Catheter ablation of junctional ectopic tachycardia by guarded low dose radiofrequency energy application.

The prognosis of junctional ectopic tachycardia has been poor. A 9-year-old boy with dilated cardiomyopathy and this incessant form of tachycardia underwent RF ablation. Without retrograde atrial depolarization during tachycardia, serials of low dose RF energy were applied near the His-bundle area to find out the arrhythmogenic foci. The optimal site for ablation showed rate acceleration at low dose application and rate slowing down followed by conversion upon increasing the energy. By using this guarded low dose ablation technique, the tachycardia was eliminated without AV block. The LV function also improved.