An implantation system for a vascular implant comprises a sheath (20, 120) having a longitudinal axis, a lumen formed therein and a distal opening (26, 124). A pusher (30, 130, 230, 260) is positioned within the sheath, the pusher adapted to contact a vascular implant to deliver the implant from the sheath. A sheath centering structure (40, 140, 240, 270) includes an elongated portion (43, 143) and a plurality of arms (43, 44, 143, 144) extending from a distal portion of the elongated portion, the arms movable from a reduced profile position to an expanded position to move the sheath away from a vessel wall to a more centered position. The centering structure is movable relative to the pusher.
