[Human adult left atrial volume estimated by M-mode echocardiography]

There are few systematic reports of the regression equation for humans, for estimating left atrial volumes from the anteroposterior left atrial dimensions measured by M-mode echocardiography (LADAP). In addition, several pitfalls were inherent in the M-mode method. In view of these pitfalls, we estimated the anteroposterior left atrial dimensions by directing the ultrasonic beam toward the "center" of the left atrium under the guidance of two-dimensional echocardiography. Simultaneously, we estimated left atrial volumes from anteroposterior and left lateral biplane left atrial angiocardiograms using a film changer at three frames per sec. The maximum elapsed time between the echocardiographic and angiocardiographic studies was two days. Left atrial volumes were calculated using the method of Sauter et al. Maximum left atrial volume was calculated at the end of the T wave. The results were as follows: For phantom experiments, a cylindrical container with varying amounts of contrast material was tested by biplane angiography using a film changer. The actual volume (x) and the calculated volume (y) were in good agreement with the regression equation; y = 1.05x-0.1 (r = 0.99, p less than 0.001, n = 6). The anteroposterior left atrial dimension in M-mode echocardiography (LADAP: x axis) and left atrial volume (ml) angiocardiographically obtained (y axis) showed the curvilinear regression equation; y = 1.4x3+23 (r = 0.83, p less than 0.01, n = 19). The relation between the left atrial cross-sectional area (cm2) obtained from the left ventricular long-axis view by two-dimensional echocardiography (x axis) and the left atrial volume (ml) by angiocardiography using a film changer (y axis) showed the regression equation; y = 1.2x1.5+17 (r = 0.82, p less than 0.01, n = 14). As a preliminary study, we calculated left atrial volume (LAVcine) for five patients by performing biplane cineangiocardiography at 50 frames per sec. The results were nearly the same as those obtained using a film changer. In summary, the derived equation predicts left atrial volume using M-mode echocardiography with considerable accuracy.