Changes in electrical parameters of the heart in an experimental model of malignant tumor growth during of hyperthyroidism

Experimental and clinical studies demonstrate the possibility of modulating the development of malignant tumors in thyroid imbalance, in particular hyperthyroidism, which negatively affects the electrophysiology of the heart. In an experimental model of tumor growth during of hyperthyroidism, activation of the tumor was shown. Aim: To study electrophysiological parameters of the mouse heart at the initial stages of transplantable tumor growth during of hyperthyroidism. Material and Methods. In female mice of the C57BL/6 line (n = 20) was created a model of melanoma B16/F10 growth during of hyperthyroidism, which was induced by daily intraperitoneal administration of liothyronine sodium (T3) for a long time and confirmed by determining the content of thyroid-stimulating hormone and triiodothyronine in the blood using the radioimmune method. On the 5th day of T3 administration, the melanoma was transplanted. ECG was recorded non-invasively (ecgTUN- NEL, ecgAVG software, emka TECHNOLOGIES, France) on the 1st and 3rd days of T3 administration, in groups with a tumor – on the 6th day after its transplantation. Results. Pathological changes were revealed: in the group with hyperthyroidism – rhythm irregularity, decrease the amplitude of P and T below the isoline, widening of the QRS, on the 3rd day – the death of 1 mouse was noted due to large-focal myocardial infarction; in the group with melanoma – only sinus arrhythmia and decreased heart rate; in the group with a combination of pathologies – an almost normal ECG, with the exception of an increase in P amplitude and a slight increase in QRS. Conclusion. Already in the early stages of hyperthyroidism or tumor growth, there was a violation of myocardial depolarization/ repolarization processes, capable of causing even death of the animal. In case of comorbidity, the majority of ECG parameters normalized, indicating the inclusion of compensatory mechanisms in the interaction of pathologies. The results demonstrate the need for a deeper study of the mechanisms of interaction of several simultaneously existing pathologies in the body.