Slitting tool for slitting open a catheter shaft, including a housing, a blade fastened on the housing, a pushbutton, which is mounted so it is displaceable on the housing, and clamping forceps, which are mounted so they are movable on the housing. The clamping forceps are partially located inside the housing, and include two clamping legs, which are connected to one another at their base located in the housing and have a mutual pre-tension, and which cause the fixation of an electrode line on their periphery located outside the housing, such that the pushbutton, which is mounted so that it is displaceable, and the clamping forceps, which are mounted so that they are movable, act together with one another in such a manner that an actuation of the pushbutton causes an opening of the fixation in the periphery of the clamping forceps.