Definition

A heart murmur is an abnormal sound made by turbulent blood flow in the heart. Some adults and many children have incidental heart murmurs that are harmless (benign). At least 30% of children may have an innocent heart murmur at some point during childhood. However, some heart murmurs can signal an underlying heart problem.

	Heartbeat: Anatomy of the Heart
	© 2008 Nucleus Medical Art, Inc.

Causes

Benign heart murmurs are caused by:

• Turbulent blood flow through a highly dynamic, but normal circulatory system
• Slight valvular abnormality with no long-term consequences (such as mitral valve prolapse , a congenital condition)

Abnormal heart murmurs can be due to:

• Structural abnormalities of the heart valve (most common):
  • Congenital (present at birth) defects
  • Acquired (eg, arteriosclerosis , rheumatic fever )
• Structural abnormality of the heart muscle:
  • Congenital defects
  • Acquired (eg, myocardial infarction , congestive heart failure , long-standing high blood pressure )
• Abnormal holes in the structure of the heart persisting after birth:
  • Septal defects —connection between the heart's chambers
  • Patent ductus-arteriosus —connection between the major artery and vein of the heart
• Endocarditis —infection of the inner lining of heart valves and chambers (endocardium)
• Pericarditis —inflammation of the saclike membrane that encloses the heart (pericardium). This may be caused by:
  • Severe kidney disease
  • Heart attack
  • Autoimmune disease
• Cardiac myxoma—a benign soft tumor within the heart (rare)

Risk Factors

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

Risk factors for normal heart murmurs include:

• Age: 3-7 years old
• Pregnancy

Risk factors for abnormal heart murmurs include:

• Rheumatic fever
• Arteriosclerosis
• High blood pressure
• Autoimmune disease
• Congenital heart defects or disease

Symptoms

Benign heart murmurs usually cause no symptoms. Patients with mitral valve prolapse sometimes complain of vague chest discomfort and other symptoms. It remains unclear whether or not the valvular abnormality is causing the symptoms.

Symptoms of abnormal heart murmurs include:

• Shortness of breath
• Lightheadedness
• Chest pain
• Palpitations (feeling of rapid or irregular heartbeat)
• Exercise intolerance

Diagnosis

Most benign heart murmurs are diagnosed during the course of a routine physical exam with a stethoscope. Some abnormal heart murmurs are also discovered this way. Other abnormal heart murmurs are discovered initially by their symptoms.

Tests may include:

• Electrocardiogram —a test that records the heart's electrical activity using electrodes attached to the surface of the chest. This does not diagnose the cause of the murmur, but can provide other useful information about the condition of the heart.
• Chest x-ray—an x-ray to determine the approximate size and shape of the heart, and the presence of associated lung swelling (pulmonary edema)
• Echocardiogram —a test that uses high-frequency sound waves (ultrasound) to examine the size, shape, and motion of the heart
• Cardiac catheterization —a tube inserted into the heart through an artery (usually in the groin) to detect problems with the heart's structure, function, and blood supply
• Blood tests—to check for evidence of a recurrent heart attack or other diseases that may affect the heart (eg, kidney disease, infections, autoimmune conditions)

Treatment

Benign heart murmurs require no treatment. Treatment of other heart murmurs depends on the underlying cause and extent of the problem.

Treatments include:

Medication

Medications can either treat the cause of the heart abnormality associated with the murmur or help compensate for its dysfunction:

• Diuretics, angiotensin-converting enzyme inhibitors, digitalis—to treat heart failure
• Antibiotics—to prevent or treat endocarditis
• Anti-inflammatory drugs—to treat pericarditis

Surgery

Surgery is often necessary to treat severe heart abnormalities:

• Replacement of defective heart valves with artificial ones
• Correction of congenital heart defects
• Removal of heart tumors

Prevention

Preventing benign heart murmurs are unnecessary. To help reduce your risk of developing an abnormal heart murmur:

• Get prompt testing and treatment for strep throat to prevent rheumatic fever.
• Reduce your risk of atherosclerosis to help prevent valvular heart disease in the distant future. To do this:
  • Eat a low fat diet.
  • Get regular exercise.
  • Monitor blood pressure.

If you have valvular heart disease, even if you have no symptoms, you may be at risk for endocarditis. It may be necessary to take antibiotics before and after any medical or dental procedure that could allow bacteria to enter your blood stream. Also, never use intravenous drugs.

RESOURCES:

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

Heart Information Network
http://www.heartinfo.org

CANADIAN RESOURCES:

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

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

References:

American Heart Association website. Available at: http://www.americanheart.org . Accessed October 13, 2005.

Harvard Medical School Consumer Health Information website. Available at: http://hms.harvard.edu/hms/info.asp . Accessed October 13, 2005.

The Merck Manual of Medical Information—Home Edition . Simon and Schuster, Inc; 2000.

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