Overview

Heart murmurs are sounds — such as whooshing or swishing — made by turbulent blood in or near your heart. Your doctor can hear these sounds with a stethoscope. A normal heartbeat makes two sounds like "lubb-dupp" (sometimes described as "lub-DUP") when your heart valves are closing.

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

Heart murmurs can be harmless (innocent) or abnormal. An innocent heart murmur is not a sign of heart disease and doesn't need treatment. Abnormal heart murmurs require follow-up testing to determine the cause. Treatment is directed at the cause of your abnormal heart murmur.

Symptoms

If you have an innocent heart murmur, you likely won't have any other signs or symptoms.

An abnormal heart murmur may cause the following signs and symptoms, depending on the cause of the murmur:

  • Skin that appears blue, especially on your fingertips and lips
  • Swelling or sudden weight gain
  • Shortness of breath
  • Chronic cough
  • Enlarged liver
  • Enlarged neck veins
  • In infants, poor appetite and failure to grow normally
  • Heavy sweating with little or no activity
  • Chest pain
  • Dizziness
  • Fainting

When to see a doctor

Most heart murmurs aren't serious, but if you think you or your child has a heart murmur, make an appointment to see your family doctor. Your doctor can tell you if the heart murmur is innocent and doesn't require any further treatment or if an underlying heart problem needs to be further examined.

Causes

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)

A heart murmur may be innocent or abnormal.

Innocent heart murmurs

A person with an innocent murmur has a normal heart. This type of heart murmur is common in newborns and children.

An innocent murmur can occur when blood flows more rapidly than normal through the heart. Conditions that may cause rapid blood flow through your heart, resulting in an innocent heart murmur, include:

  • Physical activity or exercise
  • Pregnancy
  • Fever
  • Not having enough healthy red blood cells to carry adequate oxygen to your body tissues (anemia)
  • Too much thyroid hormone in your body (hyperthyroidism)
  • Phases of rapid growth, such as adolescence

Innocent heart murmurs may disappear over time, or they may last your entire life without ever causing further health problems.

Abnormal heart murmurs

In adults, abnormal murmurs are most often due to acquired heart valve problems. In children, abnormal murmurs are usually caused by structural problems of the heart (congenital heart defects).

Common congenital defects that cause heart murmurs include:

  • Holes in the heart. Known as septal defects, holes in the heart may or may not be serious, depending on the size of the hole and its location.
  • Cardiac shunts. Cardiac shunts occur when there's an abnormal blood flow between the heart chambers or blood vessels, which may lead to a heart murmur.
  • Heart valve problems present from birth. Examples include valves that don't allow enough blood through them (stenosis) or those that don't close properly and leak (regurgitation).

In older children and adults, causes of abnormal heart murmurs include infections and conditions that damage the structures of the heart. For example:

  • Valve calcification. This hardening or thickening of valves, as in mitral stenosis or aortic valve stenosis, can occur as you age. Valves may become narrowed (stenotic), making it harder for blood to flow through your heart, resulting in murmurs.
  • Endocarditis. This infection of the inner lining of your heart and valves typically occurs when bacteria or other germs from another part of your body, such as your mouth, spread through your bloodstream and get stuck in your heart.

    Left untreated, endocarditis can damage or destroy your heart valves. This condition usually occurs in people who already have heart valve problems.

  • Rheumatic fever. Although now rare in the United States, rheumatic fever is a serious condition that can occur when you don't receive prompt or complete treatment for a strep throat infection. It can permanently affect the heart valves and interfere with normal blood flow through your heart.

Risk factors

You have an increased risk of a heart murmur if someone in your family had a heart defect associated with the unusual sounds.

Many different medical conditions can increase your risk of heart murmurs, including:

  • A weakened heart muscle (cardiomyopathy)
  • An infection of the lining of the heart (endocarditis)
  • Blood disorders marked by a high number of certain white cells, called eosinophils (hypereosinophilic syndrome)
  • Certain autoimmune disorders, including lupus and rheumatoid arthritis
  • Chemicals from a rare tumor in the lungs or gastrointestinal system that enter your bloodstream (carcinoid syndrome)
  • Heart valve disease
  • High blood pressure (hypertension)
  • High blood pressure in the lungs (pulmonary hypertension)
  • History of rheumatic fever
  • Overactive thyroid (hyperthyroidism)

Having uncontrolled diabetes or a rubella infection during pregnancy increases your baby's risk of developing heart defects and a heart murmur. Use of certain medications, alcohol or drugs during pregnancy can lead to heart defects in a developing baby, which may cause a heart murmur.

Prevention

While there's not much you can do to prevent a heart murmur, it is reassuring to know that heart murmurs are not a disease and are often harmless. For children, many murmurs go away on their own as children grow. For adults, murmurs may disappear as the underlying condition causing them improves.