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Your heart has four chambers. The upper two receiving chambers are called atria and the lower two chambers are called ventricles. In the congenital heart disorder atrial septal defect (ASD), the wall (septum) separating the two atria doesn’t fully develop and has a hole in it. (See graphic below.) This defect is three times as common in girls as in boys, and also is more common in people with Down syndrome.
As a result of the defect, some of the blood that normally would go into the left ventricle from the left atrium is shunted into the right atrium. This results in extra blood circulating through the lungs, which may cause lung congestion. Commonly, especially if the defect is small, an ASD causes no symptoms and may only be detected in adult life.
The definitive treatment is closure of the defect by open-heart surgery. Small defects may be closed using just sutures. If the defect is large, a patch of synthetic material may be required. The risk of such surgery is low and the results excellent in most instances.
An approach to closing ASDs that’s in the clinical trial phase uses an expandable device inserted into the hole in the septum through a catheter. This approach avoids open-heart surgery. The expandable device, called a septal occluder, is made of a superelastic wire mesh framework with polyester patches sewn into it. The occluder is positioned across the septal defect and once in place, it’s expanded to seal the hole.