Chapter 15

• Symptoms and signs of heart failure with predominant right-sided findings.
• Normal left and right ventricular size and systolic function with dilated atria.
• Diastolic ventricular functional abnormalities suggestive of reduced ventricular compliance.
• Increased ventricular filling pressure (left > right) and reduced cardiac output.

### Definitions and Terminology

#### Restrictive Cardiomyopathy

The World Health Organization defines cardiomyopathies as heart muscle diseases of unknown cause; restrictive cardiomyopathy is one of three forms (the others are dilated cardiomyopathy and hypertrophic cardiomyopathy). Restrictive cardiomyopathies are classified as primary (endocardial fibrosis and eosinophilic endomyocardial disease) or secondary to cardiac infiltrative diseases. Diseases with a defined cause that produce a dilated cardiomyopathy with restrictive characteristics are specifically excluded from this classification of cardiomyopathies.

For the clinician, restrictive cardiomyopathy is usually due to infiltrative diseases, such as the cardiomyopathy that occurs in systemic amyloidosis, hemochromatosis, sarcoidosis, and glycogen storage diseases (Table 15–1). These secondary cardiomyopathies are included because the cardiac involvement typically displays features of restrictive physiology that are pivotal in the diagnosis. Restrictive cardiomyopathies represent less than 1% of cases of congestive heart failure, and most of these are of the secondary form.

Table 15–1. Classification of Restrictive Cardiomyopathy.

#### Restrictive Physiology

Also known as diastolic dysfunction and diastolic heart failure, restrictive physiology requires a precise definition, even though clinical methods often yield only indirect evidence of this functional abnormality. It is characterized by elevated filling pressures and impaired ventricular filling from myocardial or endocardial abnormalities in a nondilated ventricle with no significant impairment of systolic performance. Numerous common cardiac diseases can produce the functional abnormalities of the restrictive or diastolic type, but the diseases are not classified as a restrictive cardiomyopathy.

#### Infiltrative Cardiomyopathy

An alternative term applied to many of these diseases, infiltrative cardiomyopathy emphasizes that the endocardial, interstitial, or intracellular infiltration of a variety of materials (eg, extensive collagen bundles, amyloid protein) is the central histologic and pathophysiologic feature. The infiltration of material with tissue less compliant than normal myocardium and the increase in the wall thickness of the cardiac chambers reduce chamber compliance.

#### Obliterative Cardiomyopathy

This term is sometimes used to describe the reduction in left ventricular chamber volume as the consequence of endocardial fibrosis and extensive mural thrombus formation.

### Pathophysiology

#### Abnormalities in Diastolic Function

Although there are several causes of abnormal diastolic function in restrictive cardiomyopathy, loss of ventricular chamber compliance is the most common. Fibrosis and the presence of amyloid and hemosiderin all ...

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