An atrial septal defect is a type of congenital heart defect
As a baby’s heart develops during pregnancy, there are normally several openings in the wall dividing the upper chambers of the heart (atria). These usually close during pregnancy or shortly after birth.
If one of these openings does not close, a hole is left, and it is called an atrial septal defect. The hole increases the amount of blood that flows through the lungs and over time, it may cause damage to the blood vessels in the lungs. Damage to the blood vessels in the lungs may cause problems in adulthood, such as high blood pressure in the lungs and heart failure. Other problems may include abnormal heartbeat, and increased risk of stroke.