Thyroid hormones have an effect on every tissue of the organism because they carry out the functions of a catalyst of the oxidize reaction and the main regulator of metabolism. The thyroid hormones have an effect on the heart and cardiovascular system through β-receptors and they are synergistic with catecholamine. The excess and the deficiency of thyroid hormones in an organism is a cause of disorders in the cardiovascular system. These disorders are demonstrated as strong and nagging signs in animals and humans with hyperthyroidism and hypothyroidism. The disorders of heart functioning in hyperthyroidism may result in congestive heart failure (CHF). The development of heart failure in hyperthyroidism is connected with multidirectional changes in the cardiovascular system.
The aim of this work was to prove if diagnostic, transe- sophagal pacing of the left atrium of the heart resulted in changes of the serum Mg concentrations and if there was a dependance between changes of serum Mg level and electrophysiological parameters. The patients with transesophagal pacing induced arrhythmias were characterized by lower input serum Mg level in comparison to those in which the arrhythmias didn't occur. Mg concentration increased after the pacing in their case.