AVSD comprises a heterogeneous group of congenital defects.
Abnormal endocardial cushion, mesenchymal cap and DMP development may result in AVSD.
Genetic and maternal risk factors for AVSD and developmental aspects are discussed.
AV-valve regurgitation after correction is common and can be assessed with 4DFlow MRI.
Non-syndromic and Down syndrome patients have different anatomy and outcome.