A prosthetic system for heart valve replacement comprises an annular support structure (60) within which a valved prosthetic body can be expanded until it meets opposition. The annular support is provided in two or more ring segments (61, 62) having terminal connection means (63) for forming, in the condition of use of the prosthetic system, a stable and durable annular structural continuity capable of withstanding the opposition exerted by the valved prosthetic body.