Heart Murmurs: What’s Behind the Scary Sounds
By Angelo S. Milazzo, MD, and Dennis Clements, MD, PhD

Many children’s hearts make sounds or vibrations known as heart murmurs. During each normal heartbeat, the heart produces a series of expected sounds as its valves open and close. Murmurs are extra sounds that occur in addition to the expected sounds. They are usually easy to hear with a stethoscope, and are often noticed during routine examinations.

The vast majority of children with heart murmurs have normal, healthy hearts. The extra sounds are simply the result of the way blood flows through their hearts. Heart murmurs in these children may be called normal, innocent or functional heart murmurs.

As many as 50 to 75 percent of all children will have an audible murmur at some point in childhood. Normal heart murmurs are heard in many children of all ages, but they are particularly common in young infants, children of pre-school and early school age (3 to 5 years), and adolescents. A normal murmur may be heard throughout childhood, or it may disappear at any time. In most cases, a normal murmur will disappear completely at some point in childhood, although some persist into adulthood. Certain conditions (such as fever, anemia, exercise, pregnancy, and changes in body position) may change the way a normal murmur sounds, making it easier or more difficult to hear.

In the case of a child with a normal heart murmur, no specific testing beyond a comprehensive physical examination is typically needed to make the diagnosis. During the examination, the physician carefully notes the qualities of the murmur—the area of the body where it is heard best, the volume or intensity of the sound, the quality of the sound, and other features—because normal murmurs have typical features which are the same from patient to patient.

In some cases, a primary care provider may not be certain by examination alone whether or not a heart murmur is normal, and he or she may order tests such as an electrocardiogram (EKG) or chest x-ray to screen for the possibility of cardiac disease. In other cases, a provider may consult with or make a referral to a pediatric cardiologist, who specializes in diagnosing and treating cardiovascular diseases in children. In that case, the cardiologist may recommend or perform additional testing, such as an echocardiogram (or “echo”), which is an ultrasound examination of the heart. Children with normal heart murmurs do not require treatment of any kind. They do not require antibiotics prior to dental visits or prior to surgical or other procedures. They are not restricted from participation in competitive athletics, from any type of physical activity or recreation, or from any type of employment. They will not be ineligible for medical or life insurance.

In only a very small number of children is a heart murmur the sign of an abnormal heart or cardiac disease. In an even smaller number of children is a heart murmur the sign of life-threatening cardiac disease. In these cases, the quality of the murmur itself, combined with other features of the patient’s examination and medical history, will provide a significant clue that underlying cardiac disease is present. If an abnormality is suspected, the patient will very likely be referred for evaluation by a pediatric cardiologist.

It is important to remember that a heart murmur is usually only a sound made by a heart that is otherwise healthy and normal. Imagine owning a car with an engine that makes a funny sound but runs perfectly. You might bring it to your mechanic, who, after examining it, discovers that, despite the noise, it runs exactly as it should. That is the case with the vast majority of children who are diagnosed with a heart murmur.

Angelo S. Milazzo, MD, is a pediatric cardiologist and medical director of Duke Children's Raleigh Consultative Services Clinic. Dennis Clements, MD, PhD, is interim chair of the Department of Pediatrics at Duke University Medical Center. For more information, visit www.dukehealth.org