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Benign heart murmurs in children

The exact cause of all innocent or benign murmurs is not well-known

heart murmur

A heart murmur is the audible vibration of blood flow. Many children have murmurs; the types we hear most commonly vary depending on a child’s age. If we were to listen to the heart for someone’s entire childhood, we likely would hear a murmur in most children. Since only about 1 percent of children have congenital heart disease, this means 99 percent of the extra sounds or murmurs we hear are normal. The exact cause of all innocent or benign murmurs is not well-known. Often, it is easier to hear soft murmurs because children have thin chest walls and the heart is closer to our stethoscopes, or because the heart is beating faster and increases the turbulence of blood flow. These factors allow us to hear the flow of blood through a structurally normal heart.

Benign or innocent murmurs tend to be soft, and are heard in early systole. The intensity of these murmurs tends to increase when a patient moves from a standing to a supine position. The most common benign murmur is known as a Still’s murmur and is described as vibratory and “musical.” This typically localizes to the left lower sternal border. If murmurs are so common, then when should a child with a murmur have further testing? Any time you are concerned about your patient’s heart, it is reasonable to refer to a cardiologist to help, but below are a few suggestions.

When to refer a child with a heart murmur

  • Loud murmurs (> 3/6 in intensity) or increased intensity with standing/Valsalva maneuver
  • Diastolic murmurs
  • Associated exertional symptoms such as palpitations, syncope or chest pain
  • Associated poor growth
  • Clinical concern for heart failure such as shortness of breath, poor feeding
  • Family history of heritable heart problems in first-degree relative (noncoronary artery disease)

Ashley E. Neal, M.D., is assistant professor of pediatrics and co-director of medical education, Division of Pediatric Cardiology, University of Louisville School of Medicine. She is a pediatric cardiologist with UofL Physicians – Pediatric Cardiology.

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