Session S21.4

Quantification of Aortic Valve Stenosis Using Transesophageal Real-Time 3D Echocardiographic Images

F Veronesi, C Corsi, V Mor-Avi, L Sugeng,
L Wienert, RM Lang, C Lamberti*

Universidad de Bologna
Bologna, Italy

Background: Aortic stenosis (AS) is the most common native valve disease. Its severity assessment is routinely performed using transthoracic 2D echocardiography. In particular, aortic valve area (AVA) is usually assessed by the continuity equation, although this measurement relies on geometrical assumptions, or by planimetry on transesophageal echocardiography. Accordingly, the aim of this study was to develop and test a new technique to assess the severity of AS using data acquired with the new real-time 3D matrix transesophageal echocardiographic (MTEE) probe.
Methods: We studied 20 patients undergoing clinically indicated TEE. MTEE imaging (Philips iE33) was performed in 10 subjects with normal mitral valve (MV) and aortic valve (AV), and in 10 patients with moderate to severe AS ( AVA <1.4 cm²) and normal MV. Custom software was used to manually initialize the aortic annulus (AoA) in 3D space, and then to automatically track its motion frame-by-frame throughout the cardiac cycle. The tracked annulus was used to automatically crop the data in order to isolate the AV and to align it to AV axes in each frame. Maximum intensity projection images obtained from this data were segmented to measure AV orifice. The quantitative results of this procedure included: AVA, AoA area (computed as the projection of AoA on AV base plane) and their ratio (AVA/AoA area), for every frame in the cardiac cycle.
Results: In patients with AS, AVA computed with our technique (0.94±0.28 cm²) showed good correlation with AVA computed from continuity equation (0.89±0.31; r=0.93), with a bias of 0.1 cm². In addition while the maximum AoA area (during first third of systole) was similar in both groups (NL: 5.0±1.3cm², AS: 4.8±1.2cm²), the maximum change in AoA area was significantly reduced in patients with AS (NL:23±7%, AS:13±4% of max AoA area). Also, AVA and AoA ratio were significantly different in the two groups (NL: 69±11%, AS: 25±11%).
Conclusions: Our technique allows quantitative volumetric measurements of dynamic AV parameters, and thus constitutes a new tool for objective assessment of the severity of AS. This technique fully exploits 3D MTEE data without relying on geometrical assumptions, thus promising improved accuracy.

(Abstract Control Number: 208)