(Atrioventricular Canal Defect; Endocardial Cushion Defect)
Pronounced: A-tree-o-ven-TREAH-q-lar sep-TAL DEE-fect
The heart is divided into four chambers that help circulate blood through the body. The top two chambers are called atria. The bottom two chambers are called ventricles. Two valves are between the upper and lower chambers. Tissue called the septum divides the chambers. The tissue grows as the fetus develops.
An atrioventricular septal defect is present at birth. It occurs when any of the tissues that divide the septum do not grow completely. This leaves one or more holes. It may also leave one leaky valve instead of two separate valves.
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This condition is caused when the septal tissue fails to grow correctly as the fetus develops in the womb.
Risk factors that increase the chance that a baby will be born with a ventricular septal defect include:
- A family history of heart defects
- Down syndrome
- Alcohol consumption or drug abuse by the mother during pregnancy
- A mother with diabetes
- Rubella infection during the first three months of pregnancy
- Exposure to thalidomide, anticonvulsant medications, or lithium salts while in the womb
- Exposure to certain industrial chemicals during pregnancy
- Difficulty feeding
- Failing to gain weight
- Lung congestion
- Difficulty breathing, especially during feeding
- A bluish tint to lips and fingernails
- Pale skin
- Frequent pneumonia
- Lack of appetite
- Swollen legs or abdomen—rare in children