Heart Murmur


What Is It?

A heart murmur is an abnormal sound made by abnormal, turbulent blood flow within the heart. Some common causes of heart murmurs include:

  • A heart valve abnormality — The heart has four valves: the aortic, mitral, tricuspid and pulmonary valves. A heart murmur can occur when any one of these valves develops one of three problems:
    • Stenosis — valve narrowing that interferes with the outflow of blood
    • Insufficiency — valve leakage
    • Regurgitation — leakage that cause a significant backflow of blood

    Many heart valve abnormalities are caused by rheumatic fever, an inflammatory illness that can follow an untreated strep throat infection.

  • Mitral valve prolapse — In this condition, the leaflets of the mitral valve fail to close properly.

  • Congenital heart problems — Congenital means the disorder was present at birth. Congenital heart problems include:
    • Septal defects — These are also known as holes in the heart. They are abnormal openings in the heart’s septum (the wall between the heart’s left and right sides).
    • Patent ductus arteriosus — Before birth, the channel between the pulmonary artery and the aorta (called the ductus arteriosus) allows blood to bypass the lungs because the fetus is not breathing. Once a child is born and his or her lungs are functioning, the ductus arteriosus normally closes. Patent ductus arteriosus occurs when blood flow through the ductus arteriosus continues after birth.

  • Endocarditis — Endocarditis is an inflammation and infection of the heart valves and endocardium, the inner lining of the heart chambers.

  • Cardiac myxoma — A myxoma is benign, soft tumor. Rarely, it can grow inside the heart and obstruct blood flow.

About 10 percent of adults and 30 percent of children (most often between ages 3 and 7) have a harmless (innocent) murmur produced by a normal heart. An innocent murmur can become more apparent if the person being examined is anxious, has a low blood count, has just finished exercising or has a fever.


An innocent murmur does not cause any symptoms. For other types of heart murmurs, symptoms vary depending on the cause. In general, when a heart murmur significantly interferes with the heart’s ability to pump blood, you can experience one or more of the following symptoms:

  • Shortness of breath
  • Light-headedness
  • Episodes of rapid heartbeat
  • Chest pain
  • Decreased tolerance for physical exertion and, in later stages, symptoms of heart failure


Many murmurs are discovered unexpectedly when a doctor listens to someone’s heart with a stethoscope during a routine physical exam. In other cases, when someone is having symptoms of heart problems, the doctor will ask questions related to a specific type of heart ailment. For example, he or she may ask about a history of rheumatic fever because rheumatic fever is a major cause of heart-valve abnormalities. Because endocarditis can follow intravenous drug use or certain medical or dental procedures, your doctor may ask about these risk factors. If the patient is an infant, the doctor will ask whether there is a family history of congenital heart problems.

Because specific heart problems are associated with specific types of murmurs, your doctor often will make a tentative diagnosis based on your medical history, symptoms and the murmur’s distinctive sound and timing (whether the murmur occurs when the heart is pumping or resting). To confirm the diagnosis, your doctor will order diagnostic tests, which may include:

  • Electrocardiography (EKG) — This painless procedure measures the electrical activity of the heart.

  • Chest X-ray — This is used to check for an enlarged heart and for certain congenital abnormalities.

  • Echocardiography — This noninvasive test uses sound waves to create an image of the heart’s structure, including the structure of its valves.

  • Doppler echocardiography — This test is similar to echocardiography, but it creates an image of the heart’s blood flow patterns rather than its structure.

  • Cardiac catheterization — In this test, a small, sterile tube called a catheter is guided into the heart to measure pressures and oxygen levels in the heart’s chambers. A dye is injected through the catheter to produce an X-ray image of the heart’s internal structure and blood flow patterns.

  • Blood tests — Blood tests are used to check for infection in people with suspected endocarditis or pericarditis.

Expected Duration

When an innocent heart murmur is triggered by fever, anxiety or exertion, it can disappear after the triggering condition goes away. In healthy children with more constant innocent murmurs, the murmur often becomes softer as the child grows, and it can disappear completely.

When a murmur is caused by a heart problem, its expected duration depends on the type of underlying cardiac disorder. For example, some forms of endocarditis begin suddenly and progress rapidly over a few days, while others produce milder symptoms over weeks or months. Murmurs caused by valve problems or congenital heart problems usually persist throughout life, and in some cases, they can worsen over time.


There is no way to prevent the congenital heart defects that cause some heart murmurs.

If you are at high risk of endocarditis, your doctor or dentist will prescribe special antibiotics before performing any medical or dental procedure during which bacteria have a chance of entering your blood and infecting your heart. You also can help to prevent endocarditis by avoiding intravenous drug use.

You can prevent many heart-valve abnormalities by preventing rheumatic fever. To do this, take antibiotics exactly as prescribed whenever you have strep throat.

People who already have had one episode of rheumatic fever may need to take antibiotics for up to 10 years after the initial attack to prevent the disease from returning.


Innocent heart murmurs do not need to be treated. Other types of murmurs that do not cause any symptoms also may not require any treatment, although they should be monitored regularly by your doctor. When treatment is required, it varies depending on the cause of the murmur.

  • Heart valve abnormalities — Depending on the type of abnormality, medications such as digitalis (Lanoxin) or angiotensin-converting enzyme (ACE) inhibitors may be used to treat symptoms. Severe cases can be corrected surgically, often by replacing the diseased valve with an artificial one.

  • Mitral valve prolapse — In people with a mitral valve that is significantly deformed, antibiotics may be given to prevent endocarditis. People with cardiac arrhythmias or chest pain are treated with beta-blockers (medications that reduce the heart’s workload by slowing the heart rate and reducing the force of heart muscle contractions) or drugs that prevent heart-rhythm abnormalities. In rare cases in which prolapse progresses to severe mitral regurgitation, the abnormal mitral valve will be repaired or replaced surgically.

  • Congenital heart problems — Most cases of congenital heart disease must be corrected surgically.

  • Endocarditis — When endocarditis is caused by a bacterial infection, it usually is treated with two to six weeks of antibiotics. In most cases, this antibiotic treatment is given intravenously (into a vein) while the patient is hospitalized. Sometimes, the infected heart valve must be replaced surgically.

  • Cardiac myxoma — A cardiac myxoma is removed surgically.

When To Call A Professional

Call your doctor if you begin to experience:

  • Shortness of breath
  • Persistent light-headedness
  • Episodes of rapid or irregular heartbeat
  • Chest pain


In people with innocent heart murmurs, the prognosis is excellent. For people with other types of heart murmurs, the prognosis depends on the type of underlying heart problem and its severity. In general, even when heart surgery is required, the prognosis is good.

Johns Hopkins patient information

Last revised:

Diseases and Conditions Center

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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.