The neck of a juxtarenal aneurysm is often too short for stable hemostatic stent-graft implantation. Fenestrations (holes) in the stent-graft permit implantation at a more favorable level by providing a route for flow to the renal arteries. In cases of pararenal and thoracoabdominal aortic aneurysm, the aorta around the renal and visceral arteries is too dilated for hemostatic contact with the wall of the stent-graft. There is a gap, which must be bridged by a branch of the stent-graft. In