A stent graft having a tubular body with a ostium in the side wall of the tubular body and a side arm extending from the ostium. The side arm comprising a tube of graft material extending at least partially helically around and longitudinally along the tubular body of the stent graft at least one-fourth the circumference of the tubular body to an open end and has a resilient reinforcing ring attached about and encircling its open end. The resilient reinforcing ring is permanently attached to the tubular body with a tie down arrangement that passes through the graft material of the tubular body and through the side arm and engages the resilient reinforcing ring to permanently hold the open end of the side arm against the tubular body surface. A line of radiopaque markers extends along the length of the side arm from the ostium to the open end.
