Radiofrequency ablation in a patient with atrioventricular reentrant tachycardia and atrioventricular nodal reentrant tachycardia with 2:1 atrioventricular block.

The authors report the case of 15-year-old girl with a history of palpitations and shortness of breath during exercise. The electrocardiogram showed ventricular preexcitation suggesting a Wolff-Parkinson-White syndrome with a posteroseptal accessory pathway. During the electrophysiological study a left posterospetal accessory pathway was identified and an orthodromic atrioventricular reentry tachycardia was reproducibly induced (cycle length 400 ms). After disappearance of the ventricular pre-excitation with radiofrequency ablation, a dual physiology of atrioventricular node condution was documented and a slow-fast atrioventricular nodal reentrant tachycardia was repeatedly induced. Upon induction, this tachycardia presented a proximal atrioventricular block with 2:1 condution converted to 1:1 condution with overdrive pacing from the proximal coronary sinus (cycle length 270 ms). Radiofrequency ablation of the slow pathway was performed with success. We discuss the need to suspect and seek different arrhythmogenic substracts of tachycardia in a single patient, the electrophysiologic conditions that could explain the inducibility of different arrhythmias in this case, and the controversy regarding ablation of more than one reentry circuit in a single procedure.