Intra-atrial Re-entrant Tachycardia with Wenckebach Periodicity

A 15-year-old girl, previously asymptomatic for palpitations, underwent a successful atrial septal defect (ASD) device closure. Twelve weeks after the procedure, the patient was admitted complaining of dyspnoea on effort and palpitations. The twelve-lead ECG showed a narrow QRS tachycardia with slight heart rate irregularity, with a mean HR of 170bpm. P waves were not clearly identified with a suspicious of negative P-waves in II, III and aVF leads. No clear relationship could be observed between the suspected P waves and QRS complexes