The Precordial Electrocardiogram during Exercise

C ONTINUOUS recording of the precordial electrocardiogram during vigo-ous exereise has been tested in 150 persons through the use of a new lead system, a new method of electrode attachment, and special types of electrodes and electrode paste. This technic has resulted in tracings that are almost free of skeletal muscle potentials and baseline shift in subjects performing the Master's 2-step test. Many studies of the electrocardiogram taken after the completion of exercise have been reported.' 4 While much valuable information has been acquired from the postexercise electrocardiogram, the test has distinct limitations. The technic is not without hazard, since patients with heart disease may develop serious reactions before the completion of the exercise.12 Consequently patients with abnormal resting electrocardiograms are not usually tested. Continuous recording of the electrocardiogram during the actual performance of exercise may have the following potential advantages: significant changes may develop during but not after the exercise; the test can be terminated at the first evidence of definite electrocardiographic abnormality or perhaps safely continued beyond any limits previously prescribed; the prompt recognition and timing of the earliest electrocardiographic manifestations of ischemia or arrhythmia permit greater flexibility in the amount of