Unidirectional delivery system

A tubular prosthesis delivery system has an inner tubular member having a distal end including a prosthesis-carrying portion and a proximal end intended to remain outside the patient. An outer tubular member has a distal end spaced from the prosthesis-carrying portion of the inner member. A coupling member couples the inner and outer tubular members to each other in fixed relationship generally at a location intended to remain outside the patient. An intermediate tubular member located between the inner and outer tubular members has a distal end adapted to cover the tubular prosthesis and a proximal end that projects proximally beyond the proximal ends of both the inner and outer tubular members. The proximally projecting end of the intermediate tubular member is longitudinally movable with respect to the coupled inner and outer tubular members by a distance sufficient to retract the intermediate tubular member distal end from any position covering the prosthesis carried by the inner member.