A debranching Great vessel stent graft and methods for its use, where the stent graft comprises, a main body stent graft with a first bifurcation defining a first leg and a second leg, the main body stent graft has distal and proximal ends, the main body stent graft has a diameter at the proximal end in the range from about 18 mm to about 28 mm, the first leg and the second leg each have a diameter in the range from about 12 mm to about 18 mm, the distance from the proximal end of the main body to the distal end of the first leg is in the range from about 30 mm to about 50 mm, and the distance from the proximal end of the main body to the distal end of the second leg is in a range from about 50 mm to about 70 mm.
