Definition

Cardiomyopathy refers to heart muscle disease. The damaged heart does not effectively pump blood. The disease usually progresses to the point where patients develop life-threatening heart failure . In addition, people with cardiomyopathy are more likely to have irregular heartbeats or arrhythmias .

There are two major categories of cardiomyopathy: ischemic and nonischemic cardiomyopathy. Ischemic cardiomyopathy occurs when the heart muscle is damaged from heart attacks due to coronary artery disease. Nonischemic cardiomyopathy, the less common category, includes types of cardiomyopathy that are not related to coronary artery disease.

There are three main types of nonischemic cardiomyopathy:

• Dilated—Damaged heart muscles lead to an enlarged, floppy heart. The heart stretches as it tries to compensate for weakened pumping ability.
• Hypertrophic—Heart muscle fibers enlarge abnormally. The heart wall thickens, leaving less space for blood in the chambers. Since the heart does not relax correctly between beats, less blood fills the chamber and is pumped from the heart.
• Restrictive—Portions of the heart wall become rigid and lose their flexibility. Thickening often occurs due to abnormal tissue invading the heart muscle.

	Hypertrophic Heart
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Causes

In many cases, the exact cause is not known. Possible causes include:

Dilated

The cause of the initial damage is often not found, but may include:

• Ischemic heart disease with decreased blood flow to the heart
• Infections, usually viral
• Chronic exposure to toxins, including alcohol and some chemotherapy drugs
• A rare complication of pregnancy or childbirth (probably immune-related)
• Rarely, other illnesses, including rheumatoid arthritis, diabetes, or thyroid disease

Hypertrophic

Causes may include:

• Inherited: sometimes present at birth but often developing in teens
• Aging: associated with hypertension

Restrictive

This is usually related to another condition, such as:

• Amyloidosis—protein fibers collect in the heart muscle
• Sarcoidosis–small inflammatory masses (granulomas) form in many organs
• Hemochromatosis—too much iron in the body

Risk Factors

A risk factor is something that increases your chance of getting a disease or condition.

• Family members with cardiomyopathy
• Alcoholism
• Obesity
• Diabetes
• Hypertension
• Coronary artery disease
• Certain drugs

Symptoms

Symptoms vary, depending on the type of cardiomyopathy and its severity. Patients with hypertrophic cardiomyopathy often do not notice any symptoms. Sudden cardiac death may be the first indication of the condition. In dilated cardiomyopathy, it may take years for symptoms to develop. Blood clots may form due to the abnormal pooling of blood in the heart. If a clot moves to another part of the body ( embolism ), symptoms associated with that organ (the brain, for example) may be the first sign of the heart disease.

Cardiomyopathy ultimately leads to heart failure and the following symptoms:

• Fatigue
• Weakness
• Shortness of breath, often worse when lying down or with exertion
• Cough
• Swelling in feet or legs
• Chest pain
• Irregular heart rhythm

Diagnosis

The doctor will:

• Ask about your symptoms and medical history
• Perform a physical exam
• Listen to your heart with a stethoscope (Cardiomyopathies often produce heart murmurs and other abnormal heart sounds.)

Tests may include:

• Chest x-ray—to look for heart enlargement
• Electrocardiogram—a test that records the heart's activity by measuring electrical currents through the heart muscle
• Echocardiogram—a test that uses high-frequency sound waves (ultrasound) to examine the size, shape, and motion of the heart
• Blood tests—to check for damage to the heart and other organs, and possibly the underlying cause(s) of the cardiomyopathy
• Cardiac catheterization —a tube-like instrument inserted into the heart through a vein or artery (usually in the arm or leg) to detect problems with the heart and its blood supply
• Heart biopsy—removal of a sample of heart tissue for testing

Treatment

When heart failure is due to blockages in the coronary arteries, treatment directed at relieving these blockages through angioplasty, stent placement, or coronary artery bypass surgery may lead to improvements in heart function and symptoms. For certain genetic causes, other treatments may also lead to improvements in function. For many patients, however, treatment is aimed at relieving symptoms and prevent further damage.

Lifestyle Modification

Changes aim to eliminate anything that contributes to the disease or worsens symptoms:

• Avoid alcohol.
• If you are overweight, lose weight.
• Eat a low-fat diet to minimize the risk and extent of coronary artery disease.
• Limit salt intake to decrease fluid retention.
• Follow your doctor's advice for exercise. You may need to limit physical activity.

Medications

Medications may include:

• Diuretics—to eliminate extra fluid
• ACE inhibitors—to help relax blood vessels, lower blood pressure, and decrease the heart's workload
• Digitalis—to slow and regulate the heart rate, and modestly increase its force of contractions
• Calcium channel blockers—to lower blood pressure and relax the heart
• Beta blockers—to slow the heart and limit disease progression
• Anti-arrhythmia agents—to prevent irregular heart rhythms
• Immune system suppressants—including steroids (depending on underlying cause)

Surgery

Surgical options include:

• A pacemaker may be implanted to improve the heart rate and pattern.
• For patients with hypertrophic disease, doctors may remove part of the thickened wall separating the heart's chambers. Surgery may be needed to replace a heart valve.
• A heart transplant may be possible for otherwise healthy patients who do not respond to medical treatment. Candidates often wait a long time for a new heart. Those waiting may temporarily receive a ventricular assist device, which is a mechanical pump that assumes some or most of the heart's pumping function.

Prevention

Aggressively treating hypertension, coronary artery diseases, and their risk factors is the best way to prevent most cases of cardiomyopathy. Other, less common causes, however, are not preventable. People with a family history of the disease should ask the doctor about screening tests, especially before starting an intense exercise program.

RESOURCES:

American Heart Association
http://www.americanheart.org

The Cardiomyopathy Association
http://www.cardiomyopathy.org/homepage.htm

CANADIAN RESOURCES:

Canadian Cardiovascular Society
http://www.ccs.ca/home/index_e.aspx

Canadian Family Physician
http://www.cfpc.ca/cfp/

References:

Braunwald E, Zipes DP, Libby P, et al. Heart Disease: A Textbook of Cardiovascular Medicine. 6th ed. Philadelphia, PA: WB Saunders Company; 2001.

Cecil RL, Goldman L, Bennett JC. Cecil Textbook of Medicine. 21st ed. Philadelphia, PA: WB Saunders Company; 2000.

Dambro MR. Griffith's 5-Minute Clinical Consult. Philadelphia, PA: Lippincott Williams & Wilkins; 2001.

National Heart, Lung, and Blood Institute website. Available at: http://www.nhlbi.nih.gov/. Accessed October 13, 2005.

Primary Care Medicine. 4th ed. Philadelphia, PA: Lippincott Williams and Wilkins; 2000.

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