “endovascular aneurysm sealing,” “endovascular,” “endovascular aneurysm repair,” and “aortic aneurysm.”

Articles were selected based on the following criteria. Publications had to include patients with prior EVAR who underwent EVAS. The publications had to report at least one of the basic postoperative outcomes (technical success rate, all-cause complications, mortality, length of in-hospital stay, length of stay in intensive care unit, the need of re-intervention). Prospective and retrospective cohorts were included as well as case reports. Reviews and unpublished data were excluded. Suitable original articles were independently extracted by two authors (FL and JR) according to the eligibility criteria. The flow chart depicting the process for the selection of the studies is presented in Figure 1.

Data collection

From the selected articles, the number of patients, the characteristics of the initial EVAR, the procedural characteristics of the EVAS, the study design as well as the postoperative criteria were extracted and analyzed. The quality of the study was evaluated based on the study design, the number of patients included as well as the criteria used to assess the postoperative outcomes (time to follow-up, clinical and imaging criteria used). Levels of evidence of each study were evaluated according to the 2011 Oxford Centre for Evidence Based Medicine’s Levels of evidence.¹²

Results

Among the 203 publications initially screened, 11 fulfilled the inclusion criteria and were finally included in the analysis (Table 1).

Table 1.

Summary of clinical studies on the postoperative outcomes of patients with prior EVAR who underwent EVAS.

