A heart normally develops with a small opening between the two upper chambers of the heart (called atria) to allow blood to bypass the lungs. As the lungs become more developed, the heart no longer needs to bypass the blood and the opening between atria will close. An atrial septal defect occurs when the opening between the two chambers does not close completely In rare cases, the hole may spontaneously close after birth. Shunting refers to when the blood flows from the left chamber to the right chamber.
If too much blood moves from the right side of the heart, pressures in the lungs build up. The shunt can be reversed so that blood flows from right to left.
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What Causes Atrial Septal Defect?
A heart normally develops with a small opening between the two upper chambers of the heart (called atria) to allow blood to bypass the lungs. As the lungs become more developed, the heart no longer needs to bypass the blood and the opening between atria will close. An atrial septal defect occurs when the opening between the two chambers does not close completely In rare cases, the hole may spontaneously close after birth. Shunting refers to when the blood flows from the left chamber to the right chamber.
If too much blood moves from the right side of the heart, pressures in the lungs build up. The shunt can be reversed so that blood flows from right to left.
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