Living Anatomy of the Ventricular Myocardial Crescents Supporting the Coronary Aortic Sinuses.

The aortic valvar sinuses are supported, in part, by ventricular myocardium, so-called myocardial crescents. We elucidated individual variation in the extent of the myocardial support. We assessed the extent of the crescents in 84 patients who underwent cardiac computed tomography. We measured their maximal width, their extent within the circumference of the aortic root, and the influence of rotation of the root itself within the ventricular base. The maximal widths, and rotational locations, of the crescents supporting the base of the left coronary aortic sinus were significantly smaller than those supporting the right coronary aortic sinus (2.9 ± 0.8 mm vs 6.4 ± 1.2 mm, P < 0.001; 54.2 ± 12.0° vs 70.4 ± 13.5°, P < 0.001, respectively). Overall, 42.7 ± 4.3% of the circumference of the virtual basal ring was supported by myocardium as opposed to fibrous tissue. Clockwise rotation of the aortic root was correlated with a decrease in the extent of myocardial crescent supporting the left coronary aortic sinus, but an increase in the myocardial support of the right coronary aortic sinus (R = 0.3899 and R = 0.2752, P < 0.001). Clockwise rotation of the root was correlated in negative fashion with the ratio of its myocardial as opposed to fibrous support (R = 0.0527, P = 0.0356). The extent of myocardial support of the left coronary aortic sinus, on average, is less than that of the right coronary aortic sinus. This difference becomes greater when the aortic root is rotated in clockwise fashion.