Endovascular aortic repair with the Gore Excluder Conformable endograft in severe neck angulation: Preliminary experience and technical aspects

Abstract

Objectives

Endovascular procedures are now the standard of care for endovascular aortic aneurysm repair but treatment of hostile proximal neck anatomy is still challenging. New endografts were brought to the market specifically designed to accommodate severe neck angulation. Authors describe a preliminary experience and early results using the Gore Excluder Conformable endograft (W. L. Gore & Associates, Flagstaff, Ariz) and its active control system in severe neck angulation with a standardized technical approach to achieve precise deployment in this hostile anatomy.

Methods

From June 2019 to May 2020, five patients with abdominal aortic aneurysm and severe neck angulation (≥70°) were treated with the Gore Excluder Conformable endograft at two different centers. Deployment of this endograft in this kind of anatomy should be aggressive starting over the level of renal arteries due to risk of distal migration downward on the external curvature and difficulty in upward repositioning. Authors suggested a standard technique with a routine through-and-through axillary–femoral approach, using a floppy guidewire together with preventive cannulation of the lower renal artery if a short neck (<15 mm) is associated.

Results

Endovascular aortic procedures were successfully completed in all patients. Final deployment of the stent graft using our standardized technical approach was extremely precise in all cases even if redeployment of the graft was necessary in all cases. No other secondary procedures were needed. At 30 days, no type IA endoleak was recorded and no aneurysm-related secondary procedures were performed. Median follow-up for this group of patients was 5.2 months (range 1–11). Early results revealed no type IA endoleak and no migration at Ct angiogram. No aneurysm-related secondary procedures were required.

Conclusion

Routine use of through-and-through axillary–femoral guidewire associated with selective pre-cannulation of the lower renal artery allows a precise deployment of the Gore Excluder Conformable endograft in difficult anatomies possibly affecting early outcomes.

Keywords

Abdominal aortic aneurysm endovascular aortic repair Gore Excluder Conformable stentgraft severe neck angulation deployment technique endoleak

Introduction

Endovascular aneurysm repair (EVAR) has revolutionized treatment of abdominal aortic aneurysm (AAA)¹ but the applicability of EVAR is still a challenge in patients with unfavorable anatomy. Even if there is not a consensus on hostile neck definition, infrarenal proximal aortic neck angulation is a common reason for AAA treatment failure with a significantly higher incidence of long-term complications such as endoleaks (ELs) and migrations.² Several authors defined various hostility criteria and considered an infrarenal neck angulation more than 60° an unfavorable anatomy for EVAR with an angulation between 75° and 90° as an additional risk factor.^3–5 With increasing operator experience and new material availability, endografts instruction for use (IFU) are nevertheless broadened today to allow treatment of most patients anatomies even if up to 58% of EVAR are nowadays performed outside manufacturers’ indications for use.²

New endografts have been developed to fit severe neck angulation (SNA) with specific attention to flexibility, proximal adaptability, and sealing and are now available on the market to extend indications for EVAR. Recently, a last generation device for endovascular AAA repair named Gore Excluder Conformable with active control System (W. L. Gore & Associates, Flagstaff, Ariz) has been engineered to treat this kind of anatomies, with a range of treatment up to 90° with neck length ≥ 15 mm. Nevertheless, a crucial phase to obtain optimal result is the endograft deployment technique.

Authors present a small series of five cases with AAA and SNA, treated with this last generation device and managed with a standardized technical approach that allow its precise deployment in such complex anatomies. No Institutional Review Board (IRB) approval was required for the present study.

Methods

Patient cohort

Between June 2019 and May 2020, five consecutive EVAR patients (two men; mean age 78.2 years, range 74–82) with a proximal infrarenal SNA (≥70°) were treated electively with the Gore Excluder Conformable endograft at two different centers. A retrospective review of prospectively collected data was performed.

All patients were preoperatively assessed by a thoracoabdominal 64-detector row CT angiogram (Figure 1(a)). All cases were planned using a Synapse 3D workstation and measurements were recorded according to Gore Excluder standard criteria. All patients were preoperatively classified at high risk for open surgery (American Society of Anesthesiologists classification ≥ III). Written informed consent was obtained from all patients.

