Studies of electrocardiographic changes during exercise (modified double two-step test).

A method of recording electrocardiograms during the performance of a double two-step exercise test is described. Data obtained from 32 normal subjects and 54 patients are analyzed, and changes in heart rate, S-T segment, T wave and Q-T interval and the occurrence of premature beats described. Criteria for an abnormal response indicating coronary insufficiency are defined. This method retains the merits of Master's original test and in addition has several distinct advantages. STUDIES of the electrocardiogram during and after exercise (walking on a tread-mill ergometer at standard speed and grade) in normal subjects have shown a definite pattern of change in the Q-T interval and no evidence of coronary insufficiency." 2 On the other hand, a large percentage of patients with various cardiopulmonary diseases showed definite and striking abnormal changes. Since Master's "two-step" test3' 4 has been widely used in different clinics, similar studies of the electrocardiogram during exercise were undertaken with modification of the original method. It is the purpose of this report to describe the procedure and to present the results obtained in 32 normal subjects and 54 patients with various cardiovascular disease. These studies suggest that the modified method can be used wherever the exercise electrocardiogram is indicated and that it contributes significantly to its sensitivity and safety.