[Congenital atrio-ventricular blocks in infants. Histological study of the conduction system].

The authors present a clinico-pathological study of three cases of complete congenital atrio-ventricular block in the infant. In one case the disorder was familial, and the heart was macroscopically normal. In the other two cases, the associated abnormalities (complete discontinuity of the aortic arch in one, and situs inversus with a patent ductus and high VSD in the other) were not responsible for the conductive defect. This was explained after study of serial sections of the inter-atrio-ventricular septum; these showed an interuption or absence of the penetrating portion of the bundle of His associated, in one case, with agenesis of the atrio-ventricular node.