3D-Transesophageal Echocardiography in Paradoxical Low-Flow, Low-Gradient Aortic Stenosis

Abstract

Background: In paradoxical low-flow, low gradient (PLFLG) aortic stenosis, 2D-transthoracic echocardiography (2D-TTE)may underestimate flow because it assumes a circular left ventricular outflow tract (LVOT) shape. Three-dimensional transesophagealechocardiography (3D-TEE) is a better method to measure LVOT area.Objectives: The aim of this study was to evaluate left ventricular stroke volume index (SVi) by 2D-TTE and 3D-TEE in patientswith normal heart (NH) and with severe aortic stenosis (SAS) and to determine how many patients are categorized asPLFLG by 2D-TTE and 3D-TEE.Methods: Thirty-five patients were evaluated by 2D-TEE and 3D-TEE: NH=17 patients and SAS=18 patients. Left ventricularoutflow tract area was estimated during early systole by 2D-TTE (ES2DLVOT Ar) and by 3D-TEE (ES3DLVOT Ar)planimetry, and as systolic average (Avg 3DLVOT Ar). Each LVOT area was multiplied by its corresponding flow integral toobtain SVi (ES2D-TTE SVi, ES3D-TEE SVi and Avg 3D-TEE SVi) in NH and SAS groups. Paradoxical LFLG was determinedin SAS following standard criterion.Results: NH: ES2DLVOT Ar vs. ES3DLVOT Ar p<0.05; SAS: ES2DLVOT Ar vs. ES3DLVOT Ar p<0.001 and vs. Avg 3DLVOTAr p<0.023; ES2D-TTE SVi vs. ES3D-TEE SVi p<0.002 and vs. Avg 3D-TEE SVi p<0.038. In the NH group, the lower limitof normal SVi for 2D-TTE, ES3D-TEE and Avg 3D-TEE was <34, <38.9 and <35.9 ml/m2, respectively. Three SAS patientswere categorized as PLFLG by 2D-TTE, but none by 3D-TEE.Conclusions: Patients with PLFLG by 2D-TTE could