12-lead electrocardiogram (ECG) of a left anterior lateral accessory pathway

Electrocardiogram during atrial pacing in a patient with the Wolff-Parkinson-White syndrome shows QRS complexes that are maximally preexcited. The PR interval is short, there is a right bundle branch morphology, and the axis is rightward. The delta wave is positive in the lateral leads I, avL, and V6, localizing the pathway to the left anterior lateral region.