A thoracic arch stent graft (1) has a tubular body of a biocompatible graft material (3) and at least one fenestration (13, 15) in the wall on one side thereof. A combination guide and tubular side arm assembly (20, 22) is mounted into the or each fenestration. The combination guide and tubular side arm assembly comprises a tubular portion (24) and a funnel portion (26) extending from a distal end of the tubular portion. The funnel portion has an angled open end. The tubular portion and the funnel portion are formed from a biocompatible graft material wall and have a lightweight space frame (38 40) formed from a resilient wire and supporting the graft material and defining the combination guide and tubular side arm assembly.
