Did your child’s doctor say your child has a physiologic murmur? Both adults and children can have physiologic or functional murmurs although they’re more common in kids. What is a physiologic murmur – and should you be concerned if your child has one?
What is a Physiologic Murmur?
A murmur is an extra sound a doctor hears when listening to the heart using a stethoscope. Heart murmurs may be soft or loud and may have distinctive sound qualities such as harsh, musical or scratchy.
A heart murmur may be heard when a child has certain types of heart problems such as a congenital heart defect or a malfunctioning heart valve. But they’re also common in children with normal hearts – without any evidence of heart disease. When this is the case, doctors call this extra sound a functional, innocent or physiologic murmur.
What Causes a Physiologic Murmur?
Children have thin chest walls and a faster heart rate than adults, which makes it easier to hear the normal sound of blood moving through the heart. When a child exercises or becomes excited and his heart rate increases, a physiologic murmur becomes more pronounced, because there’s more blood flowing through the chambers of the heart.
The fact that the murmur becomes louder under these conditions is normal and doesn’t mean a child has heart disease. Children who have anemia or an overactive thyroid can also have a physiologic murmur. The murmur may come and go and may vary with changes in position.
How Do You Know It’s a Physiologic or Functional Murmur?
Certain characteristics of a murmur make it more likely to be innocent. Innocent heart murmurs are usually soft, less than 3 out of 6 on an intensity scale, and vary with a child’s position. They’re usually systolic, meaning they occur during the phase of the heartbeat when the heart is ejecting blood.
Children with a physiologic murmur never have symptoms of heart disease such as shortness of breath, chest discomfort, lightheadedness, fainting or excessive fatigue. If a child has any of these symptoms, further testing is always needed.
Since physiologic murmurs are so common in children, if a heart murmur has certain characteristics, a workup isn’t always necessary. On the other hand, loud, non-systolic murmurs and any murmur associated with symptoms, needs evaluation.
The work-up will usually include a chest x-ray to look for enlargement of the heart, an ECG and an echocardiogram to look for problems with a heart valve or a congenital heart problem. If these are negative, it’s likely a physiologic murmur that a child will usually, but not always, outgrow. Nevertheless, a physiologic murmur doesn’t increase a child’s risk of heart disease later.
The Bottom Line?
Physiologic murmurs are very common in children, and no treatment or restriction in activities is needed. This is a condition that your child will very likely outgrow.
References:
J Pediatr Health Care. 1997 Sep-Oct;11(5):207-14.
Merck Manual. Eighteenth edition. 2006.
