Cardiomyopathy

Cardiomyopathy
Opened left ventricle of heart shows a thickened, dilated left ventricle with subendocardial fibrosis manifested as increased whiteness of endocardium.
Classification and external resources
Specialty	Cardiology
ICD-10	I25.5, I42, I43
ICD-9-CM	425
DiseasesDB	2137
MedlinePlus	001105
Patient UK	Cardiomyopathy
MeSH	D009202

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." Cardiomyopathy and myocarditis resulted in 443,000 deaths in 2013, up from 294,000 in 1990.

Differential diagnosis

Cardiomyopathies are either confined to the heart or are part of a generalized disorder, both often leading to death or progressive heart failure. Other diseases that cause heart muscle dysfunction are excluded, such as coronary artery disease, hypertension, or abnormalities of the heart valves.

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.

Types

Cardiomyopathies can be classified using different criteria:

Hypertrophic cardiomyopathy HE stain

Structural categories of cardiomyopathy (constrictive cardiomyopathy is not pictured)

• Primary/intrinsic cardiomyopathies
  • Genetic
    • Hypertrophic cardiomyopathy
    • Arrhythmogenic right ventricular cardiomyopathy (ARVC)
    • LV non-compaction
    • Ion Channelopathies
    • Dilated cardiomyopathy (DCM)
    • Restrictive cardiomyopathy (RCM)
  • Acquired
    • Stress Cardiomyopathy
    • Myocarditis
    • Ischemic cardiomyopathy
• Secondary/extrinsic cardiomyopathies
  • Metabolic/storage
    • Fabry’s disease
    • hemochromatosis
  • Endomyocardial
    • Endomyocardial fibrosis
    • Hypereosinophilic syndrome
  • Endocrine
    • diabetes mellitus
    • hyperthyroidism
    • acromegaly
  • Cardiofacial
    • Noonan syndrome
  • Neuromuscular
    • muscular dystrophy
    • Friedreich’s ataxia
  • Other
    • Obesity-associated cardiomyopathy

Mechanism

Symptoms may include shortness of breath after physical exertion, fatigue, and swelling of the feet, legs, or abdomen. Additionally, arrhythmias and chest pain may be present.

The pathophysiology of cardiomyopathies is better understood at the cellular level with advances in molecular techniques. Mutant proteins can disturb cardiac function in the contractile apparatus (or mechanosensitive complexes). Cardiomyocyte alterations and their persistent responses at the cellular level cause changes that are correlated with sudden cardiac death and other cardiac problems.

Diagnosis

Among the diagnostic procedures done to determine a cardiomyopathy are:

• Physical exam
• Family history
• Blood test
• EKG
• Echocardiogram
• Stress test
• Genetic testing

Treatment

Treatment may include suggestion of lifestyle changes to better manage the condition. 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.

External links

• Cardiomyopathy at DMOZ
• Cardiomyopathy information for parents.