Figure 1.

(a) Patient PG—Case 2. Preoperative Angio-CT Scan revealed a 6 cm AAA associated with a very severe infrarenal neck angulation (122°), a proximal aortic neck length of 15 mm and diameter of 28 mm. (b) Case 2. Diagnostic angiography with the graft in place after positioning of the axillary–femoral through-and-through guide wire and preventive distal renal artery selective cannulation.

In this cohort, the average infrarenal proximal neck angulation was 89.4 (range 70–122) and length was 18.4 (range 13–24). Two patients showed a very SNA (≥90°), one patient a short neck (<15 mm) associated with a 70° infrarenal neck angulation and another patient presented with a severe angulated, reversed conical and thrombosed proximal neck, but 24 mm in length. Table 1 reports the most significant aortic anatomical features of these patients.

Table 1.

Anatomical characteristics and early outcomes of the five patients with severe neck angulation (SNA) treated with the Gore Excluder Conformable Endograft.

Proximal neck	N (range/%)
• Diameter (mm)	25.8 (23–28)
• Length (mm)	18.4 (13–24)
• Angulation ≥ 60°	3 (70–85)
• Angulation ≥ 90°	2 (100°–122°)
• Conical shape	1 (20%)
• >50% calcification or thrombus	1 (20%)
Follow-up (months)	5.2 (1–11)
30-days outcomes
• Type IA endoleak	0 (–)
• Endograft migration	0 (–)
• Aneurysm-related secondary procedures	0 (–)
Early outcomes
• Type IA endoleak	0 (–)
• Endograft migration	0 (–)
• Aneurysm-related secondary procedures	0 (–)

Surgical technique

In relation to aortoiliac morphology and presence of SNA all patients were treated with the Gore Excluder Conformable device, combined with two particular technical tricks consisting of a routine through-and-through axillary–femoral approach with a floppy guidewire and selective preventive cannulation of the lower renal if a short proximal neck (≤15 mm) was associated. All procedures were performed by experienced vascular surgeons in a dedicated vascular operative room equipped with a mobile C-arm (Ziehm Imaging GmbH; Nuremberg, Germany); echo duplex scan (Esaote AU 5; Genova, Italy); and intravascular ultrasound (IVUS, Eagle Eye Gold; Volcano Therapeutics, Rancho Cordova, CA, USA). Under general anesthesia, a bilateral eco-guided percutaneous femoral artery access with pre-deployment of two 90° Proglide closure systems (the preclose technique) were performed, while a surgical or percutaneous left brachial approach was adopted according to the type of procedure and operators experience or preference.

In the case of preventive renal cannulation (proximal neck length ≤ 15 mm), an 8 Fr 70 cm introducer sheath (e.g., Flexor, Cook Medical Inc., Bloomington, IN) was advanced into abdominal aorta over the stiff 0.035-inch wire through a surgical brachial access, and 10 Fr sheaths were placed in right and left femoral artery. The 0.035-inch stiff wire was exchanged to a Terumo J-floppy wire, and then snared from the left femoral access, obtaining an axillary–femoral through-and-through wire. The distal renal artery was then cannulated from the brachial access through the 8 Fr sheath in a buddy wire approach, then a stiff wire (e.g., Rosen, Cook Medical Inc., Bloomington, IN) was left in place.

If renal cannulation was not performed (proximal neck length > 15 mm), a Terumo J-floppy wire was advanced in the thoracic aorta from a surgical or percutaneous left brachial access, over a 5 or 6 Fr introducer and a 5 Fr diagnostic catheter, and then snared from the femoral access obtaining the through-and-through axillary–femoral guide wire.

After diagnostic angiography, the main body was advanced into aorta above the lower renal artery ostium, over the through-and-through Terumo guidewire which was kept in tension (Figure 1(b)). At that point, the tension in the through-and-through wire was released and the Gore Excluder Conformable angulation system was activated to achieve the main body to conform to the aortic curvature, obtaining the ideal aortic neck–endograft alignment.

