[Atrio-ventricular block in Steinert's disease. Electrophysioligic and histologic study of the conduction system].

An anatomical study of the conducting pathways was carried out in a case of Steinert's disease complicated by a complete atrio-ventricular block with syncope. Electrical study of the potentials in the bundle of His located the block within and below the bundle. When the patient died, an anatomical study of the conducting pathways was carried out. There were foci of fibrosis mainly within the conducting system, but these changes were moderately marked only, and seemed to be the final stage of a disorder which was not itself visible optically. The basic underlying pathological process is probably biochemical, and the lesions seen microscopically are simply a late sign of the disorder.