A system comprising a sluice and a catheter. The catheter including an inner, a middle and an outer tube. A stent is disposed in a distal-end portion of the catheter between the inner and outer-tube. The middle-tube ends distally at the proximal end of the stent. An actuating unit having a drive unit provided in the proximal region of the catheter for releasing the stent. A connecting portion is provided between the drive unit and the sluice. The drive unit is cooperating with the middle-tube and the connecting portion where the drive unit is operated the middle-tube is displaced in the distal direction and the actuating unit together with the outer-tube attached thereto is displaced in the proximal direction. The inner-tube is cooperating with the middle-tube and/or the connecting portion and/or the drive unit in such a way that the inner-tube is displaced at least to some extent relative to the actuating unit.