Abstract
This study was designed to investigate the dynamic nature of aortic annulus size during the cardiac cycle and to assess the utility of two-dimensional (2D) echocardiographic measurement of annulus diameter in predicting the surgeon's choice of prosthesis size. 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. Averaging end-diastolic and mid-systolic diameters resulted in no bias with 95% limits of agreement of ± 4 mm of the averaged diameter. Patients with a small annulus dimension (end-diastole ≤ 20 mm; mid-systole ≤ 22 mm) have a high probability (86% and 78%, respectively) of requiring a small prosthesis (≤ 21 mm).