Atrioventricular Canal Defect | Symptoms and Causes

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What are the symptoms of atrioventricular (AV) canal defect?

A child with AV canal defect will usually develop symptoms within the first few weeks of life. These symptoms may include:

  • disinterest in feeding, or tiring while feeding
  • poor weight gain
  • fatigue
  • sweating
  • pale skin
  • cool skin
  • rapid breathing
  • heavy breathing
  • rapid heart rate
  • congested breathing
  • blue color
  • heart murmur (detected by doctor)

If your child has any of these symptoms, your pediatrician will probably refer you to a pediatric cardiologist for testing, diagnosis and a determination of treatment.

What causes atrioventricular canal defect?

When the heart is forming during the first eight weeks of fetal development, it begins as a hollow tube. Over time, partitions that form within the tube eventually become the walls dividing the right side of the heart from the left.

Atrial and ventricular septal defects occur when the partitioning process doesn’t occur completely, leaving openings in the atrial and ventricular walls (septa). The valves that separate the upper and lower heart chambers are formed toward the end of this eight-week period, and often they don’t develop properly. Frequently, instead of two separate AV valves (tricuspid and mitral valve), there is a single large common valve that sits between the upper and lower chambers of the heart, allowing blood to flow freely between the chambers above and below the valve — mixing oxygen-rich and oxygen-poor blood.

Do genetics play a role in atrioventricular canal defect?

Genetics may play a role in the development of AV canal defect. And some studies have investigated a possible link between the use of retinoic acid (for the treatment of acne and facial wrinkles) while pregnant and the development of atrioventricular canal in the fetus.

The majority of cases have associated genetic syndromes. AV canal affects about 15 to 20 percent of children with Down syndrome. The condition affects about 45 percent of children with Down syndrome who have a heart defect, and about one-third of children born with AV canal also have Down syndrome.

14 percent of mothers with an AV canal defect give birth to a child with the disease.

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