A heart murmur is a sound made by turbulent blood flow in the heart. Some heart murmurs may be harmless. Others may be the sign of an underlying heart problem.
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Harmless murmurs are caused by the normal flow of blood. The murmur may come and go over time. Increased blood flow can increase the murmur sound. The murmur may be louder with:
Abnormal heart murmurs can be due to:
- Structural abnormalities of the heart valves (most common)—these may be congenital (present from birth) or acquired later in life. Examples include:
- Septal defects—hole in the inside wall of the heart
- Patent ductus-arteriosus—abnormal connection between major blood vessels near the heart
- Other defects present from birth such as:
- Changes to the heart because of heart attack, heart failure, and long-standing high blood pressure
- Endocarditis—infection of the inner lining of heart valves and chambers
- Rheumatic fever—inflammation and damage of the heart valves from poorly treated strep throat
- Cardiac myxoma—a benign soft tumor within the heart (rare)
Normal heart murmurs are more common in children 3 to 7 years old. Pregnant women are also at increased risk.
The risk for abnormal heart murmurs increases with any of the conditions listed above.
Harmless heart murmurs usually do not cause symptoms. Signs and symptoms of abnormal heart murmurs may be:
- Rapid breathing or trouble breathing
- Blue lips (cyanosis)
- Lightheadedness and/or fainting
- Chest pain
- Rapid or irregular heartbeat
- Exercise intolerance
- Inability to gain weight in children
- Abdominal swelling
- Enlarged neck veins
When Should I Call My Doctor?
Call the doctor if you think that you or your child has a heart murmur.
Most heart murmurs are found during a routine exam. The murmur can be heard with a stethoscope. More tests will be done for murmurs that are causing problems. Blood tests may be done to rule out other problems. Images may be taken of your heart. This can be done with:
- Chest x-ray
- Cardiac catheterization
- Echocardiogram—to examine the size, shape, and motion of the heart
The heart's electrical activity may also be tested. This can be done with an ECG.
Harmless heart murmurs do not need treatment.
Treatment will be based on the cause. Treating the cause may decrease or stop the murmur.
Antibiotics may need to be taken before and after some medical or dental procedures. It may be needed if the procedure could allow bacteria to enter your bloodstream. This is no longer a routine step for all heart murmurs.
A healthy heart may reduce the risk of some abnormal heart murmurs. Steps may include:
American Heart Association
National Heart, Lung, and Blood Institute
Canadian Cardiovascular Society
The College of Family Physicians of Canada
Antibiotic prophylaxis. American Dental Association website. Available at: http://www.ada.org/en/member-center/oral-health-topics/antibiotic-prophylaxis. Update August 5, 2019. Accessed February 10, 2020.
Heart murmurs. American Heart Association website. Available at: http://www.heart.org/HEARTORG/Conditions/More/CardiovascularConditionsofChildhood/Heart-Murmurs_UCM_314208_Article.jsp#.Wc5_b1tSxxA.Updated February 17, 2016. Accessed February 10, 2020.
Heart murmur in children. EBSCO DynaMed website. Available at:https://www.dynamed.com/condition/heart-murmur-in-children. Updated December 18, 2015. Accessed February 10, 2020.
Heart murmurs and your child. Kids Health—Nemours Foundation website. Available at: http://kidshealth.org/en/parents/murmurs.html. Updated January 2017. Accessed February 10, 2020.
Last reviewed September 2019 by EBSCO Medical Review Board Marcin Chwistek, MD Last Updated: 8/26/2020