A heart murmur is an extra, unexpected, or abnormal sound that is caused by the flow of blood through the heart.
What is going on in the body?
Except in unusual cases, a heart murmur is only noticed by a healthcare provider when he or she listens to the heart with a stethoscope. The heart normally makes certain sounds while beating. However, extra, unexpected, or abnormal sounds may also be heard. These are called murmurs. A murmur can be normal or abnormal. In abnormal cases, a heart murmur may signify a serious heart disease.
What are the causes and risks of the condition?
Normal or "innocent" heart murmurs are caused by normal blood flow. They are not a cause for concern.
Causes of abnormal heart murmurs include:
anemia, or low red blood cell counts
high levels of thyroid hormone, called hyperthyroidism
rheumatic fever, a complication of strep throat that can damage heart valves
endocarditis, an infection of the heart that can also damage heart valves
other types of heart valve damage or changes, such as stiffened valves from calcium deposits, which are common in the elderly. Damaged valves are often described as "leaky," which is called regurgitation, or "narrowed," which is also called stenosis. A heart attack can also cause a murmur from heart valve changes.
artificial heart valves
congenital heart disease, or heart defects present at birth, which can cause holes in the heart or deformed heart valves
mitral valve prolapse, which is a "leaky" heart valve that often has no known cause and is usually not serious
thickening of the heart muscles or enlargement of the heart, which can occur due to high blood pressure
heart failure, also called congestive heart failure
Other causes are also possible.