Figure A shows the normal anatomy and blood flow of the interior of the heart. Figure B shows a heart with a murmur caused by leaking and narrowed valves. Figure C shows a murmur caused by a ventricular septal defect. Please note that many heart murmurs occur in normal hearts and occur without underlying heart disease. These are known as innocent heart murmurs.
A heart murmur is an extra or unusual sound heard during your heartbeat. Murmurs range from very faint to very loud and sometimes sound like a whooshing or swishing noise. Normal heartbeat sounds – "lub-DUPP" or "lub-DUB" – are the valves closing as blood moves through the heart.
A heart murmur is not a disease; it is a sound that the doctor hears with a stethoscope. It may be normal, or it could be a sign that something may be wrong. Most heart murmurs are harmless. Some are signs of heart problems, especially if other signs or symptoms of a heart problem are present.
Types of murmur
What causes heart murmurs?
Innocent heart murmurs
Innocent murmurs are heard when blood moves noisily through a normal heart. Sometimes these murmurs occur when:
Illnesses or conditions that can cause blood to flow faster than usual through the heart include:
Many, if not most, children will have a heart murmur heard by their doctor at some time in their lives. After childhood, the most common cause of an increased amount of blood flowing through the heart is pregnancy. Most murmurs found in pregnant women are innocent. They are due to the extra blood that women's bodies make while they are pregnant.
Innocent murmurs are sometimes due to changes to the heart resulting from heart surgery or from aging.
Abnormal heart murmurs
The most common cause of abnormal murmurs is congenital heart defects. Congenital heart defects occur when the heart, heart valves, or blood vessels attached to the heart do not develop normally before a baby is born. Some babies are born with a combination of heart defects. Common defects that cause murmurs include:
Infections and other conditions that damage heart valves or other structures of the heart also may cause murmurs. These include:
What are the signs and symptoms of heart murmurs?
Most people with heart murmurs do not have any other signs and symptoms of a heart problem. The murmur is usually innocent (harmless).
Some people with heart murmurs do have signs and symptoms of a heart problem. The signs and symptoms may include:
The signs and symptoms depend on the cause and the severity of the problem causing the murmur.
How are heart murmurs diagnosed?
Doctors use a stethoscope to listen to heart sounds and hear murmurs. They often notice innocent heart murmurs during routine checkups or physical exams.
Doctors may also find abnormal murmurs during routine checkups. Murmurs caused by congenital heart defects are often heard at birth or during infancy. Doctors may hear murmurs caused by other heart problems at any age.
Doctors usually refer people with abnormal murmurs to a heart specialist (a pediatric cardiologist for children or a cardiologist for adults) for further evaluation and testing.
Doctors listen carefully to the heart with a stethoscope to help decide if a murmur is innocent or abnormal. They listen to the loudness, location, and timing of the murmur to classify and describe the sound. This helps the doctor begin to diagnose the cause of the murmur.
The doctor also:
Evaluation of murmurs
When evaluating a heart murmur, the doctor pays attention to a number of things, including:
Classification of the murmur
Doctors classify murmurs as:
When doctors hear a murmur that might be abnormal, they order tests, such as:
A heart specialist – a pediatric cardiologist or a cardiologist – will most likely do the follow-up testing. These tests might include:
How are heart murmurs treated?
Healthy children with innocent murmurs do not need treatment because they have a normal heart. If your child has an innocent murmur, alert your pediatrician during regular checkups. Pregnant women with innocent murmurs due to increased blood volume also do not need treatment.
If you have an innocent 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.
The treatment for heart problems that cause abnormal murmurs varies depending on the specific heart problem.
The treatment of congenital heart defects is based on the type and severity of the heart defect or defects causing the murmur. Treatment may include medicine or surgery. Children with congenital heart defects are treated by doctors who specialize in treating children's heart problems (pediatric cardiologists). See congenital heart defects for more information.
The treatment of heart problems caused by infection or disease depends on the type and severity of the damage to the heart. The treatment may include medicine or surgery.