A new cardiac transplantation technique that preserves the shape of the left atrium and leaves the right atrium intact has been introduced. To compare the new and the standard techniques, we studied cardiac physiology with Doppler echocardiography and catheterization in 26 patients who underwent operation with the standard technique (group A) and I1 who underwent operation with the new technique (group B). Right atrial dimensions were significantly lower in group B (right atrial area index 8.4 +/- 1.5 vs 14.5 +/- 1.9 cm2/m2, p < 0.001), whereas left atrial dimensions were slightly lower (left atrial area index 10.8 +/- 2.0 vs 16.4 +/- 7.0 cm2/m2, p = 0.07). Right atrial contraction, as reflected by peak late tricuspid velocity, was greater in group B (37 +/- 15 vs 30 +/- 10 cm/sec, p < 0.05). The subsequent systolic vena caval flow-velocity integral was also greater in group B at all respiratory phases (inspiration 10.0 +/- 4.0 vs 5.2 +/- 4.0 cm, p < 0.001; expiration 4.8 +/- 1.9 vs 2.9 +/- 1.4 cm, p < 0.001; apnea 5.3 +/- 2.0 vs 2.9 +/- 1.9 cm, p < 0.001) suggesting better atrial relaxation. Filling pressures on the right side of the heart were lower in group B (mean right atrial pressure 5.5 +/- 2.4 vs 6.6 +/- 2.8 mm Hg, p = 0.1; right atrial A wave 6.0 +/- 3.1 vs 8.3 +/- 3.2 mm Hg, p < 0.01; right atrial V wave 6.8 +/- 3.1 vs 9.2 +/- 3.2 mm Hg, p < 0.01; right ventricular end-diastolic pressure 5.6 +/- 3.2 vs 7.3 +/- 2.9 mm Hg, p < 0.05); however, no significant differences were found in left ventricular end-diastolic pressure or cardiac index. We conclude that patients undergoing the new technique exhibit cardiac physiologic improvements. Follow-up study is indicated to ascertain whether this finding implies improved long-term prognosis.