Aim	Study design	Number of patients	Main results	Level of evidence	References
Assess the technical success and clinical outcome of re-interventions using EVAS to treat complications after EVAR	- Retrospective multicenter study- Indications for EVAS • 10 type Ia endoleaks • 5 type III endoleaks: 3 type IIIa and 2 type IIIb- EVAS treatment • 5 standard EVAS • 10 chimney-EVAS due to unfavorable neck anatomy, an inadequate landing zone or extension of the aneurysm above the renal arteries	15	- Technical success: 100%- Postoperative outcomes (median follow-up of 8 months) • 1 case of endobags protrusion • 4 deaths nonrelated to AAA • 1 renal artery guidewire injury requiring a nephrectomy due to active bleeding • No re-intervention, graft thrombosis, endoleak, or chimney graft occlusion	3	Youssef et al.¹⁴
Report the management of type I and type III endoleaks with EVAS technique	- Prospective single-center study- Indications for EVAS • 6 type Ia endoleaks • 1 type IIIb endoleak • 3 undetermined-type endoleak, initially considered as type IIIb endoleaks- EVAS treatment • 5 patients with standard EVAS • 5 patients with chimney-EVAS	10	- Immediate postoperative outcomes • Immediate technical success: 100% with type Ia endoleaks • No peri-operative death • 1 patient had a bleeding from a perforated renal artery that required embolization- Postoperative outcomes (median follow-up: 20.5 months) • Resolution of all type Ia endoleak, except in 1 patient who developed a new type Ia endoleak • 2 of the 3 undetermined-type endoleaks had continued sac expansion and required a re-intervention which identified type II endoleaks	3	Paraskevaset al.²⁰
Report the treatment of type Ia and type III endoleaks following EVAR or chimney-EVAR using EVAS and chimney-EVAS	- Retrospective single-center study- Indications for EVAS • 5 type Ia endoleaks • 3 type IIIa endoleaks • 2 type IIIb endoleaks- EVAS treatment • 6 patients with standard EVAS • 4 patients with chimney-EVAS	10	- Postoperative outcomes (median follow-up: 13.5 months) • 2 deaths nonrelated to AAA • 1 type II endoleak at 5 months after EVAS • 1 type Ia endoleak at 5 months after EVAS- No graft thrombosis, chimney graft occlusion, or endobag protrusion	3	Lareyre et al.¹⁹
Report a series of patients treated with chimney-EVAS for type Ia endoleak after EVAR	- Retrospective single-center series of case reports- Indications for EVAS • 3 type Ia endoleaks- EVAS treatment • 3 chimney-EVAS	3	- Technical success: 100%- Postoperative outcomes (follow-up at 14 months) • 1 death nonrelated to AAA • 2 dissections of the left subclavian artery during the procedure • 1 postoperative hematoma and common femoral artery pseudoaneurysm • 1 new type II endoleak at 14 months • Stable AAA sac size, patency of the Nellix and visceral stents with no residual type Ia endoleak	4	Joseph et al.²¹
Describe the treatment of 2 patients with type IIIb endoleak using EVAS	- Retrospective series of case reports- Indications for chimney-EVAS • 2 type IIIb endoleaks	2	- Postoperative outcomes (follow-up: 7 and 6 months) • Technical success: 100% • 1 death nonrelated to AAA • No endoleak, stable aneurysm diameter, patent flow	4	Van den Ham et al.¹⁶
Report the use of EVAS outside of instruction for use	- Retrospective case report- Indications for EVAS • 1 type Ia endoleak	1	- Postoperative outcomes (follow-up during the in-hospital stay) • Technical success achieved	4	Torella et al.²²
Report the application of EVAS to treat type Ia endoleak	- Retrospective case report- Indications for EVAS • 1 type Ia endoleak	1	- Postoperative outcomes (follow-up: 6 months) • Technical success achieved: resolution of type Ia endoleak with bilateral chimney stent-graft patency	4	Hughes et al.¹⁷
Report the use of chimney-EVAS for the treatment of type Ia endoleak	- Retrospective case report- Indications for EVAS • 1 type Ia endoleak- EVAS treatment • 1 chimney-EVAS	1	- Postoperative outcomes (follow-up: 1 month) • Technical success achieved: resolution of type Ia endoleak with normal chimney stent-graft patency	4	Quintas et al.²³
Report the use ofEVAS for the treatment of type Ia endoleak after EVAR	- Retrospective case report- Indications for EVAS • 1 type Ia endoleak	1	- Postoperative outcomes (follow-up: 12 months) • Technical success achieved: adequate sealing of the Nellix, resolution of type Ia endoleak and stability of the aneurysmal sac	4	Martinelli et al.¹⁸
Report the use of EVAS in the management of proximal stent-graft collapse associated with thrombosis following EVAR	- Retrospective case report- Indications for EVAS • Collapse of the aortic stent-graft extension associated with thrombosis of the aortic main graft, iliac limbs, and left common iliac artery- EVAS treatment • 1 chimney-EVAS	1	- Postoperative outcomes (follow-up: 25 months) • Technical success achieved: AAA sealing, no thrombosis or endoleak, and patency of the renal and visceral vessels	4	Lareyre et al.¹³
Report early experience in the treatment of patients with post-EVAR complications and challenging neck anatomy	- Retrospective series of case reports- Indications for EVAS • 1 type Ia endoleaks	1	- Postoperative outcomes (follow-up during the in-hospital stay) • Technical success: 100%	4	Bockler et al.¹⁵

AAA: abdominal aortic aneurysm; EVAS: EndoVascular Aneurysm Sealing; EVAR: endovascular aneurysm repair.

All the patients had had prior EVAR: 22 patients (47.8%) had had a bifurcated endograft, 11 (23.9%) a chimney graft, 2 a fenestrated endograft (4.3%), and 1 a tube endograft (2.2%). For 10 patients (21.7%), the type of endograft used was not detailed. The clinical and procedural characteristics of patients with prior EVAR who underwent EVAS are summarized in Table 2. This includes age, maximum AAA diameter, time elapsed between EVAR and EVAS, as well as the procedural time and the polymer fill volume.

Table 2.

Clinical and procedural characteristics of patients with prior EVAR who underwent EVAS.

