The system, which comprises at least one stent, with an end portion to be introduced into a vessel and to connect it there, has a sheath designed to be introduced into the vessel and comprising a first expansible balloon (8b), for shaping and stabilizing the prosthesis in the vessel, and a second expansible balloon (7), for sealing the junction between said end portion of the prosthesis and the vessel, the system additionally comprising means for expanding the balloons (8b, 7).
