Innocent Heart Murmurs in Children

Dr. Tafadzwa Kasambira, M.D., M.P.H. is a pediatrician who received his undergraduate training at McGill University in Canada, and graduated in 2002 from Tufts University School of Medicine, where he also completed a degree in public health. He completed his pediatric residency training at Harvard University in 2005, and completed a fellowship in infectious diseases at Johns Hopkins University in 2008. He has been a medical officer at the FDA for the last six years. He and his husband are the proud fathers of three children.


The heart murmur is a fairly common pediatric medical condition that can, nevertheless, cause apprehension in many a parent. The notion that there could be a medical problem with the heart of one’s child is understandably stressful. The majority of heart murmurs that are heard in children, however, occur secondary to normal blood flow and are harmless, leading to no discernible long term impact on a child’s developmental outcome.

A murmur is generally defined as the sound that blood makes as it flows through the heart and large blood vessels. Often, children diagnosed with murmurs are found to have this condition on a routine examination in the pediatrician’s office. Most of these murmurs are benign, and are known as functional or innocent murmurs. Astute physicians can discover an audible murmur in young infants who are only a few months old. These murmurs are most often found, however, in children aged 3 to 7 years, and may change in quality with the child’s position or breathing.

This was the case with our second daughter, whom I shall call Supergirl. At her two-month routine healthcare maintenance visit, her pediatrician noticed what she thought was a murmur on physical examination. Supergirl did not have any physical signs that might indicate that she was having any ill effects secondary to any heart problems, but the physician sent her for follow-up with a pediatric cardiologist, just to be certain.

Our fears were like those of any parent, but being a physician myself, I was cognizant of the high likelihood that the murmur would be an innocent one. Unfortunately, it was not. We went through the stressful rigmarole of cardiology visits and echocardiograms (ultrasound of the heart), including a particularly worrying one that had to be completed under sedation, as Supergirl would not stay still. Our daughter’s heart defect is a fairly common but significant one, and is not life threatening, but she receives regular cardiac follow-up to chart her growth and development, and monitor for any unlikely changes in the heart defect that might occur.

There are several types of functional murmurs. A Still’s murmur has a unique vibratory quality, and is most common in early childhood. A pulmonary flow murmur is caused by the blood flow into the pulmonary arteries, which travel from the heart to the lungs. These murmurs are most common in adolescents. Systemic flow murmurs are harsh murmurs caused by blood flow into the aorta and the head and neck vessels. A venous hum is caused by blood flow returning to the heart in the jugular veins, which are large veins in the neck.

With children who have functional murmurs, no special precautions or restrictions need to be placed on their activity, nor are any special diagnostic tests required, as the heart is normal and the child is not at risk of developing health problems in this regard. At times, the murmur lessens or disappears with age.

There are circumstances in which a murmur found on exam should be referred to a cardiologist by the pediatrician. These include instances when there is a family history of sudden death (cardiac disease is often the cause); when there is a history of cyanosis (blue discoloration around the mouth and/or fingers, suggesting low levels of oxygen in the blood); when a child has chest pain, palpitations, or fainting spells (syncope) with exercise; when there is a history of poor growth or the child is easily fatigued; or when there is swelling of the legs and feet (edema).

It may be a trying experience to learn during a routine pediatric examination that one’s child has a murmur, particularly if the child has previously had normal cardiac exams and this is a new finding. A majority of children will have an innocent murmur heard by their healthcare provider at some point during their childhood. In addition, such murmurs do not develop into harmful conditions later on in life. Outside the circumstances previously outlined, which should prompt further investigation, the functional murmur is simply an innocuous incidental finding.

Legal Disclaimer: This article is designed to provide general information related to pediatric care. The information presented in this article should not be construed as formal medical advice, nor is it intended to create a doctor-patient relationship. The content is intended solely for informational and not for treatment purposes.

This article is not a substitution for professional medical diagnosis or treatment.

REFERENCES

Bianchaniello T. Innocent murmurs. Circulation 2005; 111:e20-e22

Naik RJ, Shah NC. Teenage heart murmurs. Pediatr Clin North Am 2014;61(1):1-16

Punnoose AR, Burke AE, Golub RM. Innocent (Harmless) Murmurs in Children. JAMA 2012;308(3):305

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