We investigated right and left heart function in 51 patients with a body mass index of >35 kg/m(2) who underwent evaluation for gastric bypass surgery using standard Doppler echocardiography and color tissue Doppler imaging. Left atrial diameter (3.7 +/- 0.5 vs 3.3 +/- 0.4 cm, p <0.001), left ventricular end-diastolic diameter (5.0 +/- 0.6 vs 4.5 +/- 0.4 cm, p <0.001), and left ventricular mass index (119 +/- 49 vs 76 +/- 26 g/m, p <0.001) were increased in patients with severe obesity. Early diastolic mitral annular velocity (7.5 +/- 2.1 vs 9.6 +/- 3.0 cm/s, p <0.001), early diastolic/late diastolic mitral annular velocity ratio (1.38 +/- 0.6 vs 1.94 +/- 1.3, p = 0.007), early diastolic tricuspid annular velocity (7.8 +/- 2.6 vs 9.5 +/- 2.4 cm/s, p = 0.002), early diastolic/late diastolic tricuspid annular velocity ratio (0.9 +/- 0.36 vs 1.1 +/- 0.4, p = 0.048), and mitral annular systolic velocity (5.7 +/- 1.3 vs 6.5 +/- 1.5 cm/s, p = 0.012) were significantly lower in obese patients. Early diastolic mitral inflow/mitral annular velocity ratio was increased in the obese (13.5 +/- 4.7 vs 9.1 +/- 3.6, p <0.001). Tricuspid annular systolic velocities did not differ.