Figure 3.

Electrophysiology and ablation for twin atrioventricular nodal reentrant tachycardia in a patient with right atrial isomerism. She received electrophysiology studies at the age of 4 years. (A) and (C) In the left panel, we can see antegrade His signal at the ablation catheter (ABLd) and located in the right posterior area (arrow), which marked the location of antegrade major AV node. (B) and (D) In the right panel, during tachycardia, we can see retrograde His signal at the ablation catheter (ABLd), which was also at the nearby location of earliest retrograde A (not shown in this tracing). The ablation catheter was at the right anterior AV groove, which was the common site of minor AV nodes. Radiofrequency energy applied at this site successfully eliminated this twin AV nodal reentrant tachycardia. The black sketch indicated the atrioventricular valve area. AV indicates atrioventricular.