Atrial Septal Defect (ASD)

Heart Conditions in Children - Atrial Septal Defect (ASD)

What is an atrial septal defect?

Anatomy of the heart, normal
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An atrial septal defect 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. ASD is a congenital (present at birth) heart defect. As the fetus is growing, something occurs to affect heart development during the first eight weeks of pregnancy, resulting in an ASD.

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, and 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.

Illustration of the anatomy of a heart with an atrial septal defect
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Atrial septal defects occur in 6 to 8 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 within the tube develop 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.

What are the types of atrial septal defects?

There are four types of atrial septal defects:

Why is an atrial septal defect a concern?

This heart defect can over time 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. This extra blood passes through the pulmonary artery into the lungs, causing higher amounts of blood flow than normal in the vessels in the lungs.

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 lungs are able to cope with this blood flow for a long period of time. In some patients, the extra blood flow eventually raises the blood pressure in the lungs, usually after several decades. This then hardens the blood vessels in the lungs, causing them to be diseased, resulting in irreversible changes in the lungs.

What are the symptoms of an atrial septal defect?

Many children have no symptoms and seem healthy. However, if the ASD is large, permitting a large amount of blood to pass through to the right side of the heart, 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. However, each child may experience symptoms differently. Symptoms may include:

The symptoms of an atrial septal defect may resemble other medical conditions or heart problems. Always consult your child's physician for a diagnosis.

How is an atrial septal defect diagnosed?

Your child's physician may have heard a heart murmur during a physical examination, and referred your child to a pediatric cardiologist for a diagnosis. A heart murmur is simply a noise caused by the turbulence of blood flowing through the opening from the left side of the heart to the right.

A pediatric cardiologist specializes in the diagnosis and medical management of congenital heart defects, as well as heart problems that may develop later in childhood. The cardiologist will perform a physical examination, listening to the heart and lungs, and make other observations that help in the diagnosis. The location within the chest that the murmur is heard best, as well as the loudness and quality of the murmur (harsh, blowing, etc.) will give the cardiologist an initial idea of which heart problem your child may have. Diagnostic testing for congenital heart disease varies by the child's age, clinical condition, and institutional preferences. Some tests that may be recommended include the following:

Treatment for atrial septal defect

Specific treatment for ASD will be determined by your child's physician based on:

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 whether 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 long-time exposure to extra blood flow. The decision to close the ASD may also depend on the size of the defect. Individuals who have their atrial septal defects repaired in childhood can prevent problems later in life.

Treatment may include:

Post-procedure care for your child:

Your child may need other equipment, not mentioned here, to provide support while in the ICU, or afterwards. The hospital staff will explain all of the necessary equipment to you.

Your child will be kept as comfortable as possible with several different medications; some of which relieve pain and some of which relieve anxiety. The staff may also ask for your input as to how best to soothe and comfort your child.

After discharge from the ICU, your child will recuperate on another hospital unit for a few days before going home. You will learn how to care for your child at home before your child is discharged. Your child may need to take medications for a while and these will be explained to you. The staff will provide instructions regarding medications, activity limitations, and follow-up appointments before your child is discharged.

Care for your child at home following ASD repair

Most children feel fairly comfortable when they go home, and have a fair tolerance for activity. Your child may become tired quicker than before the repair, but usually will be allowed to play with supervision, while avoiding blows to the chest that might cause injury to the incision or breastbone. Within a few weeks, your child should be fully recovered and able to participate in normal activity.

Pain medications, such as acetaminophen or ibuprofen, may be recommended to keep your child comfortable at home. Your child's physician will discuss pain control before your child is discharged from the hospital.

Long-term outlook after ASD repair

The majority of children who have had an atrial septal defect 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.

Outcomes also depend on the type of ASD, as well as how early in life the ASD was diagnosed and whether or not it was repaired. With early diagnosis and repair of an ASD, the outcome is generally excellent, and minimal follow-up is necessary. When an ASD is diagnosed later in life, if complications occur after surgical closure, or the ASD is never repaired, the outlook may be worse than normal. There is a risk of developing pulmonary hypertension (high blood pressure in the blood vessels of the lungs) or Eisenmenger's syndrome. These individuals should receive follow-up care at a center that specializes in congenital heart disease.

Consult your child's physician regarding the specific outlook for your child.

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