Atrioventricular septal defect — structured oral (viva)

Branch 1 — Anatomy and classification

Examiner: "What is the most likely diagnosis, and what is the underlying anatomy?" Candidate: The combination of Down syndrome, an infant with heart failure, a pansystolic murmur of atrioventricular valve regurgitation, a loud pulmonary component suggesting pulmonary hypertension, and a superior QRS axis is a complete atrioventricular septal defect. The anatomy is a deficient atrioventricular septum producing a common atrioventricular junction at the crux, with a primum atrial septal defect, a large inlet ventricular septal defect, and a single common atrioventricular valve with bridging leaflets. ^{[1] [2]}

Examiner: "Classify the complete form for me." Candidate: The complete form is graded by the Rastelli classification of the superior bridging leaflet. Type A is divided and attached to the crest of the ventricular septum; type B attaches anomalously to a right ventricular papillary muscle; and type C is a free-floating undivided common leaflet. Rastelli type C is the form most often seen in Down syndrome and carries the highest risk of left atrioventricular valve regurgitation and a more complex repair. ^[2]