A radially expandable stent graft 10 for placement in a lumen of a patient is disclosed. The stent graft 10 comprises: a prosthetic trunk 100 comprising a trunk lumen 110 there-through a prosthetic branch 300 comprising a branch lumen 310 extending there-through, wherein the branch lumen 310 is in fluid communication with the trunk lumen 110 through a lateral opening 115 in the trunk lumen 110 a valve 150 comprising a fenestration 152 for providing temporary lateral access into the trunk lumen 110, the valve 150 positioned opposite the lateral opening 115 in the trunk lumen 110 and a valve actuator. The valve actuator closes the fenestration 152 as the stent graft 10 expands.
