Heart murmurs

By Mayo Clinic Staff
May 27, 2022

Overview

Heart murmurs are sounds — such as whooshing or swishing — made by rapid, choppy (turbulent) blood flow through the heart. The sounds can be heard with a device called a stethoscope. A typical heartbeat makes two sounds like "lubb-dupp" (sometimes described as "lub-DUP") when the heart valves are closing.

Heart murmurs can be present at birth (congenital) or develop later in life (acquired).

Some heart murmurs are harmless (innocent). An innocent heart murmur is not a sign of heart disease and doesn't need treatment. Other heart murmurs may be a sign of a serious heart condition. Tests are needed to check the heart and heart valves. Heart murmur treatment depends on the cause.

Symptoms

Harmless (innocent) heart murmurs usually don't cause any other symptoms.

Symptoms of worrisome heart murmurs depend on the cause. Heart murmur symptoms may include:

  • Blue or gray fingernails or lips
  • Chest pain
  • Cough that doesn't go away
  • Dizziness
  • Swollen liver
  • Swollen neck veins
  • Fainting
  • Heavy sweating with little or no activity
  • In infants, poor appetite and lack of growth
  • Shortness of breath
  • Swelling or sudden weight gain

When to see a doctor

Most heart murmurs aren't serious. If you're concerned about a heart murmur, make an appointment to see your primary care provider. Your provider can tell you if follow-up care is needed.

Causes

A heart murmur is caused by rapid, choppy (turbulent) blood flow through the heart. A heart murmur may happen:

  • When the heart is filling with blood (diastolic murmur)
  • When the heart is emptying (systolic murmur)
  • Throughout the heartbeat (continuous murmur)

Harmless (innocent) heart murmurs

A person with an innocent murmur usually has a typical heart. Innocent heart murmurs are common in newborns and children.

Things that might change blood flow and cause an innocent heart murmur include:

  • Fever
  • Lack of healthy red blood cells that carry oxygen to body tissues (anemia)
  • Overactive thyroid (hyperthyroidism)
  • Phases of rapid growth, such as adolescence
  • Physical activity or exercise
  • Pregnancy

Innocent heart murmurs may go away over time. Sometimes, heart murmurs continue for life without causing serious health problems.

Worrisome heart murmurs

In children, worrisome murmurs are usually due to a problem with the heart's structure that's present at birth (congenital heart defect).

Congenital causes of worrisome heart murmurs include:

  • Holes in the heart. A hole may form before birth in the wall between the upper or lower heart chambers, or both. Examples are atrial septal defect and ventricular septal defect.
  • Cardiac shunts. A heart structure problem present before birth (congenital heart defect) causes irregular blood flow between the heart chambers or blood vessels.

In adults, worrisome heart murmurs are usually due to heart valve problems that develop later in life (acquired heart valve disease). Things that can damage the heart valves include:

  • Calcium deposits. Calcium deposits can cause a heart valve — such as the mitral valve or the aortic valve — to become stiff and narrow (valve stenosis). A calcified valve also may not close completely, letting blood flow backward. The changes in blood flow create a murmur. When calcium affects the heart valves, it's called calcific or degenerative valve disease.
  • Infection of the inner heart lining and valves (endocarditis). Bacteria or other germs cause this infection. The germs spread through the blood to the heart from another part of the body, such as the mouth. A murmur may occur if the infection is untreated and affects the heart valves.
  • Rheumatic fever. This is a serious complication of strep throat. It's rare in the United States. Rheumatic fever may occur in those who don't get or complete treatment for strep throat. When rheumatic fever affects the heart valves, it's called rheumatic heart disease. A heart valve problem can cause a murmur.

Risk factors

Things that increase the risk of heart murmurs in babies includes:

  • Family history of heart problems linked to murmurs
  • Uncontrolled diabetes in the mother during pregnancy
  • German measles (rubella) in the mother during pregnancy
  • Use of certain medications, alcohol or illegal drugs by the mother during pregnancy

Some medical conditions can increase the risk of heart murmurs, including:

  • A rare cancerous tumor that releases certain chemicals into the bloodstream (carcinoid syndrome)
  • A weakened heart muscle (cardiomyopathy)
  • An infection of the lining of the heart (endocarditis)
  • Anemia
  • Blood disorders marked by a high number of certain white cells, called eosinophils (hypereosinophilic syndrome)
  • Certain autoimmune disorders such as lupus and rheumatoid arthritis
  • Heart valve disease
  • High blood pressure in the lungs (pulmonary hypertension)
  • History of rheumatic fever
  • Overactive thyroid (hyperthyroidism)

Prevention

There's no known prevention for heart murmurs. But healthy lifestyle changes can improve heart health and prevent some conditions linked to murmurs in adults. Many childhood heart murmurs go away on their own as children grow.
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