Atrioventricular Septal Defect

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 congenitalheart 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 specialistsknow how to help children understand their illnesses and treatments in ways that make sense for their age.

  • We provide the care that is right for your child at the right time. This begins with accurate diagnosis, thoughtful counseling and pregnancy management support through our Prenatal Diagnosis and Treatment Program.

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

  • 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.

    Read more about the supportive care we offer.

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 206-987-2515 to request an appointment, a second opinion or more information.

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