Are Heart Murmurs Harmful?

The sound of blood flowing through your heart (lub-dub, lub-dub) is normally soft and quiet. Occasionally, an extra sound-a "murmur"-may accompany your heartbeat. Usually, this noise is harmless: an "innocent murmur." If it's accompanied by other signs, though, it may be an "abnormal murmur." Understanding the difference between the two can help you know when to relax and when to seek medical advice.

Innocent: Don't Worry About That Swoosh
About two-thirds of all newborns have a heart murmur that may sound like a swoosh, blow, whistle, rasp, or hum. The murmur may disappear by eight weeks or remain into adulthood without any effect on the person's health. There are different types of innocent murmurs. The most common are Still's murmur, which  occurs when blood flows through the aortic valve, and physiologic murmur, which occurs when it flows through the pulmonary valve. Both are associated with a baby's naturally quick heart rate.

Venous hum refers to the sound of blood circulating in large arteries close to the skin. Peripheral Pulmonary Stenosis occurs because infants' blood vessels are still very small and as blood flows into them, it causes "turbulence" that you can be heard through a stethoscope. Another type of innocent heart murmur is mammary soufflé, which develops during pregnancy when more blood begins flowing to the breasts. In some instances, innocent murmurs may also accompany conditions such as anemia, hyperthyroidism, or high fevers; these pass once the illness is treated.

Abnormal: When a Murmur Isn't Just a Murmur
While the majority of murmurs are temporary and harmless, there are times when that little sound in the chest is a sign of danger. An abnormal murmur itself won't cause pain or problems. Rather, it can be a red flag for a congenital heart defect present at birth or acquired heart valve disease in adults

Babies born with murmurs are examined for congenital heart disease, which includes holes in the heart or narrow valves that disrupt blood flow. Treatment and prognosis for these defects vary depending on the exact problem and other factors affecting the child's health.

Acquired heart valve disease can develop with age-related calcium build-up in the heart or may be a sign of high blood pressure, atherosclerosis, or other heart conditions. You can also develop acquired heart valve disease if you have had rheumatic fever or a rare infection know as infective endocarditis.

Because they are so often benign, doctors may not immediately tie a heart murmur to a more serious condition. However, if you know you have a heart murmur, beware of the following signs and symptoms:

  • Chest pain
  • Excessive sweating not due to heat or exertion
  • Shortness of breath
  • Dizziness or fainting
  • Bluish coloring in the extremities

If you experience any of these, talk to your doctor about your risk of related heart problems. You may need to be treated or take precautions such as paying special attention to oral hygiene or taking antibiotics before certain medical procedures to prevent further complications.



"Heart Murmur." Cardiac Center The Children's Hospital of Philadelphia. n.d. Web. March 18, 2012

"Heart Murmurs." American Heart Association. August 25, 2010. Web. March 19, 2012

"What Is a Heart Murmur?" Cleveland Clinic. n.d. Web. March 19, 2012