As usual in this kind of anatomy, stentgrafts experienced a slight distal migration during deployment. If a new deployment was necessary, devices were constrained and straightened, the through-and-through wire was put back in tension to advance the main body upward and then the graft redeployed just below the lowest renal artery, releasing tension in the through-and-through wire. Angiographic control through the axillary flexor sheath was usually performed at this time to check the correct position of the endograft just above the distal renal artery (Figure 2). After complete deployment of the contralateral leg, the conformable active angulation was retrieved and the main body device removed. During molding, the through-and-through wire was kept in tension to avoid distal graft migration. Final angiography was then performed to verify the correct position of the endograft and the absence of kinking and EL.

Figure 2.

Case 2. Angiographic control after device deployment revealed the correct position of the endograft just above the distal renal artery.

Surveillance

In presence of hostile anatomy or EVAR outside IFU, patients are elected for a specific follow-up protocol consisting of predischarge duplex scan, a CT angiogram at 1, 6, and 12 months and afterward an ultrasound examination every six months.

Study outcomes

Technical success was defined as the ability to adequately deploy the endograft in the intended position and complete the procedure without complications. Correct endograft positioning was defined as the deployment of the Gore Excluder endograft just below the most distal renal artery at the end of the procedure, independently of the redeployment maneuvers. Migration was defined as ≥5 mm device displacement on postoperatively CT scan.

The presence of EL and the need for secondary procedures was also recorded and defined according to standard criteria.⁶

Results

Technical success was achieved in all cases. In all patients, the device experienced a slight distal migration during deployment. Therefore, the grafts were constrained and straightened, the through-and-through wire was draw back in tension to move the device upward or downward and then the graft redeployed. Redeployment of the graft was necessary four times upward for distal migration above renal arteries and one time downward for accidental renal coverage although distal migration occurred. Final position of the stent graft was extremely precise in all cases, no final accidental coverage of a renal ostium was experienced and no aneurysm-related intraoperative adjunctive procedures needed.

Two intraoperative type I EL was recorded in the two patients with the worst infrarenal angle (100°; 122°). In both cases, final angiography confirmed regular patency of renal arteries but the presence of a type IA EL related to low apposition of the graft in the severe acute inner or outer curve between neck and the aneurismal sack. Endoleaks were successfully solved by angioplasty with a compliant balloon (Figure 3(a) and 3(b)). One type II EL was recorded at final angiography which was left untreated and is still under surveillance.

Figure 3.

(a) Case 2. Final angiography showed regular patency of renal arteries and type I endoleak related to low apposition of the graft in the severe acute inner curve between neck and aneurismal sack. (b): Case 2. Proximal type I endoleak was successfully excluded by post dilatation of the neck with a compliant balloon.

Other perioperative complications included a brachial surgical site hematoma which was treated conservatively. Median postoperative hospital stay was 2.8 days (range 2–4).

Table 1 reports 30 days and early outcomes of these patients. At 30 days, no type IA EL was recorded and no aneurysm-related secondary procedures were performed.

Median follow-up for this group of patients was 5.2 months (range 1–11). At the time of the study, only two patients completed a six-month follow-up and the CT scan confirmed complete exclusion of the aneurysmal sac (Figure 4). Early results revealed no migration, no type IA EL and no graft kinking. The two patients who experienced an intraoperative type I El showed resolution of the leak at one month and six months CT scan, respectively.

Figure 4.

Case 2. Six months CT scan confirmed the correct position of the endograft with no evidence of endoleak, regular patency of renal arteries, and complete exclusion of the aneurysm sac.

Discussion

Currently more than 75% of cases of AAA are treated by endovascular approach in European vascular centers.³ Up to 58% of them are treated outside IFU, mostly related to “hostile neck” anatomy.² Infrarenal aortic neck angulation is often associated with EVAR failure related to proximal EL and migration.^4,7,8 In the last years, new devices were put on the market with specific structural features to fit SNA. The Lombard Aorfix (Lombard Medical, Inc, Oxfordshire, United Kingdom) was developed to accommodate highly angulated aortic necks and was approved to treat proximal necks up to 90°.⁹,¹⁰ The Anaconda endovascular graft (Vascutek, Terumo, Inchinnan, Scotland) was designed with hypothetic zero body columnar strength and high flexibility and the IFU advised for infrarenal angulation <90°.¹¹ Finally, the Medtronic Endurant endograft (Medtronic cardiovascular, Santa Rosa, Calif, USA) has been described to conform well to challenging anatomies, with IFU including infrarenal angle up to 75° with a neck length more than 15 mm.¹²,¹³

