Geometric characteristics of bicuspid aortic valves

We studied the coaptation angles α and β in bicuspid aortic valve geometry from computed tomography scan images.

In 45 patients, we calculated the coaptation angle α (the angle between the nonfused commissures crossing the center of coaptation), angle β (between the nonfused commissures crossing the center of the reference circle), angles γ₁ and γ₂ and ε₁ and ε₂ (angle between the nonfused commissures and the coaptation point at the raphe or the perfect midpoint, respectively), the length of the raphe, the absolute and relative sinuses' surfaces (relative to the perfect circle and the percentage exceeding the ideal circle). Spearman correlation was employed to investigate the associations among all parameters.

The coaptation angles α and β were significantly different (P < .001). We found a significant correlation of α with the length of the raphe (P = .008), whereas β was dependent on the position of the commissures. Both γ₁ and γ₂ (P = .04), or ε₁ and ε₂ (P < .001) significantly differed from each other and ε₂ was the most constant angle, although its size geometrically depends on β. The noncoronary was the largest sinus, and β was the primary determinant of its increased size in bicuspid aortic valves with righ/left fusion pattern.

The coaptation angle α is influenced by the length of the raphe, whereas angle β is dependent on the position of the commissures. The position of the raphe can vary and is not always situated in the middle of the free edge. The position of the right/non commissure is variable, whereas the right/left commissure is more fixed.