Echocardiographic assessment of atrioventricular canal defects.

AV canal defects (AVCD) are caused by maldevelopment of the endocardial cushions and typically include a primum atrial septal defect (ASD), an inlet ventricular septal defect (VSD), and a common atrioventricular valve. The variations in deformities provide the basis for the many terms used in the anatomical classifications: partial, transitional, intermediate, and complete common AVCD (balanced or unbalanced). The balanced complete common AVCDs are classified as Rastelli A, B, C depending on the anomaly of the anterior bridging leaflet division and attachments. Unbalanced complete AVCDs occur when the common AV valve leads primarily into the RV or LV. Echocardiographic apical, subcostal, and parasternal views are the best views to image AV canal defects. These views can help determine the type of repair required for the various AV canal defects.