Abstract 17783: Improved Aortic Valve Area Calculation Using a Novel Biplane Echo Continuity Equation
The aim of this study was to improve the accuracy of transthoracic echo- cardiographic (TTE) assessment of the aortic valve area (AVA) in patients with aortic stenosis (AS).
The traditional continuity equation (CE) for determining AVA requires a measurement of left ventricular outflow tract (LVOT) area, which is calculated from a linear LVOT dimension using the parasternal long axis view, assuming circular geometry. However, routine use of multidetector computed tomography (MDCT) in patients undergoing evaluation for transcatheter aortic valve replacement (TAVR) has shown that the LVOT is elliptical rather than round. Assumption of circular geometry may introduce inaccuracies into AVA assessment.
A total of 61 patients (76 ± 11 years of age, 61% men) with isolated calcific AS (mean gradient 42 ± 9 mm Hg; ejection fraction 56 ± 11%) underwent Doppler TTE as part of pre TAVR or aortic valvuloplasty evaluation. AVA was calculated by TTE using two near- perpendicular planes (parasternal long axis and apical five chamber view) to evaluate the LVOT. A modified CE was used to calculate AVA (cm2) = (π((D1 x D2)/4)x LVOT VTI)/(AV VTI) in order to account for the elliptical rather than round shape of the LVOT. AVA measurements from the traditional and modified CE were compared to invasive AVA assessment.
Biplane (Figure, Panel B+D) vs. traditional single plane (Panel A+C) TTE measurement of the LVOT yielded a significantly improved positive correlation between TTE and invasive AVA assessment (r2=0.861 vs. 0.296) and a markedly reduced mean error (0.07 cm2 vs. 0.18 cm2), p<0.001.
Utilizing the proposed modified continuity equation greatly improves the accuracy of TTE guided AVA measurements. This simple calculation can be performed using standard TTE without additional costly equipment (ie, biplane transducers), without additional echo views (ie, more sonographer time), and without the need to subject patients to further invasive or non- invasive testing (ie, TEE or MDCT).
- Aortic valve
- Computed tomography
- Valvular disease
- Transcatheter aortic valve implantation
Author Disclosures: T.M. Leucker: None. E.P. Shapiro: None.
- © 2015 by American Heart Association, Inc.