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
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.
- Innocent (harmless) murmurs. A person with 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.
- Abnormal murmurs. A person with an abnormal murmur usually
has other signs or symptoms of a heart problem. Most abnormal murmurs
in children are due to congenital
heart defects – heart defects present at birth. In adults,
abnormal murmurs are most often due to heart
valve problems caused by infection, disease, or aging.
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.
- Blood is flowing faster than usual through the heart and blood vessels
attached to the heart.
- An increased amount of blood is flowing through the heart.
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:
- Congenital septal defects, which are holes in the wall (septum) that
separates the right and left sides of the heart. They account for more
than half of abnormal murmurs in children.
- Congenital valve defects, which include narrow valves that do not
allow enough blood to flow through them and leaking valves that do not
|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.
Infections and other conditions that damage heart valves or other structures
of the heart also may cause murmurs. These include:
- Rheumatic fever, a serious
illness that can develop after a person has an untreated or incompletely
treated infection caused by the bacteria that cause strep
throat or scarlet fever. Rheumatic
fever can lead to permanent damage to the heart. If your doctor diagnoses
strep throat, be sure your child takes all of the antibiotics prescribed,
even if he or she feels better before the antibiotics run out.
- Endocarditis, an inflammation
of the inner lining of the heart and valves that is usually caused by
a bacterial infection. Endocarditis is a serious disease that can lead
to permanent heart damage and other complications. Endocarditis usually
occurs in an abnormal heart.
- Calcification (hardening and thickening) of valves as a result
of aging. The hardened and thickened heart valves do not work as they
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.
- Blue coloring of the skin, especially on the fingertips and inside
- Poor eating and failure to grow normally (in infants)
- Fast breathing
- Excessive sweating
- Chest pain
- Shortness of breath
- Fatigue (feeling very tired)
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
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:
- Takes a medical and family history
- Does a complete physical exam, looking for signs of illness or physical
problems (such as blue coloring of the skin, delayed growth, and feeding
problems in an infant)
- Asks about symptoms, such as chest pain, shortness of breath (especially
with exercise), dizziness, or fainting
Evaluation of murmurs
When evaluating a heart murmur, the doctor pays attention to a number of
- How faint or loud the sound is. The doctor grades the murmur on a
1–6 scale (1 is very faint and 6 is very loud).
- When the sound occurs in the cycle of the heartbeat.
- Exactly where the sound is heard in the chest, and whether it can
also be heard in the neck or back.
- Whether the sound has a high, medium, or low pitch.
- How long the sound lasts.
- How breathing, exercise, or change of body position affects the sound.
Classification of the murmur
Doctors classify murmurs as:
- Systolic – heard when the heart is squeezing and pumping blood
out of the heart.
- Diastolic – heard when the heart is relaxing and filling with
blood. Diastolic murmurs are often a sign of a heart defect or heart
disease and should be further evaluated.
- Continuous – heard during the entire heartbeat. These are often
a sign of a heart defect or heart disease and should be further evaluated.
When doctors hear a murmur that might be abnormal, they order tests, such
A heart specialist – a pediatric cardiologist or a cardiologist –
will most likely do the follow-up testing. These tests might include:
- Chest X-ray. A chest X-ray
takes a picture of your heart and lungs. It can show if the heart is
enlarged, and it can show some problems of the heart and lungs.
- EKG (electrocardiogram).
This test is used to measure the rate and regularity of your heartbeat.
The EKG can help rule out a variety of heart problems.
- Echocardiogram. This
test uses sound waves to create a moving picture of your heart. Echocardiogram
provides information about the size and shape of your heart and how
well your heart chambers and valves are functioning. The test also can
identify areas of poor blood flow to the heart, areas of heart muscle
that are not contracting normally, and previous injury to the heart
muscle caused by poor blood flow. There are several different types
of echocardiograms, including a stress echocardiogram. During this test,
an echocardiogram is done both before and after your heart is stressed
either by having you exercise or by injecting a medicine into your bloodstream
that makes your heart beat faster and work harder. A stress echocardiogram
is usually done to find out if you have decreased blood flow to your
heart (coronary artery disease).
- Cardiac catheterization and angiography. Cardiac
catheterization is a procedure in which a thin, flexible tube (catheter)
is passed through an artery or vein in your upper thigh (groin) or in
your arm to reach the heart, after you are sedated. This allows measurement
of pressure inside the heart and blood vessels. Angiography involves
injecting a dye that can be seen by using X-ray. This helps the doctor
see the flow of blood through the heart and blood vessels.
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
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.
Source: U.S. National
Heart, Lung and Blood Institute