Age (years)	Maximal AAA diameter at the time of EVAS (mm)	Time between EVAR and EVAS (months)	Procedural time (min)	Polymer fill volume (mL)	References
79 (69–93)	78.5 (65–110)	48 (18–84)	171 ± 81	56.7 ± 47.8	Youssef et al.¹⁴
82 (78–89)	94.5 (55–120)	54 (24–144)	NA	NA	Paraskevas et al.²⁰
76 (66–83.3)	76 (64–92.3)	41.5 (29–81.8)	222.5 (138.8–418.8)	51.5 (32–57.5)	Lareyre et al.¹⁹
80, 85, 84	65, 59, 70	96, 3, 9	355, 200, 300	NA	Joseph et al.²¹
75, 83	61, 85	96, 30	NA	40, 55	Van den Ham et al.¹⁶
87	91	NA	NA	NA	Torella et al.²²
87	NA	24	NA	NA	Hughes et al.¹⁷
74	138	36	NA	NA	Quintas et al.²³
70	NA	54	NA	38	Martinelli et al.¹⁸
76	57	1	330	7	Lareyre et al.¹³
75	65	NA	NA	24	Bockler et al.¹⁵

Values are expressed as number or median with interquartile range, or means ± standard deviation.

AAA: abdominal aortic aneurysm; EVAS: EndoVascular Aneurysm Sealing; EVAR: endovascular aneurysm repair; NA: not available.

The EVAS system was used to treat endoleaks in 45 cases (97.8%) (Table 1): 29 type Ia endoleaks (63%), 6 type IIIa endoleaks (13%), and 10 type IIIb endoleaks (21.7%). One study reported the use of EVAS in the treatment of a collapse of the aortic stent-graft extension associated with aortic thrombosis.¹³ EVAS was used in two patients with contained rupture.¹⁴

Standard EVAS procedure was performed in 21 patients (45.7%),^14–20 and 25 patients (54.3%) had chimney procedure in combination with EVAS (chimney-EVAS). This included two patients with one-target vessel,¹⁴ eight patients with two-target vessels,^14,19,21,22, nine patients with three-target vessels,^{13,14,19,21,23} and one patient with four-target vessels.¹⁴ For five patients, the number of target vessels during the chimney-EVAS was not detailed.²⁰

The technical success was defined as the successful treatment of the complication post-EVAR (resolution of endoleaks or of the stent-graft collapse and aortic thrombosis) as well as the patency of the Nellix device and the renovisceral vessels at the end of the intervention. The technical success was achieved in all the studies. A study reported a dissection of the left subclavian artery in two patients, which were identified during the procedure and successfully treated with stenting.²¹ One postoperative hematoma and common femoral artery pseudoaneurysm was identified, which thrombosed spontaneously.²¹. One renal artery guidewire injury was reported and required a nephrectomy due to active bleeding.¹⁴ One patient developed an acute kidney injury during in-hospital stay due to a bleeding from a perforated renal artery which required embolization.²⁰

The length of follow-up varied among the studies (Table 1). No aneurysm-related mortality was reported. Two patients (4.9%) died during the 30-day postoperative period. The causes of the death were not related to the AAA or to vascular complications (myocardial infarction and intracerebral hemorrhage secondary to a trauma).^19,21 During the follow-up, six more patients (14.6%) died of nonrelated AAA causes.^14,16,19 One endobag protrusion was observed without clinical consequence.¹⁴ The presence of endoleaks was reported in five patients (9.8%) during the follow-up: four type II endoleaks and one type Ia endoleak.^19–21 The type II endoleaks occurred at 14-, 5-, 26-, and 12-month postsurgery. The type Ia endoleak was diagnosed at five-month postsurgery. These complications required a re-intervention using embolization procedure. No graft thrombosis, migration, or aneurysm sac expansion was reported.

