Pathology of the cardiomyopathies.

The following article reviews the anatomic and pathologic basis of various cardiomyopathies and illustrates the dilated, hypertrophic, and restrictive types in various echocardiographic planes. Two types of cardiomyopathy are defined: (1) heart muscle disease of unknown cause (idiopathic, primary) and (2) heart muscle disease of known cause or associated with disorders of other organ systems (secondary). Of the cardiomyopathies of unknown cause, the dilated type is the most common. The anatomic diagnosis of hypertrophic cardiomyopathy is based on several morphologic features, the most important of which are asymmetric septal hypertrophy, small left ventricular cavity, and myocardial fiber disarray. Endomyocardial fibrosis with or without peripheral eosinophilia represents the unknown type of restrictive or obliterative form of cardiomyopathy. Selective specific heart muscle diseases (amyloid, iron, myocarditis, toxic, storage disease) are briefly reviewed.