A to Z: Atrial Septal Defect (ASD)

May also be called: ASD

An atrial septal defect, or ASD — sometimes referred to as a hole in the heart — is a type of congenital heart defect in which there is an abnormal opening in the dividing wall between the upper filling chambers of the heart (the atria).

More to Know

The heart has four chambers: The two lower pumping chambers (the ventricles) and the two upper filling chambers (the atria). Blood that is low in oxygen returns from the body to the right atrium before passing to the right ventricle and then to the lungs to receive oxygen. Oxygen-rich blood returns to the left atrium before passing to the left ventricle, where it is pumped out to the rest of the body.

The right and left atria are separated by a thin shared wall called the atrial septum. Kids with an ASD are born with an opening in this wall that allows oxygen-rich and oxygen-poor blood to mix, increasing the total amount of blood that flows toward the lungs. The blood flowing through the hole creates an extra noise, known as a heart murmur, that can be heard when a doctor listens to the heart with a stethoscope.

Treatment for an ASD depends on the child's age and the size, location, and severity of the defect. Very small ASDs may close on their own. Larger ASDs usually won't close and must be treated medically. Most of these can be closed in a cardiac catheterization lab, although some will require open-heart surgery. Large ASDs can cause symptoms like poor appetite, poor growth, fatigue, shortness of breath, and lung problems or infections, such as pneumonia.

Keep in Mind

A small ASD will usually close without treatment within the first 2 years of a child's life. If a larger ASD is not treated, health complications can develop later, but most kids with ASDs are diagnosed and treated long before the heart defect causes physical symptoms. Typically, after repair and adequate time for healing, kids with ASDs rarely have further symptoms.

All A to Z dictionary entries are regularly reviewed by KidsHealth medical experts.