Preliminary results of adjunctive use of endoanchors in the treatment of short neck and pararenal abdominal aortic aneurysms

The Impact of Heli-FX EndoAnchor Application on Endograft Material: An Experimental Study

Objective

The physical impact of the application of Heli-FX EndoAnchors (EA; Medtronic, Minneapolis, USA) on endograft (EG) material is unclear. This study aimed to examine the possible EG membrane alterations after EA implantation.

Methods

Heli-FX EndoAnchors were applied in vitro into four aortic endocuffs: AFX2 (Endologix Inc., Irvine, USA); Endurant II (Medtronic, Minneapolis, USA); Gore Excluder (W.L. Gore and Assoc., Flagstaff, USA); and Zenith Renu (Cook Aortic Interventions, Bloomington, USA). Two of these, Endurant II and Renu, are made of polyethylene terephthalate (PET), while Excluder and AFX2 are made of expanded polytetrafluoroethylene (ePTFE). The penetration angle was measured for each EA. The EAs were then carefully removed, and perforations examined with digital and fluorescent microscopy. The area and perimeter of the holes were digitally calculated, and material alterations were analysed.

Results

Of the 13 EAs applied, 12 remained in place. The mean penetration angle was 79°. The ePTFE perforations had oval openings, while PET perforations were round. After EA removal, comparisons between ePTFE and PET material perforations suggested a larger hole area (p = 0.011) and perimeter (p = 0.003) in the former. The ePTFE perforations in the AFX2 were the largest compared with the holes in other endocuffs (p = 0.050). The perforation channel of the ePTFE membrane of the Excluder cuff retained its form after EA removal. Local dissection like layer damage extended further. The perforations in both the Endurant II and the Renu endocuffs shared similar characteristics, with multiple fibres of PET elongated, distorted, or ruptured.

Conclusion

During EA placement, the EG membrane undergoes local alteration and or destruction. Expanded PTFE, particularly AFX2 endocuffs (for which EA use is not recommended), are characterised by a more extensive degree of material alteration compared with PET. Additional studies are required to chronologically supplement these findings in fatigue tests.

Endograft platform does not influence aortic neck dilatation after infrarenal endovascular aneurysm repair with primary endostapling

OBJECTIVES

Aortic endografts used for endovascular aneurysm repair (EVAR) are based on varying skeletal platforms such as stainless steel or nitinol stents, using radial force applied to seal at the aneurysm neck, and varying proximal fixation methods, applying either suprarenal or infrarenal fixation. This study assesses whether varying skeleton/fixation platforms affect neck-related outcomes after primary endostapling with Heli-FX EndoAnchors at EVAR.

METHODS

Retrospective analysis of a prospective database of infrarenal EVAR undertaken at a single centre. Chimney-EVAR, secondary cases were excluded. Primary outcomes analysed included neck diameter evolution from pre-EVAR to latest imaging follow-up, including a comparison of stent platforms to see if there was any outcome difference between those using stainless steel or nitinol, as also freedom from type I endoleakage and migration. Secondary outcomes assessed included average number of EndoAnchors, and sac size patterns before and after EVAR.

RESULTS

A total of 101 patients underwent endostapled infrarenal EVAR between September 2013 and March 2020. After exclusion of ineligible patients, 84 patients (76 male, 8 female, age 73.7 ± 7.8 years) were available for analysis. 57/27 endografts used suprarenal/infrarenal fixation, whilst 16/68 devices were based on stainless steel/nitinol platforms, respectively. Mean oversizing was higher for stainless steel/suprarenal fixation endografts (p = 0.02). A total of 582 EndoAnchors were deployed, averaging 7 ± 2 per patient. Median neck diameter was 25 mm (IQR 22-31) with 22 necks having non-parallel morphology (conical, tapered or bubble). Median follow-up period was 28.5 (IQR 12-43) months. Neck evolution studies suggested aortic neck dilatation of 5 ± 4 mm (p <0.001, paired T-test), independent of platforms employed (p = NS, ANOVA). There was no endograft migration; one immediate post-EVAR endoleak settled by eight weeks. There was a mean 5.7 ± 8.2 mm sac size reduction (p < 0.001, paired T-test).

