The influence of thyroid extract and hyperthyroidism on the electrocardiogram, with special reference to the T-waves

Abstract

It is apparent, therefore, that there has been no uniformity in the electrocardiographic findings in patients with thyrotoxicosis. The “thyroid” T-waves seem to bear no relation to the pulse rate nor to the basal metabolic rate. Furthermore, there is no constancy in their occurrence. Patients with marked degrees of tachycardia may fail to show T-waves of high amplitude and, conversely, with a slow pulse rate they may be encountered. This would seem to eliminate the heart rate as a factor in determining the height of the T-waves. And similarly it appears that the basal metabolic rate can be shown to have no relation to the amplitude of the T-waves. Characteristic, so-called “thyroid” T-waves have been found in our records of patients with thyrotoxicosis with metabolic rates as low as —32. Some other factor must be sought to explain their occurrence. This factor, we believe, is probably unrelated to the thyroid gland per se, since we have found similar T-waves in cases of neurocirculatory asthenia. Since a high pulse pressure is common in thyrotoxicosis and is not infrequent in neurocirculatory asthenia, we are investigating its relation to the amplitude of the T-waves, but can express no opinion at the present time.