In asymmetric model hearts volume was estimated by two-dimensional echocardiography (2-dE) and radiography, and the results compared to directly measured volume in the range from 10 to 320 ml (n = 22). The disc method, and the area-length and ellipsoid methods were used for both single-plane and biplane calculations. When biplane 2-dE measurements were calculated by the disc method and compared with directly measured volumes the regression equation was acceptably linear. For single-plane calculations, no linearity was found. For the disc method, the regression equation was given by y = 0.91x + 8.4, the correlation coefficient (r) was 0.989, and the standard error of estimate (s.e.e.) was ± 12.8 ml. The confidence interval was 0.85 to 0.98. With the area-length method the regression equation was y = 0.93x + 7.4, r = 0.987, s.e.e. = ± 14.0 ml. For the ellipsoid method, the regression equation was y = 0.89x + 1.2, r = 0.966, s.e.e. = ±22.0 ml.
With radiographic biplane calculations compared to directly determined values the regression equation was also found to be linear. For single-plane calculations such linearity was not found. For the disc method the regression equation was y = 0.99x + 5.9, r = 0.991, and s.e.e. = ±12.6 ml. The confidence interval was 0.93 to 1.06. For the area-length method the regression equation was y = 1.01x + 9.0, r = 0.987, s.e.e. = ±15.0 ml, and for the ellipsoid method y = 0.97x − 3.3, r = 0.992, s.e.e. = ±11.2 ml.
Thus, 2-dE is an accurate method for volume determination in asymmetric model hearts using biplane calculations and the disc method. Area-length and ellipsoid methods seemed to be less accurate.
Compared to radiography, 2-dE yielded similar correlation coefficients and s.e.e.s. Whereas 2-dE slightly underestimated model heart volume (−4.5 ± 14.7 ml, NS), radiography overestimated the volume (+5.7 ± 12.3 ml, P <0.05). The mean difference between 2-dE and radiography was 10.2 ± 21.2 ml, P <0.05). These results ought to be taken into account when left ventricular volume determinations are done in patients with coronary artery disease.