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).

Heart enlargement, congestion of the lungs, decreased movement/functioning of the heart, or heart failure may show on:

 
• echocardiogram  
• chest X-ray  
• chest CT scan  
• coronary angiography  
• Nuclear heart scans (MUGA, RNV)

A heart biopsy may help determine the cause of dilated cardiomyopathy.

Laboratory tests vary depending on the suspected cause.

Cardiomyopathy is classified as idiopathic when all known possible causes have been ruled out.

Treatment

Hospitalization may be required when symptoms are severe. Treatment is essentially the same as that for heart failure. A low-salt diet may be recommended. Advice to stop smoking and stop drinking alcohol may be given, because these habits may make the symptoms worse.

Daily weighing may be recommended. A weight gain of 3 or 4 pounds or more over 1 or 2 days may indicate fluid accumulation. Activity may be restricted as symptoms progress; other patients may need to initiate an exercise program.

Medications for dilated cardiomyopathy may include diuretics, ACE-inhibitors, digitalis, angiotensin II receptor blockers, inotropes, anticoagulants, antiarrhythmics, and beta-blockers.

In some individuals with severely weak heart pumping function, a special pacemaker (called a biventricular pacemaker) may be needed. It makes the contraction of the left and right bottom chambers more efficient. In very specific cases, biventricular pacemakers with defibrillation functions are used.

Some patients may be offered surgical procedures such as the ventricular assist device (VAD), cardiomyoplasty, mitral or tricuspid valve repair, or partial left ventriculectomy. A heart transplant may be considered if heart function is very poor.

Expectations (prognosis)

The outcome varies. There is no known cure for idiopathic dilated cardiomyopathy. Some affected individuals remain stable for long periods, some deteriorate gradually, and some deteriorate rapidly.

Some patients with dilated cardiomyopathy have a risk of unexpected death due to life-threatening rhythm abnormalities (arrhythmias) coming from the bottom chambers of the heart. These patients may need an implantable defibrillator.

Complications

 
• cardiac arrhythmias, including lethal arrhythmias  
• pulmonary (lung) edema  
• total failure of the heart to function (circulatory collapse or shock)  
• side effects of medications, including:       o low blood pressure (hypotension)       o light-headedness, fainting       o gastrointestinal (GI) upset       o digitalis toxicity

Calling your health care provider

Call your health care provider if symptoms indicate cardiomyopathy may be present.

Call your health care provider or go to the emergency room if chest pain, palpitations, faintness, or other new or unexplained symptoms develop.

Prevention

Modify risk factors that can be controlled. Eat a generally well-balanced, nutritious diet, exercise to improve cardiovascular fitness, and avoid or minimize smoking and consumption of alcohol. Consult your primary physician if a recent viral infection leaves you very tired.

Medical Encyclopedia

All ArmMed Media material is provided for information only and is neither advice nor a substitute for proper medical care. Consult a qualified healthcare professional who understands your particular history for individual concerns.