One aspect of the present disclosure relates to a branched vessel prosthesis for repair of a failed stent graft. The branched vessel prosthesis can include a main stent graft body having a proximal end portion, a distal end portion, and a frusto-conical midsection that tapers to the distal end portion. The main stent graft body can include a tubular wall that defines a main lumen. The midsection can include a fenestration in the tubular wall and a collapsible internal limb that extends from the fenestration into the main lumen. The internal limb can be configured to receive an iliac limb extension.
