Understanding a Heart Murmur

Cross section of heart showing valves.

The heart makes sounds as it beats. These sounds occur as the heart valves open and close to allow blood to flow through the heart. A heart murmur is an extra noise heard during a heartbeat. The noise is caused when blood does not flow smoothly through the heart. Heart murmurs can be innocent (harmless) or abnormal (caused by a heart problem).

What causes a heart murmur?

An innocent heart murmur can be a normal finding for many people. It may also be caused by:

  • Fever

  • Exercise

  • Pregnancy

  • Anemia

  • Overactive thyroid gland

An abnormal heart murmur can be caused by heart problems such as:

  • A damaged or diseased valve. The valve may be too narrow for blood to flow through easily. Or it may have problems opening or closing, and may leak blood backward.

  • A hole in the heart (septal defect). This is a problem with the heart’s structure that a person is born with (congenital). It causes blood to leak through the wall that normally divides the left and right sides of the heart.

What are the symptoms of a heart murmur?

Heart murmurs do not usually cause symptoms. They tend to be found when your healthcare provider is listening to your heart for another reason. People with an abnormal heart murmur may have symptoms of the problem causing the murmur. Symptoms can include:

  • Feeling weak or tired

  • Shortness of breath, especially with exercise

  • Chest pain

  • Fast, pounding, or skipping heartbeat

  • Swollen ankles, feet, abdomen

  • Feeling dizzy or faint

  • Poor feeding and failing to grow normally (babies only)

How is a heart murmur treated?

An innocent heart murmur does not usually need treatment unless there is a clear cause, such as anemia. In such cases, treating the underlying cause should cure the murmur. In some cases, an innocent heart murmur may go away on its own.

Treatment for an abnormal heart murmur depends on the cause. Options may include:

  • Medicines to help relieve symptoms

  • Procedures or surgery to fix or replace a diseased or damaged heart valve

  • Procedures or surgery to fix a hole in the heart

What are the complications of a heart murmur?

An innocent heart murmur has no complications. Complications of an abnormal heart murmur will vary depending on the cause. Possible complications include:

  • Heart failure. This problem occurs when the heart is so weak it no longer pumps blood well.

  • Infection of the heart’s valves or inner lining (infective endocarditis)

  • Blood clots and stroke

  • Fainting

  • Heart attack

  • Sudden cardiac arrest. This problem occurs when the heart suddenly stops beating.

When should I call my healthcare provider?

Call your healthcare provider right away if you have any of these:

  • Chest pain

  • Shortness of breath

  • Fever of 100.4°F (38°C) or higher, or as directed

  • Symptoms that don’t get better with treatment, or symptoms that get worse

  • New symptoms