Discussion

In this systematic review, we aimed to summarize the current knowledge on the postoperative outcomes of patients with prior EVAR who underwent EVAS. The devices used during EVAR were mainly conventional bifurcated grafts, but remarkably, EVAS could also be managed in patients with pre-existing fenestrated or chimney grafts. The indications of EVAS were mainly the treatment of type I and type III endoleaks. The development of endoleaks is one of the most frequent complications following EVAR and exposes to the risk of sac enlargement and aneurysm rupture.^4,24,25 The presence of type I or type III endoleaks may require a re-intervention which can be challenging due to the presence of the device making difficult the cannulation of visceral vessels.

EVAS has the ability to conform to the anatomical and prosthetic structures. The use of chimney-EVAS offers the possibility to extend the sealing to land in the suprarenal aortic segments and represents an off-the-shelf solution to treat type Ia endoleaks.²⁶ In case of type III endoleak, the bilateral Nellix stent grafts allow to reline the endograft and do not increase the distraction force in case of type IIIb endoleak.²⁷ In this context, EVAS has appeared as a potential alternative in the treatment of failed EVAR, even though it is currently outside the IFU.

The studies suggested the efficiency of EVAS in the treatment of type Ia, type IIIa, and type IIIb endoleaks following EVAR with an immediate technical success achieved in all patients; no death related to vascular complications during the follow-up and a small rate of endoleaks.

In the whole cohort, the development of type II endoleak was observed for four patients during the follow-up, and a type Ia endoleak was diagnosed in one patient. Type Ia endoleak after EVAS can result from a suboptimal patient selection, an improper device placement or a migration of the device.⁹ Therapeutic options include endovascular approaches such as embolization or the use of balloon-expandable covered stents⁹ or open repair. Type II endoleak following EVAS is not a frequent complication and could be favored by an incomplete furling of the endobags.²⁸ The endoleak may resolve spontaneously or can require an embolization procedure.

Even if the studies suggested the safety and the efficiency of EVAS in the treatment of failed EVAS, several considerations should be addressed. First, the number of cases treated was small, and the level of evidence was low. A longer follow-up on larger multicenter cohorts would be necessary to draw any definitive conclusions. The follow-up protocol including the frequency of imaging surveillance remains to be consensually defined. It should also be kept in mind that EVAS requires a learning curve. The training and the experience of the operators is mandatory before considering it as a potential therapeutic alternative. In addition, several technical considerations should be addressed. Even though the EVAS has some advantages to manage type I and type III endoleaks, it does not add additional fixation, and it should be important to check the fixation and the stability of the original endograft to limit the risk of migration. The pressure monitoring and the pre-fill of the endobags is a critical step to achieve a successful sealing and limit the risk of endobags protrusion or rupture. Optimal filling volume remains to be determined for the use of EVAS in patients with prior EVAR. While the use of EVAS in the treatment of type I and type III endoleaks has been described, the procedure could potentially be useful in other indications, as suggested by its description in a case of a collapse of the pre-existing aortic stent graft.¹³ The use of EVAS in failed EVAR is currently outside the IFU. So far, only a few studies have reported outcomes after primary EVAS beyond postoperative follow-up.²⁹ Stenson et al. collected outcomes from a series of 295 EVAS with a median follow-up of 2.42 years and reported a therapeutic failure in 33.2% of cases, with the need of a secondary procedure in 5.36% of cases. Early encouraging results of the EVAS as a primary procedure have been eroded, and the recent loss of the CE mark of the device may limit further studies to address its interest to treat failed EVAR.

Conclusion

The studies included in this review suggest the safety and the efficiency of EVAS in the treatment of complications following EVAR including type Ia, type IIIa, and type IIIb endoleaks. Further studies on larger cohorts and longer follow-up periods are required to confirm these results and determine the interest of the EVAS to treat complications post-EVAR. The field is still in its infancy, and further clinical protocols may help to better evaluate the interest of the device in the endovascular management of failed EVAR.

Footnotes

Declaration of conflicting interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) received no financial support for the research, authorship, and/or publication of this article.

ORCID iD

Fabien Lareyre

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