A kit for penetrating the cardiac septum and for implanting a transeptal lead, including a lead for the detection/stimulation of a left heart cavity. This kit includes a screw lead (16) and a radio-frequency puncture generator (32). The lead includes: a lead body with a deformable sheath (18); a proximal end having an electrical connector (20) for coupling to an implanted medical device housing; a distal end having a lead head (22) with an electrode including a projecting conductive helical screw (24) for penetrating into the septum (10) due to a screw movement applied from the proximal end of the lead, and a conductor (26) connecting the electrode to the electrical connector, the electrode including the screw. The radio-frequency puncture generator (32) is connected to the electrical connector to provide a controlled application by the helical screw of a radio-frequency energy on the septal wall and, in conjunction with the screw motion applied to the lead head, punctures through and results in the lead head crossing through the septum wall.