Atrial septal defect

Definition

Atrial septal defect is an abnormality of the upper chambers of the heart (atria) where the wall between the right and left atria does not close completely. This defect is present at birth (congenital).

Alternative Names

Causes

Atrial septal defect (ASD) is a congenital heart defect. 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. Sometimes, blood flows from the right atrium to the left atrium (a right to left shunt).

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:

• Pulmonary overcirculation
• Heart failure
• Atrial fibrillation (in adults)
• Stroke
• Pulmonary hypertension

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.