A method of treating cardiac arrhythmia, including guiding a distal end portion of a catheter, the distal end portion having a distal tip and accommodating at least one ablation electrode into a desired intracardiac region, for example, from the inferior vena cava into the right atrium of a human heart, and then from the right atrium into the right ventricle of the heart, pulling the catheter backwards, for example, towards the inferior vena cava, until the distal tip engages an edge of an intracardiac orifice, for example, the tricuspid annulus whereby the at least one electrode engages a target tissue, for example, the isthmus of tissue between the tricospid annulus and the inferior vena cava, deflecting the distal tip into a hook-shaped configuration, and activating the at least one electrode to produce a substantially continuous lesion on the target tissue. The method makes use of a catheter pre shaped at its distal end, steerable with pull wires in two different normal planes, having one electrode which slides along the distal tip of the catheter.