When doctors listen to a child’s heart, what they usually hear is a simple rhythm: “lub-dub, lub-dub, lub-dub…” Sometimes, they’ll hear an extra sound in between the lub and the dub. That extra sound is called a heart murmur.
Although the name is unsettling, heart murmurs are very common in children. Usually, they are normal sounds made as the blood is pumped through the heart chambers, valves and arteries–like a whooshing or swishing noise. Rarely, they may need to be checked by a specialist to rule out any problems.
What kind of murmur is it?
There are two kinds of heart murmurs: innocent murmurs and pathologic murmurs. The doctor will listen to the murmur’s loudness, timing and how long it lasts in the cardiac cycle, which is the end of one heartbeat to the start of the next. Sometimes, it is hard to tell the difference between the two kinds of murmurs just by listening. Some heart abnormalities may not produce a murmur at all. In those cases, an echocardiogram may be helpful.
If your doctor has a question about your child’s heart murmur, they may refer you to a pediatric cardiologist. Pediatric cardiologists have special training to look for heart problems that affect children.
Innocent murmurs (functional murmurs)
Innocent murmurs are harmless, but common. Over two-thirds of school-age children may have an innocent murmur. They may get louder if a child is excited, stressed, or ill. Many disappear as the child grows, although some do last into adulthood. Your doctor can detect these murmurs by simply listening to your child’s heart with a stethoscope.
Children with innocent heart murmurs do not have a related heart problem. They do not need any medical treatment, surgery, sports restrictions, or follow-up with a pediatric cardiologist.
Even when pediatricians believe a child’s murmur is innocent, however, they may still recommend a second opinion from a pediatric cardiologist to be certain. A referral to a pediatric cardiologist does not mean that the murmur is abnormal. Pediatricians are more likely to refer an infant with a heart murmur that occurs during the first six months of life.
Rarely, a murmur can indicate a problem with the heart. This is called a pathologic murmur. Pathologic murmurs are much rarer and occur in less than 1% of the population. Sometimes, they may be related to congenital heart defect that a baby was born with.
Why does it sound like that?
Pathologic murmurs are usually loud and may include an extra sound called a click, which is heard with a stethoscope.
Causes of pathologic murmurs may include:
- abnormal connections between the right and left heart chambers.
- abnormal connections between the major blood vessels coming from the heart.
- blood that flows through a thickened or leaky heart valve.
Sometimes, the murmur gets louder when the patient changes position, such as standing up. Certain conditions are linked to pathologic murmurs, including:
- Mitral valve prolapse with regurgitation: The mitral valve moves in an abnormal way and leaks.
- Hypertrophic cardiomyopathy: An abnormal thickening of the heart.
Pathologic murmurs often are not life-threatening
While not normal, pathologic murmurs often are not life-threatening. They usually are heard when a child has a minor heart defect. But, if a child has a heart murmur and also develops symptoms such as shortness of breath, trouble eating or gaining weight, sweating while eating, or cyanosis (a blue tint to lips and skin), it could be a more serious condition that needs medical attention right away.
Your child’s pediatric cardiologist may do some testing, using an electrocardiogram and an echocardiogram, to confirm any heart abnormality.
Conditions that may be linked with pathologic heart murmurs
Certain syndromes or genetic conditions may be associated with a cardiac abnormality related to heart murmurs. These include:
- Down syndrome. All children with Down syndrome should have a cardiac evaluation. Many of these patients may have a simple or more complex heart defect.
- Patent ductus arteriosus. Premature infants may have this condition. It occurs when a blood vessel (ductus arteriosus) does not close. This causes blood to circulate abnormally between the two major arteries near the heart. It is often found shortly after birth and can be confirmed by echocardiography.
Do murmurs need treatment?
Innocent murmurs do not require treatment. If your child has a pathologic murmur, your pediatrician and pediatric cardiologist will talk with you about whether treatment is needed. Depending on the type of pathologic murmur your child has, they may need medication and follow-up care, or referral to a pediatric heart surgeon.