Observations on the Mechanism of Circulatory Failure in Diphtheria.

Abstract

This report consists of study by means of the string galvanometer of the effects of diphtheria toxin upon the heart. It has long been known that a circulatory collapse may occur in diphtheria, which frequently results in death. There is still considerable uncertainty, however, as to whether it is the heart or the vasomotor apparatus which is primarily effected.

In the present study electrocardiographic observations were carried out (1) on a series of diphtheria patients (2) on animals injected with diphtheria toxin.

Previous observers 1 , 2 , 3 , 4 have noted electrocardiographic changes indicating myocardial injury during the acute stage of diphtheria. The present investigation was made during the convalescent or late stage of the disease, since circulatory failure may occur during this period also.

Readings were taken of 15 diphtheria patients during the period of convalescence, beginning usually in the 3rd or 4th week of their illness. In all cases, the local throat condition had entirely cleared up, and the cultures for the diphtheria bacillus were negative. The general symptoms of toxemia had disappeared, and practically the only abnormality was a heart which increased in rate very easily. Of the 15 cases, 8 had suffered a severe type of infection and of these, 7 showed significant abnormalities in the electrocardiogram. A summary of the readings shows the following: There was an absence of high-grade irregularities, occasional ventricular extrasystoles being the only arrhythmia noted in two cases. There was no evidence of prolonged auriculoventricular or intraventricular conduction. The longest P-R interval was .18 second and the Q. R. S. complex was not altered in any case. The chief significant change was in the T wave. A definite inversion of the T was present in all.