Radiofrequency catheter ablation of an orthodromic tachycardia in a patient with single ventricle.

Radiofrequency catheter ablation of a recurrent orthodromic tachycardia was performed in a 10-year-old child with single ventricle and bidirectional Glenn procedure before a Fontan operation. Identification of a His bundle electrogram was achieved at the postero-inferior atrioventricular (AV) groove by the inferior vena cava route, and electrophysiological demonstration of a concealed accessory pathway-mediated tachycardia was possible when a ventricular extrastimuli given during the His bundle refractoriness showed advancement of the atrium. A single energy application during tachycardia in the right antero-superior region of the AV groove resulted in the definitive interruption of the accessory pathway.