Atrial Septal Defect_KH_Kids  Atrial Septal Defect   What Is an
Atrial Septal Defect?  Atrial septal defect (say: ay-tree-ul
sep-tul dee-fekt), or ASD for short, is a heart condition that
can affect kids. To understand an ASD, it helps to know how the
heart works. The heart has four chambers. The lower chambers of
the heart are called the ventricles. There are two ventricles: a
left ventricle and a right ventricle. The upper chambers are the
atria and there are two of them — a left atrium and a right
atrium. (Atrium is an old word that meant the main room in an
ancient Roman house, so the atria are "rooms" in your heart!)
Between the right and left atria, there is a wall called the
septum that normally separates the blue and red blood. In a
person with an atrial septal defect, there's an opening in that
wall. This hole in the wall lets oxygen-rich blood from the left
atrium mix with oxygen-poor blood on the other side. The extra
blood that ends up crossing through the hole and flowing through
the heart and