CONCLUSION

Aortic neck dilatation occurs after EVAR with primary endostapling, but the process may be independent of stainless steel/nitinol platforms, possibly due to the attenuating effect of EndoAnchors. Adjunct aneurysm neck fixation by primary endostapling prevents migration regardless of whether suprarenal/infrarenal fixation is the primary fixative method. Device platform choice therefore may be left to the operator discretion if primary endostapling is applied at EVAR. Freedom from complications such as migration and endoleakage in the intermediate term suggests a higher level of 'tolerance' to aortic neck dilatation with primary endostapling. We would therefore suggest routine usage of EndoAnchors at EVAR when not otherwise contraindicated.

Anthropomorphic and biomechanical mockup for abdominal aortic aneurysm

Abdominal aortic aneurysm (AAA) is an asymptomatic condition due to the dilation of abdominal aorta along with progressive wall degeneration, where rupture of AAA is life-threatening. Failures of AAA endovascular repair (EVAR) reflect our inadequate knowledge about the complex interaction between the aortic wall and medical devices. In this regard, we are presenting a hydrogel-based anthropomorphic mockup (AMM) to better understand the biomechanical constraints during EVAR. By adjusting the cryogenic treatments, we tailored the hydrogel to mimic the mechanical behavior of human AAA wall, thrombus and abdominal fat. A specific molding sequence and a pressurizing system were designed to reproduce the geometrical and diseased characteristics of AAA. A mechanically, anatomically and pathologically realistic AMM for AAA was developed for the first time, EVAR experiments were then performed with and without the surrounding fat. Substantial displacements of the aortic centerlines and vessel expansion were observed in the case without surrounding fat, revealing an essential framework created by the surrounding fat to account for the interactions with medical devices. In conclusion, the importance to consider surrounding tissue for the global deformation of AAA during EVAR was highlighted. Furthermore, potential use of this AMM for medical training was also suggested.

[New developements in endovascular infrarenal aortic aneurysm treatment]

CLINICAL/METHODICAL ISSUE

New technical developments in endovascular aortic repair (EVAR) have broadened the range of patients eligible for minimally invasive aneurysm treatment. Optimization of delivery sheaths and catheters by considerable downsizing of diameters, increase of pushability and stability combined with flexibility are important parameters.

PERFORMANCE

Especially patients characterized by small and tortuous iliac access vessels can nowadays be treated by EVAR. Ease and effectiveness of applicability guarantee safety and quality improvement, which results in better treatment of patients. Progress in stent-graft design with integrated options for repositioning, active positioning and aneurysm sealing facilitate treatment of angulated vessel segments or hitherto unsuitable sealing zones.

PRACTICAL RECOMMENDATIONS

Interventionalists have to be familiar with all available stent-graft materials and techniques. Profound knowledge helps to choose the best material for a patient's individual anatomy, confident application and long-term satisfactory results.

Treatment of type 1A endoleak using coil embolization: a case report

In a type 1A endoleak, the endograft is unable to fully seal the proximal aneurysm neck and blood flow leaks between the wall of the aortic neck and the graft material. This article reports a case in which coil embolization was used and presents a literature review (PubMed, LILACS, and SciELO). Searches were run for articles published in the past 5 years using the descriptors “endoleak 1A”, “coil embolization,” and “treatment”. Type 1A endoleak occurs in 1.1% of patients within 30 days of graft placement. Treatment of an endoleak is obligatory and usually consists of sealing the proximal graft neck using stents and balloons to expand the landing zone or to increase the radial force of the graft. Some studies have suggested using embolization techniques with cyanoacrylate, fibrin glue, and Onyx, demonstrating success rates that exceed 97%. However, correction of type 1A endoleak using coil embolization has seldom been described.

The use of EndoAnchors in endovascular repair of abdominal aortic aneurysms with challenging proximal neck: Single-centre experience

Objectives

The aim of this study was to present a single-centre experience with EndoAnchors in patients who underwent endovascular repair for abdominal aortic aneurysms with challenging proximal neck, both in the prevention and treatment of endograft migration and type Ia endoleaks.

