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OBJECTIVE: Aortic root grafts have been developed that generally flare outward in the sinus region, and this feature has contributed importantly to technical procedural ease. However, current devices are not based on normal geometry, and a fully anatomic aortic root graft could facilitate valve-sparing root procedures.
METHODS: High-resolution CT angiograms from 11 normal human aortic roots were used to generate high-density x,y,z coordinates of valve and root structures in Mathematica. Three-dimensional least squares regression analyses of leaflet-sinus coordinates precisely assessed geometry of the aortic valve and root. Shapes and dimensions of all root components were quantified, and minor variations were simplified.
RESULTS: In 3-dimensioal least square regression analyses, normal aortic root geometry was represented as 3 leaflet-sinus general ellipsoids nested within a funnel-shaped aorta. Sino-tubular junction diameter was uniformly 5 mm larger than the valve base, consistent with an observed 10-degree outward commissural flare. Thus, aortic diameter flared outward from the base to the mid-valve region, but was cylindrical above that. The base of the valve was elliptical (minor-major diameter ratio = 0.65), but the mid-aorta and sinotubular junction were circular above the mid-valve level. Commissural post location on the base circumference was symmetrical. Based on the average 3-dimensional diameters of the 3 sinus ellipsoids, 2 design variations in an aortic root graft were developed (Figure). A partial root graft (left) represented the normal anatomy for a remodeling procedure (used in conjunction with a sub-annular aortic annuloplasty ring of the same design). Additionally, a full root graft (right) with incorporated annuloplasty ring could be used for reimplantation procedures or for RV outflow tract reconstruction using additional glutaraldehyde-fixed autologous pericardial leaflets.
CONCLUSIONS: An anatomic aortic root graft was designed based on mathematical analyses of CT angiograms. The design incorporated 3 fully anatomic sinuses, commissural symmetry, 10-degree outwardly flaring commissural posts, and modest outward lower aortic flare. These more anatomic grafts could prove useful for restoring aortic root geometry toward normal during reparative aortic valve and root surgery.