Robert Sachner MD, Presenter: Nothing to Disclose

Avinoam Shiran, Abstract Co-Author: Nothing to Disclose

Salim Adawi MD, Abstract Co-Author: Nothing to Disclose

Ronen Rubinstein, Abstract Co-Author: Nothing to Disclose

Nathan Peled MD, Abstract Co-Author: Nothing to Disclose

Tamar Gaspar MD, Abstract Co-Author: Nothing to Disclose

Measurement of left ventricular outflow tract area (LVOTa) for estimation of aortic valve area (AVA) and for transcatheter aortic valve implantation (TAVI) using transthoracic echocardiography (TTE) and the continuity equation assumes a round shape for the LVOT. The aim of this study was to determine LVOTa and shape and estimate its effect on LVOTa and AVA estimation using TTE, 3D echocardiography (3DE) and cardiac computerized tomography (CT).

We prospectively studied 43 pts (age 6812y, 21 males, 22 with aortic stenosis (AS) and 21 without AS). LVOTa and AVA were estimated using TTE and the continuity equation ((LVOTd/2)2 assuming a circular LVOT) and LVOTa and diameters (D1 & D2) were measured using 3DE and CT. AVA was also planimetered using CT in mid systole. TTE estimated LVOTa and AVA were correlated with 3DE and CT measurements.

In most patients the LVOT was oval and not circular, with an eccentricity index (D2/D1) of 1.240.10 for CT and 1.170.11 for 3DE. There was good correlation between TTE and MDCT for LVOTa (r=0.88) but TTE systematically underestimated LVOTa (and therefore AVA) by 1514% (AS vs. no AS p=0.4). The correlation between 3DE & CT for LVOTa was only moderate (r=0.72). AVA was 0.920.35 cm2 by TTE and 1.420.73 cm2 by CT. There was good correlation between TTE and CT for AVA (r=0.92), but TTE underestimated AVA by 5032% (-0.50.43 cm2, p<0.0001).

LVOTa is oval in most cases, resulting underestimation by 15% of LVOTa and AVA using TTE. Other reasons may account for the difference between TTE and CT determined AVA (anatomical vs. effective valve area, pressure recovery, and errors in CT measurements). Current 3DE image quality is inadequate to determine LVOTa. These findings carry important implications for selecting AS patients for surgery or TAVI.

Measurement of LVOTa using TTE for estimation of AVA assumes a round shape. We used CT to determine LVOT area and shape and estimate its effect on AVA.

Sachner, R, Shiran, A, Adawi, S, Rubinstein, R, Peled, N, Gaspar, T, The LVOT Is Oval, Leading to Underestimation of LVOT and Aortic Valve Area by Echocardiography.  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11008853.html