Aortic valve cusp size and shape in dilated trileaflet aortic roots

The objective of the study was to quantify the differences in cusp size and shape in patients with normal and dilated trileaflet aortic roots and in dilated roots with or without aortic regurgitation.

A retrospective analysis of computed tomography studies in patients with normal and dilated trileaflet aortic roots was performed measuring root and cusp dimensions. Normal root size was defined as sinuses of Valsalva diameter less than 40 mm, dilated as 45 mm or greater. Root measurements normalized to basal ring diameter and cusp measurements normalized to geometric height were analyzed to assess the shape. Additionally, comparison of dilated roots with or without aortic regurgitation was made.

We analyzed 146 normal and 104 dilated aortic roots and 73 propensity-matched pairs. Dilated roots were larger in all dimensions and had increased ratio between commissural and basal ring diameter (1.58 ± 0.23 vs 1.11 ± 0.10, P < .001). Cusps in dilated roots were larger in all measured dimensions and were elongated with increased normalized cusp insertion length (3.64 ± 0.39 vs 3.26 ± 0.20, P < .001) and normalized free margin length (2.53 ± 0.30 vs 2.16 ± 0.19, P < .001). In patients with dilated root and no cusp prolapse (n = 83), those with moderate or severe aortic regurgitation had larger commissural diameter but similar cusp dimensions compared with those with no or mild aortic regurgitation.

The cusps in dilated roots elongate transversely and to a lesser degree radially. Functional aortic regurgitation is caused by extensive commissural dilatation and not by inadequate cusp adaptation.