The association between commissural height and graft size selection in valve-sparing aortic root replacement

OBJECTIVES: For selecting graft sizes in valve-sparing aortic root replacement (VSARR), commissural height is often referenced as a fixed variable; however, it may be affected by the diameter of the graft implanted. Using a novel aortic root sizer, we explored whether commissural height interacts with graft size. METHODS: The novel sizer is a semi-translucent, rigid tube that is applied externally on the trimmed aortic root. It has 3 longitudinal slits with 120° orientation, which allows suspending the commissural stitches, symmetrically. The sizer is intended to identify the best graft size for a given anatomy by applying sizers of differing internal diameters, by which the quality of coaptation is inspected. Furthermore, each commissural slit is embedded with a ruler that allows measuring commissural heights. Using 5 normal porcine aortic roots with various annular diameters (23-31mm), we applied the 6 sizers in varying diameters (26, 28, 30, 32, 34 and 36 mm) on each of the root. We examined the correlations between the commissural height and baseline anatomical parameters and diameter of the sizer. RESULTS: The commissural height correlated positively with annular dimension (r = 0.55, P = 0.002), free-edge length (r = 0.54, P = 0.002), geometric height (r = 0.51, P = 0.004) and negatively with diameter of the sizer (r = -0.75, P = 0.002). Binary linear regression models validated that the sizer's diameter negatively correlated with the commissural height after adjustments with each of the anatomical parameters (R2, 0.83-0.87; P < 0.001 for all). CONCLUSION: Commissural height is not a fixed factor, but it interacts with the native aortic root size and the dimension of the implanted graft in VSARR.