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Assessing aortic valve area in aortic stenosis by continuity equation: a novel approach using real-time three-dimensional echocardiography

2008; Oxford University Press; Volume: 29; Issue: 20 Linguagem: Inglês

10.1093/eurheartj/ehn022

1522-9645

Kian Keong Poh, Robert A. Levine, Jorge Solı́s, Liang Shen, Matthew L. Flaherty, Young-Joon Kang, J. Luis Guerrero, Judy Hung,

Cardiac Imaging and Diagnostics

Two-dimensional echocardiographic (2DE) continuity-equation derived aortic valve area (AVA) in aortic stenosis (AS) relies on non-simultaneous measurement of left ventricular outflow tract (LVOT) velocity and geometric assumptions of LVOT area, which can amplify error, especially in upper septal hypertrophy (USH). We hypothesized that real-time three-dimensional echocardiography (RT3DE) can improve accuracy of AVA by directly measuring LVOT stroke volume (SV) in one window.RT3DE colour Doppler and 2DE were acquired in 68 AS patients (74 +/- 12 yrs) prospectively. SV was derived from flow obtained from a sampling curve placed orthogonal to LVOT (Tomtec Imaging). Agreement between continuity-equation derived AVA by RT3DE (AVA(3D-SV)) and 2DE (AVA(2D)) and predictors of discrepancies were analysed. Validation of LVOT SV was performed by aortic flow probe in a sheep model with balloon inflation of septum to mimic USH. There was only modest correlation between AVA(2D) and AVA(3D-SV) (r = 0.71, difference 0.11 +/- 0.23 cm(2)). The degree of USH was significantly associated with difference in AVA calculation (r = 0.4, P = 0.005). In experimentally distorted LVOT geometry in sheep, RT3DE correlated better with flow probe assessment (r = 0.96, P < 0.001) than 2DE (r = 0.71, P = 0.006).RT3DE colour Doppler-derived LVOT SV in the calculation of AVA by continuity equation is more accurate than 2D, including in situations such as USH, common in the elderly, which modify LVOT geometry.