A CORRELATION OF CLINICAL AND HEMODYNAMIC STUDIES IN PATIENTS WITH HYPOTHYROIDISM1

Abstract

The cardiac output index at rest in 12 patients with myxedema (1.88 [plus or minus] SD 0.8 l/minute/m2) was the same as in 7 patients in chronic congestive heart failure from ultimately fatal myocardial disease. In the patients with hypothyroidism the reduction in cardiac output was proportional to the reduction in O2 consumption; in the congestive failure patients, however, the reduction in output occurred in the presence of a normal O2 consumption and hence the arteriovenous difference was quite elevated. Pressures within the right heart were normal in hypothyroidism and elevated in failure. With exercise the cardiac output, arteriovenous difference and intracardiac pressures in the patients with myxedema responded as in healthy persons, while in the patients with congestive failure inadequate cardiac output responses, abnormal rises of arteriovenous differences and intra-cardiac pressures were observed during exercise. The frequent finding of "diastolic dips" in the right ventricular pressure tracings of the patients with myxedema suggested that pericardial effusion was frequently responsible for the common enlargement of the cardiac silhouette. These data suggest that the decreased circulatory load of hypothyroidism overshadowed any decreased myocardial reserve caused by the myxedematous state.