It is the development of a hole in the wall (septum) that separates the upper chambers of the heart (atria) from the lower chambers (ventricles).

AVCD is a developmental disorder, it occurs when the heart is forming in the womb before birth.

Children with Down syndrome are susceptible to AVCD. Other associated factors are family history of heart problems by birth, consumption of alcohol or certain medicines during pregnancy by the mother.

If suspected AVCD (by hearing a whooshing murmur sound on stethoscope), doctors often prescribe an echocardiogram, electrocardiogram, chest x-ray with or without injecting a dye that makes the heart structures more visible on x-ray film.

The only treatment for AVCD is surgery, usually done within 6 months of birth.

In AVCD surgery, the hole in the septum is covered by artificial patches in an open heart surgery. Later, lining of the heart encloses the patch and becomes continuous repairing the defect permanently. If any valve defect or other congenital defect is present, it is corrected simultaneously.