Cardiac output calculation and three-dimensional echocardiography.

OBJECTIVE To compare the determination of stroke volume (SV) and cardiac output (CO) using 2-dimensional (2D) versus 3-dimensional (3D) transesophageal echocardiography (TEE). DESIGN Prospective observational study. SETTING Tertiary care university hospital. PARTICIPANTS 35 patients without structural valve abnormalities undergoing isolated coronary artery bypass grafting. INTERVENTIONS Left ventricular outflow tract (LVOT) diameter determined with 2D TEE was used to estimate LVOT cross-sectional area (CSALVOT). LVOT area was measured directly with 3D TEE by planimetry on an en face view. SV and CO were calculated for both methods using the continuity equation. MEASUREMENTS AND MAIN RESULTS The area of the LVOT differed significantly between methods, being significantly larger in the 3D method (3.57±0.70 cm(2)v 3.98±0.93 cm(2)) . This resulted in a 10% lower CO with the 2D method of LVOT area estimation. CONCLUSIONS LVOT area is underestimated with the single- axis 2D method when compared with 3D planimetered area. This results in a CO that is approximately 10% lower with the 2D method.