CASE 9661 Published on 28.11.2011

Chimney technique in endovascular aorta repair (EVAR) to preserve a large polar renal artery


Interventional radiology

Case Type

Clinical Cases


Fabio Pozzi Mucelli1, Barbara Ziani2, Laura Ukovich2, Luca De Paoli1, William Toscano1, Maria Cova1

(1) Struttura Complessa di Radiologia,
Az. Ospedaliero-Universitaria Ospedali Riuniti di Trieste, Trieste, Italy;
(2) Struttura Complessa di Chirurgia Vascolare,
Az. Ospedaliero-Universitaria Ospedali Riuniti di Trieste, Trieste, Italy

62 years, male

Area of Interest Arteries / Aorta, Cardiovascular system ; Imaging Technique Catheter arteriography, CT-Angiography
Clinical History
62-y.o.-man with multiple comorbidities (ischaemic cardiopathy,chronic renal failure (CRF),hypertension) with AAA (diameter:9 cm!). Due to multiple risk factors endovascular abdominal aorta repair (EVAR) treatment was scheduled. Considering patient CRF and proximal nech anatomy it was mandatory to try to save a big polar left renal artery arising over the aneurysm.
Imaging Findings
Preoperative CT shows a large inferior mesenteric artery (IMA) and left polar renal artery (Fig.1) and right renal artery stenosis. Two days before EVAR patient underwent preliminary coil embolisation of IMA (Fig. 2). EVAR was done with a surgical access of both femoral arteries while a percutaneous left brachial access was used to engage the left polar artery. Through this access a 7F/90cm long introducer-sheath (Cordis-Brite-tip) was advanced inside the polar artery and a balloon-expandable stent-graft(Advanta-Atrium 6x58 mm) was placed partially inside the polar artery and partially in the aorta and an Endurant (Medtronic) stent-graft was placed close to the main renal arteries (Fig. 3a,b). The renal stent and the main body of the stent-graft were deployed and "ballooned" simultaneously (Fig. 3c). The procedure was completed as usual (Fig. 3d). A CT done two months later showed correct stent-graft deployment and regular patency of the left renal stent (Fig. 4).
EVAR is a safe, durable and effective treatment only when certain anatomical criteria are fulfilled. Length and angulation of proximal aortic neck are the most important criteria to guarantee a successful fixation at the attachment site. Hostile proximal neck anatomy is defined by at least one of the following features: short neck, neck bulge, tapered neck, angulated neck and neck thrombus/calcium[1]. Patients with very short infrarenal necks would require complex surgical open repair(OR), with increased mortality and morbidity[2]. So many patients with short proximal neck and high surgical risk are not eligible for OR and several strategies have been investigated to treat them with modified EVAR. One option is to use fenestrated stent-grafts, but the procedure requires specialised training and is not feasible in angulated proximal necks. Furthermore fenestrated stent grafts need to be custom made for each patient, are expensive and not so easily available. Another option recently introduced in the clinical practice to treat short aortic neck aneurisms is the “Chimney Graft technique”(CGT) or “Snorkel” technique, which utilises conventional commercially available stent-grafts and stents for the aorta and renal arteries and/or superior mesenteric artery. This technique consists in placing a covered stent in the lower renal artery (or both renal arteries) that runs parallel to the main aortic stent-graft to preserve renal flow in the stent-graft sealing zone.
In 2003 Greenberg described the CGT[3]; since then others have extended this technique to treat iuxtarenal, pararenal and aortic arch aneurysms to preserve flow to aortic branches covered during EVAR.
The case shown here differs from other reported "chimney cases" for the fact that CGT was used not for a problem of "short neck" but to preserve patency of a large polar artery in a patient with CRF. Renal function remained unchanged (pre-EVAR:51ml/min;post-EVAR:48ml/min). Unlike to "standard" CGT we decided to choose a longer balloon-expandable-stent-graft and we took extreme care to avoid that this stent could cover the ostium of renal arteries with a "check" angiogram with main body partially open and balloon-expandable-stent-graft inside the sheath but already in position (Fig.3b). We believe that also selfexpandable stent-graft can be a good option however we preferred balloon-expandable-stent-graft because we have more experience with these stents. Concerning preoperative embolization of IMA we preferred to to in our cathlab 2 days before EVAR because we considered this a quite complicated manouvre to do in the operating-room with a mobile C-arm, also if of good quality.
Differential Diagnosis List
Chimey technique to preserve polar renal artery during EVAR
Abdominal aortic aneurysm-open repair
Inflammatory aneurysm
Final Diagnosis
Chimey technique to preserve polar renal artery during EVAR
Case information
DOI: 10.1594/EURORAD/CASE.9661
ISSN: 1563-4086