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Atrial septal defect

An atrial septal defect (ASD) is an opening that exists between the heart's two upper chambers. This lets some blood from the left atrium (blood that has already been to the lungs) return via the hole to the right atrium instead of flowing through the left ventricle, out the aorta and to the body. This in turn leads to enlargement of the right atrium and right ventricle. More blood flows to the lungs as well.

The one complication of a small defect is that sometimes a right to left shunt can occur so that clots sometimes present in the veins going to the heart are not filtered by the lungs and go directly to the body. These traveling clots are known as emboli and can cause strokes. Closure of very small atrial septal defects is not routinely recommended unless a stroke occurs. However, it is felt that closing larger atrial septal defects can prevent problems such as lung injury or rhythm abnormalities from developing later in life.


Most children with ASD have few, if any, symptoms. It is somewhat dependent on size. Most people with an ASD have no symptoms in childhood as symptoms usually do not occur for decades. If symptoms occur, they may include shortness of breath, difficulty with exercise, poor growth, rapid breathing and palpitations.


The diagnosis of an ASD is suspected by abnormal findings on the physical examination. These include abnormal heart murmurs as well as other features, which may be quite subtle. The diagnosis is confirmed with an echocardiogram.


Methods of closure include open-heart surgery or closure with devices in the catheterization laboratory. If open-heart surgery is used to close the ASD, sometimes only a small portion of the breastbone needs to be split to allow the surgeon access to the heart (minimally invasive surgery). Closure of the hole itself may be with stitches only (if the hole is small) or with either pericardium (leather-like sac which covers the heart) or synthetic material if the defect is larger.

Treatment Risks

The success rate for treatment of an ASD is very good no matter what the method is. Both open-heart surgery and cardiac catheterization include the risk of bleeding and infection. Special risks of open-heart surgery include the risk of cardiopulmonary bypass. Special risks of closure in the cardiac catheterization laboratory include dislodgement of the device and the possibility of injury to structures within the heart that are close to the device. However, this is why the device placement is monitored with ultrasound while it is being placed.

Long-term Effects

With closure, it is expected that patients will live a normal life. Untreated, quality of life is decreased due to the development of pulmonary vascular disease, right heart failure and rhythm abnormalities. 


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Related Specialties & Services

Read about the specialty areas and services that treat Atrial septal defect.