Complete Transesophageal Assessment of the Aortic Valve Using the Continuity Equation in Equivocal Cases of Aortic Stenosis

Background: The continuity equation (CE) used for evaluating aortic stenosis (AS) is based on values obtained from transthoracic echocardiography (TTE) with the assumption that the left ventricular outflow tract (LVOT) has a circular shape. Transesophageal echocardiography (TEE) may be used for accurate measurement of the LVOT cross-sectional area (CSA). Previous studies have focused on fusion from TEE for LVOT-CSA measurement and TTE for velocity time integrals (VTI) calculations.Objectives: To assess aortic valve area (AVA) using parameters obtained exclusively from TEE as an alternative approach.Methods: Thirty patients with equivocal AS based on TTE were evaluated using TEE for further assessment.Results: The mean pressure gradient across the aortic valve (AV) was 38 +/- 5.9 and 37.9 +/- 7.6 mmHg in TTE and TEE, respectively, P = 0.42. LVOT-CSA was larger in TEE (3.6 +/- 0.3 vs. 3.4 +/- 0.3 cm2, P = 0.049). VTI over the AVA was similar (98.54 +/- 22.8 and 99.52 +/- 24.52 cm in TTE and TEE, respectively, P = 0.608), while VTI across the LVOT was higher when measured by TTE (24.06 +/- 5.8 vs. 22.03 +/- 4.3 cm, P < 0.009). Using the CE, AVA was 0.82 +/- 0.3 vs. 0.83 +/- 0.17 cm2 in TEE vs. TTE, respectively, P = 0.608. Definitive grading was achieved in all patients (26 patients defined with severe AS and 4 with moderate).Conclusions: In equivocal cases of AS, full assessment using TEE may be a reliable modality for decision making.