The differences between bisecting and off-center cuts of the aortic root: The three-dimensional anatomy of the aortic root reconstructed from the living heart.

BACKGROUND: It is axiomatic that the diameter of the virtual basal ring of the aortic root, which is elliptical rather than circular, will differ when assessed using between bisecting as opposed to off-center cuts. Such differences, however, which pertain directly to echocardiographic assessments of the so-called valvar annulus, have yet to be systematically explored.

METHODS: We retrospectively analyzed 30 patients undergoing coronary computed tomographic angiography, measuring the virtual basal ring diameter using routine multiplanar reconstructions. We made orthogonal bisecting cuts from the nadir of the hinge of the right coronary aortic leaflet to the center of the opposite inter-leaflet fibrous triangle between the noncoronary and left coronary aortic leaflets. We compared these measurements with orthogonal off-center cuts made through the nadirs of the hinges of the adjacent leaflets.

RESULTS: The measured diameter of the virtual basal ring was significantly longer when measured using the bisecting cut as opposed to all off-center cuts (mean difference: 1.35±1.34 mm, P<.0001; 0.77±0.95 mm, P=.0001, respectively). The measured diameters of the sinuses of Valsalva, in contrast, were significantly shorter when measured using the bisecting cut (mean difference: -3.24±1.38 mm, P<.0001; -2.86±1.61 mm, P<.0001).

CONCLUSIONS: There are significant differences in the diameters of the aortic root, which represent the echocardiographic annulus, when measured using bisecting as opposed to off-center cuts. Account should be taken of these differences when using cross-sectional echocardiographic measurements to assess the dimensions of the aortic root.