Rastelli classification of atrioventricular canal defects

(A) Rastelli type A: The most common type, in which the superior bridging leaflet is committed to the left ventricle with chordal attachments to the crest of the ventricular septum.
(B) Rastelli type B: The least common type, in which the superior bridging leaflet extends into the right ventricle.
(C) Rastelli type C: In this form, the superior bridging leaflet is even larger and has no chordal attachment to the interventricular septum, referred to as “free floating.” It is found in combination with other cardiac defects, such as tetralogy of Fallot, transposition of the great arteries, and heterotaxy syndromes.