Bradycardia during early childhood was mentioned first in 1896, by Schuster,1 who reported a case of rheumatic fever in a child 4 years old who had transient bradycardia, with a rate of 35, the mechanism of which was unknown. It was not until 1908 that graphic proof of congenital auriculoventricular heart block was obtained.2 In 1929, Yater3 presented an exhaustive survey of the literature and tabulated the results in thirty cases, including one of his own. The auriculoventricular block was complete in twenty-two of these cases, the remainder showing varying degrees of partial block. Since Yater's publication, additional instances of congenital auriculoventricular heart block have been reported by Nicolson, Shulman and Green,4 Leech,5 Koenen6 and Lampard.7
Two additional cases are presented, one of which is unique in view of the fact that the bradycardia was noted two months before birth, and was proved