Abstract 18192: Aortic Stenosis: The Effect of Spectral Broadening in the Left Ventricular Outflow Tract on Stroke Volume and Calculated Aortic Valve Area
Introduction: Accurate stroke volume (SV) calculation is critical for calculating aortic valve area by echocardiography. 2D-Doppler estimation of SV (SV2D) assumes uniform blood flow velocities through the left ventricular outflow tract (LVOT). Non-uniform flow through the LVOT, appreciated as spectral broadening of the LVOT Doppler signal, could result in inaccurate SV calculation.
Hypothesis: Increased spectral broadening in the LVOT will result in overestimation of SV by the SV2D method compared to 3D volumetric assessment of SV (SV3D).
Methods: Fifty-one consecutive patients with aortic stenosis underwent comprehensive 2D-TTE and assessment of SV3D. Patients with ≥ moderate mitral or aortic regurgitation were excluded. An LVOT pulse-wave Doppler signal with > 0.4 m/s difference between outer and inner edge of velocity spectral display (at time of peak velocity) was considered non-uniform flow (i.e., spectral broadening).
Results: Spectral broadening was present in 33% of the cohort. These patients were commonly female with smaller ventricles and higher ejection fraction. Spectral broadening was associated with a significant overestimation of SV on Doppler-based measurements (101±20 ml vs 78±15 mL, SV2D vs SV3D, respectively; r=0.83, p<0.0001); such differences were not seen in patients with uniform flow velocities (82±15 vs 79±14 mL, r=0.83, p=0.03). Patient characteristics by spectral broadening are shown in table 1.
Conclusion: In aortic stenosis patients with non-uniform flow, Doppler-based methods overestimated SV by 29.5% on average (maximum 64%) when compared to 3D methods. This results in a proportional increase in calculated valve area despite a similar mean gradient between groups. Substituting SV3D resulted in similar SV, valve area, and mean gradient between uniform and non-uniform groups. When spectral broadening >0.40 cm/s is present, 3D volumetric assessment of SV should be considered for accurate estimation of aortic valve area.
Author Disclosures: J.J. Thaden: None. M.Y. Tsang: None. S. Ito: None. S.V. Pislaru: None. V.T. Nkomo: None. R.M. Suri: None. T.A. Foley: None. E.E. Williamson: None. J.K. Oh: None.
- © 2014 by American Heart Association, Inc.