Noninvasive measurement of left atrial functions using transesophageal echocardiography.

The use of transesophageal pulsed Doppler echocardiography provides an ideal approach for determining both pulmonary venous flow and transmitral flow. This approach thus provides information about the flow of blood into and out of the left atrium. We designed a new method for separately evaluating left atrial functions on the basis of the time-velocity integrals of pulmonary venous flow and transmitral flow using transesophageal pulsed Doppler echocardiography, assuming that the cross-sectional areas of the mitral ring during the left ventricular diastolic phase and of the four pulmonary venous orifices throughout a cardiac cycle were constant and that the blood flows of the four pulmonary veins exhibited identical velocity profiles. Good correlation was observed between the indices of left atrial function (i.e. left atrial reservoir, conduit and forward contractile volume) using this new method of analysis of Doppler echocardiographic data and those of a conventional method using contrast angiography. In conclusion, transesophageal pulsed Doppler echocardiography provided satisfactory information about left atrial function, and our new method may be one of the most practical techniques for estimating individual left atrial functions.