Heart and Blood Conditions

Atrial Septal Defect

What is atrial septal defect?

Babies born with atrial (pronounced a-tree-ahl) septal defect (ASD) have an opening in the wall separating the 2 upper chambers of their heart: the right atrium and left atrium. The dividing wall is called the septum.

Normally, the heart works this way:

  • Oxygen-poor (blue) blood returns from the body to the right atrium.
  • It flows into the right ventricle.
  • The right ventricle pumps it to the lungs, where it receives oxygen.
  • Oxygen-rich (red) blood returns from the lungs to the left atrium.
  • It flows into the left ventricle and is then pumped out to the body through the aorta.

When there is an opening between the atria, oxygen-rich blood passes from the left atrium into the right atrium. With small openings, a small amount of blood passes between the atria and the child doesn’t have symptoms.

With larger openings, more blood passes to the right side of the heart. This causes the right side to be overworked and enlarged. Also, the lungs receive extra blood, which causes higher pressures than normal in the blood vessels of the lungs (pulmonary hypertension).



Atrial Septal Defect in Children

It is normal for babies to have a small opening, called the foramen ovale, between their atria while they are developing in the womb. This opening usually closes soon after birth.

Some babies have an abnormal opening, an ASD. Most of the time, it’s unclear why it developed. Almost 4 in every 100,000 babies have an ASD. This defect is about twice as common in girls as it is in boys.

Some children with ASD are born with other heart defects (congenital heart defects), such as ventricular septal defects. Children with certain genetic syndromes, such as Down syndrome, are at increased risk for developing an ASD.

Atrial Septal Defect at Seattle Children’s

Our heart team has years of experience in the treatment of children with atrial septal defects. This includes using cardiac catheterization to close the opening in the septum with a device or performing surgery to close the opening. We have a pediatric cardiac anesthesia team and a Cardiac Intensive Care Unit ready to care for children who need to have heart surgery.

When you come to Seattle Children’s, a team of people will take care of your child. Along with your child’s heart doctor (cardiologist), you are connected with nurses, child life specialists, social workers and others, if their expertise is needed. We work together to meet all of your child’s health needs and help your family through this experience.



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