Changes in Aortic Annulus Diameter During the Cardiac Cycle and its Effect on Predicting Aortic Valve Prosthesis Size

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).