The most common location of accessory pathways in patients with the Wolff-Parkinson-White syndrome is the:

A. Left free wall.

DISCUSSION: All major published series of the Wolff-Parkinson-White syndrome indicate that the majority of all accessory pathways appear in the left free wall space. In one series, approximately 60% of all accessory pathways occur in the left free wall space. In Ebstein's anomaly, pathways are usually located in the posterior septum and/or right free wall spaces. If these patients are excluded, approximately 70% of pathways occur in the left free wall space.