A stent graft delivery device (1) has an elongated extension piece (20) extending from its proximal end of the introducer portion (3). The elongate extension piece is selectively separable from the introducer portion. A plurality of auxiliary guide wires (50) extend from through the stent graft delivery device and through the elongate extension piece. The auxiliary guide wires can cross over at the proximal end of the extension piece and return. The stent graft delivery device can be introduced into a patient via a femoral artery and the elongated extension piece can extend out an artery of the thoracic arch whereby to extend the auxiliary guide wires out of such an artery to give through and through guide wires. Catheterization of pararenal arteries is then possible via a brachial route.