Heart failure is the final state of virtually all forms of primary or secondary heart disease. In this abnormal pathophysiological syndrome, a wide spectrum of clinical physiological cardiac states (congenital, valvular, rheumatic, hypertensive, coronary and cardiomyopathic) as well as some hyperkinetic circulatory/metabolic states leads to a low, normal or even high cardiac output--inadequate, however, in front of the requirements of the metabolizing tissues. In this revision article the A.A. successively consider the main causes of cardiac-circulatory failure, pointing out, at the end, the usefulness of recognizing the underlying and the precipitating causes of heart failure, in order to rapidly establish the appropriate therapeutic and preventive approaches. Four clinical cases are presented illustrating some of the underlying "treatable" causes of heart failure systemic hypertension, iatrogenic hypophosphatemia, chronic alcoholism and hemochromatosis.