An atrioventricular (AV) canal defect is a congenital (present at birth) heart condition. It means there’s a hole in the center of your child’s heart and issues with the valves in their heart. Babies with this condition usually need surgery soon after birth. After surgery, children need lifelong monitoring.
An atrioventricular (AV) canal defect is a congenital heart condition, meaning, it’s present at birth. It describes a constellation of several heart problems, including a hole in the wall (septum) at the center of your heart, as well as problems with the way your heart’s valves work.
The condition makes your heart work too hard to pump blood. It also lets blood flow in the wrong direction. An AV canal defect can lead to a range of health conditions, including congestive heart failure.
The surgery to fix this has a high success rate. Without the operation, children usually only live two or three years.
Knowing how blood flows through your heart can make it easier to understand an AV canal defect.
Your heart has four chambers: two upper chambers (atria) and two lower chambers (ventricles). Valves with flaps connect the upper and lower chambers. The right chambers pump blood without oxygen from your body to your lungs. The lungs give oxygen to this blood, which then flows to the left chambers. The left chambers pump this blood with oxygen back to your entire body.
A wall (the septum) separates the right and left sides of your heart, which helps keep blood flowing in the right direction. Having an atrioventricular canal defect means there’s a hole in that wall. It’s like a pipe with a leak. It allows oxygen-rich blood (normally from the left side of your heart) to mix with oxygen-poor blood (normally from the right side of your heart). These don’t mix in a normally functioning heart.
In most cases, the hole allows too much blood to flow into your lungs and not enough blood to flow to the rest of your body. If the hole is present for a long time, the flow may go in the opposite direction, with more blood going to your body than to your lungs.
Other names for AV canal defect include:
An atrioventricular canal defect can take different forms:
About 1 in 1,900 babies are born with this defect each year in the U.S. It makes up between 3% and 5% of all congenital heart defects.
Atrioventricular septal defects are common in children with Down syndrome. They also occur in up to 40% of fetuses with trisomy 21.
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Soon after birth, a baby may have atrioventricular canal defect symptoms like:
Babies with mild partial or transitional AV canal defects may not have symptoms until later in childhood or even their teen years or early adult years.
Atrioventricular septal defect causes are unclear. It’s likely a combination of genetic and environmental factors. There’s a strong correlation between this congenital heart condition and Down syndrome.
Experts haven’t identified the exact risk factors for AVSD. Genetics may be a factor. A fetus can inherit an abnormal gene or genes from a parent, which may make them more likely to develop a heart condition in the uterus.
Other risk factors during pregnancy that may increase the chances of giving birth to a baby with a congenital heart defect include:
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A severe atrioventricular canal defect can lead to:
A healthcare provider can often diagnose an atrioventricular canal defect before birth with a few tests:
A provider may use a stethoscope to listen to your baby’s heartbeat after birth. An abnormal “whooshing” sound may mean that blood is flowing through a hole in their septum. Other tests after birth might include:
In some cases, your baby may have a small septal defect that doesn’t cause symptoms right after birth. It might be several years before a healthcare provider detects the condition.
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An AV canal defect usually requires open-heart surgery. During atrioventricular septal defect repair, your surgeon will put patches on the hole in your baby’s septum. In the case of a complete defect, your surgeon also will split the single heart valve into two separate valves on the right and left sides of your child’s heart.
A baby with an unbalanced AV canal defect will need several operations leading to a Fontan procedure.
It’s best to do surgery as early as possible, before the heart sustains lasting damage. Many babies have the surgery during infancy, within their first six months of life. Some babies with a partial defect but no symptoms may get the surgery during their first three years of life.
A baby that isn’t healthy enough for surgery may need medication to manage symptoms until they gain weight and strength. Another option is a short-term procedure: pulmonary artery banding. This allows less blood to go through their pulmonary artery to their lungs. Babies who receive pulmonary artery banding can have a permanent repair later.
After surgery, a child may have:
There’s no way to prevent an AV septal defect. But if you’re pregnant, you can reduce the risk of your baby having a congenital heart defect by:
Without surgery, most children with an AV canal defect have a life expectancy of two or three years. Some live to be young adults.
About 90% of children who have repair surgery have a 10-year survival rate. This means they live for at least another decade on average after treatment. About 65% are alive 20 years after surgery.
But even after surgery, someone with an atrioventricular canal defect won’t have a typical heart. They’ll need periodic echocardiograms to monitor their heart’s function and detect complications early.
The patch over the hole can usually stay in place for the rest of a person’s life. But over time, one of the repaired heart valves may begin to leak. About 10% to 20% of people need a second surgery, 5% to 10% of them for the leaky (regurgitant) valve.
After surgery, many people don’t need medications or more operations for their heart. But cardiac arrhythmias may develop later in life and a provider may recommend minimally invasive procedures like ablation.
You may need to limit your child’s physical activity. Ask your child’s pediatric cardiologist if you need to do this.
Children with an atrioventricular septal defect may need to take antibiotics before seeing the dentist. This can prevent endocarditis, a type of infection in your heart. Your child’s cardiologist can talk with you about this as well.
You should take your child to regular appointments with a pediatric cardiologist. They can monitor your child’s heart for any issues that develop. Some children with an AV canal defect need more treatment after surgery. A patch can leak and a repaired heart valve may develop a leak or get too narrow.
A child with an AV canal defect may also have neurological or developmental disorders. They may need help with these as well.
Once your child reaches adulthood, they should switch to an adult congenital heart specialist for annual visits.
Questions you may want to ask your child’s doctor include:
Hearing that your newborn has a heart issue can bring out a range of emotions. But your newborn’s healthcare providers are there to help you and they want the best for your child. Learn about the specific details of your child’s condition. Ask your child’s healthcare providers questions if there’s anything you want them to clarify. Now is the time to be an advocate for your child’s health.
Last reviewed on 12/06/2023.
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Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. Policy