Although EVAR has been performed since 1990s , anatomical factors such as unfavorable neck due to angulation, morphology, or calcification are still a challenge for vascular surgeons . In this case, the hostile neck and the tortuous iliac artery made her unfavorable for EVAR. However, in consideration of the need of rapid intervention and a rather older age, an endovascular approach was performed.
EVAR in patients with hostile neck anatomy
Argues exist in the efficacy of EVAR in patients with hostile neck anatomy. Hostile neck was defined as conditions that were not consistent with the instructions for use of endograft devices employed in the selected studies. In one study, the neck length < 15 mm, neck angulation > 60 degrees and proximal neck thrombus or calcification covering > 50% circumference of the aortic diameter and a reverse taper morphology were considered as hostile neck anatomy . The meta-analysis enrolled seven studies compared the outcomes of EVAR in patients with hostile and friendly neck anatomy. They found that, in technically, patients with hostile anatomy required an increased number of adjunctive procedures to achieve proximal seal compared with friendly ones. The immediate and early outcome showed that although no significant differences in the incidence of type I endoleak and reintervention rates within 30 days of treatment was identified between the EVAR and open surgery groups, patients with unfavorable neck anatomy suffered from higher risk of 30-day morbidity (OR, 2.278; 95% CI, 1.025-5.063). In the one year follow up, higher risk of type I endoleak and aneurysm-related mortality were noticed in hostile anatomy patients and a nine fold increased risk of aneurysm-related mortality within 1 year of treatment. They came to the conclusion that EVAR should be used cautiously in patients with hostile neck anatomy . The data from European Collaborators on Stent-Graft Techniques for Aortic Aneurysm Repair database showed a significantly increased risk of proximal endoleaks at short-term and medium-term follow-up after EVAR in patients with short (< 15 mm) proximal neck. Severe (> 60 degrees) infrarenal aortic neck angulation was found to be associated with higher incidences of proximal neck dilation, proximal type I endoleak, and need for secondary interventions [5, 6]. Stather et al. systemically reviewed the outcomes following EVAR in patients with hostile neck anatomy (HNA) and those with favorable neck anatomy, they suggested that EVAR in patients with HNA may accompanied with increased technical difficulty and a worse short-term outcomes. Besides, they found higher rates of early and late type I endoleaks, along with secondary interventions in HNA patients and recommended that increased monitoring should be performed in these patients .
In this case, we performed EVAR despite the unfavorable hostile neck with a 90° angle and the severely tortuous iliac artery. Additional cuff was placed so as to avoid the type Ib endoleak after deploying of two iliac legs above the right iliac artery. It has been very difficult to finish this complex procedure in such a tortuous iliac artery.
The balloon-assisted technique designed here provided efficient positioning of the stiff wire, which stablly facilitated the advancement of the guide wire. This approach has been used when advancing a sheath hindered by a tortuous or angulated course. Prieto et al. described a similar balloon-assisted technique using a balloon inflated in a distal pulmonary artery branch to better anchor the wire while advancing the sheath through a tortuous anatomy . Peeling et al. reported their experience of balloon-assisted technique to overcome extreme tortuous cervical carotid. They found that hypercompliant balloon catheters can be reliably used to facilitate safe and rapid distal positioning of guiding catheters beyond severe cervical tortuosity . This technique enabled us efficiently advance guidewire through the unfriendly anatomy, thus decreasing operation time and radiation exposure. Meanwhile, this could also help us to avoid undesirable injuries to vessels when toughly introducing the stiff sheath. Of course, besides the strategy we used, several other maneuvers might be adopted in that particular situation. For examples, we could catch the wire by snares through a brachial artery puncture. In addition, the wire could also be fixed through the two directions of brachial artery and humeral artery. However, the risk of aortic dissection was accordingly increased. Because the elderly patient usually accompanied with a tortuous aorta or angulated artery of distal part from subclavian artery, it is probable to damage the initial part of descending aorta when fixing the wire.
Despite the rising prevalence of endoleak with the increasing number of EVAR, endoleak management continues to be a challenge . In this particular case, additional cuff was deployed after the implantation of aortic main body and two iliac legs in order to avoid the Ib endoleak. Besides, a severe Ia endoleak was noted intraoperatively, therefore we deployed another cuff distal to the opening of the left renal artery to seal the endoleak. It was reported that the more unfavorable an AAA neck anatomy is the higher incidence of complications such as endoleak is accompanied with . Fortunately, the use of off-the-shelf technique for endoleak management has been proven to be reliable [8, 15]. For example, Perdikides et al.  reported 13 AAA patients with unfavorable neck performing EVAR, two proximal Ia endoleaks were detected after completion angiography, and a cuff was deployed in one of them which successfully sealed the endoleak. Although no endoleak was found after 3 months follow up in this case, life-long follow up is still needed.
