How Serious Are Heart Murmurs in Children?

A heart beats in a rhythmic loop — lub-dub, lub-dub, lub-dub — that serves as a soundtrack of life. This internal groove comes from vibrations as cardiac valves open and close and blood flows through your heart’s chambers.

But sometimes, an extra sound enters the mix. This whoosh or a swish or hum is known as a heart murmur. It’s quite common, especially in kids.

But that doesn’t make a child’s heart murmur diagnosis any less scary for parents. In fact, researchers found that anxiety levels climb in parents after a heart murmur is detected in their kid.

The good news? Worries decreased once parents got the facts about heart murmurs. To get you answers, let’s turn to pediatric cardiologists Rashmi Rao, MD, and Holly Nadorlik, DO.

How common are heart murmurs in kids?

Approximately 60% of children develop a heart murmur at some point while growing up, most commonly during the elementary school years, notes Dr. Rao. They’re typically discovered during a child’s routine well-check visit with their pediatrician.

The vast majority of heart murmurs are considered innocent, or benign. “That means there’s no abnormality in the heart,” she says.

Heart murmurs in kids commonly occur in the first few days after birth and during growth spurts. Most children eventually just outgrow a heart murmur, though some may last a lifetime with no adverse effects.

Innocent murmurs typically sound soft and can even vary with the position of the child, says Dr. Nadorlik. These types of murmurs can sound louder if a child is sick or dealing with some sort of stress.

So, what causes the extra sound? “It’s a sound created by blood flowing normally through the heart or heart vessels,” explains Dr. Rao. “But there’s really no true steadfast reason as to why these innocent murmurs happen.”

Can murmurs signal heart issues?

In some cases, yes. Heart murmurs in children could be a sign of a condition such as:

• Anemia (low red blood cell count).
• A congenital heart defect, including a septal defect (hole in the heart).
• Hyperthyroidism (overactive thyroid).

The sound of a murmur as heard through a stethoscope may be a sign of whether it’s “innocent” or not. More concerning murmurs often have a harsher quality or clicking sound, notes Dr. Nadorlik.

Pitch, timing and volume of a murmur can offer hints of an underlying heart valve or muscle issue. (How loud can murmurs get? “You can hear really loud murmurs without a stethoscope and even feel them with your hand,” says Dr. Nadorlik.)

A concerning murmur may bring a recommendation for monitoring and testing. “An echocardiogram, or ultrasound of the heart, can help us learn more about what’s going on,” says Dr. Rao.

Does physical activity need to be limited with a heart murmur?

A heart murmur on its own typically isn’t a reason to sideline a child from sports. “The vast majority of children with murmurs, particularly innocent ones, can participate in any sport or activity they choose,” states Dr. Rao.

There may be restrictions suggested for certain activities if the murmur is connected to a heart or health issue.

Final thoughts

If your child gets diagnosed with a heart murmur, take a deep breath and get more information. “A heart murmur is pretty common — and it’s not usually a sign that there’s something bad or scary going on with your child’s heart,” reassures Dr. Rao.