To overcome the problem of proximal sealing in such anatomy, next generation endografts were developed to meet the requirement of actively conforming the proximal edge of the endograft to the arterial wall before final deployment. The Gore Excluder Conformable self-expanding endoprosthesis was built with individual stent rows and a unique stent-to-graft attachment on the trunk body that allow the device to adapt well to aortic infrarenal neck angulation. Thereafter, the Gore Active Angulation System (W. L. Gore & Associates, Flagstaff, Ariz) allows a perpendicular alignment of the endograft to the native aortic wall and flow lumen obtaining an accurate placement of the graft and maximizing its wall apposition.¹⁴ Treatment of a highly angulated neck (136°) in a quite long proximal aortic neck (23 mm) with the standard Gore Excluder device outside IFU was previously reported in literature.¹⁵ We believe that the association of high adaptability in tortuous anatomy of the standard graft, the conformable flexibility of the proximal end and the reposition system could be the ideal approach to SNA.

In our past experience, deployment of the Gore Excluder endograft in tortuous neck anatomy resulted in inability to reposition the graft upward once main body was partially released. Following the Gore IFU, before endograft release, the stiff support wire is exchanged for floppy wire in order to allow endograft to conform to the aortic curvature, which can additionally be improved using the endograft’s unique conformability mechanism. Most likely, as the endograft becomes fully conformed to aortic tortuosity, excessive friction generated between the graft and the aortic wall makes impossible to reposition it upward, even after stiff support wires are reintroduced. Authors think that in such anatomy the two aspects of the Gore active system (conformability and repositionability) are mutually exclusive of each other if a through-and-through guidewire is not in place. In our opinion, the routine usage of an axillary–femoral guide wire during Gore Conformable endograft deployment is crucial during multiple steps if facing very SNA. This simple maneuver facilitates endograft main body advancement in tortuous aortoiliac anatomies and at the same time, allows endograft to be repositioned once partially deployed and conformed, by closing the distal part of the graft, retrieving the angulation and putting back in tension the through-and-through wire. This maneuver moves the endograft toward the centerline, away from the aortic wall, thus reducing friction between the graft and aorta, allowing it to slide upwards or downwards. Finally, during post dilatation of proximal landing zone, the axillary–femoral guide wire provides a great support for a molding balloon avoiding risk of distal endograft migration.

In addition, deployment of the Gore Excluder Conformable main body endograft in very SNA (>75°) and short length neck (<15 mm) should be very aggressive with release of the graft starting over the level of renal arteries due to “risk” of distal migration with the proximal graft sitting down on the external curvature. Thereafter, if angulation is more than 90° and renal artery are the same level, a correct visualization of both is sometimes difficult to achieve at intraoperative angiography. Thus, deployment carries the risk of accidental renal artery coverage and further downward repositioning of the graft could be difficult. In this setting, we pre-cannulate the lower renal artery with a buddy wire technique from brachial access, allowing a precise infrarenal deployment as well as bailout strategies.

Now, our standard approach to very SNA (>75°) and short neck (<15 mm) with the Gore Conformable endograft consists of a routine through-and-through axillary–femoral Terumo floppy guidewire associated to preventive cannulation of the lower renal artery from a brachial access. Authors believe that in case of long necks (>15 mm) or less than 75° infrarenal neck angulation the through-and-through axillary–femoral guidewire should be performed avoiding renal artery cannulation for the lower risk of renal coverage.

Finally, authors suggest an oversize of almost 20% to optimize graft adaptability to inner or outer aortic wall curvature where the device could sometimes not achieve a perfect perpendicular release and cause a proximal EL. We have never experienced and had no evidence of gutters-related ELs possibly linked to a greater oversize at postoperative CT scan in such settings.

