A stent assembly (42) adapted for endoluminal placement by endovascular deployment for the treatment of a false lumen (10) associated with a vascular dissection. The stent assembly has a number of self expanding stents (35) connected together to define an elongate substantially cylindrical lumen wall engaging surface. The stents are adapted to provided pressure on the wall of the lumen adjacent to and extending away from a rupture. A deployment device (40) for the stent assembly includes a sheath (48) and a retention and release arrangement (50) to retain the proximal end (37) of the stent graft to the deployment device. Release of the stent assembly is by withdrawal of the sheath before release of its proximal end by the use of a trigger wire (54) of the retention and release arrangement.