A guide wire for introducing an implantable electrode line, wherein the electrode line is particular a heart electrode line for intracardial sensing of cardiac actionpotentials and/or for electrical stimulation or defibrillation of the heart, and wherein the guide wire is adapted for interlocking with the electrode line, and wherein the guide wire comprises a deformation, in particular curved, wavy, V-shaped, zig-zag, or trapezoidal, enlarging the effective contact diameter of the guide wire to a value corresponding essentially to the inner diameter of a lumen of the electrode line or greater than this.