During the course of the acute infectious diseases in childhood, certain changes in the heart muscle are prone to occur, due to the action of the specific toxins. In diphtheria these changes are more or less characteristic. It is my purpose to describe how these changes may give rise to clinical manifestations, and how diphtheria is related to the problem of chronic disease. The study is based on eighty cases that have been under observation in the St. Louis Children's Hospital. The electrocardiographic studies have been made in the Heart Station of the Washington University School of Medicine.
In diphtheria pathologic changes occur throughout the body, particularly in the highly specialized tissues, such as cardiac muscle, nerve, kidney and liver. These changes have been described by Hayem,1 Babes,2 Romberg,3 Councilman, Mallory and Pearce,4 and others. The changes have been produced experimentally by Welch and