Preformed guiding stylet for introducing a septal lead in contact with the septum or other intra-corporal device in contact with body tissue. This stylet includes a flexible wire to be introduced by its distal end in a central lumen of the lead, and a control handle. The wire is elastically deformable in bending and has sufficient rigidity in torsion to enable transmission by the handle rotation of a rotational movement over the entire length of the wire. Unstressed, the wire comprises successively in its distal part a first curvilinear portion a first straight portion a second curvilinear portion and optionally a second straight portion. The first and second curvilinear portions extend in respective planes making an angle between them defining a dihedral which axis comprises the first straight portion. The total length of the first curvilinear portion coincides with the anatomical curvature of the venous system.
