Conditions
Heart Murmurs
Heart
murmurs are the blowing, whooshing, or rasping sounds produced
by turbulent blood flow in or near the heart. Often, they are
caused by blood flow through the heart valves, and can be caused
by various factors.
The heart has four chambers—two upper chambers (called atria)
and two lower chambers (ventricles). The heart has valves that
temporarily close to permit blood flow in only one direction.
The valves are located between the atria and ventricles, and
between the ventricles and the major arteries from the heart.
Normal heart sounds are called S1 and S2. They are the "lubb-dupp" sounds
that are thought of as the heartbeat. These sounds are produced
when the heart valves close.
Because the heart is also divided into a "right side" and
a "left side," sometimes these sounds may be somewhat
divided—most commonly noted is a "split S2," caused
when the right and left ventricles contract at very slightly
different times. This is normal, but occasionally the nature
of the split can indicate an abnormality such as enlargement
of one of the ventricles.
A murmur does not necessarily indicate a disease or disorder,
and all heart disorders do not cause murmurs. Murmurs are classified
("graded") depending on their ability to be heard by
the examiner. The grading is on a scale with grade I being barely
detectable. An example of a murmur description is a "grade
II/VI murmur." (This means the murmur is grade 2 on a scale
of 1 to 6).
Understanding
the Heart
Causes of a Heart Murmur
Murmurs in children are usually caused by:
Children often have murmurs that are a normal part of development
and do not require treatment. These innocent murmurs include:
- Still's murmur
- Venous hum
- Pulmonary flow murmurs
More information on innocent heart murmurs (American Heart Association)
Diagnosing a Heart Murmur
The initial diagnosis of a heart murmur is made during a routine
examination - the doctor will hear the murmur by listening to
the heartbeat through a stethoscope.
In order to diagnose the cause of the heart murmur, the murmur
is then described by the stage of the heartbeat when the murmur
is heard.
The location where the health care provider hears the murmur
loudest is also often noted. The following
are
important
clues to
the cause of the murmur:
-
Does the murmur occur in the resting stage (diastole) or
contracting stage (systole)?
-
Does it occur early or late in
the stage?
-
Does it occur throughout the heartbeat?
For example, a presystolic
murmur is heard just BEFORE systole and is usually caused
by narrowing of the mitral
or tricuspid
valve (the valves between the atria and the ventricles).
Your child's doctor may ask the following questions:
-
Have other family members had murmurs or other abnormal
heart sounds?
-
Is there any family history of heart problems?
-
What other
symptoms are present, such as cyanosis, liver enlargement,
distended neck veins, or lung sound changes
(rales)?
Other diagnostic tests may include:
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