Atrioventricular Canal Defect

A complete atrioventricular canal defect is an opening between the upper and lower chambers of the heart. There also usually are abnormalities in the mitral valve, which separates the left atrium and left ventricle or the tricuspid valve, which is a three-part valve that separates the right atrium from the right ventricle.

In the partial form, there may be a problem with the wall between the upper chambers of the heart, just above the highest point of the wall that separates the lower chambers of the heart.

This type of defect represents about 5% of all heart defects that are present at birth.


When this defect is present, a baby may have:

  • Bluish or purplish skin color indicating a lack of oxygen
  • A heart murmur that indicates abnormalities of the heart's valves
  • Heart failure
  • Disease of the blood vessels of the lungs, if surgical repair is delayed past the first six to 12 months of life.


A diagnosis can be made on the basis of:

  • An electrocardiogram (EKG), which creates a graph of the variations in electrical impulses generated by the heart muscle
  • An X-ray, which will show enlargement of the heart

Confirmation of the diagnosis can be done using two-dimensional echocardiography.


When surgery to repair the defect is done depends on the child's overall health. It should be done before the child is two. In some medical centers, this type of surgery is done as young as three to four months of age.