A stent graft (2) for treatment of an emergency rupture of, for instance, the aorta adjacent the aortic bifurcation. The stent graft comprising a tubular body (8) with a bifurcation (10) in the tubular body defining a first long leg (12) and a second short leg (14). The second leg has a valve arrangement (18) to prevent fluid flow through the second leg from the stent graft. The valve can be opened from external of the stent graft for the placement of a leg extension stent graft (90) therethrough.