Atrioventricular Canal Defect

What is an atrioventricular canal defect?

An atrioventricular septal defect (also known as an atrioventricular canal defect) is a congenital heart condition, which means it’s present at birth. It describes 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 forces your heart to work too hard to pump blood. It also allows blood to flow in the wrong direction. It can lead to a range of health conditions, including congestive heart failure.

Atrioventricular septal defects are very common in children with Down syndrome.

How does blood flow through the heart?

Knowing how blood flows through your heart can make it easier to understand an atrioventricular 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 from your body to your lungs. The left chambers carry blood from your lungs back to your body. .

A wall (the septum) separates the right and left sides of your heart, which helps keep blood flowing in the right direction. But an atrioventricular canal defect means there’s a hole in the wall. It’s like a pipe with a leak. In most cases, the hole allows too much blood to flow backward into your lungs and not enough blood flows forward to the rest of your body. If the hole is present for a long time, the flow may go the opposite direction, with more blood going to your body than to your lungs.

What’s the difference between a complete and partial atrioventricular canal defect?

An atrioventricular canal defect can be complete or partial:

• Complete atrioventricular canal defect: The hole is big enough to provide an opening between all four chambers of your heart. Instead of the normal two valves between the upper and lower chambers, there’s just one valve. Its flap might not open and shut correctly.
• Partial atrioventricular canal defect: The hole is only between the wall of the two upper chambers (most typical) or the two lower chambers, not all four. There are two valves between the upper and lower chambers, but one of them (usually the mitral valve between the upper left atrium and lower left ventricle) doesn’t work correctly.

How common is an atrioventricular canal defect?

About 1 in 1,859 babies are born with this defect each year in the U.S. It makes up between 3% and 5% of all congenital heart defects.

What causes atrioventricular canal defects?

It’s not clear what causes atrioventricular septal defects. It’s likely a combination of genetic and environmental factors. There’s a strong correlation between this congenital heart condition and Down syndrome.

Who is at risk for an atrioventricular canal defect?

Experts haven’t identified exact risk factors for this heart condition. Genetics may be a factor. A baby 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:

• Certain medications.
• Recreational drug or alcohol use.
• Exposure to environmental toxins or chemicals.
• Nutrient or vitamin deficiencies.
• Having obesity.
• Smoking or using tobacco products.
• Unmanaged chronic health conditions, such as diabetes or high blood pressure (hypertension).
• Viruses or fevers, such as influenza (flu).

What are the symptoms of an atrioventricular canal defect?

Soon after birth, a baby with an atrioventricular canal defect may have:

• Cyanosis (bluish tint to the skin).
• Difficulty feeding.
• Fatigue, especially when feeding.
• Heart palpitations or racing.
• Shortness of breath (dyspnea).
• Slow weight gain.
• Swelling (edema) in the abdomen or legs.
• Weak pulse.

What are the complications of an atrioventricular canal defect?

A severe atrioventricular canal defect can lead to:

• Arrhythmia.
• Congestive heart failure.
• Endocarditis.
• Pulmonary hypertension.

How is an atrioventricular canal defect diagnosed?

A healthcare provider can often diagnose an atrioventricular canal defect before birth with a few tests:

• Prenatal ultrasound shows moving pictures of the fetus in the uterus, including its heart. A large septal defect may be visible on an ultrasound.
• A fetalechocardiogram creates images of the heart that are more detailed than ultrasound. It can give a healthcare provider important information about the structure of the heart and how well it’s pumping blood.

After birth, a healthcare provider may use a stethoscope to listen to your baby’s heartbeat. An abnormal “whooshing” sound may indicate that blood is flowing through a hole in the septum. Other tests after birth might include:

• Chest X-rays to show the size and shape of your baby’s heart.
• Electrocardiogram (EKG) to track the electrical activity of your baby’s heart.

In some cases, a 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.

How is atrioventricular canal defect treated?

An atrioventricular canal defect usually requires open-heart surgery. During atrioventricular septal defect repair, your surgeon puts patches on the hole in the septum. In the case of a complete defect, your surgeon also separates the single heart valve into two separate valves on the right and left sides of your child’s heart.

It’s best to do surgery as early as possible, before the heart sustains permanent damage. Many babies have the surgery during infancy, within their first six months. A baby that isn’t healthy enough for surgery may need medication to manage symptoms until they gain weight and strength.

Is an atrioventricular canal defect preventable?

There’s no way to prevent an atrioventricular canal defect, but if you're pregnant, you can reduce the risk of your baby developing a congenital heart defect by:

• Avoiding recreational drugs, alcohol and smoking or using tobacco products.
• Getting all necessary vaccinations to prevent illness.
• Maintaining a healthy body weight.
• Managing chronic health conditions.
• Taking prenatal vitamins, including folic acid, as directed by your healthcare provider.

What’s the prognosis (outlook) for babies with an atrioventricular canal defect?

About 90% of children who have repair surgery have a 10-year survival rate, which means they live for at least another decade after treatment. But even after surgery, someone with an atrioventricular canal defect will never have a “normal” 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 a person’s lifetime. However, over time, one of the repaired heart valves may begin to leak. About 5% to 10% of people need a second surgery for the leaky (regurgitant) valve.

Many people lead full, active lives after their surgery. Once your child reaches adulthood, they should transition into the care of an adult congenital heart specialist.

What questions should I ask my child’s doctor?

Questions you may want to ask your child’s doctor include:

• Does my child have a partial or complete defect?
• What symptoms might indicate that the condition is getting worse?
• When will you do surgery?
• Will my child need medication after the surgery?
• Will I need to limit my child’s activities?

A note from Cleveland Clinic

An atrioventricular septal defect is a congenital heart condition. It means there’s a hole in the center of your child’s heart and problems with the valves in their heart. Babies with this condition usually need surgery soon after birth. After surgery, a lot of children go on to live full, active lives. However, people with congenital heart conditions need lifelong monitoring.