12-lead electrocardiogram (ECG) of a right anterior septal accessory AV pathway

Electrocardiogram from a patient with Wolff-Parkinson-White syndrome during sinus tachycardia shows a maximally preexcited QRS complex which has a left bundle branch block pattern and is markedly positive in the inferior leads. The delta wave is isoelectric in leads aVL and V6. These features localize the accessory pathway to the right anterior septum.