The invention relates to a kit including a tubular endoprosthesis having an inner surface delimiting a channel with a longitudinal axis. The kit includes a prosthetic valve designed to be implanted in the channel. The valve includes a supporting frame having an outer surface designed to be pressed against the inner surface, and a flexible cover connected to the frame. The inner surface has at least two segments with variable cross-section along the longitudinal axis. The segments form respectively a proximal stop and a distal stop to lock the axial displacement of the outer surface along the inner surface along two opposite directions.