Endoanchor Deployment

The Heli-FX EndoAnchor System (Medtronic Endovascular, Santa Rosa, California, USA) consists of the helical anchors, the EndoAnchor implant (supplied in a cassette containing 10 EndoAnchors), the Heli-FX Applier (a catheter-based device for placement of the EndoAnchor), and the Heli-FX Guide (a deflectable sheath to position the Applier). The system is designed to attach an endograft to the aortic wall by endovascularly placed screws. The EndoAnchors are manufactured from medical-grade nickel-cobalt wire in a helical shape. The leading end is sharpened to a conical point to act as an integral needle, facilitating atraumatic but adequate deployment through the endograft into the vessel wall up to the media, without penetrating the adventitia.

The Heli-FX Applier implants one EndoAnchor at a time using a motorized, two-stage deployment mechanism with reposition ability. It can be used to implant multiple EndoAnchors in a single patient. The Heli-FX Applier is a 12-French (l2F) (outer diameter [OD]) catheter with an integrated control handle.

The Heli-FX Guide is a sterile, single-use, disposable device designed to direct the Heli-FX Applier to the desired location for EndoAnchor implantation. The guide has a high degree of fluoroscopic visibility. The device is compatible with a 0.035-inch guidewire. The Heli-FX Guide consists of a 12F-compatible (inner diameter [ID]) guide sheath with integrated control handle and a matching obturator. Deflection of the distal tip of the catheter is accomplished by rotating the control knob located on the control handle. The Heli-FX Guide is available in both 62-cm (low-profile l6F OD) and 90-cm (l8F OD) working lengths. Multiple deflectable tip lengths are available to accommodate a range of aortic diameters.

Indications

According to the instructions for use, the Heli-FX EndoAnchor system is intended for use where augmented radial fixation or endograft sealing is required to maintain (prophylactic) or regain (therapeutic) adequate aneurysm exclusion. Furthermore, this system is intended to treat type Ia endoleaks at the initial implantation or in late-onset cases where sealing has been lost because of proximal neck expansion, device deficiencies (e.g., fracture of suprarenal stent supporting structures), or other problems that result in loss of adequate sealing. When loss of seal is accompanied by endograft migration, EndoAnchors must be used in conjunction with aortic extension cuffs to restore sealing to the renal artery level.

Initial Experience (Staple Trials)

In a 2009 prospective, single-arm study (STAPLE-1), 21 patients enrolled at five U.S. centers received 96 EndoAnchors (range, 2-10; median, 4). All patients completed 1-month and 6-month follow-up evaluation, and 14 had 1-year follow-up. Two proximal cuffs were used as adjunctive endograft components at implantation. No further interventions in the proximal aortic neck were performed during the follow-up. Preliminary results of the STAPLE-1 trial demonstrated excellent 6-month and 1-year results.

In 2012, Mehta et al. reported the 24-month outcomes of the STAPLE-2 study of 155 patients; 147 and 121 patients completed 1-year and 2-year follow-up, respectively. A total of 810 EndoAnchors were implanted (median, 5/patient) in conjunction with the Aptus endograft, a device designed without an inherent fixation mechanism, instead relying on EndoAnchors to maintain stability. There were no late type I or III endoleaks. Two cases of migration were observed at the 2-year follow-up, both caused by neck elongation, without actual movement of the endograft from its level of original deployment, and no evidence of graft or staple dislocation, type I endoleak, or reintervention. The authors concluded that the STAPLE-2 trial successfully met the endpoints of safety and efficacy, with aneurysm sac regression in many patients and few reinterventions during the 2-year follow-up. The 3-year outcomes of the STAPLE-2 trial confirmed persistently low rates of type Ia and III endoleaks and reintervention.

Anchor Trial

The Aneurysm Treatment Using the Heli-FX Aortic Securement System Global Registry (ANCHOR) trial is a multinational registry of EndoAnchor use in a variety of endografts, for prophylaxis against proximal neck problems in patients with hostile aortic neck anatomy, or as therapy when type Ia endoleak or endograft migration occurs. The preliminary 1-month outcomes of the ANCHOR trial reported in 2013 involved 149 patients at 23 U.S. and four European centers over 15 months. The most common indication for EndoAnchor use was a hostile neck in primary procedures (88%) and existing type Ia endoleak in redo procedures (76%). Procedural success was 99% (109 of 110 patients) in primary procedures and 92% (35/38) in redo procedures. Absence of type Ia endoleak was reported in 97% (96/99) and 89% (32/36) of patients, respectively, at 1 month.

In 2014 the early outcomes of the ANCHOR trial were reported. Over a 2-year period, 319 patients were enrolled at 43 sites in the United States and Europe. The study included 242 patients undergoing first-time EVAR (primary arm) and 77 patients with proximal neck complications remote from the initial endograft implantation (revision arm). Over a median imaging follow-up of 7 months, 183 of 202 patients (90.1%) remained free of type Ia endoleaks. The authors concluded that EndoAnchor implantation can be a useful adjunct to EVAR as prophylaxis against proximal attachment site complications in patients with hostile aortic neck anatomy or endograft migration. The most challenging patients, however, presented with type Ia endoleaks remote from initial EVAR; success rates were substantially lower in this group.

Outcomes over longer follow-up were reported in late 2014. Jordan et al. found freedom from secondary procedures in 94.4% of patients (301/319) over mean follow-up of 9.3 months. Among the 18 secondary procedures, eight were performed for residual type Ia endoleaks, and the others were unrelated to EndoAnchors. Use of EndoAnchors to treat existing (late) and acute (at initial endograft implantation) type Ia endoleaks was successful in most cases. Even prophylactic use of EndoAnchors in patients with hostile aortic neck anatomy appeared promising, but robust conclusions must await long-term follow-up data.

The 14-month follow-up outcomes of the ANCHOR trial were reported in 2015. Among 130 of 208 patients with postprocedure computed tomography angiography (CTA), core laboratory analysis identified two patients (1.5%) with persistent type Ia endoleaks. Jordan et al. concluded that prophylactic EndoAnchor use for challenging aortic neck anatomy was associated with satisfactory midterm results.