[Transesophageal Doppler echocardiographic measurement of cardiac output using mitral anulus method]

The method of measuring cardiac output with transesophageal pulsed Doppler two-dimensional echocardiography was developed and validated by comparison with the thermodilution technique in 65 adult patients. With the use of transesophageal four-chamber view, the Doppler sample volume was placed in the center of the mitral ring and the mitral flow velocity-time integral was obtained through planimetric measurements of the mitral flow velocity curve. The diameter of the mitral valve anulus was measured at the time of peak rapid filling flow velocity, and the cross-sectional area of the mitral valve anulus was calculated, assuming a circular shape. Doppler-determined cardiac output was calculated by using the following formula: Cardiac output [1.min-1] = pi (D [cm] /2)2.MFVI [cm].heart rate [bpm].10(-3), where MFVI is mitral flow velocity-time integral, and D is the diameter of the mitral valve anulus. There was a weak correlation between thermodilution and Doppler measurements of cardiac output (r = 0.64, p less than 0.01), while a good correlation was observed between percent changes in thermodilution-derived cardiac output and those in Doppler-determined cardiac output (r = 0.92, p less than 0.01) during different loading conditions. It has been suggested that this method may be useful for assessing relative changes in cardiac output during short time periods.