Atrial Septal Defect


Condition Description

An atrial septal defect (ASD) is a congenital heart condition where there is a hole (defect) in the wall (septum) between the upper chambers of the heart (atria). In early fetal development, the heart starts out as a single tube that gradually differentiates into 4 chambers. Abnormalities can arise at several steps in the process, resulting in defects in the muscular wall that normally separate the atria. About 80% of ASDs will close in the first 18 months of life; if an ASD has not closed by age 3 years, it is not likely to close and treatment will be necessary.

This defect may not be detected in childhood, but if it is large it is usually apparent by at least 30 years of age. Small ASDs may not be detected until middle age or later; they will often be detected at that time because of heart enlargement and a specific sound of the heart (fixed split of the second heart sound). Children with symptomatic ASDs may fatigue easily, have rapid breathing with shortness of breath, and grow slowly.


Atrial septal defects occur in 4 of 100,000 live births. They make up 10% of congenital heart defects and have a higher rate of occurrence in boys than girls (3:2 ratio).

Common Associated Conditions

Atrial septal defects often occur as single conditions (i.e., the child has no other congenital conditions). However rarely they are part of a genetic condition called Holt Oram syndrome; children will have defects of the upper limbs as well as the ASD.

Short-Term Treatment and Outcomes

An ASD will be diagnosed by a chest x-ray and an echocardiogram followed by cardiac catheterization (putting a tube that can be seen on x-ray into the heart to examine the anatomy and measure the pressure of the blood in the various parts of the system). An angiogram will also be done to determine the condition of the blood vessels leading into and from the heart.

Surgery will typically be necessary to close an ASD, and often a silicone patch will be used to cover the hole. The body will soon cover that patch with its own tissue and the heart will be strong and function well. Small ASDs can be closed without open-heart surgery in some cases, using a catheter with an umbrella-type of apparatus (called an Amplatzer septal occluder) that opens within the heart and closes the hole between the upper pumping chambers.

Long-Term Treatment and Outcomes

ASD repair must be carefully timed, carefully performed and closely followed to detect complications and treat them promptly.

Surgery to repair ASDs is successful 99% of the time, and beyond the immediate post-operative recovery period, there will be no long–term problems. After surgery the enlarged heart will return to normal size and pressure in the lungs should return to normal. Children will need to see a cardiologist periodically to be assessed for any signs of heart failure or other difficulties. They do not need to take antibiotics for dental work.

Common Complications

When there is a hole between the 2 upper chambers, blood can flow through this hole between the atria and cause the heart chambers to have extra blood and therefore to have to work extra-hard to pump this blood. Blood typically flows from the left to the right side so there is no cyanosis (bluish color of the skin from lack of oxygen in the blood). Because of the increased work from pumping extra blood, the heart can increase in size (dilate), the heart muscle's pumping action can weaken (called heart failure). The extra blood flow can cause thickening of the blood vessels in the lungs (pulmonary hypertension) that can permanently damage the lungs. Other complications can be an infection of the heart (called endocarditis) and an abnormally fast heart rhythm called atrial fibrillation.

Implications for Children's Development

Children with repaired ASD generally do very well and have no restrictions of their activities. They do not have developmental delays of any sort. They may have somewhat delayed growth, although recent surgical techniques and close follow-up usually leads to children having the repair done before their growth is affected.

For more information about Atrial Septal defects, including resources for parents and general information about congenital cardiac conditions, visit the following websites:

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