THE STUDY OF HEMODYNAMICS AND ELECTROCARDIOGRAPHIC CHANGES BEFORE AND AFTER EXERCISE

Abstract

To reaffirm hemodynamically the electrocardiographic criteria for the evaluation of an optimal exercise level proposed by N. Kimura in 1956, exercise study was performed in 86 patients with ischemic heart disease and/or concomitant systemic hypertension. Cardiac output at rest and after a roughly estimated level of exercise was determined by means of Dye-dilution technique using Earpiece method. The following results were obtained.1. After exercise such as to cause more than 1 mm of ST depression, mean cardiac output increased scarcely and mean stroke volume decreased. This exercise level developed insufficiency in coronary flow so that this was indicative of excessive cardiac load.2. Following exercise such as causing more than 1 mm of ST elevation, this exercise level might be suggestive of excessive cardiac load, although the statistical significance in their hemodynamic responses was not available because of the lack of cases.3. The subjects showing significant changes of T wave but no deviation of ST segment after exercise were divided into the 3 groups ie, group 3, 4, 5, according to the type of T wave changes.In each of these 3 groups, however, both mean cardiac index and mean stroke index increased modestly to the identical level regardless of T wave changes. As a whole the statistical significance in the mean hemodynamic responses was discovered only between group 1 and group 3, 4, 5. Although group 3 showing postexertional flattening of T wave wiuhout significant deviation of ST segment might be indicative of an optimal load, its validity has remained equivocal for some reasons as described before. Therefore only these exercise levels such as causing shallowing of negative T wave or augmentation of positive T wave without any significant deviation of ST segment were considered to be optimal for any patient except for cases showing an unusual augmentation of T wave.4. In conclusion the present study demonstrated that the electrocardiographic criteria for physical training proposed by N. Kimura was valid as a whole not only in the clinical practice but also in the hemodynamic aspects.Several interesting problems which made the decision equivocal has remained unsolved, however.