Heart and Blood Conditions

Atrioventricular Septal Defect

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    • For appointments in Seattle, Bellevue, Everett, Federal Way, Olympia, Tri-Cities and Wenatchee, call 206-987-2515.
    • For appointments in Tacoma and Silverdale, call 253-272-1812.
    • For appointments in Alaska, call 907-339-1945.
    • How to schedule

    If this is a medical emergency, call 911.

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  • Locations +

    • Seattle Children's Main Campus: 206-987-2515
    • Bellevue Clinic and Surgery Center: 425-454-4644
    • Everett: 425-304-6080
    • South Clinic in Federal Way: 253-838-5878
    • Olympia: 360-459-5009
    • South Sound Cardiology Clinics: 253-272-1812
    • Tri-Cities (Richland): 509-946-0976
    • Wenatchee: 509-662-9266
    • Pediatric Cardiology of Alaska: 907-339-1945
    • Seattle Children's doctors provide many cardiac services at regional sites throughout the Pacific Northwest. See our complete list of Heart Center locations.

  • Refer a patient +

    • If you are a provider, fax a New Appointment Request Form (NARF) (PDF) (DOC) to 206-985-3121 or 866-985-3121 (toll-free).
    • No pre-referral work-up is required for most conditions. If you have already done testing such as an EKG, Holter monitor or echocardiogram, please fax this information as well as relevant clinic notes and the NARF to 206-985-3121 or 866-985-3121 (toll-free).
    • Your patient will be seen as quickly as possible by the provider who is the best match for managing the current problem.
    • View our complete Heart Center Referral Information (PDF).

What is atrioventricular septal defect?

Atrioventricular (pronounced A-tree-oh-ven-TRIK-yu-lar) septal defect (AV septal defect) is a condition in which the center of the heart is not fully formed at birth. It is also known as atrioventricular canal defect or endocardial cushion defect.

The normal heart has a total of four chambers. There are two upper chambers, called the right atrium and left atrium. There are also two lower chambers, called 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.

Atrioventricular Septal Defect at Seattle Children’s

We provide accurate diagnosis, thoughtful counseling and pregnancy management support through our Prenatal Diagnosis and Treatment Program.

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). Children with AV septal defect receive compassionate, comprehensive care through our Single Ventricle Program.

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 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 newborn specialists (neonatologists), cardiac intensivists, lung doctors (pulmonologists), 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.

Seattle Children’s has been treating children since 1907. Our team members are trained in their fields and in meeting the unique needs of children. For example, the doctors who give your child anesthesia (sedation) 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.

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

Atrioventricular Septal Defect in Children

It is 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, which occurs around the seventh week of pregnancy.

In some babies, the holes in the septum do not close all the way and the atrioventricular valves do not fully form.

About 2 in every 10,000 babies are born with AV septal defect. Most of the time, it is not clear why this happened. In some cases, it may be related to a genetic condition such as Down syndrome, where up to 50% of people may have congenital heart disease.

Contact Us

Contact the Heart Center at 206-987-2015 for a cardiac referral, a second opinion or more information.