Endocardial cushion defect type III is AV canal.

• A. ASD
• B. VSD
• C. PDA
• D. AV canal

Answer: (D)

Endocardial cushion defects arise when the endocardial cushions fail to fuse properly, leaving a communication through the atrioventricular (AV) canal that connects both atria and ventricles and often involves a common AV valve. Type III refers to the complete AV canal defect, where the primum ASD and inlet VSD are combined with a single, shared AV valve. This explains why the lesion is identified as AV canal. Isolated ASD, VSD, or PDA describe other, non–AV canal defects and don’t capture this full atrioventricular involvement.