A reproducible, noninvasive method for estimating right ventricular (RV) function would greatly facilitate evaluation of infants in whom the RV supplies the systemic circulation. Therefore, 2-dimensional echocardiographically derived parameters, RV area-change fraction and RV ejection fraction (EF), were evaluated in 19 preoperative infants (age 1 to 30 days, mean 7 days), 12 with hypoplastic left heart syndrome and 7 with transposition of the great arteries. The area enclosed by the RV was measured in both a subxiphoid long-axis (coronal plane) and short-axis (parasagittal plane) view. From these measurements end-systolic and end-diastolic volumes were derived using Simpson's rule and the EF was calculated. The total area change fraction was calculated as the average of the long and the short-axis area change fraction. Similar measurements were made independently from biplane cineangiograms obtained within 3 days of the echocardiogram. The echocardiographically derived EF and area-change fraction were compared with the angiographic EF using linear regression analysis. The echocardiographic EF (mean 49 +/- 11) correlated well with the angiographic EF (mean 51 +/- 12, r = 0.84). The echocardiographic area-change fraction was somewhat less closely correlated with the angiographic EF (r = 0.79). Comparing short- and long-axis area-change fraction to echocardiographic EF, the short-axis measurements were better correlated than long-axis measurements (r = 0.86 and 0.75, respectively). (ABSTRACT TRUNCATED AT 250 WORDS)