Atrial Septal Defect
What is it?
Atrial Septal Defect (ASD) is an abnormal opening in
the wall separating the left and right upper chambers
(atria) of the heart. This abnormal opening causes blood
from the left atrium to flow into the right atrium. There
are three different types of ASDs, and are classified
according to where the defect occurs. Secundum ASDs are
the most common, representing 80% of all ASD’s. It is
caused by the failure of a part of the atrial septum to
close completely during development of the heart. Primum
ASDs are cause by a split in the leaflet of the valve, or
cleft mitral valve. Least common are Sinus Venosus ASDs,
which occur at the junction of the supior vena cava and
the right atrium.
Who gets it?
ASDs occur in about 1 out of 1,000 babies, and are
twice as common in females as in males. The defect does
not appear to be inherited.
What causes it?
The cause of ASDs is unknown. A gene defect or other
influences may prevent the heart tissues of a developing
fetus from forming properly. ASDs usually do not prevent
the heart or the baby from developing normally.
What are the symptoms?
Children who are born with an ASD usually have no
symptoms, and may not develop any until later in
adulthood. Most adults over 40 with an ASD will experience
symptoms such as shortness of breath and rapid abnormal
beating of the atria (atrial fibrillation). The extra
blood flow through the lungs may cause an increase in
blood pressure in the lungs. Congestive heart failure may
develop, with cough and swelling of the legs or ankles.
How is it diagnosed?
Because most children don’t experience any symptoms, an
ASD is usually discovered upon pre-school entrance
examinations when the physician hears a heart murmur. The
diagnosis is confirmed by echocardiography, which may
visualize the actual defect and estimate its size, as well
as the connection of the pulmonary veins. In addition, a
chest x-ray and an electrocardiogram (ECG, an electrical
printout of the heartbeats) can also be used to identify
this condition. In some cases, an ASD may be diagnosed by
using a test called cardiac catheterization. With this
test, doctors can detect a higher-than-normal amount of
oxygen in the heart's right atrium, right ventricle, and
the large blood vessels that carry blood to the lungs,
where the blood would normally subsequently get its
oxygen.
What is the treatment?
About twenty percent of ASDs will close spontaneously
in the first year of life, with the majority of the
remaining cases by the age of two. If the opening does not
close by itself, surgery may be done by sewing the hole
closed, or by sewing a patch of Dacron material or a piece
of the sac that surrounds the heart (the pericardium),
over the opening. A new procedure, which became
FDA-approved in early 2002, is done in a heart
catheterization laboratory instead of the typical
operating room, and the patient can remain awake. Using
only a local anesthetic, a small ultrasound catheter is
inserted through the groin and threaded through large
veins directly into the heart. This is done to enable
proper visualization and positioning of an appropriately
sized closure device made of nickel and titanium alloy. It
is attached to a tiny cable that is threaded through the
catheter until it reaches the site of the heart defect.
Self-care tips
If your child has been diagnosed with an ASD and has no
symptoms, encourage him or her live as normally as
possible. Call your doctor if you notice a sudden increase
in shortness of breath, your child awakens at night short
of breath, or you become aware of an irregular heartbeat.
Regular checkups are recommended.
This information has been designed as a comprehensive and quick reference
guide written by our health care reviewers. The health information written
by our authors is intended to be a supplement to the care provided by your
physician. It is not intended nor implied to be a substitute for
professional medical advice.
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