Complete atrioventricular canal with guarded primum septal defect.

Common atrioventricular canal (CAVC) is a common congenital heart lesion resulting from a defect in development of the endocardial cushions during early embryogenesis. Depending on the type of defect, CAVC can encompass a spectrum of lesions ranging from partial atrioventricular (AV) canal to complete AV canal. We describe a case of CAVC with unique anatomy in a 4-month-old male infant with Down syndrome.