A heart murmur is a whooshing sound between the beats that a doctor hears through a stethoscope. The whoosh is just an extra noise that the blood makes as it flows through the heart. Doctors usually discover murmurs during regular checkups or when kids see the doctor because they're sick. Just like kids, murmurs have grades. Grade 1 is the softest-sounding murmur, and Grade 6 is the loudest. A murmur graded 4, 5, or 6 is so loud you can actually feel a rumbling from it under the skin if you put your hand on the person's chest.

What Happens If You Have a Murmur?
More than half of all children have a heart murmur at some time in their lives and most heart murmurs don't mean anything is wrong. Doctors may call these "innocent," "functional," or "normal" murmurs. They are caused by blood rushing through the valves in a normal heart and are nothing to worry about.

One common type of normal murmur is Still's murmur, named for the doctor who first described it. This murmur is most often heard in healthy kids 3 to 7 years old. A normal murmur can get louder when the blood flows faster through the heart, like when kids have a fever or run around. That's because an increase in body temperature or activity makes the heart pump more blood. When your temperature goes down, the murmur may get quieter or even disappear.

It can be easier to hear heart murmurs in kids because they have less fat, muscle, and bone between the murmur and the doctor's stethoscope. Many normal murmurs become harder to hear as children grow older, and some eventually disappear. Even though most murmurs do not mean anything is wrong, sometimes a heart problem can cause a murmur. The heart may have a hole in it, a heart valve may leak, or a valve may not open all the way. If your doctor thinks your heart murmur could be due to a heart problem, you will need to see a pediatric cardiologist. This kind of doctor knows a lot about children's hearts.