A shape imparting mechanism (10) for a catheter includes an elongate element(12) dimensioned to fit within a lumen of an electrode sheath 14 of a catheter.An insertion facilitating arrangement (22) is carried at a distal end of the elongateelement (12) for facilitating insertion of the distal end of the elongate element(12) into the lumen of the electrode sheath (14) of the catheter.