Methods

We retrospectively analysed 17 consecutive patients treated with EndoAnchors between June 2015 and May 2018 at our institution. EndoAnchors were applied during the initial endovascular aneurysm repair procedure (primary implant) to prevent proximal neck complications in difficult anatomies (nine patients), and in the follow-up after aneurysm exclusion (secondary implant) to correct type Ia endoleak and/or stent-graft migration (eight patients).

Results

Mean time for anchors implant was 23 min (range 12–41), with a mean of 5 EndoAnchors deployed per patient. Six patients in the secondary implant group required a proximal cuff due to stent-graft migration ≥10 mm. Technical success was achieved in all cases, with no complications related to deployment of the anchors. At a median follow-up of 13 months (range 4–39, interquartile range 9–20), there were no aneurysm-related deaths or aneurysm ruptures, and all patients were free from reinterventions. CT-scan surveillance showed no evidence of type Ia endoleak, anchors dislodgement or stent-graft migration, with a mean reduction of aneurysm diameter of 0.4 mm (range 0–19); there was no sac growth or aortic neck enlargement in any case.

Conclusions

EndoAnchors can be safely used in the prevention and treatment of type Ia endoleaks in patients with challenging aortic necks, with good results in terms of sac exclusion and diameter reduction in the mid-term follow-up.

Safety of EndoAnchors in real-world use: A report from the Manufacturer and User Facility Device Experience database

Objectives

A hostile proximal neck anatomy is the most common cause of abdominal aorta endovascular aneurysm repair failure leading to a higher risk of device migration, proximal type I endoleak, and subsequent open surgical repair. Endostapling is a technique to attain better fixation of the endograft to the aortic wall, and the only available device in the USA is Aptus Heli-FX EndoAnchor system (Medtronic Vascular, Santa Rosa, CA, USA). Preliminary data have shown efficacy and safety of its use, and the aim of this study is to assess device-related adverse events in real-world clinical use.

Methods

We quarried data from the publicly available Manufacturer and User Facility Device Experience database to identify Aptus Heli-FX EndoAnchor system-related adverse reports in endovascular aneurysm repair since FDA approval till August 31, 2017. An estimate of total devices implanted in the United States was quoted around 7,000 (Medtronic marketing internal data).

Results

Our query identified 229 separate reports, of which there were 85 adverse events (1.2% of the estimated EndoAnchor systems used). The most common adverse events were device dislodgement/fracture (65) and applicator malfunction (20).

Conclusion

In early post-FDA approval use in a real-world setting, the EndoAnchor system is associated with a low rate of adverse events. Device dislodgement and embolization remain the most common adverse events. With increasing use of these devices in more difficult anatomy, careful patient selection and careful attention to technique may help to reduce these events even further.

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

PURPOSE

To review midterm clinical outcomes of EndoAnchor placement during or after endovascular aneurysm repair (EVAR) or chimney EVAR (ch-EVAR).

MATERIALS AND METHODS

A retrospective analysis was conducted of 51 consecutive patients [median age 75 years; 38 men] who underwent EVAR/ch-EVAR with EndoAnchor placement between June 2010 and December 2016 to prevent seal failures (31, 61%) or to treat type Ia endoleak and/or migration (20, 39%). Median aortic neck diameter was 27.7 mm and median neck length was 9.0 mm. Thirty-three (65%) had a conical neck; 48 (94%) had at least 1 hostile neck characteristic. Thirty-two (63%) patients had severe comorbidities (ASA score ⩾III). Eight patients had a single ch-EVAR procedure. Baseline patient characteristics, anatomic variables, procedure details, early and late complications, reinterventions, and aneurysm-related and all-cause mortality rates were recorded. Follow-up imaging was performed with computed tomography angiography (CTA) or duplex ultrasonography.

RESULTS

Median procedure time was 100 minutes; a median of 6 EndoAnchors were implanted. There were 10 (10%) residual type Ia endoleaks at the end of the procedure; 9 had resolved by the first postoperative CTA. One residual and 2 new type Ia endoleaks were identified at the first postoperative imaging. Median follow-up for the entire cohort was 24.0 months, during which 3 new type Ia endoleaks were identified. Five of the 6 type Ia endoleaks were treated, 1 resolved spontaneously. There was 1 endograft limb occlusion without clinical consequences, 1 chimney graft occlusion without possibilities for a reintervention, 1 rupture after type IV endoleak (a Nellix device was successfully deployed within the main device), and 1 complete graft explantation for infection. There was no new-onset hemodialysis. Kaplan-Meier estimates of freedom from type Ia endoleak, proximal neck-related reinterventions, and aneurysm-related mortality at 2 years were 87.3%, 92.2%, and 94.0%, respectively.

