Suprarenal fixation resulting in intestinal malperfusion after endovascular aortic aneurysm repair

Abstract

Superior mesenteric artery (SMA) and coeliac axis (CA) occlusion after endovascular abdominal aneurysm aortic repair (EVAR-AAA), using endograft with suprarenal fixation, are uncommon. However, we are reporting a case of visceral malperfusion, which occurred 7 days after successful EVAR with suprarenal fixation for symptomatic AAA. Endograft metal stent barbs caused severe stenosis of SMA and CA. A successful recovery of SMA was carried out by means of a balloon-expandable stent released through bare metal stent barbs. We believe that an unfavourable anatomy of a proximal aortic neck and visceral aorta may have caused a wrong stent strut deployment with the coverage of CA and SMA.

INTRODUCTION

Intestinal ischaemia, due to coeliac axis (CA) or superior mesenteric artery (SMA) occlusion after EVAR with suprarenal fixation, is a rare complication and is most commonly reported after thoracic endovascular aortic aneurysm repair (TEVAR) [1]. We are presenting a case of postoperative visceral malperfusion after EVAR with suprarenal fixation due to the coverage of CA and SMA by the graft bare metal struts.

CASE REPORT

An 84-year old woman was admitted to Emergency Department with symptomatic AAA. Her medical history revealed hypertension, hypercholesterolaemia and coronary artery disease. Computed tomography angiography (CTA) showed a 6.5-cm AAA without rupture (Fig. 1A). SMA and CA were patent. A 22-mm Zenith low profile endovascular graft (Cook Medical, Bloomington, IN, USA) through bilateral percutaneous femoral approach under local anaesthesia (Prostar XL System, Abbot Vascular, Santa Clara, CA, USA) was used.

Figure 1:

(A) Preoperative CTA shows large AAA with unfavourable proximal neck features. (B) Sagittal view of the postoperative aorta at CTA, showing severe stenosis of CA and SMA without distal embolization. CTA: computed tomography angiography; AAA: abdominal aortic aneurysm; CA: coeliac axis; SMA: superior mesenteric artery.

The main body was deployed through the right femoral artery access. The preoperative course was uneventful. During the postoperative 7 days, diffused abdominal pain, tenderness, diarrhoea with elevated leucocytes and metabolic acidosis occurred. The CTA showed massive dilatation of small bowel loops, wall thickening without pneumatosis or perforation and high-grade stenosis of SMA and CA (Fig. 1B). An emergent endovascular recanalization was planned. SMA was engaged with a 5-Fr Bern catheter over 0.035 stiff guidewire through the left brachial artery approach with a 6-Fr long introducer sheath.

A 6×15 mm balloon-expandable stent (Express Monorail system, Boston Scientific, MA, USA) was deployed over a 0.014 guidewire. The angiography showed SMA recovery with good distal retrograde perfusion of the CA (Fig. 2). The postoperative course was normal. A CTA scan was planned, but the patient refused. A Duplex scan examination at 3 months showed good stent patency.

Figure 2:

Angiography shows revascularization of SMA and late opacification of CA. CA: coeliac axis; SMA: superior mesenteric artery.

DISCUSSION

In vitro modelling of bare metal struts placed across an arterial orifice did not result in flow reduction, and few reports have demonstrated that barbs attached in suprarenal aorta have resulted in renal or visceral artery occlusion [1].

Several visceral occlusion mechanisms have been proposed, such as dissection, thrombus dislodgement, plaque prolapse, recurrent trauma and thrombo-embolism [2].

Unfavourable anatomical features (hostile proximal aortic neck, small, angulated and short visceral aorta or anomalies in SMA/CA origin) seem to be major risks for asymmetric deployment and stent graft infolding, increasing the possibility of visceral branch occlusion.

In our case, the asymmetric release of stent struts with steel barbs impinging on the SMA and CA orifice was caused by a challenging neck and visceral aorta anatomy, wrong proximal oversizing and femoral access selection. In angulated necks, stent graft oversizing of >15° (based on diameter measurements perpendicular to the aorta) should be carried out to avoid asymmetric placement. The surgeon should anticipate stent graft deployment over stiff and less stiff guidewires, which influences the symmetry of stent graft placement. Choosing the right femoral access site and graft selection plays a significant role in difficult anatomies.

The endograft should allow controlled and safe deployment, by means of a flexible introduction system and conformable design with low columnar force, allowing the stent graft to conform to the original anatomy, reducing the aneurysmal neck stress. According to the published data, the Endurant device shows satisfactory outcomes in extreme angulation of a proximal neck [3]. Endograft with infrarenal fixation could be an option in a hostile neck. C3 Excluder stent grafts have increased accuracy with proximal controlled deployment and repositioning at the proximal landing zone, and good results, in terms of migration and early and late Type 1a endoleaks, have been reported [4]. SMA multiplanar roadmapping to assess its relationship with struts should be performed. A 0.035 guidewire placed in SMA through a brachial approach to achieve prompt recovery of SMA could be useful.

A Chimney graft technique (CGT) or fenestrated/branched graft (F/B–EVAR) should be considered and planned to prevent this complication and achieve proximal sealing without doubt regarding visceral vessel perfusion. Regarding malperfusion management, prompt diagnosis with CTA is mandatory before a transmural intestinal ischaemia occurs. An endovascular approach seems to be feasible and shows satisfactory long-term results. In our case, SMA recovery was carried out with a balloon-expandable bare metal stent through brachial access. This approach leads to a more comfortable SMA engagement in angulated aortic necks. No consensus was reported between self-expanding, balloon-expanding or covered stents [5]. We prefer balloon-expandable stents in ostial lesions, because they show high radial force, visibility and precise release, in contrast to self-expanding or covered stents, such as those generally used in non-ostial lesions. Moreover, balloon-expandable stents contrast the endograft struts, thus avoiding kinking, stent occlusion and restenosis. In our case, the CA was not treated, as its isolated occlusion rarely causes symptomatic mesenteric ischaemia, due to a rich collateral vessel network from the SMA.

CONCLUSION

Hostile proximal neck anatomy, associated with an angulated and short visceral aorta, is a major concern in EVAR with suprarenal fixation. To prevent this complication, careful preoperative planning is mandatory. The use of new grafts designed for an extremely angulated aortic neck, CGT or F/B–EVAR endograft should be considered. In the case of an SMA occlusion, prompt diagnosis and treatment are mandatory to restore bowel perfusion, thus avoiding transmural ischaemia, which still results in high mortality.

Conflict of interest: none declared.