AN ELECTROCARDIOGRAPHIC STUDY OF CARDIAC AGING BASED ON RECORDS AT REST AND AFTER EXERCISE

Abstract

The electrocardiograms before and after exercise of 88 normal men were studied. The subjects were healthy adults with no evidence of disease disclosed by history, physical examination, urinalysis, blood Wassermann and Kahn tests, and teleoroentgenogram of the heart. They were divided equally between the 3d and 5th decades. Each was subjected to a standard 2-step exercise test with tracings taken before and immediately after the effort. The conventional limb leads and CF4 were used. The significant waves and intervals were measured and the appropriate statistical techniques applied. The study demonstrated few significant differences between the rest electrocardiograms of the 2 groups. Aside from the significantly smaller T waves in leads I and II in the older group, the differences could be ascribed to a difference in electrical axis due to a difference in habitus between the groups. The effect of exercise on the 2 groups showed only two significant differences. In lead II the decrease in voltage of the R wave was significantly greater in the older group. The frequency of S-T segment depression in one or more of the limb leads was significantly greater in the older group. T wave changes due to exercise were not significantly different in the two groups. From the data of the study the following criteria for an abnormal electrocardio-graphic response to exercise in the age groups considered are suggested: depression of the S-T segment by exercise of more than 0.75 mm. in lead I, 1.5 mm. in lead II, 0.75 mm. in lead III, and 1.75 mm. in lead CF4; inversion of the T waves in leads I, II, or CF4; and low voltage of the T waves in all of the limb leads.