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. 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 Murmurs
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.
Symptoms and Diagnosis
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:
- Blue coloring of the skin, especially on the fingertips and inside the
mouth
- Poor eating and failure to grow normally (in infants)
- Fast breathing
- Excessive sweating
- Chest pain
- Dizziness
- Shortness of breath
- Fainting
- Fatigue (feeling very tired)
The signs and symptoms depend on the cause and the severity of the problem
causing the murmur.
When evaluating a heart murmur, the doctor pays attention to a number of
things, including:
- 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.
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
as:
- 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.
A heart specialist—a pediatric cardiologist or a cardiologist—will most
likely do the followup testing. These tests might include:
- 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.
Causes
Innocent Heart Murmurs
Innocent murmurs are heard when blood moves noisily through a normal heart.
Sometimes these murmurs occur when:
- 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.
Illnesses or conditions that can cause blood to flow faster than usual
through the heart include:
- Fever
- Anemia
- Too much thyroid hormone in the body (hyperthyroidism)
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:
- 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 close
properly.
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 should.
Treatment
Innocent Murmurs
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.
Abnormal Murmurs
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.
Reference:
National Heart, Lung, and Blood Institute, USA.
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