Complete two-dimensional echocardiography and Doppler flow studies were performed on 17 swine as part of an experimental protocol involving cardiopulmonary bypass with circulatory arrest. Indices of left ventricular function and pulmonary vein morphology and flow velocity were taken before (17/17) and after bypass (11/17). A total of 70 measurements were available for analysis. Doppler flow velocity within the right pulmonary vein was 0.5 +/- 0.06 m/sec and was 0.52 +/- 0.05 m/sec in the left pulmonary vein. The swine were found to have a marked reduction in left ventricle function compared with that in previous reports, though no statistical difference was seen between pre- and post-cardiopulmonary bypass studies (preoperative shortening fraction was 21 +/- 5% and ejection fraction was 41 +/- 8%; postoperative shortening fraction was 23 +/- 5% and ejection fraction was 42 +/- 7%). Swine with shortening and ejection fractions of < 20% were found to have more unstable hemodynamics during cardiopulmonary bypass.