Figure 6.

Possible mechanisms underlying THE bicuspid aortic valve BAV. (A) Cartoon illustrating several possible mechanisms underlying BAV in the situation of outflow tract septation. These can result in different numbers of sinuses and raphes and can occur early in development (as shown) or later in development as a consequence of pathological processes. Valvar stenosis could also be caused by over fusion of the cushions, at the commissures. (B) Cartoon illustrating possible valve outcomes when outflow septation fails. In the case of the proposed situation where the SHF is deficient, the numbers of leaflets can be highly variable, possibly depending on the extent of deficiency.