In 3 patients radiofrequency (RF) ablation of AV node (n = 2) and left sided accessory pathway (n = 1) was performed because of intractable tachyarrhythmias. RF ablation was made in the first patient (ablation of AV node) using 135 Watts during 72 sec., in the second patient (AV node ablation) 331 Watts during 185 sec., and in the last patient 883 Watts during 695 sec. In the last patient ablation of accessory pathway was unsuccessful and the patient has been successfully operated. AV conduction was interrupted in 2 cases. No complications were noted. General anesthesia was not required. All the patients were discharged in a good state.