[Evaluation of the functional state of the myocardium before and after drug therapy of thyrotoxicosis].

Thirty-five patients with grave and medium-grave thyrotoxicosis were subjected to a quantitative analysis of the initial and end part of the ventricular complex of the ECG before and after specific drug therapy. The data obtained were compared with the radionuclide data on the cardiovascular system, the blood content of T3 and T4 and amount of potassium in the body. At the height of the disease the patients manifested a decrease in the output fraction of the left ventricle, stroke volume, minute volume, coefficient of circulation effectiveness, the deceleration of the lung blood flow and a rise of the total peripheral resistance to the blood flow as compared to normal. The treatment brought about a significant reduction of the area of the QRS complex and ST-T segment, as compared to the findings obtained during the acute period, mainly in the II, III, AVR, AVF and V5 leads of the ECG. A direct correlation was established between the blood content of T3 and the area of the ST-T segment in the II, III, AVR and AVF leads. It has been found that intracellular concentration of potassium may have an effect on the ECG changes revealed in the patients.