Directions of atrial excitation wavefront influenced antegrade conduction of manifest accessory atrioventricular pathway: a case report.

We report a case of left accessory atrioventricular pathway (AP) which antegrade conduction was manifest during pacing from the anterior site of the atrial insertion, but absent during pacing from the posterior site. Infusion of adenosine triphosphate during pacing from the posterior site induced a conduction block of atrioventricular node without affecting the persistent antegrade conduction block of the AP. These findings suggested that the different response of the AP according to the directional change of atrial conduction was not due to a "linking" phenomenon, but may relate to the impedance mismatch because of an oblique fashion of the pathway.