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Peer Review

Peer Reviewed

Case Report

Causes and Management of Failing Unibody EVAR Grafts

Hiranya A. Rajasinghe, MD1; Larry E. Miller, PhD2; Santiago H. Chahwan, MD1; Alvaro J. Zamora, MD1

 

1The Vascular Group of Naples, Naples, Florida; 2Miller Scientific Consulting, Asheville, North Carolina

November 2018
2152-4343

Abstract

Objectives. To describe the incidence of type III endoleak observed in our experience with the AFX Strata and Duraply materials (Endologix) as well as to describe endovascular management techniques to treat these graft failures. Methods. A total of 83 patients underwent elective endovascular aneurysm repair (EVAR) with the AFX stent-graft at a single center between 2010 and 2017. The AFX with Strata was used in 49 patients from 2010 to 2013 and the AFX with Duraply was used in 34 patients from 2014 to 2017. Main outcomes of this study were incidence of type III endoleak and associated secondary interventions. Results. During follow-up, serious type III endoleaks were observed in 6 patients (including 1 that resulted in rupture), all initially treated with the older AFX Strata. Overall, the type III endoleak rate was 12% with AFX Strata and 0% with AFX Duraply. All type III endoleaks were electively treated with modular bifurcated endografts with a single contralateral gate-docking limb. All repairs were technically successful and no complications have been observed during follow-up. Conclusion. Patients treated with AFX Strata have an elevated risk of type III endoleak, which may be treated with relining. Liberal and aggressive imaging surveillance may be warranted in these patients to aid with early detection of type III endoleak.

VASCULAR DISEASE MANAGEMENT 2018;15(11):E130-E132

Key words: abdominal aortic aneurysm, endoleak, endovascular aneurysm repair

​​​Unibody endovascular aortic stent grafts have been commercially available for infrarenal abdominal aortic aneurysm repair since 2003 following United States Food and Drug Administration approval of the Powerlink system (Endologix). The device is a unibody, bifurcated, self-expanding, fully stented endovascular graft with an endoskeleton constructed as a single-wire cobalt-chromium alloy body with a double spine covered with expanded polytetrafluoroethylene (ePTFE) graft material. The graft material is sutured to the endoskeleton only at the ends of the device.

Figure 1In 2011, the lower-profile AFX system was introduced that utilized a thin, conformable, ePTFE graft fabric material (Strata). However, this device was associated with numerous reports of late type III endoleak,1-3 which is a separation of overlapping stent-graft components that allows blood flow to repressurize the aneurysm sac. The suspected failure mode of these type III endoleaks was progressive uncoupling of the main unibody endograft from the proximal endoprosthesis extension, particularly in cases with progressive aortic tortuosity (Figure 1). Furthermore, explanted unibody endografts revealed graft erosions in the region of the bifurcation, which were referred to as type IIIb endoleaks (Figure 2). In 2013, Endologix conducted an investigation into reports of type IIIa endoleaks (separation of bifurcated and extension stent-grafts at the point of overlap), which was followed by an investigation into type IIIb endoleaks (disruption of the stent graft material).4Endologix ultimately revised the instructions for use to recommend maximizing overlap between the main unibody and proximal endoprosthesis component.4

Figure 2Additionally, modifications to the endograft were implemented, with the Strata material replaced with a new graft material (Duraply). Our group has extensive experience with the AFX stent-graft in elective and urgent treatment of abdominal aortic aneurysms. The purpose of this report is to describe the incidence of type III endoleak observed in our AFX experience with the Strata and Duraply materials as well as to describe endovascular management techniques to treat these graft failures.

Methods

A total of 83 abdominal aortic aneurysm patients were electively treated with the AFX stent-graft at a single center (Vascular Group of Naples, Naples, Florida) between 2010 and 2017. The AFX with Strata was used in 49 patients from 2010 to 2013 and the AFX with Duraply was used in 34 patients from 2014 to 2017. Main outcomes of this study were incidence of type III endoleak and associated secondary interventions.

Results

During follow-up, serious type III endoleaks (one resulting in rupture) were observed in 6 patients treated with the older AFX Strata. Overall, the type III endoleak rate in our experience was 12% with AFX Strata and 0% with AFX Duraply. All 6 failing unibody EVARs were successfully salvaged with elective endovascular repair utilizing modular bifurcated endografts with a single contralateral gate-docking limb. The choice of endograft device was based on the need to allow for repositionability of the contralateral gate limb to ease cannulation, given the technical challenge posed by the unibody endoskeleton. In addition, a preference for durable ePTFE fabric over Dacron was made to reduce the risk of recurrent type IIIb endoleaks produced by friction and/or tears with the existing unibody endoskeleton. Consequently, we selected the Gore C3 modular bifurcated stent-graft to treat all failing AFX grafts. All repairs were technically successful and no complications have been observed during follow-up.

