Atrioventricular Canal Defect (ACD)

What is an Atrioventricular Canal Defect?

Frequently associated with Down syndrome, atrioventricular canal defect is a birth defect affecting the center of the heart. It’s a defect that results in a hole between heart chambers and a problem with heart valves. This type of defect causes excess blood to flow to the lungs. The extra blood makes the heart work harder and enlarges the heart muscle.


Caused by a defect with development during birth, an atrioventricular canal defect can be limited to the upper chambers or the heart (partial ACD) or affect all four chambers of the heart (complete ACD). Both forms of the condition result in excess blood circulating through the lungs. Symptoms linked with a full ACD typically become evident within the first few weeks of life. Symptoms of a partial ACD may not become apparent until early adult years.

What are the Symptoms of an Atrioventricular Canal Defect?

Symptoms include

  • Rapid breathing
  • Tiredness
  • Poor appetite and insufficient weight gain
  • Pale skin and bluish skin
  • Irregular heartbeat
  • Leg or foot swelling

Partial ACD symptoms

Atrioventricular Canal Defect Causes

Atrioventricular canal defect (ACD) is caused by defects that occur in vitro, when the baby’s heart is still developing.

While the true cause of the defects is unknown, there are some factors that increase the risk of a baby being born with ACD. These include the pregnant mother contracting rubella, or German measles, in early pregnancy, Down’s syndrome, diabetes.

Other heavily discouraged behaviours during pregnancy, such as smoking or drinking alcohol, may also contribute to causing ACD. Certain medications may also have an impact. A family history of congenital heart defects may increase the risk of ACD being caused in a baby.

When partial ACD occurs, there’s a hole in the septum wall that sections off the heart’s upper chambers, or atria. Often, the mitral valve between the upper and lower left sections of the heart leaks due to a defect. In babies with complete ACD, they have a large hole in the heart’s center where there should be complete walls separating the atria and ventricles (lower levels). This mixes oxygen-rich and oxygen-deprived blood via the hole.

How is an Atrioventricular Canal Defect Treated?

Due to the serious nature of the defect, it is usually detected early in life. The standard treatment is surgery within the first year of life. It’s often a two-stage surgery with an initial procedure to stop or limit blood flow to the lungs and surgery to repair the valve(s) performed when the child is older.

See a doctor

Parents are encouraged to see a doctor as soon as any unusual symptoms develop, even if it turns out not to be an atrioventricular canal defect. The sooner the defect is detected, the greater the odds are of experiencing a full recovery with no lingering health issues. Unlike similar defects, it won’t close on its own.

Atrioventricular Canal Defect Prevention

ACD can’t be predicted or prevented at the current time, although heredity probably influences who may develop this and other heart defects. If you have a family history with this type of condition, or one of your children already has a congenital heart defect, speak with a genetic counselor and then a cardiologist prior to trying for another child.

Some of the possible causes and risk factors, such as smoking and drinking alcohol, should be avoided during pregnancy. Additionally, if you’re planning to get pregnant, you should look into having an MMR booster vaccine, as this will immunise you against rubella (and mumps and measles). However, the vaccine can itself cause a risk during pregnancy, so wait a month before trying to conceive and don’t have the vaccine if you are already pregnant.