A 16-year-old woman is referred to the EP clinic because of episodes of palpitation during the past year:

• Sinus Rhythm
• Wolff-Parkinson-White  

Comment: EP studies demonstrated the presence of a right postero-septal bypass that was successfully ablated (see ECG #2). The QS pattern in V1 and V2 this ECG is different from the one commonly seen in right posteroseptal bypass (rapid transition of the R:S ratio from negative to positive). The Arruda algorithms would allow one to make the diagnosis (isoelectric or negative delta wave in V1 and negative delta wave in aVF –> posteroseptal tricuspid annulus (PSTA) accessory pathway); Arruda et al. ECG Localization of Accessory AV Pathways (J. Cardiovasc. Electrophysiology, Vol.9, pp 2-12, January 1998)

This ECG is recorded on the day after ablation. The patient has no complaints and is stable:

• Sinus bradycardia, 58/min
• Deeply inverted T waves in the inferior leads, tall T waves in V2 (memory T-waves post ablation – will likely subside in days to weeks)
• The WPW pattern is no longer present