Poremećaji kardiovaskularne funkcije i ehokardiografskih parametara srca u manifestnom i subkliničkom hipotireoidizmu

Abstract

Decreased thyroid function leads to changes in cardiovascular hemodynamics, changes in myocardial contractility and accelerated atherosclerosis. Peripheral circulation in hypothyroidism is characterized by increased vascular resistance and prolonged circulatory duration. Endothelial dysfunction that occurs in hypothyroid patients predisposes to the development of atherosclerosis, and increases arterial stiffness. The influence of subclinical hypothyroidism on the cardiovascular system is manifested through systolic and diastolic cardiac function, myocardial anatomy and effort endurance. Subclinical hypothyroidism in acute myocardial infarction increases cardiac mortality 3.6-fold and 2.3-fold overall mortality. Overt hypothyroidism is characterized by hypercholesterolemia, significantly elevated LDL cholesterol and apolipoprotein B. Subclinical hypothyroidism is associated with a small increase in LDL cholesterol, a decrease in HDL cholesterol, increasing the risk of developing atherosclerosis and coronary artery disease. Isovolumic relaxation time (IVRT) is significantly prolonged in hypothyroid patients, which indicates impaired passive relaxation of the left ventricle. Global right ventricular strain and right ventricular free wall strain are reduced in hypothyroid patients compared to healthy subjects. These changes are completely reversible after the application of thyroid replacement therapy and mostly after 6 months of L-thyroxine administration.