A cardiac monitoring andor stimulation system includes a housing coupled to a plurality of electrodes configured for subcutaneous non-intrathoracic sensing. The bottom part of said frame is provided with a plate identical to the plate and of substantially identical dimensions to those of the frame. Each disc cutter includes a set of mutually spaced cutting members arranged to create, during a turn of the drill bit, a corresponding set of cut sections of the cut created by the disc cutter, and wherein the cutting members are arranged so that the sets of cut sections created during subsequent drill bit turns are staggered relative to each other.