Thyrotoxicosis and the heart--a review of the literature.

Thyroid hormone has effects on both the peripheral circulation and the myocardium. These include a decline in the systemic vascular resistance and an increase in cardiac output and cardiac contractility. Exposure to excess thyroid hormone, as occurs in thyrotoxicosis, can not only aggravate preexisting cardiac disease but also by itself lead to cardiac disease. More patients are being reported with thyrotoxicosis in Nigeria while the facilities for diagnosis and treatment are improving and becoming more available. There should therefore be a greater awareness of the cardiac problems associated with thyrotoxicosis, especially atrial fibrillation and cardiac failure. Initial management of heart disease in thyrotoxicosis should focus on the prompt alleviation of hyperthyroidism combined with judicious use of diuretics, digoxin and beta-blockers.