A 51-year-old woman had been seen in the EP clinic because of episodes of palpitation that started in her early teens. Recently they had become more frequent and prolonged and she had been in the Emergency Department three times in the past 6 months:

• Sinus rhythm, 65/min
• Wolff-Parkinson-White

Comments: The delta wave is isoelectric in V1 (septal accessory pathway) and negative in aVF (posteroseptal or coronary ostium pathway). EP studies demonstrated a bypass tract near the coronary ostium. Ablation was carried out.  (Arruda et al. J.Cardiovasc. Electrophysiol. Vol.9, pp. 2-12, January 1998)