Preoperative assessment of aortic annulus dimensions: comparison of noninvasive and intraoperative measurement

Preoperative assessment of aortic annulus diameter is crucial for valve sizing in patients scheduled for transcatheter aortic valve replacement. Computed tomographic (CT) measurements of the aortic annulus are not standardized and may yield different results depending on view due to its elliptic shape. The purpose of this study was to compare the measurement of the aortic annulus during surgery in patients undergoing conventional aortic valve replacement with noninvasive methods.

In 33 patients with aortic valve stenosis (18 males, mean age 77.2 ± 7.9), aortic annulus diameter was measured with cardiac CT and TEE (transesophageal echocardiography) prior to open aortic valve replacement. In CT, aortic annulus diameter was assessed as the calculated average diameter of luminal area at the level of basal attachments of the leaflets by means of planimetry. Operative measurements were performed with a Hegar dilator. A Pearson analysis was applied to test for degree of correlation.

Calculated average diameter by CT correlated significantly with intraoperative measurements (r = 0.923, p < 0.001) and with the size of implanted valve (r = 0.867, p < 0.001), while correlation of TEE and intraoperative measurements was weak (r = 0.523, p = 0.002). The TEE tends to underestimate the dimensions of aortic annulus.

The CT-measured aortic annulus diameter, assessed as the calculated average diameter of planimetric annulus area, seems to provide adequate dimensions similar to operative measurements with a Hegar dilator. This approach may minimize the dependency of single-view CT measurement on the elliptic shape of the aortic annulus and appears to be a feasible alternative for aortic annulus assessment in terms of candidates' selection for transcatheter aortic valve replacement.