Patients with supraventricular or ventricular tachyarrhythmias resistant to antiarrhythmic drugs are candidates for surgical ablation of the bundle of His, and of accessory pathways or ventricular or atrial foci responsible for the arrhythmia. During the past 6 years closed-chest catheter techniques have been devised that allow electrical shock ablation of the atrioventricular junction, accessory pathways, or foci responsible for arrhythmias. The promising results of these ablative procedures (especially of the atrioventricular junction and posteroseptal accessory pathways) justify their trial in suitable patients before cardiac electrosurgery.