Congenital heart defects (also called congenital heart diseases) are structural abnormalities that are present in the heart at birth.

Atrial Septal Defect

Atrial Septal Defect

What is an atrial septal defect (ASD)?

An atrial septal defect (ASD) is a hole in the septum, or muscular wall, that separates the heart’s two upper chambers (atria). An ASD occurs when part of the atrial septum does not form properly.

What causes atrial septal defects?

About 10 percent of congenital heart problems are caused by specific genetic defects. Most congenital heart defects are likely due to maternal environmental factors combined with a genetic predisposition. Environmental factors include use of alcohol and street drugs, as well as diseases such as diabetes, lupus and rubella.

Who is affected by atrial septal defects?

Atrial septal defects account for about seven percent of all congenital heart defects, making them the third most common type. In addition, ASDs are the most common congenital defect in adults and are more common among women than men.

What are the long-term effects of atrial septal defects?

Normally, the right side of the heart pumps blood that is low in oxygen to the lungs, while the heart’s left side pumps oxygen-rich blood to the body. When there is an ASD, blood from the left and right sides mix, and the heart generally does not work at its most efficient level.

The risk of problems is greater when the defect is large (greater than 2 cm). Problems may include:

  • Right heart enlargement (leading to right heart failure)
  • Heart rhythm disturbances, including atrial fibrillation or atrial flutter, occur in 50 to 60 percent of all patients over age 40 with an ASD.
  • Stroke
  • Pulmonary hypertension (high blood pressure in the arteries that supply blood to the lungs). Blood normally flows from the left side of the heart to the right, but in patients with an ASD and severe pulmonary hypertension, the blood flow across the ASD can reverse (flow right to left). As a result, oxygen levels in the blood will decrease, leading to a condition known as Eisenmenger syndrome.
  • Leaking tricuspid and mitral valves as a result of enlargement of the heart