Effect of left and right lateral decubitus positions on Doppler mitral flow patterns in patients with severe congestive heart failure.

Patients with severe congestive heart failure (SCHF) complain of increasing dyspnea when adopting left lateral decubitus (LLD) position that improves when turning over to the right lateral decubitus (RLD) position (trepopnea). We hypothesize that this clinical sign is due to changes in left ventricular (LV) preload and such changes would modify mitral flow. This study analyzes the effect of RLD and LLD positions on LV filling pattern assessed by Doppler echocardiography in patients with SCHF. Seventeen men and seven women (aged 56.22 +/- 18.52 years) with SCHF in New York Heart Association functional class III-IV and nine normal control subjects (eight men and one woman aged 56.96 +/- 18.14 years) were studied. We analyzed early (E) and late (A) LV filling velocities, E/A ratios, deceleration time, mitral time-velocity integral in each decubitus position, and the differences between them. Patients with SCHF have smaller mitral time-velocity integral, shorter deceleration time, greater E velocity and E/A ratio, and lower A velocity in LLD position than do normal control subjects. On assuming RLD position, patients with SCHF show decreases in E velocity and E/A ratio and lengthening of the deceleration time, suggesting a decrease in LV preload on changing position. This pathophysiologic mechanism may explain why patients with SCHF willingly adopt RLD position.