What is a heart murmur?
In most circumstances blood flow is silent. Occasionally it is possible to hear the blood flowing through the body, and it this sound that is called a “heart murmur”. A heart murmur is simply the noise made by blood as it travels through the heart, much like the noise made by water as it flows in a stream or in the pipes of your home.
Is there more than one kind of heart murmur?
Yes. Perhaps the simplest way to think of murmurs is to divide them into 2 groups…normal and abnormal.
If a patient has a normal heart and we can hear the blood flowing in it, we call this an “innocent” or “functional” murmur (there are actually many, many names for this finding and they all mean the same thing…the heart is completely normal and we just happen to be able to hear the blood flowing through it).
Abnormal (or pathologic) heart murmurs occur when blood passes through a malformed structure in the heart, causing the blood flow to become turbulent (think of what happens when you put your finger over the end of a garden hose forcing the water to spray all over the place). The abnormality can be a hole, a leaky or tight valve or (rarely) something more severe.
How can the doctor tell the difference?
Innocent heart murmurs have certain features which are able to be detected by doctors trained to do so. As a very general rule, soft murmurs are normal while harsher ones tend to be abnormal.
After taking a thorough history the doctor will try to illicit any signs of heart disease by examining your child. This involves not only listening to the heart (often in different positions) but also feeling for an enlarged liver (in the belly) and for normal pulses in the legs.
Will my child outgrow their innocent heart murmur?
If your child has an innocent heart murmur, then the heart is normal and there is nothing to outgrow. However, after few years the murmur may no longer be audible as the chest wall gets thicker and the heart rate slows down.