Abstract: The invention relates to a release system for a self-expanding endoprosthesis, comprising a catheter, an endoprosthesis (2) having a first volume-reduced shape under an external constraint and, after elimination of the external constraint, assuming a second expanded shape at the placement site and being movably arranged in the catheter, a means for holding (6, 7) the endoprosthesis (2) in the catheter as well as means suitable to exert the external force on the endoprosthesis (2), wherein the means for exerting the external force on the endoprosthesis (2) is a tubular film (3) whose distal end encloses the endoprosthesis (2) in its reduced-volume form and whose proximal end extends to the proximal end of the catheter in such a way that it can be withdrawn from the endoprosthesis (2) thus eliminating the external constraint.

Abstract: The invention relates to a release system for a self-expanding endoprosthesis, comprising a catheter, an endoprosthesis (2) having a first volume-reduced shape under an external constraint and, after elimination of the external constraint, assuming a second expanded shape at the placement site and being movably arranged in the catheter, a means for holding (6, 7) the endoprosthesis (2) in the catheter as well as means suitable to exert the external force on the endoprosthesis (2), wherein the means for exerting the external force on the endoprosthesis (2) is a tubular film (3) whose distal end encloses the endoprosthesis (2) in its reduced-volume form and whose proximal end extends to the proximal end of the catheter in such a way that it can be withdrawn from the endoprosthesis (2) thus eliminating the external constraint.

Abstract: that at least a proximal end ring in combination with its associated links is the mirror image of a distal end ring and its associated links. The rings that form the proximal end and the rings that form the distal end have a radial stiffness associated therewith, and said stiffness is greater than a stiffness of the rings that form the interior portion of the stent. The dual stiffness of the stent leads to a more uniform expansion in the presence of uneven radial forces on the stent during the expansion process.