Catheter ablation of atrioventricular conduction.

35 patients with refractory supraventricular arrhythmias were treated in three centres by high-energy shocks delivered to the atrioventricular conduction system from a conventional transvenous pacing catheter. After a mean interval of ten months, 26 patients (74%) had persistent complete heart block, 2 (6%) had intermittent complete heart block, and 3(9%) had first-degree heart block. 3 patients continued to have conducted atrial fibrillation, but with slower ventricular rates than previously, and 1 had normalisation of dual atrio-His conduction. In 1 patient a septal accessory pathway was ablated. 30 patients (86%) are completely symptom-free without additional therapy. There were no important long-term complications. Transvenous ablation of atrioventricular conduction is a safe and effective technique for treating a wide range of refractory atrial and junctional arrhythmias.