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

BACKGROUNDThe 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.OBJECTIVESTo assess aortic valve area (AVA) using parameters obtained exclusively from TEE as an alternative approach.METHODSThirty patients with equivocal AS based on TTE were evaluated using TEE for further assessment.RESULTSThe 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).CONCLUSIONSIn equivocal cases of AS, full assessment using TEE may be a reliable modality for decision making.