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What Is Atrioventricular Septal Defect?

Atrioventricular (pronounced A-tree-oh-ven-TRIK-yu-lar) septal defect is a condition in which important parts at the center of the heart are not fully formed at birth. It’s also called AV septal defect.

The heart has two upper chambers (atria), the right atrium and left atrium, and two lower chambers, the right ventricle and left ventricle. There are also two heart valves that divide the atria from the ventricles (atrioventricular valves). The valve on the right side is the tricuspid valve. The valve on the left side is the mitral valve.

In AV septal defect, there is a hole in the wall (septum) between the right and left atria (atrial septal defect, ASD). There is also a hole in the septum between the right and left ventricles (ventricular septal defect, VSD).

In addition, the two atrioventricular valves are not formed correctly. A baby with AV septal defect may have just one larger valve opening in the middle, instead of one on each side of the heart.

Together these problems may create a hole in the center of the baby’s heart. As a result, blood does not flow the way it should between the chambers. So the heart has to work harder to pump blood to the lungs and the rest of the body.

This condition is also known as atrioventricular canal defect or endocardial cushion defect.

Atrioventricular Septal Defect in Children

It’s normal for babies to have holes between the atria and the ventricles while the heart is developing in the womb. The holes should close by the time the heart is fully developed.

In some babies the holes in the septum don’t close all the way and the atrioventricular valves do not form right.

AV septal defects are somewhat common. About two in every 10,000 babies are born with AV septal defect. Most of the time, it’s not clear why this happened. In some cases, it may be related to a genetic condition, such as Down syndrome. Congenital heart disease, particularly AV septal defect, is common in children with Down syndrome.

Atrioventricular Septal Defect at Seattle Children’s

Our heart team has treated many children with AV septal defect. We have extensive experience with the treatment these patients may require, including surgery to close the holes in the septa, to repair the valves, and to replace the valves (which some children need later in life). We also have a pediatric cardiac anesthesia team and a cardiac intensive care unit ready to care for children who undergo heart surgery.

When you come to Children's, a team of people will take care of your child. Along with your child's cardiologist, you are connected with neonatologists, pulmonologists (lung doctors), 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.

Since 1907, Children's has been treating children only. Our team members are trained in their fields and also in meeting the unique needs of children. For example, the doctors who give your child anesthesia are board certified in pediatric anesthesiology. This means they have extra years of training in how to take care of kids. Our child life specialists know how to help children understand their illnesses and treatments in ways that make sense for their age. Our expertise in pediatrics truly makes a difference for our patients and families.

The Adult Congenital Heart Disease Program shared by Children’s and the University of Washington can help with care throughout your child’s life.

Who Treats This at Seattle Children's?

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Summer 2014: Good Growing Newsletter

In This Issue

  • Understanding the Power and Influence of Role Models
  • Legal Marijuana Means Greater Poisoning Risks for Children
  • Why Choose Pediatric Emergency Care?

Download Summer 2014 (PDF)