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.
    • For appointments in Montana, call 406-771-3223.
    • 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
    • Pediatric Cardiology of Montana: 406-771-3223
    • Seattle Children's doctors provide many cardiac services at regional sites throughout the Pacific Northwest. See our complete list of Heart Center locations.

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    • 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 4 chambers. There are 2 upper chambers, called the right atrium and left atrium. There are also 2 lower chambers, called the right ventricle and left ventricle. There are also 2 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 2 atrioventricular valves are not formed correctly. A baby with AV septal defect may have just 1 larger valve opening in the middle, instead of 1 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.

  • 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.

Atrioventricular Septal Defect at Seattle Children’s

  • Seattle Children’s Heart Center is among the best pediatric cardiology programs in the United States and is the top-ranked program in the Northwest, according to U.S. News & World Report. With more than 40 pediatric cardiologists, we have experience diagnosing and treating every kind of heart problem.

    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.

    See our statistics and outcomes for AV canal repair.

    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.

  • 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.

Symptoms of Atrioventricular Septal Defect

AV septal defects range from small to large. Small defects might cause only mild symptoms. It depends on how much blood is moving between the heart’s chambers in a way that is not normal.

AV septal defects can cause symptoms such as these:

  • Fast breathing
  • Shortness of breath or working hard to breathe when feeding
  • Arrhythmia
  • Sweating, particularly with feeding in infants
  • Failure to thrive
  • Trouble exercising
  • Fatigue
  • Palpitations

Most children with AV septal defect have symptoms within the first several weeks after birth. Rarely, some may develop symptoms later in childhood.

If not repaired, AV septal defect can lead to serious health problems, like high blood pressure in the lungs and heart failure.

Diagnosing Atrioventricular Septal Defect

To diagnose AV septal defect, your doctor will examine your child, check their heartbeat and listen to their heart. In children with AV septal defect, doctors can often hear a heart murmur.

The doctor will ask for details about any symptoms your child has, their health history and your family health history.

Your child will likely need other tests, such as echocardiography, an electrocardiogram or chest X-rays.

They may need other tests that provide more information about how their heart looks and works. These might include an MRI (magnetic resonance imaging) of the heart and cardiac catheterization.

Treating Atrioventricular Septal Defect

The large majority of infants and children with AV septal defects will have symptoms that indicate their heart is not pumping blood normally, and they will need surgery to fix the defect. The surgeon will operate to close the holes in the septa using patches and to divide the central, or common, valve into 2 valves: 1 on the right and 1 on the left.

The details of the surgery will depend on how severe your child’s defect is and will be planned to meet your child’s needs.

If your child has heart failure, they may need other treatment to help their heart work in addition to the surgery.

Transitioning to Adult Care

To meet your child’s long-term healthcare needs, we have a special Adult Congenital Heart Disease Program to transition your child to adult care when they are ready.

Contact Us

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