In theory, an endovascular approach to TAAA repair has two main advantages. First, the stent-graft is inserted through a trans-luminal route; there is no need to expose the aneurysm. Second, the grafts are inserted without clamping the aorta; there is no need to interrupt flow to the abdominal organs. More than a decade has passed since endovascular repair of abdominal aortic aneurysm (AAA) and thoracic aortic aneurysm (TAA) first started to displace open surgery as first-line therapy, yet endovascular repair of TAAA is still confined to a handful of centres worldwide.

The fundamental problem is how to maintain flow to the visceral branches of a TAAA while excluding the aneurysm itself from the circulation. The two main alternatives are: a combination of visceral artery bypass and endovascular exclusion, and branched stent-graft insertion.

The first option is a combination of conventional visceral bypass and endovascular aneurysm exclusion. The surgical bypass grafts to the visceral arteries originate outside the field of endovascular exclusion, usually from the distal aorta or common iliac aneurysm. Once the aneurysm has been ‘debranched’, endovascular exclusion can proceed in the usual way. The second option, multi-branched stent-graft implantation, eliminates the need for trans-cavitary incisions and interruption of visceral arterial flow. However, the procedure is far from simple, because each branch of the stent-graft represents a separate line of insertion. All these lines of insertion intersect in the aorta where the branches join the trunk. The nature of that junction determines the type of branched stent-graft. Unibody multi-branched stentgrafts have permanent sutured connections, whereas modular fenestrated multi-branched stent-grafts have only a ring of contact between each balloon expanded covered stent and the corresponding hole (fenestration) in the wall of the primary stent-graft. Modular cuffed multi-branched stent-grafts occupy an intermediate position between these two extremes. The primary stent-graft of a cuffed multibranched stent-graft has branches sewn into its surface, but these are not long enough to reach the orifices of the visceral arteries. Instead, they serve only to enhance the connection between the primary stent-graft and self expanding covered stents.