Two-dimensional echocardiographic method for the estimation of cardiac output independent of left ventricular geometry. Comparison with cardiac catheterization in mitral stenosis.

An hydraulic formula for the estimation of cardiac output independent of the geometric status of the left ventricle was studied by comparing the predictions based upon echographic and catheterization data with the results of the standard Fick principle method for cardiac output. The formula tested specifies cardiac output as Q = (1/21) RAT2, where Q is the cardiac output in ml, R is the heart rate, A is the mitral valve area in cm2 and T is the diastolic filling period in seconds per minute. Cardiac output estimated by this equation corresponds with cardiac output as determined by the Fick principle method at a level characterized by a correlation coefficient of r = 0.92 and a standard error of SE = 0.15 L/min for N = 26. The results suggest that the new expression may be useful for estimating cardiac output from echographic data.