Determination of stroke volume and cardiac output during exercise: comparison of two-dimensional and Doppler echocardiography, Fick oximetry, and thermodilution.

Abstract

Simultaneous estimates of cardiac output were made during graded upright maximal exercise in 10 male subjects by means of Doppler velocity spectrum of ascending aortic flow, apical two-dimensional echocardiograms, thermodilution, and Fick oximetry. In 15 subjects, aortic annular and root diameters were measured during similar exercise from parasternal two-dimensional echocardiograms. The linear correlation between Doppler, two-dimensional echocardiography, and the invasive estimates ranged from r = .78 to r = .92. Both echocardiographic techniques were able to predict changes in invasive flow estimates with reasonable accuracy. Two-dimensional echocardiographic flow estimates underestimated invasive values by about 60%. The accuracy of Doppler flow estimates varied with the method of estimating aortic cross-sectional area. Greatest accuracy was obtained with areas calculated from diameters measured at the aortic value anulus with the leading edge-to-leading edge method of measurement. Correlation coeffici...