Chimney Technique in the Endovascular Repair of Juxtarenal Abdominal Aortic Aneurysm

Abstract

IntroductionThe treatment of aortic aneurysms via an endovascular approach was fi rst described in 1991 [ 1 ] . In the 20 years since that time, endovascular aneurysm repair (EVAR) has become an accepted standard of care for aortic aneurysms with suitable anatomical criteria [ 2 ] . Exclusion of the aneurysm relies on obtaining a mechanical seal proximal and distal to the aneurysm. A signi fi cant proportion of patients, 20-50 % in some series, are not candidates for EVAR based on their anatomy [ 3 ] . Of those excluded based on anatomical considerations, up to half are excluded because of insuf fi cient aneurysm neck length to achieve a seal proximally. EVAR attempted on abdominal aortic aneurysms (AAAs) with short necks (<10-15 mm) are more likely to fail with subsequent migration, or endoleak, and possible aneurysm rupture [ 4,5 ] .Neck lengths less than 5-10 mm do not offer a suf fi cient infra-renal sealing zone. Extending the sealing zone proximally can be achieved by using custom-made devices with either fenestrations or branches through which bridging stents can be placed.In the medium term, these techniques appear to be safe and durable alternatives when standard EVAR is not appropriate [ 6,7 ] . Fenestrated devices have recently been approved in the USA, for juxtarenal aneurysm EVAR in selected centers [ 8 ] . The disadvantage of this technology includes cost and lengthy manufacturing times of these custom-made devices preventing timely repair in very large or symptomatic aneurysms. In some settings of extreme arterial tortuosity, fenestrated stent grafting may be technically impossible.The chimney technique was initially described as a bailout solution in cases where important aortic branch vessels were accidentally partially covered by an aortic endograft [ 9 ] . Since their initial description, chimney grafts have been used in all major branches of the aorta. They have also been used in both emergent and elective settings. The technique effectively extends the proximal sealing zone above important aortic branches by placing covered stents within arterial branches and then deploying an endograft across this region (Fig. 29.1a-c ).