CONCLUSION

EndoAnchors are helpful in the endovascular treatment of unfavorable proximal aortic necks, with fair midterm results.

Outcomes of using endovascular aneurysm repair with active fixation in complex aneurysm morphology

OBJECTIVE

The ideal treatment option for patients with complex aneurysm morphology remains highly debated. The aim of this study was to investigate the impact of endovascular aneurysm repair (EVAR) with active fixation on outcomes in patients with complex aneurysm morphology.

METHODS

There were 340 consecutive patients who underwent EVAR using active fixation devices, 234 with active infrarenal fixation (AIF; Gore Excluder; W. L. Gore & Associates, Flagstaff, Ariz) and 106 with active suprarenal fixation (ASF; 85 Medtronic Endurant [Medtronic, Santa Rosa, Calif] and 21 Cook Zenith [Cook Medical, Bloomington, Ind]). Demographics, comorbidities, anatomic features, and outcomes were analyzed for patients receiving devices with active fixation. Outcomes of using active fixation in necks with <15-mm neck lengths, >60-degree infrarenal neck angle (β), >30-mm infrarenal neck diameter, severe aortic neck calcification or thrombus, and nonstraight neck morphology were evaluated.

RESULTS

Of the 340 patients, 106 (78 men; mean age, 74.5 ± 9.3 years at the time of surgery) received implants with ASF and 234 (191 men; mean age, 74.6 ± 8.9 years at the time of surgery) received implants with AIF. In comparing AIF and ASF devices, patients in the suprarenal fixation group had significantly shorter follow-up time (25 ± 17 months vs 44.3 ± 32 months; P < .0001). Patients in the ASF group had shorter aortic neck lengths (25.5 ± 15.1 mm vs 28.6 ± 14.9 mm; P = NS) and significantly larger infrarenal neck diameters (25.9 ± 6.3 mm vs 23.4 ± 3.2 mm; P < .0001) and aneurysm diameters (59.9 ± 11.6 mm v. 55.9 ± 10.0 mm; P = .002). Outcomes were similar between groups, with no significant differences in reintervention, proximal endoleak, sac growth, abdominal aortic aneurysm-related death, or rupture. Of the complex anatomic neck features investigated, neck diameter >30 mm and nonstraight neck morphology had the highest rates of reintervention in ASF devices.

CONCLUSIONS

In cases of hostile infrarenal neck morphology, ASF appears to be used more frequently. Our data suggest that ASF may be useful for certain patients but may be unfavorable for others, such as those with wide necks or several difficult neck features. Nevertheless, further research is needed to evaluate more optimal treatment options, such as fenestrated EVAR, branched EVAR, and endovascular adjuncts such as EndoAnchors (Aptus Endosystems, Sunnyvale, Calif), in dealing with high-risk anatomic characteristics that may not be optimally managed with standard EVAR devices with active fixation.

Infrarenal endovascular aneurysm repair: New developments and decision making in 2016

New developments in infrarenal abdominal aortic aneurysm stent-graft devices have made more patients eligible for endovascular aneurysm repair (EVAR). Recent US Food and Drug Administration approval for fenestrated endograft repair and impending approval for iliac branch devices extend the proximal and distal landing zones. Better deployment systems allow for partial deployment of endografts to facilitate repositioning, and more flexible designs allow for treatment of angulated infrarenal aneurysm necks and tortuous iliac arteries. New iterations of endografts have smaller delivery catheter diameters, which facilitate traversal of smaller access vessels. Long-term outcomes data are still accumulating and it remains to be seen whether EVAR for this expanded-indication abdominal aortic aneurysms anatomy has the same durability as standard EVAR. More options for repair also mean vascular surgeons must select the best EVAR device based on each patient's abdominal aortic aneurysm anatomy.