A heart murmur is an extra sound that occurs during a heartbeat and is caused by turbulence in blood flow through the heart. Most heart murmurs are innocent, which means they do not cause health problems and may disappear with age. But some heart murmurs require medical treatment because they are a sign of a problem in the heart's walls, lining, or valves, or are indications of other diseases or conditions.
Heart murmurs may also occur when one or more of the heart's four valves is operating abnormally. Sometimes the valves do not close completely, which may allow blood to leak back from one chamber to another, which should not occur. Valves also might not open completely, which causes blood to rush through a smaller opening than normal. The murmur can result from a hole, usually in the wall between the left and right sides of the heart.
Some people are born with valve defects or with holes that cause heart murmurs. Others develop a heart murmur after bouts with endocarditis * or rheumatic fever * . Both of these infections may damage heart valves. For these patients, doctors may advise prophylactic * (preventive) antibiotic treatment to be taken before a surgical or dental procedure because bacteria entering the bloodstream during the procedure may adhere to abnormal or damaged heart valves, causing infection inside the heart.
Anemia and other medical conditions such as an irregular heartbeat (arrhythmia) may be associated with murmurs even when the heart valves are perfectly normal. A heart murmur may be found in individuals who have heart failure * . If the heart becomes enlarged (a condition called cardiomegaly), a murmur may be heard as the blood flow throughout the heart decreases.
A doctor listens to a patient's heart as part of the physical exam. That is how murmurs usually are detected. Certain defects cause particular sounds, which help doctors make their diagnosis. For example, if a valve fails to close properly between the upper and lower chambers on the heart's left side, doctors may hear a distinctive murmur that aids in diagnosing the problem.
Doctors can also use an echocardiogram to examine the heart and determine a murmur's cause. This test is done with a device that uses sound waves to create an image of the heart. It is similar to the ultrasound machine that creates images of the fetus (unborn developing baby) inside a pregnant woman.
If the murmur is innocent, nothing special needs to be done. People with innocent heart murmurs can play the same sports, eat the same foods, and engage in all the same activities as their schoolmates.
See also Heart Disease: Overview • Heart Disease, Congenital • Rheumatic Fever
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* endocarditis (en-doh-kar-DYE-tis) is an inflammation of the valves and internal lining of the heart, known as the endocardium (en-doh-KAR-dee-um), usually caused by an infection.
* rheumatic fever (roo-MAH-tik) is a condition associated with fever, joint pain, and inflammation affecting many parts of the body, including the heart. It occurs following infection with certain types of strep bacteria.
* prophylactic (pro-fih-LAK-tik) refers to something that is used to prevent an illness or other condition, such as an infection or pregnancy.
* heart failure is a medical term used to describe a condition in which a damaged heart cannot pump enough blood to meet the oxygen and nutrient demands of the body. People with heart failure may find it hard to exercise due to the insufficient blood flow, but many people live a long time with heart failure.