A stent graft (10) has a tubular body with a side aperture (16) covered by a valve arrangement (18) and an arrangement to hold the valve open (32) with a release wire (30). Retraction of the release wire closes the valve. The stent graft can have a tubular body with a first bifurcation (134) with first and second legs (130, 132) extending from the bifurcation. The side aperture and valve arrangement can be in one of the legs. One of the legs (132) has a further bifurcation (142) to define a side arm (140). The stent graft can be deployed into the vasculature of a patient with the tubular body being in an aorta of the patient, a first leg extending down an iliac artery, a second leg being directed towards a contralateral iliac artery and the side arm directed to an internal artery of the contralateral iliac artery.