EFFECTS OF REPEATED WORK TESTS AND ADRENERGIC BETA-BLOCKADE ON ELECTROCARDIOGRAPHIC ST AND T CHANGES

The effect of a number of repeated work tests on different electrocardiographic ST and T changes has been studied and the effect compared with that after an adrenergic beta-receptor blockade. In subjects with different ECG changes but without any apparent organic heart disease there was a normalization of the ST and T changes during the period of repeated work tests. The normalizing effect was almost identical to that after adrenergic blockade. Different patterns of ST and especially T depressions on the ECG at rest, in the standing position and during and after work are described. In patients with organic heart diseases the repeated work tests generally had no effect on the ECG patterns typical of coronary insufficiency and myocarditis. In one patient with signs of a vasoregulatory disturbance there seemed to be ST and T changes of different origin, probably both functional and organic. The effect of the adrenergic blockade was almost identical to that of the repeated work tests. The study gives support to the results of a previous investigation in which the possibility of using an adrenergic blockade for differentiating between ECG changes of functional and organic origin was pointed out. The normalization effect of 4–6 work tests over a period of 4–6 days on functional ST and T changes on the ECG is supposed to be due to a physical and psychic adaptation to the work tests and to the examination situation.