Geometric characteristics of bicuspid aortic valves

Objective: We studied the coaptation angles a and b in bicuspid aortic valve geometry from computed tomography scan images.Methods: In 45 patients, we calculated the coaptation angle alpha (the angle between the nonfused commissures crossing the center of coaptation), angle beta (between the nonfused commissures crossing the center of the reference circle), angles gamma(1) and gamma(2) and epsilon(1) and epsilon(2) (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.Results: The coaptation angles alpha and beta were significantly different (P <.001). We found a significant correlation of a with the length of the raphe (P = .008), whereas b was dependent on the position of the commissures. Both gamma(1) and gamma(2) (P = .04), or epsilon(1) and epsilon(2) (P <.001) significantly differed from each other and epsilon(2) was the most constant angle, although its size geometrically depends on beta. The noncoronary was the largest sinus, and beta was the primary determinant of its increased size in bicuspid aortic valves with righ/left fusion pattern.Conclusions: The coaptation angle alpha is influenced by the length of the raphe, whereas angle beta 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.