The aortic annulus is a fibrous ring of the heart surrounding the aortic orifice. It serves for the attachment of the aorta artery, which a major vessel carrying oxygenated blood from the heart to the body. Accurate preoperative assessment of the aortic annulus dimensions is critical in patients undergoing transcatheter aortic valve implantation (TAVI) for severe AS. Using multislice computed tomography (MSCT), a novel approach has been evaluated to quantify aortic annulus dimensions using cross-sectional area (CSA) assessment and average diameter calculation compared with the commonly applied electronic caliper measurements in patients undergoing transapical implantation of the Edwards SAPIEN Transcatheter Heart Valve.
Preoperative measurements of aortic annulus diameter at end-diastole and mid-systole were compared with implanted prosthesis size in 26 patients. Annulus diameters were larger at mid-systole than end-diastole in all patients (24 ± 3 mm vs. 22 ± 3 mm; P < 0.0001). Both end-diastolic and mid-systolic diameters correlated with the surgeon's choice of prosthesis size (r = 0.74 and 0.71, respectively). However, prosthesis size was underestimated slightly by end-diastolic diameter (1 ± 2 mm; P = 0.03), and overestimated slightly by mid-systolic diameter (1 ± 2 mm; P = 0.01). The 95% limits of agreement for prosthetic size was -3 to +5 mm for enddiastolic diameter, or -5 to +3 mm for mid-systolic diameter.