An atrioventricular canal is a congenital heart defect that connects chambers of your child’s heart that shouldn’t be connected. Atrioventricular canals usually require surgical treatment.

An atrioventricular (AV) canal is a congenital condition, meaning it’s present from birth. It occurs in about 1 in 1,859 babies per year in the United States, according to the Centers for Disease Control and Prevention (CDC). It makes up about 3–5% of congenital heart conditions.

It usually isn’t known what causes an AV canal, but they occur in nearly half of people who also have Down syndrome. They’re also associated with other genetic syndromes such as Ivemark syndrome and Smith-Lemli-Opitz syndrome.

In this article, we take a deeper look at AV canals including symptoms, how they’re treated, and the outlook for those diagnosed with them.

These AV canals go by other names such as:

An AV canal is a heart defect where a hole connects the chambers on the left and right sides of your child’s heart.

AV canals cause oxygenated blood from the left side of your heart to mix with unoxygenated blood on the right side.

Normal movement of blood through the heart

The primary function of your heart is to pump blood throughout your body so that your tissues can receive oxygen. The inside of your heart is made up of four chambers. The top two chambers are called atria. The bottom two are called ventricles.

Blood normally moves through your heart in the following pattern.

  1. Unoxygenated blood that was circulating throughout your body returns to your right atrium.
  2. Your heart pumps blood through your tricuspid valve to your right ventricle.
  3. Blood pumps from your right ventricle to your lungs.
  4. Oxygenated blood from your lungs enters your left atrium.
  5. Your heart pumps blood through the mitral valve to your left ventricle.
  6. Blood pumps from your left ventricle to all the tissues in your body.

Learn more about the anatomy of your heart.

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Types of AV canal defects

AV canal defects can be complete or partial.

A complete AV canal is when a large hole forms in the middle of your heart and connects all four chambers.

People with this type of defect have one valve in the middle of their heart separating the top and bottom chambers. Normally, this central valve becomes two separate valves on the right and left sides of your heart while you’re developing in the womb.

A partial AV canal occurs when a hole in the heart causes blood to flow through two chambers that are not normally connected. In most cases, the hole develops between the atria or between the ventricles.

People with partial AV canals usually have fully formed valves in their heart, but one of their valves may not close properly. In most cases, it’s the mitral valve on the left side of the heart that does not close properly.

Septal defects are another name for AV canals.

The septum is a band of tissue that separates the left and right chambers of your heart. A septal defect is a hole in your septum.

A ventricular septal defect is when the hole occurs between your ventricles and an atrial septal defect is when it occurs between your atria.

The severity of symptoms depends on the size and type of AV canal your child has. Symptoms often appear within the first 6 months of life. Some infants with partial AV canals might not have noticeable symptoms for a couple of years.

The backflow of blood from the left to the right side of your child’s heart can increase pressure in the blood vessels that lead to their lungs. They might experience symptoms such as:

Your child’s doctor may be able to hear a heart murmur with a stethoscope. Other signs and symptoms can include:

These symptoms often appear by roughly 6–8 weeks.

Partial and complete AV canals usually require surgery. Doctors perform open-heart surgery to repair the hole in your child’s heart with patches.

When treating complete AV canals, your child’s surgeon will divide the valve in the middle of their heart into two valves. If the mitral valve on the left side of their heart doesn’t function properly, it may need to be repaired or replaced.

It’s generally recommended for surgery to be performed as early in life as possible. Irreversible damage to the blood vessels leading to the lungs can occur within 2 years.

Medications can help improve your child’s heart and lung function before or while they’re recovering from surgery. They may be given:

The long-term outlook for an AV canal is often good with surgical treatment. Doctors have been performing AV canal repairs since the mid-1950s.

At least 90% of children who receive treatment are still alive 10 years later. About 3% of children die during surgery or shortly after.

Once the canal has been closed, your child may not need to limit any physical activities. About 10–20% of children will need a second surgery.

Your child’s pediatric cardiologist will schedule regular visits to monitor and to examine your child after their surgery to make sure they do not have any long-term complications.

An AV canal is a birth defect that causes blood to flow irregularly through the chambers of your child’s heart.

A complete AV canal is a hole that connects all four chambers in the heart. A partial AV canal usually connects the two top or two bottom chambers.

AV canals are usually treated with surgery. Many children regain normal function of their heart after surgery without the need to limit physical activity or take medications.