While learning your child has a heart murmur may be concerning, in most cases, it’s not a sign of a problem.

“There can be a lot of confusion around heart murmurs in children, and they’re so, so common,” said Dr. Michael Di Maria, a pediatric cardiologist with Children’s Hospital Colorado who cares for patients at UCHealth Pediatric Heart and Vascular Clinic in Steamboat Springs.

Below, Di Maria explains what you need to know about heart murmurs in kids.

What is a heart murmur?

A heart murmur is an extra sound that’s heard when the heart is beating.

The typical ‘lub-dub’ sound of a heartbeat is made when the heart’s inflow valves open, then the outflow valves close. If an extra whooshing sound of blood moving is also heard, there’s a heart murmur.

“In some cases, the extra sound is caused by an abnormality in the heart’s structure,” Di Maria said. “But most of the time, the heart is structurally normal, and the doctor is simply hearing the blood moving around the heart.”

In that latter case, the sound is known as an ‘innocent murmur.’

How is a heart murmur detected?

A doctor can hear a heart murmur while listening to your child’s heart with a stethoscope. A murmur may be noticed during a routine office visit, even if it hasn’t been heard before.

Often, a child with a heart murmur will be referred to a pediatric cardiologist for further evaluation.

“Most of the time, I can put my stethoscope on the child’s chest and I can say, ‘This is one of those innocent murmurs,’” Di Maria said. “But if I can’t be sure, or if I listen and think it’s not normal, it’s the easiest thing in the world to pop into the next room, put on a movie and let the patient hang out while they get an echocardiogram, which is a fancy name for an ultrasound of the heart. That’s the definitive test.”

How common are innocent murmurs?

While innocent murmurs can be heard at any age, they are especially common in younger children. Up to 75 percent of three- to five-year-olds have an innocent heart murmur.

“We see a lot of kids in preschool and kindergarten for murmur evaluations, and the vast majority are fine,” Di Maria said.

What if there is a problem?

Congenital heart disease, an abnormality in the way the heart develops before birth, is the most common birth defect, affecting about 1% of babies.

But there’s good news: most issues can be successfully treated.

“Even if something is amiss, most heart conditions in kids are very treatable,” Di Maria said.

What are signs of a heart issue?

“The big red flags for children of any age are symptoms such as chest pain, getting dizzy, passing out or turning blue – especially if the symptoms occur with exercise,” Di Maria said. “If that happens, stop whatever you’re doing, don’t exert yourself and get an evaluation as soon as possible.”

Do innocent murmurs go away?

Yes. That may simply be the result of the child growing bigger.

“It’s a really common thing to hear, ‘I had a murmur, but I grew out of it,’” Di Maria said. “When kids are small, there’s a small amount of tissue between the stethoscope and heart. As an adult, that very soft sound of an innocent murmur becomes dampened by muscle and bone.”

Should I worry if my child has an innocent murmur?

No. Remember that an innocent heart murmur doesn’t affect a child’s activity or life in any way.

“The big take-home message about innocent murmurs is nothing is wrong, you don’t have to worry, you don’t have to screen other family members,” Di Maria said. “It really is a normal finding.”

For more information, check out the American Heart Association’s webpage on heart murmurs in kids.