A kit includes an implantable treatment element (13) which can be radially deformed between a retracted state and a deployed state, and a sheath (15) for maintaining the treatment element (13) in its retracted state. The kit also includes a member (19) for pulling the treatment element (13) into the sheath (15), which includes a sleeve (17) for receiving the treatment element (13) which can slide in relation to the sheath (15) between an expanded position for receiving the treatment element (13) and a compressed interposed position between the treatment element (13) and the sheath (15). The treatment element (13) is substantially axially fixed in relation to the receiving sleeve (17) when the sleeve (17) moves between its receiving and interposed positions. The kit can be used to insert endoprostheses into a blood vessel.
