Thyroid hormones are essential to maintain normal function of many systems including the cardiovascular system. Their excess or deficiency may upset human body homeostasis. Hyperthyroidism leads to cardiovascular system’s hyperdynamic status which is characterized by tachycardia, increased difference between systolic and diastolic arterial pressure, significant increase of the stroke volume and improvement of the left ventricular diastolic function. Long-lasting thyrotoxicosis in patient with heart disease may result in atrial fibrillation, deterioration of angina pectoris or congestive heart failure.
Hypothyroidism leads to hemodynamic disturbances which are quite different than those observed in hyperthyroidism, but cardiac symptoms are scant in clinical practice. Hypothyroidism’s clinical significance is limited to atherosclerosis progression and intensification of ischaemic heart disease symptoms. Both leads to symptomatic cardiovascular system failure or its deterioration. We should emphasize that cardiovascular system dysfunction associated with thyrometabolic disturbances subsides when euthyreosis is restored. It sounds promising that there are reports suggesting a potential advantage of thyroxin treatment in patients with acute or chronic cardiovascular system diseases. These hypotheses result from the observations that heart dysfunction in hypothyroidism is similar to that observed in heart failure. (Pol J Endocrinol 2007; 58 (3): 228-235)