Imagine taking your 18-month-old child to see her pediatrician for her regular well-child visit. The doctor listens to her for an extended period of time looking somewhat concerned. He then turns to you and says, “Has anyone told you that your child has a heart murmur?” You tell him no, he then says, “We need to send you to see a pediatric cardiologist.” You ask what it means to have a heart murmur. He explains that a murmur is an extra noise, it’s probably nothing but it might be a hole in the heart or might be a heart valve problem, but that the cardiologist will explain it. The doctor finishes his well-child examination, you leave the office with a scheduled visit at the cardiology clinic in a week, and perhaps a sick feeling in your stomach.
This is a very common scenario in every pediatric cardiology clinic. A seemingly healthy child presents with a new finding and a concerned parent not sure what to make of the situation. A lot of the anxiety in this situation is produced by poor understanding of what is meant by a heart murmur.
Dictionaries define the word murmur as a low, indistinct, continuous sound that might be made by low, grumbling voices or soft waves. They also define it as an extra sound heard, caused by blood flow, when listening to the heart. In other words, all the term really means is that when we are listening to the heart, we hear some sound that we believe is caused by blood flowing through the heart or through the blood vessels. It does not tell us the cause of the murmur or its significance. Think of it like the term “cough” which describes the noise that we make with our throat, but doesn’t explain whether we have a cold, bronchitis or pneumonia.
The most common cause of a heart murmur in infants and young children is a normal heart with normal blood flow. The heart and blood vessels work like a pumping system, pumping blood through the body like water through pipes. Because a baby is small, and the chest wall is thin, the heart and the blood vessels are as close as a quarter of an inch away from our stethoscope when we listen to them. So it is understandable that we can hear normal blood flow just as we could hear water flowing through pipes if we put our ears a quarter inch away, even if there is nothing wrong with the water, pipes or pump.
Up to 75 percent of normal healthy infants and children can have a “normal blood flow” heart murmur, and we describe these normal heart murmurs as innocent, functional or physiologic murmurs. All of these terms mean “normal.” These innocent murmurs may come and go, and can change with patient anxiety, levels of hydration or when a child is sick. Less than 1 percent of children have pathologic murmurs, which can have many causes including holes in the heart, narrowed or leaky heart valves, or narrowed blood vessels. Regardless of the cause however, we have only one term to describe them all—murmur.
Although some pathologic murmurs are distinctive in their loudness or quality, there are abnormal heart conditions whose murmurs sound very innocent. Even in the hands of experienced cardiologists, listening with a stethoscope may not be adequate. Just as a doctor may order an X-ray to help clarify the reason you come to the office with a cough, a cardiologist may need to perform an echocardiogram to further delineate the cause of a heart murmur. An echocardiogram is a simple and noninvasive ultrasound test that can accurately assess the hear’ts anatomy, function and blood flow patterns. This test will provide your doctors with information that is more comprehensive and specific than a physical examination alone.
Innocent murmurs do not usually require follow up cardiology care, since they are normal. If a cardiac abnormality is found, additional testing or treatments may be required, depending on the abnormality identified. The specific problem and its treatment will be explained to you by your cardiologist at the time of your office visit. The results of the cardiology evaluation and echocardiogram will also be shared with your primary care physician and any additional plans will be coordinated with them.
Remember however, that the vast majority of heart murmurs are innocent and simply the sound made by normal blood flow. Understanding this should make any unexpected conversations about heart murmurs with your physician far easier.