Cardiomyopathy

Cardiomyopathy
Classification and external resources
Opened left ventricle of heart shows a thickened, dilated left ventricle with subendocardial fibrosis manifested as increased whiteness of endocardium.
ICD-10	I42.0
ICD-9	425.4
DiseasesDB	2137
MedlinePlus	001105
MeSH	D009202

Cardiomyopathy, which literally means "heart muscle disease", is the deterioration of the function of the myocardium (i.e., the actual heart muscle) for any reason. People with cardiomyopathy are often at risk of arrhythmia or sudden cardiac death or both. Cardiomyopathy can often go undetected, making it especially dangerous to carriers of the disease.

Although in theory the term "cardiomyopathy" could apply to almost any disease affecting the heart, in practice it is usually reserved for "severe myocardial disease leading to heart failure".

Classification

Cardiomyopathies can be categorized as extrinsic or intrinsic.

• An extrinsic cardiomyopathy is a cardiomyopathy where the primary pathology is outside the myocardium itself. Most cardiomyopathies are extrinsic, because by far the most common cause of a cardiomyopathy is ischemia. The World Health Organization calls these specific cardiomyopathies:

• An intrinsic cardiomyopathy is defined as weakness in the muscle of the heart that is not due to an identifiable external cause. This definition was used to categorize previously idiopathic cardiomyopathies although specific external causes have since been identified for many. For example, alcoholism has been identified as a cause for some forms of dilated cardiomyopathy. To make a diagnosis of an intrinsic cardiomyopathy, significant coronary artery disease should be ruled out (amongst other things). The term intrinsic cardiomyopathy does not describe the specific etiology of weakened heart muscle. The intrinsic cardiomyopathies consist of a variety of disease states, each with their own causes. Many intrinsic cardiomyopathies now have identifiable external causes including drug and alcohol toxicity, certain infections (including Hepatitis C), and various genetic and idiopathic (i.e., unknown) causes.

It is also possible to classify cardiomyopathies functionally, as involving dilation, hypertrophy, or restriction.

Types

• Primary/intrinsic cardiomyopathies
  • Genetic
    • Hypertrophic cardiomyopathy (HCM or HOCM)
    • Arrhythmogenic right ventricular cardiomyopathy (ARVC)
    • Isolated ventricular non-compaction
    • Mitochondrial myopathy
  • Mixed
    • Dilated cardiomyopathy (DCM)
    • Restrictive cardiomyopathy (RCM)
  • Acquired
    • Takotsubo cardiomyopathy
    • Loeffler endocarditis

• Secondary/extrinsic cardiomyopathies
  • Metabolic/storage
    • amyloidosis
    • hemochromatosis
  • Inflammatory
    • Chagas disease
  • Endocrine
    • diabetic cardiomyopathy
    • hyperthyroidism
    • acromegaly
  • Toxicity
    • chemotherapy
    • Alcoholic cardiomyopathy
  • Neuromuscular
    • muscular dystrophy
  • Nutritional diseases
  • Other
    • "Ischemic cardiomyopathy" is a weakness in the muscle of the heart due to inadequate oxygen delivery to the myocardium with coronary artery disease being the most common cause. Not supported by current cardiomyopathies classification schemes.

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.

EKG 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

Treatment depends on the type of cardiomyopathy, but may include medication, implanted pacemakers, defibrillators, or ventricular assist devices (LVADs), or ablation. 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. Due to the severity of the disease, treatment requires the use of numerous chemicals and drugs, which have to be taken for the rest of the patient's life.

External links

• Cardiomyopathy at the Open Directory Project