EVAR has been widely used as an alternative to open repair for patients with AAA since it was first reported by Parodi in 1991 [10]. However, unfavorable morphology of aneurysm especially hostile proximal neck has restricted the widespread application of EVAR. In a meta-analysis, hostile neck was defined as conditions that were not suitable for use of engdograft devices employed in the selected studies, which included anatomical factors such as neck length <15 mm, infrarenal neck angulation > 60°and neck calcification or thrombus covering > 50% circumference of aortic diameter and a reverse taper morphology [11]. Interestingly, growing recent studies showed feasibility and safety of EVAR in patients with hostile neck, but the anatomical indications of outside EVAR instruction for use (“off-label use”) reach no common consent [4,12,13]. Given the need of intervention and patient’s refusal to open surgery, an endovascular approach was performed despite severely angulated neck and hostile artery access in our case.
Disputes still exist in the efficacy of EVAR in patients with hostile neck. Stather et al. reported a largest study to date investigating the effects of neck angulation, neck diameter, neck flare, and neck thrombus on outcomes following EVAR, and contained the mean follow-up 4.1 years. They came to the conclusion that hostile neck anatomy could be successfully treated with EVAR. However, surveillance was necessary to detect and treated late type I endoleaks in hostile neck patients [3]. Antoniou et al. systemically reviewed the studies compared the outcomes of EVAR in patients with hostile and friendly neck anatomy. They found that although patients with hostile neck had no significant increased early incidence of type I endoleak and re-intervention rates, EVAR in patients with hostile neck required more adjunctive procedures to achieve proximal seal compared to the patients with friendly anatomy. Furthermore it resulted in a twofold increased risk of 30-day morbidity, a fourfold increased risk of type I endoleak and a ninefold increased risk of aneurysm-related mortality within 1-year follow-up. They finally suggested that EVAR should be cautiously used in patients with hostile neck [11]. The evidences from European Collaborators on Stent-Graft Technique for aortic aneurysm repair database demonstrated a significantly higher incidences of proximal neck dilation, proximal endoleaks and need for secondary interventions in patients with severe (>60°) infrarenal angulation [14]. But a morphological study about remodeling of proximal neck angulations of AAA after EVAR showed a larger angulation reduction and a smaller diameter shrinkage of AAAs with a neck angulation >60° in a mid-term follow-up, and concluded that proximal neck angulation was not a major issue in AAAs with adequate proximal neck length [15].
We performed EVAR in this complex case despite failed attempt at an outside hospital. Short-term outcome was satisfactory without endoleaks or stent-graft migration. Occlusion of the internal iliac artery (IIA) during AAA repair has been associated with buttock claudication, impotence, colon ischemia and pelvic necrosis [16]. But with regard to aneurysmal dilation and severe calcification of bilateral iliac arteries in this case, bilateral IIAs occlusion was considered in order to reduce the potential risk of endoleaks and future rupture. Pavlidis et al. reported that buttock claudication was a frequent complication after interventional occlusion of internal iliac artery, which often persisted during follow-up [17]. Alternatives such as iliac side-branched graft or sandwich technique maintained pelvic perfusion should be considered. However, these adjunctive procedures inevitably increase the risk of endoleaks and technical difficulties, especially under local anesthesia. Fortunately, we didn’t find significant complications in this case during follow-up, otherwise open repair maintained perfusion to IIA would be suggested.
As far as we know, no data exist on direct comparison of the performance of different stent-graft type in EVAR for AAA, and optimal selection of stent-graft type in hostile neck remains unclear [9]. A retrospective review of patients undergoing EVAR with unfavorable neck anatomy using the C3 Excluder repostitionable stent-graft demonstrated favorable short-term results and significantly reduced the need for proximal extension cuffs [18]. Bastos et al. also reported satisfactory early results using the Endurant stent-graft system in severe proximal neck angulation and no sealing length was lost in extremely angulated cases, confirming the device’s high conformability [19]. In addition, Perdikides et al. and Albertini et al. reported that endovascular repair using a flexible Aorfix stent-graft was feasible in patients with highly angulated necks and mid-term results were acceptable [12,20]. Considering first failure of EVAR with Endurant graft-stent from left access, we decided to use another flexible Excluder stent-graft from right access in this difficult case. Highly conformable devices (such as the Excluder) can adapt to the underlying anatomy, and reduce the displacement forces on the graft and avoid the gaps that originate type I endoleaks. Intraoperative angiography and 6 months follow-up CTA demonstrated a complete sealing of AAA without stent-graft endoleaks and migration, but life-long follow up is still needed.
Beside hostile proximal neck anatomy, challenging artery access conditions such as small-caliber vessels, iliac tortuosity, excessive calcification and occlusive diseases, represent the second most common excluding factor for EVAR [8]. Technical developments including downsizing lower profiles, improved flexibility of the stent grafts and wire techniques (stretch guidewire technique and buddy wire technique) expanded the application of EVAR. In this case, tortuous aorta and aortoiliac access made the insertion of the stent-graft delivery system very difficultly and the wire access to left iliac limb was unable to be obtained through the routine access from femoral artery. Therefore, we proposed a snare to create wire access from right radial artery to left femoral artery which ensured left iliac leg through tortuous anatomy, thus decreasing procedural time and radiation exposure. Of course, several other maneuvers might be adopted in this particular situation. Buddy wire technique can straighten iliac artery and provide support to facilitate stent-graft deployment but should be cautiously used for severe calcified artery. Balloon-assisted technique can better anchor the wire while advancing the sheath through the tortuous path which eased guidewire engagement [21]. However, the balloon blocking the aorta in the technique brings greater circulation disturbance and higher risk of visceral ischemia.
