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Atrial septal defect
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Atrial Septal Defect
What is an atrial septal defect?
The normal heart has two sides, the left and the right, which are separated by a muscular
wall called the septum. Each side of the heart also has two parts -- an upper chamber called
an atrium, and a lower chamber called a ventricle. Atrial septal defect (ASD), a congenital
(present at birth) defect, occurs when there is an opening in the atrial septum, or dividing
wall between the two upper chambers of the heart, known as the right and left atria.
Normally, oxygen-poor (blue) blood returns to the right atrium from the body, travels to the
right ventricle, then is pumped into the lungs where it receives oxygen. Oxygen-rich (red)
blood returns to the left atrium from the lungs, passes into the left ventricle, then is pumped
out to the body through the aorta.
An atrial septal defect allows oxygen-rich (red) blood to pass from the left atrium through the
opening in the septum, and then mix with oxygen-poor (blue) blood in the right atrium. An
ostium secundum, an opening in the middle of the atrial septum, is the most common type of
ASD.
Atrial septal defects occur in 5 to 10 percent of all children born with congenital heart disease.
For unknown reasons, girls have atrial septal defects twice as often as boys.
What causes an atrial septal defect?
The heart is forming during the first eight weeks of fetal development. It begins as a hollow
tube, then partitions develop within the tube that eventually become the septa (or walls)
dividing the right side of the heart from the left. Atrial septal defects occur when the
partitioning process does not occur completely, leaving an opening in the atrial septum.
Some congenital heart defects may have a genetic link, either occurring due to a defect in a
gene, a chromosome abnormality or environmental exposure, causing heart problems to
occur more often in certain families. Most atrial septal defects occur sporadically (by chance),
with no clear reason for their development.
Why is an atrial septal defect a concern?
This heart defect can cause lung problems if not repaired. When blood passes through the
ASD from the left atrium to the right atrium, a larger volume of blood than normal must be
handled by the right side of the heart, causing the right side to become overworked and
enlarged. Extra blood then passes through the pulmonary artery into the lungs, causing
higher pressure than normal in the blood vessels in the lungs, a condition known as
pulmonary hypertension.
A small opening in the atrial septum allows a small amount of blood to pass through from the
left atrium to the right atrium. A large opening allows more blood to pass through and mix
with the normal blood flow in the right heart. The larger the volume of blood that goes to the
lungs, the higher the pressure.
The lungs are able to cope with this extra pressure for a while, depending on how high the
pressure is. After a while, however, the blood vessels in the lungs become diseased by the
extra pressure. If this combination of lung disease and damage to the right side of the heart
is severe, it could lead to an inability of the heart to pump effectively, called congestive heart
failure.
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What are the symptoms of an atrial septal defect?
Many children have no symptoms and seem healthy. If the ASD is large and permits a large
amount of blood to pass through to the right side of the heart, however, the right atrium,
right ventricle and lungs will become overworked, and symptoms may be noted. The following
are the most common symptoms of atrial septal defect. Each child may experience symptoms
differently. Symptoms may include:

child tires easily when playing

fatigue

sweating

rapid breathing

shortness of breath

poor growth

frequent respiratory infections
The symptoms of an atrial septal defect may resemble other medical conditions or heart
problems. Always consult your child's physician for a diagnosis.
What are the treatments for atrial septal defect?
Specific treatment for ASD will be determined by your child's physician based on:

your child's age, overall health and medical history

extent of the disease

your child's tolerance for specific medications, procedures or therapies

how your child's doctor expects the disease to progress

your opinion or preference
Ostium secundum atrial septal defects may close spontaneously as a child grows. Once an
atrial septal defect is diagnosed, your child's cardiologist will evaluate your child periodically
to see if it is closing on its own. Usually, an ASD will be repaired if it has not closed on its own
by the time your child starts school, to prevent lung problems that will develop from longterm exposure to extra blood flow. The decision to close the ASD also may depend on the size
of the defect. Treatment may include:

Medical Management -- Many children have no symptoms and require no
medications, however some children may need to take medications to help the heart
work better, since the right side is under strain from the extra blood passing through
the ASD. Medication that may be prescribed includes the following:
o
Digoxin - a medication that helps strengthen the heart muscle, enabling it to
pump more efficiently.
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o
Diuretics - the body's water balance can be affected when the heart is not
working as well as it could. These medications help the kidneys remove excess
fluid from the body.

Infection Control — Children with certain heart defects are at risk for developing an
infection of the inner surfaces of the heart known as bacterial endocarditis. It is
important that you inform all medical personnel that your child has an ASD so they
may determine if the antibiotics are necessary before a procedure.

Cardiac Catheterization — If the defect is large and your child develops severe
symptoms, or the defect seems to be causing injury to the aortic valve, your child's
cardiologist may recommend cardiac catheterization treatment or surgery immediately.
One recent development allows treatment through cardiac catheterization. A patch
shaped like an umbrella is closed (like a closed umbrella) and inserted into the
damaged area through a small tube, called a catheter. The umbrella patch is then
opened to cover the hole. This method requires a small incision, avoiding the need for
open-heart surgery.

Surgical Repair — The surgical closure of an ASD is carried out through an incision in
the middle of the chest. A heart-lung machine is used to do the work of the heart while
the heart is cooled, stopped, emptied and opened through the right atrium. The hole in
the wall between the right and left atrium is closed with stitches if it is small, or, if too
large, with a patch of thin leather-like material called pericardium, which makes up the
sac covering the heart. The right atrium is then closed and the heart is restarted as
the heart-lung machine is withdrawn. Advancements in cardiovascular surgical repair
include minimally invasive cardiac surgery.
What is the long-term outlook after ASD surgical repair?
The majority of children who have had atrial septal defect surgical repair will live healthy
lives. Your child's cardiologist may recommend that your child take antibiotics to prevent
bacterial endocarditis for a specific time period after discharge from the hospital.
Source: Children’s Hospital, Boston Cardiology Website, Accessible at:
http://www.childrenshospital.org/az/Site477/mainpageS477P0.html
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