Abstract
Although the incidence of atrioventricular reentry tachycardia (AVRT) using the right anteroseptal accessory pathway is low, the risk of atrioventricular block by radiofrequency catheter ablation (RFCA) of right anteroseptal accessory pathway is high.
A 10-month-old infant with narrow QRS tachycardia was noted to have narrow QRS tachycardia at 280 bpm when she was referred to a general pediatrician for fever. The tachycardia was refractory to ATP and verapamil injection, per os administration of flecainide and bisoprolol, and frequent cardioversion and intravenous infusion of amiodarone were required. She was referred to our hospital for RFCA. An electrophysiological study (EPS) was performed, and the earliest ventriculoatrial (V-A) conduction was demonstrated near the His bundle electrogram, and retrograde conduction did not demonstrate decreased conduction properties. The atrial electrogram revealed a reset phenomenon by a single extra ventricular stimulus during tachycardia. From these results, AVRT using a right anteroseptal accessory pathway near the compact atrioventricular node was suspected. V-A conduction disappeared easily with catheter-induced mechanical trauma (bumping) at the earliest atrial activation site. We performed a low energy test application of radiofrequency energy at the earliest atrial activation site where the His potential was recorded. A junction rhythm appeared during radiofrequency applications. V-A conduction did not recur after catheter-induced mechanical trauma, so we applied radiofrequency application at the site. V-A conduction was completely eliminated, and it was impossible to induce AVRT. After RFCA, there were no abnormalities of atrioventricular node function. In infants with small cardiac dimensions, radiofrequency catheter ablation was possible and useful for a right anteroseptal accessory pathway.
