Artrioventricular Canal Defects (AV Canal Defects)

What are atrioventricular canal defects (AV Canal Defects)?

An atrioventricular canal defect is a problem in the part of the heart that connects the upper chambers (atria) to the lower chambers (ventricles).

There are two types of atrioventricular canal defects: complete and partial.

Complete atrioventricular canal (CAVC)

Complete atrioventricular canal (CAVC) is a severe defect in which there is a large hole in the tissue (the septum) that separates the left and right sides of the heart. The hole is in the center of the heart, where the upper chambers (the atria) and the lower chambers (the ventricles) meet.

As the heart formed abnormally, with this large hole, the valves that separate the upper and lower chambers also developed abnormally. In a normal heart, two valves separate the upper and lower chambers of the heart: the tricuspid valve separates the right chambers and the mitral valve the left. In a child with a complete atrioventricular canal defect, there is one large valve, and it may not close correctly.

As a result of the abnormal passageway between the two sides of the heart, blood from both sides mix, and too much blood circulates back to the lungs before it travels through the body. This means the heart works harder than it should have to, and will become enlarged and damaged if the problems aren’t repaired.

Partial atrioventricular canal defects

A partial atrioventricular canal defect is the less severe form of this heart defect. The hole does not extend between the lower chambers of the heart and the valves are better formed. Usually it is necessary only to close the hole between the upper chambers (this hole is called an atrial septal defect, or ASD) and to do a minor repair of the mitral valve. Partial atrioventricular canal is also called atrioventricular septal defect, or AVSD.

What are the symptoms of atrioventricular canal defects?

In a complete atrioventricular canal defect, the following symptoms may be present within several days or weeks of birth:

  • Blue or purple tint to lips, skin and nails (cyanosis)
  • Difficulty breathing
  • Poor weight gain and growth
  • Heart murmur – the heart sounds abnormal when a doctor listens with a stethoscope
  • Fatigue
  • Sweating
  • Pale skin
  • Cool skin
  • Rapid breathing
  • Heavy breathing
  • Rapid heart rate