Opened left ventricle of heart shows a thickened, dilated left ventricle with subendocardial fibrosis manifested as increased whiteness of endocardium.
|Classification and external resources|
Cardiomyopathy (literally "heart muscle disease") is the measurable deterioration for any reason of the ability of the myocardium (the heart muscle) to contract, usually leading to heart failure. Common symptoms include dyspnea (breathlessness) and peripheral edema (swelling of the legs). Those with cardiomyopathy are often at risk of dangerous forms of irregular heart rate and sudden cardiac death. The most common form of cardiomyopathy is dilated cardiomyopathy. Although the term "cardiomyopathy" could theoretically apply to almost any disease affecting the heart, it is usually reserved for "severe myocardial disease leading to heart failure".
The term 'cardiomyopathy' only came into use about 50 years ago. The definition has advanced as knowledge has increased and new diagnostic tests have been introduced. In 2008, the European Society of Cardiology defined it as a myocardial disorder in which the heart muscle was structurally abnormal and functioned abnormally.   Two years earlier, the American Heart Association had pointed out that cardiomyopathies were either confined to the heart or were part of a generalized disorder, both often leading to death or progressive heart failure. Both groups excluded heart disease due to coronary artery disease, hypertension, abnormalities of the heart valves, and heart disease present at birth from the definition. Earlier, simpler, categories such as intrinsic, (defined as weakness of the heart muscle without an identifiable external cause), and extrinsic, (where the primary pathology arose outside the myocardium itself), became more difficult to sustain. For example, as more external causes were recognized, the intrinsic category became smaller. Alcoholism, for example, has been identified as a cause of dilated cardiomyopathy, as has drug toxicity, and certain infections (including Hepatitis C). On the other hand, molecular biology and genetics have given rise to the recognition of various genetic causes, increasing the intrinsic category. For example, mutations in the cardiac desmosomal genes as well as in the DES gene may cause arrhythmogenic right ventricular cardiomyopathy (ARVC).
At the same time, a more clinical categorization of cardiomyopathy as 'hypertrophied', 'dilated', or 'restrictive', became difficult to maintain when it became apparent that some of the conditions could fulfill more than one of those three categories at any particular stage of their development.
The current American Heart Association definition divides cardiomyopathies into primary, which affect the heart alone, and secondary, which are the result of illness affecting other parts of the body. These categories are further broken down into subgroups which incorporate new genetic and molecular biology knowledge.
- Primary/intrinsic cardiomyopathies
- Secondary/extrinsic cardiomyopathies
- Nutritional diseases
Signs and symptoms
Symptoms and signs may mimic those of almost any form of heart disease. Chest pain is common. Mild myocarditis or cardiomyopathy is frequently asymptomatic; severe cases are associated with heart failure, arrhythmias, and systemic embolization. Manifestations of the underlying disease (e.g., Chagas' disease) may be prominent. Most patients with biopsy-proven myocarditis report a recent viral prodrome preceding cardiovascular symptoms.
ECG abnormalities are often present, although the changes are frequently nonspecific. A pattern characteristic of left ventricular hypertrophy may be present. Flat or inverted T waves are most common, often with low-voltage QRS complexes. Intraventricular conduction defects and bundle branch block, especially left bundle branch block, are also common. An echocardiogram is useful to detect wall motion abnormalities or a pericardial effusion. Chest radiographs can be normal or can show evidence of congestive heart failure with pulmonary edema or cardiomegaly.
Treatment depends on the type of cardiomyopathy and condition of disease, but may include medication (conservative treatment) or iatrogenic/implanted pacemakers for slow heart rates, defibrillators for those prone to fatal heart rhythms, ventricular assist devices (VADs) for severe heart failure, or ablation for recurring dysrhythmias that cannot be eliminated by medication or mechanical cardioversion. The goal of treatment is often symptom relief, and some patients may eventually require a heart transplant. Treatment of cardiomyopathy (and other heart diseases) using alternative methods such as stem cell therapy is commercially available but is not supported by convincing evidence.
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- Cardiomyopathy at DMOZ
- Cardiomyopathy information for parents.
-  The CMA information on cardiomyopathy