Atrial Septal Defect (ASD)

An opening or hole in the wall that divides the upper chambers of the heart, the atrial septum, is known as an atrial septal defect. This hole causes oxygen-rich blood to leak from the left side of the heart to the right side. This causes extra work for the right side of the heart, since more blood than necessary is flowing through the right ventricle to the lungs.

There are three types of ASDs, named according to where they occur in the heart: ostium secundum or patent foramen ovale, primum defects, and sinus venosus defects.

These defects are usually identified when a doctor hears a heart murmur. Tests to help diagnose ASD include chest X-ray, electrocardiogram, and echocardiogram.

ASDs make up 6% to 10% of all heart abnormalities, and occur in 1 child per 1,500.

Atrial Septal Defect
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A hole in the wall dividing the upper chambers of the heart results in oxygen-rich blood leaking into the right atrium.
What are the symptoms of atrial septal defect?

Because the heart is usually able to compensate for this defect, there are usually few symptoms. In about 40% of cases, the hole closes on its own before the age of 2. When this does not happen, there are 2 methods that may be considered to close the hole:

  • Many holes can be closed with a device during a cardiac catheterization.
  • If the hole is very large or is located close to a valve, open heart surgery is done to close the hole using sutures or a patch.

What is the long-term outlook for children with atrial septal defect?

Research indicates that children with ASD that is diagnosed and repaired in childhood are expected to live as long as would be expected for an average person.

Those who are diagnosed and treated after the age of 25, however, do not fare quite as well. There is a small risk of sick sinus syndrome or arrhythmia.

Fraser Golding, MD, FRCPC