SUCCESSFUL ABLATION OF CONCEALED ACCESSORY PATHWAY MEDIATED SUPRAVENTRICULAR TACHYCARDIA IN A 5-YEAR-OLD CHILD WITH EBSTEIN ANOMALY.

Here we report a case of a 5-year-old boy with Ebstein anomaly and supraventricular tachycardia. He was diagnosed with Ebstein anomaly at the age of 3 months during the workup for afebrile convulsions, and has been followed by a pediatric cardiologist since. Electrocardiography recorded a small Rr` pattern in V1 on a few occasions, without other abnormalities. At the age of 2.5 years, the first episode of supraventricular tachycardia was recorded and stopped with adenosine. He was started on atenolol and was asymptomatic until a year later when he presented with the second recorded supraventricular tachycardia. He was referred to our institution for an electrophysiology study with ablation. Tachycardia was entrained and all the maneuvers were in accordance with atrioventricular reentry tachycardia. Tricuspid annulus was mapped during tachycardia. The earliest atrial signals appeared in the posteroseptal region of the valve, mechanical blocking of the tachycardia was recorded in that region, and early fractionated signal was present during ventricular retrograde pacing. The pathway was successfully ablated. Basal electrocardiogram was without change after ablation and the patient did not experience recurrence of tachycardia during follow-up. This case shows the efficacy and importance of ablation in Ebstein anomaly, without x-ray or intracardiac echocardiography.