[Wolff-Parkinson-White syndrome caused by association of atrio-hisian fibers and Mahaim's fibers. Comparison between the electrophysiology and histology].

A child of six who had had several losses of consciousness died suddenly during a spell of tachycardia. The EKG showed at times a type B Wolff-Parkinson-White syndrome, at times a Lown-Ganong-Levine syndrome. Intracavitary electrophysiological explorations had been carried out. The interest of this case lies in the comparison between these electrophysiological explorations and the histological examination of the normal and accessory conduction pathways. The short PR interval, which did not lengthen under the effect of premature atrial stimulation, was accounted for by the presence of atrio-His bundle tracts. The intermittent delta wave was due to Hissio-ventricular Mahaim fibres. These two accessory conduction pathways are considered as abnormal.