A heart murmur is simply an extra or unusual sound or noise that a nurse, doctor or advanced practice provider (nurse practitioner or physician assistant) hears during a checkup or physical examination.

A heart murmur is simply an extra or unusual sound or noise that a nurse, doctor or advanced practice provider (nurse practitioner or physician assistant) hears during a checkup or physical examination.

In a normal heart, they are caused by blood circulating through the heart.

Not all heart murmurs are signs of heart disease. Normal murmurs are referred to as innocent, functional or benign murmurs. In fact, approximately 50 percent of all children with normal hearts will occasionally have an innocent heart murmur heard by their doctor.

These innocent murmurs are not related to congenital heart defects and often resolve by the time a child reaches adulthood. Innocent murmurs are also oftentimes easier to hear if your child has a fever or other illness.

Some heart murmurs, however, are caused by heart problems, such as abnormal holes or valve abnormalities. Murmurs may also be caused by congenital heart defects -- this means that the defect was present at birth.

In some babies, a congenital heart defect may be detected within the first few days of life. Common symptoms to watch for include rapid breathing, difficulty feeding, blueness in the lips and a difficulty feeding or growing.

If your primary care provider wants the murmur evaluated further, referral to a cardiologist can help sort out whether the sound is normal or needs more testing. The cardiologist will evaluate a murmur based on several factors, such as the pitch, loudness and duration of the murmur.

Murmurs are often graded according to their intensity or degree of "loudness."

An electrocardiogram (ECG or EKG) may be helpful during the cardiologist or primary care evaluation of a murmur, however, this is not always necessary.

Many primary care providers hear innocent or functional murmurs every single day. A heart ultrasound or echocardiogram may be needed if congenital heart disease is suspected, but not all murmurs need an echocardiogram evaluation.

If your primary care provider or cardiologist diagnoses an innocent murmur, special precautions are not needed. Specifically, activity restrictions and antibiotics before dental procedures are not needed when your child has an innocent murmur.

Dr. Kerry Rosen is Director of Outpatient Services at The Heart Center at Nationwide Children's Hospital and an Associate Professor of Clinical Pediatrics at The Ohio State University College of Medicine.