ABSTRACT
Anatomy The aortic annulus is usually hypoplastic to some extent, the leaflets are thickened and the commissures are fused to varying degrees. Dysplastic or unicuspid valves (Figure 14.1a), often seen in newborns, are present in about 10% of infants and 3% of older children in whom the treatment is indicated. Tricuspid valves (Figure 14.1b) are seen in 25% of infants and in 40% of older patients who require treatment. The majority of the stenotic aortic valves are bicuspid.1 There are two forms of bicuspid aortic valve: balanced or ‘anatomically bicuspid’ and unbalanced or ‘functionally bicuspid.’ The anatomically bicuspid valve is composed of two equally sized cusps with two sinuses of Valsalva (Figure 14.1c). The functionally bicuspid valve also opens as bicuspid, but it has three sinuses, two of them adjacent to a fused cusp which is actually formed by two unequal cusps conjoined by an unopened commissure. The fused cusp is larger than the opposite one, hence ‘unbalanced bicuspid valve’ (Figure 14.1d). This anatomic concept is important in regard to the prognosis of the valvuloplasty.1
In the balanced bicuspid valves as well as in tricuspid stenotic valves, the orifices are usually enlarged by a splitting of the functioning commissures, whereas in the unbalanced bicuspid valves, the fused cusp is often torn aside from the rudimental commissure (Figure 14.2),2 presumably due to unequal rigidity of the different sized cusps.