Discussion

Table 1Overall, EVAR with a unibody stent-graft has historically been associated with a higher incidence of type III endoleaks, which appears to be related to inadequate overlap between the main unibody device and the proximal endoprosthesis extension during primary implantation. Other groups have reported similarly high rates of type III endoleak with the Powerlink or AFX stent-grafts. We systematically reviewed the literature and identified 10 clinical studies with 2145 patients who underwent elective treatment with a Powerlink or AFX stent-graft with Strata.1,2,5-12 Over a median follow-up of 24 months (range, 10 to 62 months), the type III endoleak incidence ranged from 0%-14% (Table 1). Mimicking our experience, all type III endoleaks reported in the literature required reintervention. To our knowledge, there are no published series with the AFX Duraply stent-graft. However, Endologix states that the incidence of type IIIB endoleaks occurring after implementation of the Duraply graft process decreased by approximately 80%.4

Based on our 9-year experience using the AFX stent-graft with the older Strata material and subsequently the newer Duraply material, increased type III endoleak risk appears to be limited to the earlier-generation AFX Strata platform. We continue to use the AFX Duraply by maximizing overlap between the main body and proximal endoprosthesis extension. The AFX Strata utilized a comparatively thinner PTFE fabric and incorporated shorter overlap between the main body and proximal component, which together conferred the higher type III endoleak risk. Repair may be successfully undertaken by endovascular means. We have had great success in treating failed unibody grafts with modular bifurcated PTFE endografts that employ repositionability to overcome technical challenges posed by the unibody skeleton. Based on our experience, we recommend liberal and aggressive use of computed tomography imaging surveillance of post-unibody endograft EVARs, particularly in patients who have had AFX Strata or device implantation prior to 2014, to aid with early detection of type III endoleak.

Conclusion

Patients treated with the AFX Strata have an elevated risk of type III endoleak, which may be treated with relining. Liberal and aggressive imaging surveillance may be warranted in these patients to aid with the early detection of type III endoleak.

 

Disclosure: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. Dr Miller reports consultant income from Endologix. The remaining authors report no conflicts of interest regarding the content herein.

 

Manuscript submitted May 5, 2018, provisional acceptance given July 8, 2018, final version accepted August 1, 2018.

 

Address for correspondence: Hiranya A. Rajasinghe, MD, The Vascular Group of Naples, 2350 Vanderbilt Beach Road, Suite 303, Naples, FL 34109. Email: HRajasinghe@tvgnaples.com

REFERENCES

1. Skibba AA, Evans JR, Greenfield DT, et al. Management of late main-body aortic endograft component uncoupling and type IIIa endoleak encountered with the Endologix Powerlink and AFX platforms. J Vasc Surg. 2015;62(4):868-875.

2. Lemmon GW, Motaganahalli RL, Chang T, et al. Failure mode analysis of the Endologix endograft. J Vasc Surg. 2016;64(3):571-576.

3. Welborn MB 3rd, McDaniel HB, Johnson RC, et al. Clinical outcome of an extended proximal seal zone with the AFX endovascular aortic aneurysm system. J Vasc Surg. 2014;60(4):876-883; discussion pp. 883-874. Epub 2014 May 28.

4. Endologix Inc. (2016) Important Safety Update: AFXTM Endovascular AAA System. https://endologix.com/wp-content/uploads/2016/12/12-30-Physician-Letter-AFXTIII-Endoleak-FINAL.pdf. Accessed May 13, 2018.

5. Albertini JN, Lahlou Z, Magnan PE, Branchereau A, for the French Powerlink Multicenter Trial Investigators. Endovascular repair of abdominal aortic aneurysms with a unibody stent-graft: 3-year results of the French Powerlink Multicenter Trial. J Endovasc Ther. 2005;12(6):629-637.

6. Carpenter JP, Garcia MJ, Harlin SA, Jordan WD, Jung MT, Krajcer Z, Rodriguez-Lopez JA (2010) Contemporary results of endovascular repair of abdominal aortic aneurysms: effect of anatomical fixation on outcomes. J Endovasc Ther17:153-162. doi: 10.1583/09-2977.1.

7. Coppi G, Silingardi R, Tasselli S, Gennai S, Saitta G, Veraldi GF. Endovascular treatment of abdominal aortic aneurysms with the Powerlink endograft system: influence of placement on the bifurcation and use of a proximal extension on early and late outcomes. J Vasc Surg. 2008;48(4):795-801.

8. Helo N, Chang AC, Hyun C, et al. Retrospective review of billowing phenomenon-a mimic of endoleak following placement of Endologix covered stent for the treatment of abdominal aortic aneurysm. Ann Vasc Surg. 2017;45:239-246. Epub 2017 Jul 6.

9. Kouvelos GN, Nana P, Bouris V, et al. Initial clinical experience with the Endologix AFX unibody stent graft system for treating patients with abdominal aortic aneurysms: a case controlled comparative study. Vasc Specialist Int. 2017;33(1):16-21. Epub 2017 Mar 31.

10. Melas N, Stavridis K, Saratzis A, Lazarides J, Gitas C, Saratzis N. Active proximal sealing in the endovascular repair of abdominal aortic aneurysms: early results with a new stent-graft. J Endovasc Ther. 2015;22(2):174-178.

11. Qu L, Raithel D. From clinical trials to clinical practice: 612 cases treated with the Powerlink stent-graft for endovascular repair of AAA. J Cardiovasc Surg (Torino). 2009;50(2):131-137

12. Wang GJ, Carpenter JP; for the Endologix Investigators. The Powerlink system for endovascular abdominal aortic aneurysm repair: six-year results. J Vasc Surg. 2008;48(3):535-545.

 


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