Advancing sheath through such an unfavorable anatomy can be a challenge to even the most experienced interventionalist. During EVAR procedure, we tried to advance the catheter into the common iliac artery, but this proved very difficult because the severely tortuous right iliac artery resulting in repeated kinking of the catheter. Therefore, we proposed a balloon-assisted technique that better anchored the wire while advancing the sheath through the tortuous path which eased guidewire engagement. The balloon supported and guided the stiff wire by temporarily obstructing the aorta. With the balloon inflated and anchored distally, stiff wire could successfully pass through the angulated artery while maintaining distal wire position. Once the sheath is advanced across the unfavorable anatomy, the distal “anchoring balloon” was deflated and withdrawn over the guidewire without loss of wire position.
EVAR in ruptured AAA
Multiple reports have showed that EVAR for rAAA has become accepted as a viable treatment. In a recent retrospective observational study involving 338278 patients, Schermerhorn et al.  demonstrated that a reduction in overall rupture repair mortality was noticed after the introduction of EVAR for both ruptured and intact AAA. Another study from Mehta reported a single-center experience comparing EVAR and open surgery for rAAA. Over a 9-year period, EVAR was performed in 120 patients and open surgery in 163 patients. The 30-day mortality for EVAR was 24.2% while a 44.2% for open surgery (P < 0.005). Furthermore, 5-year survival was better in the EVAR group (37 vs 26%, P < 0.005). The data also showed a shift of clinical practice principle in the treatment of rAAA . Mayer et al.  examined all rAAA at two large European institutions, and found a statistical decrease in mortality of patients undergoing EVAR for rAAA compared to open surgery. Interestingly, there were differences in the analysis based on whether patients undergoing EVAR needed further abdominal decompression for compartment syndrome. Increased mortality was found in patients do not need abdominal decompression in comparison with EVAR (odds ratio = 5.6), while no such difference of mortality was observed in patients with abdominal decompression. These results demonstrated that EVAR in patients with symptomatic aneurysms or contained ruptures may achieve a better prognosis than those with frank rupture. Another systemic analysis of eleven studies involving 42,888 patients showed that EVAR was associated with significantly lower mortality than open surgery. Besides, this difference remained when the population-based data were examined separately .
As a rapid developing technique, the demerits of EVAR in rAAA can not be ignored. Despite of the technical development in EVAR, rAAA is still a difficult challenge especially in patients with hostile anatomy and unstable hemodynamics. Hoornweg et al.  reviewed 83 rAAA patients in which 45 (54.2%) were unsuitable for EVAR because of the anatomy such as unfavorable infrarenal neck or iliac arteries. While EVAR may be feasible for rAAA repairment, randomizing patients to EVAR or open surgery for rAAA was hard to perform. In one trial from UK, the researchers were only able to enroll 32 of 103 patients who were admitted with suspected rAAA. There were no differences in 30-day mortality and complications between EVAR and open surgery . Even though accumulating data showing the reduced mortality of EVAR in rAAA, concern exists that this may reflect a selection bias. It has been suggested that only the most stable patients with ruptures are chosen for EVAR, and the most common reason for open repair was hemodynamic instability preoperatively [21–23]. In a review of discharge data from four states, researchers found that lower-risk patients were selected to perform EVAR compared with those undergo open surgery .Furthermore, it should also be noticed that these promising data of EVAR in rAAA were mostly provided by experienced surgeons of famous centers. Additional observation is needed after translating this technique to small or rural hospitals.
EVAR in the elderly patients
The benefit of a prophylactic procedure in the most elderly AAA patients is unproven . Initial thoughts behind EVAR assumed that it would be more advantageous in the elderly and in those patients unfit for open repair. This debate continues these years. Schermerhorn et al.  demonstrated that although operative mortality increases with age, a low mortality rate can be achieved even in Medicare patients of 85 years and older, informing that EVAR in older patients can achieve a better result. Another investigation found that EVAR can be performed safely in octogenarians, despite of the higher American Society of Anesthesiologists classification, larger aneurysms, and more tortuous anatomy, which inducing the longer hospital stay and surgical operating times in older group . Meanwhile, some authors gave an unclear point of view on EVAR in elderly patient. de Blic et al., evaluated the short-term to midterm results after AAA repair in patients >85 years old from a single center. In conclusion, they suggested that elective repair may be proposed in these elderly patients in cases of threatening AAA. Although no significant benefits were noted in EVAR group, it was reasonable to perform this less invasive procedure in elderly patients with suitable anatomies . On the other hand, the famous EVAR 1 trial reported that the older patients had more complications than the ‘fit’ patients [2, 28]. Moreover, the Standard Open Surgery Versus Endovascular Repair of Abdominal Aortic Aneurysm (OVER) trial showed that patients over 70 years old who received open surgery tended to have lower mortality than those who were performed with EVAR [3, 29]. We suggest that EVAR might be feasible for those elderly patients who are hemodynamically stable or urgent for intervention, of course more cautions should be given to patients with hostile anatomies.
All in all, EVAR is a safe and efficacious treatment for AAA even in complicated cases. EVAR in rAAA has been shown to have improved long-term survival in certain studies. While perioperative mortality is lower with EVAR, long-term outcomes are similar between EVAR and open repair, including quality of life and cost-effectiveness. Further randomized studies comparing EVAR and open surgery for AAA are being needed to adequately make sure which is superior in the long-term results.
Written informed consent was obtained from the patient for publication of this case report including associated images and video.