Reliability of three-dimensional color flow Doppler and two-dimensional pulse wave Doppler transthoracic echocardiography for estimating cardiac output after cardiac surgery

CO assessment using 2D-PWD transthoracic echocardiography. Cardiac output was calculated using the LVOT diameter, LVOT VTI, and heart rate. In routine practice, LVOT velocity–time integrals (VTIs) could be acquired in the apical five chamber view (panel a) or apical long axis view (panel b). Diameters of the left ventricular outflow tract (LVOT) were measured in the parasternal left ventricular long axis view during the early phase of ventricular systole (panel c). LVOT VTI was automatically measured for three consecutive beats and averaged (panel d). RV, right ventricle; LV, left ventricle; LA, left atrium; AO, aort