Dilated cardiomyopathy

Alternative names

Cardiomyopathy - dilated; Congestive cardiomyopathy

Definition

Dilated cardiomyopathy is a disorder in which the heart muscle is weakened and cannot pump blood efficiently. The wall (muscle) of the ventricles may be of normal, increased or reduced thickness, but the ventricular diameter is always enlarged. This causes decreased heart function that affects the lungs, liver, and other body systems.

Causes, incidence, and risk factors

Dilated cardiomyopathy represents the end result of more than 50 different diseases. Causes of dilated cardiomyopathy include genetic disorders such as Friedreich's ataxia or myotonic dystrophy, myocarditis (a viral infection of the heart muscle), alcoholism, coronary artery disease, valvular heart disease, and others.

In many patients, however, a cause cannot be identified, and their cardiomyopathy is considered "idiopathic." Idiopathic cardiomyopathies are likely to be genetically determined.

Dilated cardiomyopathy is the most common of the cardiomyopathies, comprising more than 90% of all cases that are referred to specialized centers.

Symptoms often develop gradually and usually include symptoms of right heart failure, left heart failure, or both.

Symptoms

• shortness of breath on exertion
  
• fatigue
  
• breathing difficulty when lying down (orthopnea)
  
• waking up at night short of breath
  
• edema (swelling of the ankles)
  
• irregular heartbeat (palpitations - a feeling of racing or skipping of the heart)
  
• decreased urine output (less urination)
  
• chest pain
  

Chest pain is surprisingly common and affects not only patients with coronary artery disease but also up to 35% of patients with normal coronary arteries

Signs and tests

Dilated cardiomyopathy usually causes heart failure.

A physical examination may reveal an irregular or a rapid heartbeat. There may be distended neck veins, enlarged liver, edema (swelling of the ankles), and signs of pleural effusion (fluid around the lungs). Listening to the chest with a stethoscope may reveal lung crackles or abnormal heart sounds. Blood pressure may be low or may drop upon rising (orthostatic hypotension).

An ECG may show an enlarged heart, arrhythmias, or other abnormalities such as pseudoinfarction (a false appearance of having suffered a heart attack).