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Atrioventricular (AV) Canal

What is an atrioventricular canal defect?

An atrioventricular (AV) canal defect is a congenital heart defect. This means that your child is born with it. This condition includes the following heart problems:

  • Atrial septal defect. This is an opening in the wall (septum) between the two upper chambers of the heart. These are called the right and left atria.
  • Ventricular septal defect. This is an opening in the wall between the two lower chambers of the heart. These are called right and left ventricles.
  • Improperly formed mitral or tricuspid valves. This is when the valves that separate the upper heart chambers from the lower heart chambers aren’t formed right. This is due to a problem in the left-sided valve (mitral valve) of the heart. 

These defects may range from partial to complete. These conditions cause oxygen-rich (red) blood and oxygen-poor (blue) blood to mix. This sends extra blood to your child's lungs. 

What causes an AV canal defect?

Genes and family history may play a part in AV canal defects. They may be caused by Down syndrome or other chromosome problems.

What are the symptoms of an AV canal defect?

The symptoms of AV canal defect may be similar to symptoms caused by other heart problems.

Infants with AV canal defects often have symptoms. Symptoms can occur a bit differently in each child. They can include:

  • Tiredness
  • Sweating
  • Pale, cool skin
  • Fast, heavy breathing
  • Fast heart rate
  • Chest congestion
  • Poor feeding
  • Poor weight gain

Your child’s symptoms depend on the size of his or her septal openings. The larger the openings, the more blood is able to pass through them. This can overload your heart and lungs. This means that your child’s symptoms may be more severe.

Over time, the pressure in your child’s lungs will force blood back to his or her heart. This blood has low oxygen levels, and it’s sent to the rest body. This causes your child’s lips, nailbeds, and skin to turn blue (cyanosis).

How is an AV canal defect diagnosed?

Your child's healthcare provider  may first suspect this issue when he or she hears an abnormal sound (heart murmur) when listening to your child's heart with a stethoscope. Your child may also have symptoms of a heart problem. Your child’s healthcare provider may refer your child to a heart doctor for children (pediatric cardiologist).

The heart doctor will check your child and listen to his or her heart and lungs. The location and loudness of the murmur will help the doctor make the diagnosis.

Your child’s doctor may then do tests to confirm the diagnosis. The tests your child has depends on his or her age and condition, and the doctor’s preferences.

Chest X-ray

A chest X-ray may show changes in the heart and lungs caused by an AV canal defect.

Electrocardiogram (ECG)

This test records the electrical activity of the heart. It also shows abnormal rhythms (arrhythmias or dysrhythmias) and spots heart muscle stress. These issues may be caused by caused by an AV canal defect.

Echocardiogram (echo)

This test uses sound waves to make a moving picture of the heart and heart valves. An echo can show the pattern of blood flow through the septal openings. It can also show how large the openings are and how much blood is passing through them. Most AV canal defects are diagnosed with an echo.

Cardiac catheterization

A cardiac catheterization gives very detailed information about the structures inside the heart. In this test, a small, thin, flexible tube (catheter) is put into a blood vessel in your child’s groin. Then the healthcare provider guides it to your child’s heart. Your child’s healthcare provider will inject your child with contrast dye to see his or her heart more clearly. Your child’s healthcare provider will give him or her medicine to help relax and prevent pain (sedation). Your child’s blood pressure and oxygen levels will be checked during the procedure.

How is an AV canal defect treated?

Treatment will depend on your child’s symptoms, age, and general health. It will also depend on how severe the condition is.

All children with an AV canal defect will need to have surgery to fix it. They may also need other treatments.

Medicine

Many children will need medicine to help their heart and lungs work better. Your child may need the following medicine:

  • Digoxin. This medicine helps the heart pump better.
  • Diuretics. This medicine helps the kidneys remove extra fluid from the body.
  • ACE (angiotensin-converting enzyme) inhibitors. These medicines make it easier for the heart to pump blood to the body.

Nutrition

Infants may become tired when feeding. This may stop them from eating enough to gain weight. Your child may need the following:

  • High-calorie formula or breastmilk. Your child may need special nutritional supplements added to their formula or pumped breastmilk.
  • Supplemental tube feedings. Your child may need to be fed through a tube. This small, flexible tube passes through the nose, down into the esophagus, and into the stomach. Your child may have tube feedings in addition to or instead of formula or breastmilk.

Infection control

Children with heart problems are at risk for infections of the lining of the heart and heart valves (bacterial endocarditis). Make sure that you tell all of your child’s healthcare providers that your child has an AV canal defect. Your child may need to take antibiotics before medical tests to prevent infections.

Surgery

Your child will need surgery to repair the septal openings and heart valves. This is done to stop his or her lungs from becoming damaged. Your child's heart doctor will decide when he or she will have surgery. After the surgery, your child's heart doctor may give him or her antibiotics. This is to prevent infections after he or she leaves the hospital.

Most children have surgery by the age of 6 months. Children with Down syndrome may develop lung problems earlier, and may need to have surgery at a younger age.

What are the complications of an AV canal defect?

If left untreated, an AV canal defect can cause several problems.

Lung disease

This is because of higher than normal pressure in the blood vessels and lungs. This lung damage doesn’t happen right away. The lungs are able to cope with extra volume of blood for a while. 

Blue coloring to your child’s skin, lips, and nailbeds

As the arteries in the lungs get thicker, less blood will flow from the left to the right side of the heart and to the lungs. It will be easier for oxygen-poor (blue) blood to flow from the right side into the left side of the heart, and on to the rest of the body. This stops the body from getting enough oxygen. This causes a blue coloring to your child’s skin, lips, and nailbeds.

Infections

Bacteria in the bloodstream can cause infections of the lining of the heart and heart valves.

Living with an AV canal defect

All children with an AV canal defect will need to have surgery to repair it. Before their operation, it’s important to follow their medicine and feeding schedules. 

Many children who have had an AV canal defect will live active, healthy lives after their surgery. Their activity levels, appetite, and growth will return to normal over time. Some children will still have heart valve problems after surgery. They may eventually need another operation to repair the leaky or blocked valve or valves. Ask your child's healthcare provider about your child’s outlook.

Children with Down syndrome get help from special programs to help their mental and physical development. Ask your child’s healthcare provider about programs available in your community.

Key points about an AV canal defect

  • An AV canal defect is a heart problem that children can be born with.
  • An AV canal defect is a complex problem.
  • Children with an AV canal defect need to have surgery to repair it.
  • Many children who have had an AV canal defect will live active, healthy lives after their surgery.

Next steps

Tips to help you get the most from a visit to your child’s healthcare provider:

  • Know the reason for the visit and what you want to happen.
  • Before your visit, write down questions you want answered.
  • At the visit, write down the name of a new diagnosis, and any new medicines, treatments, or tests. Also write down any new instructions your provider gives you for your child.
  • Know why a new medicine or treatment is prescribed and how it will help your child. Also know what the side effects are.
  • Ask if your child’s condition can be treated in other ways.
  • Know why a test or procedure is recommended and what the results could mean.
  • Know what to expect if your child does not take the medicine or have the test or procedure.
  • If your child has a follow-up appointment, write down the date, time, and purpose for that visit.
  • Know how you can contact your child’s provider after office hours. This is important if your child becomes ill and you have questions or need advice.
Online Medical Reviewer: Freeborn, Donna, PhD, CNM, FNP
Online Medical Reviewer: Holloway, Beth, RN, M.Ed.
Date Last Reviewed: 3/26/2015
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