Atrial septal defect (ASD) is a congenital heart defect in which the wall that separates the upper heart chambers (atria) does not close completely. Congenital means the defect is present at birth.
Causes, incidence, and risk factors:
In fetal circulation, there is normally an opening between the two atria (the upper chambers of the heart) to allow blood to bypass the lungs. This opening usually closes around the time the baby is born.
If the ASD is persistent, blood continues to flow from the left to the right atria. This is called a shunt. If too much blood moves to 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. Many problems can occur if the shunt is large, but small atrial septal defects often cause very few problems and may be found much later in life.
ASD is not very common. When the person has no other congenital defect, symptoms may be absent, particularly in children. Symptoms may begin any time after birth through childhood. Individuals with ASD are at an increased risk for developing a number of complications including:
Larry A. Weinrauch, MD, Assistant Professor of Medicine, Harvard Medical School, and Private practice specializing in Cardiovascular Disease, Watertown, MA. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.
References
Webb GD, Smallhorn JF, Therrien J, et al. Congenital heart disease. Zipes DP, Libby P, Bonow RO, Braunwald E, eds. Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine. 8th ed. St. Louis, Mo: WB Saunders; 2007: chap 61.
