By: Juan Villafañe Jr., MD, FAAP & S. Kristen Sexson Tejtel, MD, PhD, FAAP
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.
Here's what parents need to know about heart murmurs, including different types and which may need follow-up testing.
Types of heart murmurs
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.
This type of murmur may get louder if a child is excited, stressed or sick. Your doctor can detect these murmurs by simply listening to your child's heart with a stethoscope.
Many innocent heart murmurs go away on their own as the child grows, although some do last into adulthood. Children with an innocent murmur 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 6 months of life.
Pathologic murmurs
Rarely, a murmur can indicate a problem with the heart. This is called a pathologic murmur (or an abnormal heart murmur). Pathologic murmurs are much rarer; they occur in less than 1% of the population. Sometimes, they may be related to congenital heart defects. Congenital means present at birth.
Why does a pathologic heart murmur sound like?
Pathologic murmurs are usually loud. They may include an extra sound called a click, which is heard with a stethoscope. Sometimes, the murmur gets louder when the child changes position, like when they stand up.
Differences in the heart's structure that can cause murmurs 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
Conditions linked to pathologic heart murmurs
Certain conditions children may be born make them more likely to have pathologic heart murmurs. Examples include:
Mitral valve prolapse with regurgitation
With this condition, the flaps of a heart valve are floppy and don't close tightly. In some cases, blood may leak backwards through the valve. This is called backflow, or regurgitation.
Hypertrophic cardiomyopathy is a genetic condition that causes the heart muscle to be thicker than normal. This can interfere with blood flow out of the heart and cause a murmur.
Patent ductus arteriosus (PDA)
Patent ductus arteriosus happens when a blood vessel called the ductus arteriosus doesn’t close after birth like it’s supposed to. Before birth, this vessel helps blood skip the lungs (since babies don’t use their lungs in the womb).
After birth, this blood vessel usually closes within a few days. If it stays open, it can cause unusual blood flow between two major arteries. This may cause a heart murmur (a type sometimes described as a continuous murmur). PDA is more common in preterm (premature) babies. Doctors can detect it with a heart ultrasound, called an echocardiogram.
Down syndrome
About half of children with Down syndrome are born with a heart defect, which may be minor or more complex. These can cause a patholgoic heart murmur. The American Academy of Pediatrics recommends that all newborns with Down syndrome get a thorough cardiac evaluation, including an echocardiogram.
Are pathologic heart murmurs 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. Seek medical attention right away.
Your child's pediatric cardiologist may do some
testing, using an electrocardiogram and an echocardiogram, to confirm any heart abnormality.
Do heart murmurs need to be treated?
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.
More information
About Dr. Villafane:
Juan Villafane, MD, FAAP, is a pediatric cardiologist. Within the American Academy of Pediatrics, Dr. Villafane is a member of the
Section on Cardiology and Cardiac Surgery & Publications and Communications Committee.
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About Dr. Sexson Tejtel
S. Kristen Sexson Tejtel, MD, PhD, MPH, FAAP, is a pediatric cardiologist with interest in cardiac imaging and acquired heart disease in children. Within the AAP, Dr. Sexson Tejtel is a member of the
Section on Cardiology and Cardiac Surgery Publications and Communications Committee, the Council on Sports Medicine and Fitness, and the Section on Epidemiology, Public Health and Evidence.
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