SummaryThe effects of the l.V. administration of digitalic glucosides on the circulatory dynamics of patients with heart failure have been reviewed.In heart failure due to the usual causes (hypertensive, valvular, and coronary diseases), an increase in the cardiac output and a fall in intracardiac and pulmonary arterial pressures have been observed 30 to 60 min. after the injection. The particular types of heart failure liable to be accompanied by an increase in heart output (arteriovenous aneurysms, Paget’s disease, beri-beri, anaemia, hyperthyroidism) present the same haemodynamic behavior.During right heart failure secondary to chronic lung diseases with severe anoxemia, the I.V. injection of digitalic drugs causes a decrease in the right ventricular diastolic pressure and an increase in the cardiac output, even when the latter was above the normal values; this indicates that in such cases, although apparently increased, the cardiac output is indeed insufficient for the metabolic needs of the patient.In constrictive pericarditis, the I.V. injection of digitalis docs not modify to a significant amount the volume/minute and the intracardiac and pulmonary vascular pressures; this test is therefore of interest since it enables to distinguish that which, on a given clinical and haemodynamic pattern, is the result of cardiac constriction or of heart failure.