What is an innocent heart murmur?

A heart murmur is a sound made by the blood flowing in the heart. An innocent heart murmur is a sound that occurs between beats of the heart, even though the heart and blood vessels are completely normal. Several different types of innocent murmurs occur in childhood. Some occur when a child is very young. Others are heard later in childhood. Most adults don't have heart murmurs, but many children do.

Innocent heart murmurs are also called functional, normal, vibratory, or physiologic murmurs. They are harmless. They are common in children and may disappear and reappear throughout childhood. The murmur may appear because of fever or anemia. When the fever or anemia goes away, the murmur goes away too. Innocent heart murmurs cause no problems, and most disappear for good when a child nears adulthood.

How does it occur?

Murmurs are caused by blood flowing turbulently through the heart, like the sound of a stream flowing into a whitewater pool. A murmur can occur in several different parts of the heart and in blood vessels. Your heart makes sounds ("lub-dub") when the heart valves close. Normally it is silent between beats. An innocent murmur is a murmur that is heard when nothing is wrong with the structure of the heart. It is just a sound made because of the way the blood is flowing through the heart.

How is it diagnosed?

Your health care provider will ask about your child's growth and listen to the heart with a stethoscope. Your health care provider may ask if your child is able to exercise as much as other children the same age.

Innocent murmurs have a distinctive sound. Your health care provider can usually tell the difference between an innocent murmur and a murmur that can be caused by problems. Usually it is not necessary to have any tests done when an innocent murmur is diagnosed.

How long do innocent murmurs last?

Some innocent murmurs begin in early infancy and last less than 6 months. Other innocent murmurs begin in childhood and last until the teenage years. Still other innocent murmurs occur at any age. Ask your health care provider if and when he or she expects your child's murmur to go away.

How is it treated?

No special treatments or restrictions are necessary. Children with innocent murmurs can safely participate in sports and other vigorous activities.

When should I call my child's health care provider?

Call during office hours if:

• Your child has a decrease in growth rate or ability to exercise.
• You have additional questions about innocent heart murmurs.