You Heard a What?

“Your child is very healthy and their exam is normal…except for a heart murmur.” No matter how I phrase it, telling a parent their child has a heart murmur always feels like I’m delivering bad news. As a medical student, I thought hearing a murmur was an incredible feat and that I would seldom have the opportunity to hear one. Boy was I wrong.

It is estimated that 33-75% of children will, at some time, have an innocent murmur recognized on exam between the ages of 1 and 14 years. Compare this to the mere 1% of children who have a congenital heart condition that may present with a heart murmur on exam. Despite the overwhelming majority of innocent murmurs, it is still very scary to hear that your child has something that isn’t “normal” on their heart exam. I imagine the questions which must immediately race through a parent’s mind: What is a murmur? How does my pediatrician know my child’s murmur is innocent and not a serious heart condition? What do we do now? Do we need to see a heart specialist (known as a pediatric cardiologist)?

To answer the first question, a murmur is the sound of blood flowing through the heart or blood vessels. Normally, blood flows silently through the heart and body, but sometimes there is disturbance to this smooth flow, such as a heart valve which is too stiff or too floppy, known as valvular stenosis or regurgitation, respectively. However, there can often be an innocent cause of this turbulence. Although no single cause of such innocent murmurs has been discovered, several theories have been proposed, such as a large blood vessel or an extra muscle strand in the heart that simply “gets in the way” as the heart grows.

A thorough cardiac exam is an essential part of an adolescent’s sports physical. Cardiovascular abnormalities that contribute to non-traumatic sudden deaths are estimated to occur in one out of 200,000 young athletes per year.  Certain potentially fatal conditions, like hypertrophic cardiomyopathy, can have a characteristic murmur that can be picked up by a trained ear.

Regardless of the cause, innocent murmurs can often be distinguished from pathologic murmurs simply by listening to a few key features. First, the quality of the murmur is important. Innocent murmurs tend to have a musical, gentle sound rather than the harsh sound of a more worrisome murmur. Innocent murmurs also tend to be quieter. The position on the chest from which the murmur is best heard can also make your doctor more or less concerned. Finally, certain maneuvers can help your pediatrician distinguish a benign murmur from a pathologic murmur. For instance, if a murmur gets louder when your child lies down, it is more characteristic of an innocent murmur.

Your pediatrician will use all of the above details as well as your child’s overall health to decide whether they feel your child’s murmur is concerning for a pathologic murmur which may signify a cardiac condition. Fortunately, as mentioned before, most murmurs of childhood are benign and transient. Therefore, in an otherwise healthy child, pediatricians are often comfortable simply observing for changes in the murmur or other concerning signs, such as poor weight gain or growth. (As a caveat to that rule, innocent murmurs often become louder when a child is ill, has a fever, or is dehydrated, so don’t be surprised if you take your child in for a sick visit and your pediatrician says the murmur is more noticeable.) If your pediatrician is concerned for a pathologic murmur, they will recommend a referral to a pediatric cardiologist who will be able to listen to your child’s heart and determine (with their expert ears) whether an echocardiogram (ultrasound of the heart) is warranted.

I hope that this article has quieted some of your fears of the words “heart murmur.” Remember, the majority of kids will have a heart murmur at some point during childhood and adolescence. And, most of these murmurs are benign and short-lived. However, if you have any concerns or questions, ask your pediatrician to explain why they are or are not worried by what they hear.

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