Effects of thyroid gland hormones on cardiovascular system have been known for 
many years. Thyroid gland hormones deficiency is connected with a range of 
metabolic and hemodynamic changes which can contribute to a genesis of heart 
failure. Recent works refer to an importance of connection of thyroid gland 
hormones metabolism with heart insufficiency pathophysiology. That is especially 
a syndrome of a low trijodthyronin level marked as euthyroid sick syndrome which 
is significantly more frequent in patients with chronic heart failure compared 
to a population of healthy individuals. Recent clinical works proved that 
treatment administration of thyroid gland hormones to patients with heart 
failure is connected with favourable hemodynamic changes and increased working 
capacity if the treatment is well tolerated.