The diagnosis of fatty heart was frequently made by clinicians in the past generation, but in recent years investigators have, to a large extent, avoided the problem. Considerable confusion has arisen from the use of such terms as fatty degeneration, fatty infiltration, fatty metamorphosis, adiposity of the heart (cor adiposum or adipositas cordis) and obesity of the heart. In the past, two distinct conditions have commonly been confused, and both have been alluded to as fatty heart. These are (1) the state in which there is an abnormal increase in the amount of fat in the subepicardial connective tissue and in which penetration or infiltration of fat into the connective tissue lying between the muscle bundles and the muscle fibers takes place and (2) the state in which fatty changes take place within the cell (cytoplasm) and which most pathologists1believe to be the result of a diminished utilization