A delivery system for an endoluminal prosthesis, comprising: an introducer, the introducer having a distal end intended to remain outside a patient in use and a proximal end, a carrier for an endoluminal prosthesis assembly disposed within the introducer, the endoluminal prosthesis assembly comprising, a first stent graft having a first end and a second end and an interior lumen, the first stent graft having an expanded position and a compressed position, the first stent graft defining an access port disposed through a wall of the first stent graft between the first and second ends of the first stent graft; and a second stent graft having a first end and a second end, the second stent graft being disposed within the first stent graft, the second stent graft having an expanded position and a compressed position where the second stent graft is compressed against an interior wall of the first stent graft opposite the access port; where in the compressed position, the second stent graft contacts only a portion of a circumference of the interior wall of the first stent graft such that the access port is in fluid communication with the interior lumen of the first stent graft, and in the expanded position, the second stent graft engages substantially all of a circumference of the interior wall of the first stent graft so as to seal the access port from fluid communication with the interior lumen of the first stent graft; a trigger wire arrangement engaging a first end and a second end of the second stent graft to restrain the second stent graft in the compressed position, wherein the trigger wire arrangement is removable to enable the secondary stent graft to move from the compressed position to the expanded position. an introducer, the introducer having a distal end intended to remain outside a patient in use and a proximal end, a carrier for an endoluminal prosthesis assembly disposed within the introducer, the endoluminal prosthesis assembly comprising, a first stent graft having a first end and a second end and an interior lumen, the first stent graft having an expanded position and a compressed position, the first stent graft defining an access port disposed through a wall of the first stent graft between the first and second ends of the first stent graft; and a second stent graft having a first end and a second end, the second stent graft being disposed within the first stent graft, the second stent graft having an expanded position and a compressed position where the second stent graft is compressed against an interior wall of the first stent graft opposite the access port; where in the compressed position, the second stent graft contacts only a portion of a circumference of the interior wall of the first stent graft such that the access port is in fluid communication with the interior lumen of the first stent graft, and in the expanded position, the second stent graft engages substantially all of a circumference of the interior wall of the first stent graft so as to seal the access port from fluid communication with the interior lumen of the first stent graft; a trigger wire arrangement engaging a first end and a second end of the second stent graft to restrain the second stent graft in the compressed position, wherein the trigger wire arrangement is removable to enable the secondary stent graft to move from the compressed position to the expanded position.