- A heart murmur is an extra or unusual sound heard during a heartbeat. Murmurs range from very faint to very loud. They sometimes sound like a whooshing or swishing noise.
- There are two types of heart murmurs: innocent (harmless) and abnormal. A person who has an innocent murmur has a normal heart and usually has no other signs or symptoms of a heart problem. Innocent murmurs are common in healthy children. A person who has an abnormal murmur may have other signs or symptoms of a heart problem.
- A heart murmur may be a sign of a heart problem, especially if other signs or symptoms are present.
- The most common cause of abnormal heart murmurs in children is congenital heart defects. These are problems with the heart’s structure that are present at birth. Infections or other conditions that damage the heart valves or other structures of the heart also may cause abnormal heart murmurs. Heart murmurs due to these problems are more common in adults.
- Doctors use a stethoscope to listen to heart sounds and hear heart murmurs.
- If you have an abnormal heart murmur, the amount and type of ongoing care and treatment you will need depends on how severe your condition is. Talk to your doctor about the type of care you need.
What Causes a Heart Murmur?
Innocent Heart Murmurs
Innocent heart murmurs are sounds heard when blood flows through a normal heart. These murmurs may occur when blood flows faster than normal through the heart and its attached blood vessels. Illnesses or conditions that may cause this to happen include fever, anemia, and hyperthyroidism (too much thyroid hormone in the body).
Extra blood flow through the heart also may cause innocent heart murmurs. After childhood, the most common cause of extra blood flow through the heart is pregnancy. Most heart murmurs found in pregnant women are innocent. They’re due to the extra blood that women's bodies make while they’re pregnant.
Changes to the heart that result from heart surgery or aging also may cause some innocent heart murmurs.
Abnormal Heart Murmurs
The most common cause of abnormal murmurs in children is congenital heart defects. These are problems with the heart’s structure that are present at birth.
These defects can involve the interior walls of the heart, the valves inside the heart, or the arteries and veins that carry blood to the heart or out to the body. Some babies are born with more than one heart defect. Congenital heart defects change the normal flow of blood through the heart.
Heart valve defects and septal defects (also called holes in the heart) are common heart defects that cause abnormal heart murmurs.
Heart valve defects may include narrow valves that limit blood flow or leaky valves that don’t close properly.
Septal defects are holes in the wall that separates the right and left sides of the heart. This wall is called the septum.
A hole in the septum between the heart’s two upper chambers is called an atrial septal defect (ASD). A hole in the septum between the heart’s two lower chambers is called a ventricular septal defect (VSD). ASDs and VSDs account for more than half of all abnormal heart murmurs in children.
Conditions that damage heart valves or other structures of the heart also may cause abnormal heart murmurs. These include rheumatic fever, endocarditis, calcification, and mitral valve prolapse. Heart murmurs due to these problems are more common in adults.
The bacteria that cause strep throat, scarlet fever, and, in some cases, impetigo also can cause rheumatic fever. This serious illness can develop if a person has an untreated or not fully treated strep infection.
Rheumatic fever can lead to permanent heart damage. If you or your child has strep throat, take all of the antibiotics prescribed, even if you feel better before the medicine runs out.
Endocarditis is a serious infection of the heart valves or lining of the heart. A bacterial infection usually causes endocarditis, and it usually occurs in an abnormal heart. Endocarditis can lead to permanent heart damage and other health problems.
Calcification occurs when the heart’s valves get hard and thick as a result of aging. When this happens, the valves don’t work as they should.
Mitral Valve Prolapse
Mitral valve prolapse (MVP) is a condition in which the heart’s mitral valve doesn’t work properly. In MVP, when the left ventricle contracts, one or both flaps of the mitral valve flop or bulge back (prolapse) into the left atrium. This can cause a heart murmur.
What Are the Signs and Symptoms of a Heart Murmur?
Most people who have heart murmurs don’t have any other signs or symptoms of heart problems. These murmurs usually are innocent (harmless).
Some people who have heart murmurs do have signs or symptoms of heart problems. The signs and symptoms may include:
- Blue coloring of the skin, especially on the fingertips and inside the mouth
- Poor eating and abnormal growth (in infants)
- Shortness of breath
- Excessive sweating
- Chest pain
- Dizziness or fainting
- Fatigue (feeling very tired)
Signs and symptoms depend on the problem causing the murmur and how severe that problem is.
How Is a Heart Murmur Diagnosed?
Doctors use a stethoscope to listen to heart sounds and hear heart murmurs. They often notice innocent heart murmurs during routine checkups or physical exams.
Doctors also may find abnormal heart murmurs during routine checkups. When a congenital heart defect causes a murmur, it’s often heard at birth or during infancy. Abnormal murmurs caused by other heart problems can be heard in patients of any age.
Classifying Heart Murmurs
Doctors classify murmurs as systolic, diastolic, or continuous.
A systolic murmur is heard when the heart is squeezing and pumping blood out of the heart.
A diastolic murmur is heard when the heart is relaxing and filling with blood. Diastolic murmurs often are a sign of a heart defect or heart disease, and further checking is likely needed.
A continuous murmur is heard during the entire heartbeat. These murmurs often are a sign of a heart defect or heart disease, and further checking is likely needed.
Diagnostic Tests and Procedures
If your doctor suspects you or your child has an abnormal heart murmur, he or she may order one or more of the following tests.
- chest x-ray
- electrocardiogram (ECG, EKG)
- echocardiography (ECHO)
- cardiac catheterization.
How Is a Heart Murmur Treated?
Innocent Heart Murmurs
Healthy children who have innocent heart murmurs don’t need treatment because they have normal hearts. If your child has an innocent murmur, alert his or her doctor during regular checkups.
Pregnant women who have innocent heart murmurs due to extra blood volume also don’t need treatment.
You may have an innocent heart murmur due to an illness or condition, such as anemia, hyperthyroidism, or fever. The murmur will go away once the illness or condition is treated.
Abnormal Heart Murmurs
Treatment for abnormal heart murmurs depends on the heart problems causing them. For example, treatment for a congenital heart defect depends on the type and severity of the defect. Treatment may include medicine or surgery.
When an infection or disease causes a heart murmur, treatment depends on the type, amount, and severity of the heart damage. Treatments may include medicine or surgery.
Reference: The Heart, Blood, and Lung Institute
Last updated May 2, 2017