A heart murmur is an unusual sound that your doctor may hear when listening to your heart. It’s usually described as a swishing or blowing sound.

Heart murmurs may be present at birth or develop later in life. Some are harmless and may never require treatment. Others may point to underlying health conditions. 

Read on to learn about symptoms and causes of heart murmurs, as well as when to see a doctor.

Types of heart murmurs 

There are two types of heart murmurs: innocent and abnormal.

Innocent or harmless heart murmurs don’t need to be treated. They may or may not go away over time. Since they often occur when your blood flow increases, they can sometimes be caused by exercise or pregnancy.

Abnormal heart murmurs may require medical attention. They may indicate an underlying heart disease or health condition, and symptoms can vary depending on the underlying condition.

Symptoms

Innocent heart murmurs often show no signs or symptoms and don’t need treatment.

Abnormal heart murmurs may show no obvious signs or symptoms beyond the sound of the murmur itself. When they’re caused by an underlying heart condition, however, they may be paired with other symptoms like:

  •  Dizziness
  •  Fainting
  • Enlarged liver
  • Sudden weight gain
  • Blue lips or fingertips
  • Loss of appetite
  • Chronic cough
  • Excessive sweating
  • Shortness of breath

Causes

Innocent heart murmurs happen when your blood is moving quickly through your heart. They may be caused by:

  • Exercise or physical activity
  • Pregnancy
  • Fever
  • Anemia
  • Hyperthyroidism
  • Rapid growth periods (children) 

Abnormal heart murmurs may be caused by congenital heart defects (CHDs) at birth. CHDs affect nearly 1 percent of births a year. About 25 percent of babies with CHDs may need to undergo surgery or procedures while they’re young. Common CHDs include:

  • Septal defects (holes in the heart walls)
  • Cardiac shunts (abnormal blood flow between heart chambers or blood vessels)
  • Stenosis (valves that don’t let enough blood through)
  • Regurgitation (valves that don’t fully close and may leak) 

Other causes of abnormal heart murmurs that may be more common in older children and adults include:

  • Endocarditis (an infection or inflammation in the inner lining of the heart chambers)
  • Cardiac myxoma (a rare, non-cancerous tumor that grows in the heart)
  • Valve calcification (the thickening of heart valves)

Risk factors 

Your chances of developing a heart murmur may increase over time. You may be at risk if you have a family history of heart defects or medical conditions like:

  • High blood pressure
  • Hyperthyroidism
  • Endocarditis
  • High blood pressure in the lungs
  • Carcinoid syndrome
  • Weakened heart muscle
  • Rheumatoid arthritis 

See a doctor

Murmurs are often detected during regular check-ups. However, if you have a family history of heart disease or experience symptoms like shortness of breath, dizziness, chest pain, or rapid heartbeats, you may want to see your doctor for a non-routine visit.

Diagnosis

To diagnose a murmur, your doctor will use a stethoscope to listen to your heart.

If they hear an unusual sound, they’ll use the following considerations to figure out if the murmur is innocent or abnormal:

  • Loudness
  • Frequency
  • Location in your heart
  • Low or high pitch
  • Whether it changes with different body positions 

Because heart murmurs may point to other health conditions, your doctor may also do other tests, including:

  • Chest x-ray. This will show certain abnormalities in your heart.
  • Electrocardiogram (ECG). This painless test monitors your heart’s electrical activity.
  • Echocardiogram. This test uses sound waves to create an image of your heart and its valves.
  • Doppler echocardiography. This is similar to an echocardiogram, but instead of the heart’s structure, it creates an image of your heart’s blood flow pattern.
  • Cardiac catheterization. During this test, a catheter is inserted through veins in your arm or leg to reach the heart chamber. It helps doctors determine the pressure in your heart. This test also releases dye that can be seen through an x-ray to get a better image of your heart’s structure.
  • Blood tests. These are used to detect an infection. 

Treatment

Innocent heart murmurs don’t usually require treatment. If your heart murmur is the result of an illness, it will go away as you recover.

Treatment isn’t always necessary for abnormal heart murmurs, either. Specific treatment will be determined by your doctor if your heart murmur is connected to other health or heart conditions. Your doctor will also determine if surgery or medication is necessary. They may decide to simply monitor the murmur over time.

Takeaway 

Heart murmurs are unusual sounds that are heard between heartbeats. They occur when there’s unusual blood flow in your heart valves. Heart murmurs may be innocent and can develop as a result of exercise or pregnancy. They may also be abnormal and the result of underlying health conditions or congenital heart defects.

Heart murmurs are usually found when your doctor listens to your heart during a check-up. They can help figure out if your heart murmur is innocent or abnormal, and if it requires treatment.