Conclusion

Presence of SNA affects outcomes in terms of EL and migration but currently new endografts are available on the market to fit this kind of anatomy and enlarge indication for EVAR.

The Gore Excluder Conformable device with its active angulation system could pre-curve the proximal segment of the endograft and adapt well to this kind of anatomy and should be considered a good option in these patients. Thereafter, the deployment of this graft in very SNA carries the risk of distal migration and renal artery coverage in case of aggressive suprarenal graft release. A routine through-and-through axillary–femoral guidewire associated with pre-cannulation of the lower renal artery allows a precise endograft deployment even in these difficult anatomies (angulated and short necks) and could preserve for bailout stenting, possibly affecting early outcomes.

A longer follow-up and further studies should confirm the promising results of this initial experience.

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

Ethical conduct of the study

No Institutional Review Board (IRB) approval was required for the present study.

Funding

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

ORCID iD

Sebastiano Tasselli

References

Sadat

Boyle

Walsh

, et al. Endovascular vs open repair of acute abdominal aortic aneurysms—a systematic review and meta-analysis. J Vasc Surg 2008; 48: 227–236.

Bryce

Kim

Katzen

, et al. Outcomes over time in patients with hostile neck anatomy undergoing endovascular repair of abdominal aortic aneurysm. J Vasc Interv Radiol 2018; 29: 1011–1016.

Marone

Freyrie

Ruotolo

, et al. Expert opinion on hostile neck definition in endovascular treatment of abdominal aortic aneurysms (a Delphy consensus). Ann Vasc Surg 2019; 6: In press.

Hobo

Kievit

Leurs

, et al. EUROSTAR Collaborators. Influence of severe infrarenal aortic neck angulation on complications at the proximal neck following endovascular AAA repair: a EUROSTAR study. J Endovasc Ther 2007; 14: 1–11.

Chaikof EL Fillinger

Matsumara

, et al. Identifying and grading factors that modify the outcome of endovascular aortic aneurysm repair. J Vasc Surg 2002; 35: 1061–1066.

Chaikof

Blankenstein

Harris

, et al. Reporting standards for endovascular aortic aneurysm repair. J Vasc Surg 2002; 35: 1048–1060.

Dillavou

Muluk

Rhee

, et al. Does hostile neck anatomy preclude successful endovascular aortic aneurysm repair?. J Vasc Surg 2003; 38: 657–663.

Bastos Goncalves

de Vries

van Keulen

, et al. Severe proximal aneurysm neck angulation: early results using the Endurant stentgraft system. Eur J Vasc Endovasc Surg 2011; 41: 193–200.

McGillicuddy

Fillinger

Robinson

3rd , et al. Lombard Aorfix high angulation device, sac behavior following implantation. J Vasc Surg 2017; 66: 71–78.

10.

Instructions For Use Aorfix™ AAA Flexible Stent Graft System and Aorfix™Plus AAA Flexible Stent Graft System, http://usa.lombardmedical.com/files/ifu_pn02114_issue_c.pdf

11.

Vascutek, Terumo company Anaconda AAA Stent Graft System. Instructions for USE, http://www.vascutek.Com/site/assets/files/1586/301130_2_anaconda_full_language_ifu-1.pdf (accessed 21 May 2010).

12.

Matsagkas

Kouvelos

Peroulis

, et al. Standard endovascular treatment of abdominal aortic aneurysms in patients with very short proximal neck using the Endurant stent graft. J Vasc Surg 2015; 61: 9–15.

13.

Torsello

Troisi

Donas

, et al. Evaluation of the Endurant stent graft under instructions for use vs off-label conditions for endovascular aortic aneurysm repair. J Vasc Surg 2011; 54: 300–306.

14.

Rhee

Peterson

Moore

, et al. Initial human experience with the Gore Excluder Conformable AAA endoprosthesis. J Vasc Surg Cases Innovat Techniq 2019; 5: 319–322.

15.

Zeng

Huang

, et al. Endovascular repair of abdominal aortic aneurysm with severely angulated neck and tortuous artery access: case report and literature review. BMC Surg 2015; 15: 20.