DOPPLER ECHOCARDIOGRAPHIC FLOW VELOCITY-MEASUREMENTS IN THE SUPERIOR VENA-CAVA DURING THE VALSALVA MANEUVER IN NORMAL SUBJECTS

The hemodynamic manifestations of the Valsalva maneuver are in part the result of changes in the venous return accompanying changes in intrathoracic pressure. Doppler echocardiography was performed during Valsalva maneuver in 13 normal subjects. Superior vena cave flow velocities and flow velocity integrals were measured in all 13 subjects. In the 5 subjects in whom the superior vena cava was clearly visualized throughout the maneuver, vane cava diameter was also analyzed. The superior vena cava flow velocity integral at rest was 17 ± 2 cm. It diminished significantly, disappeared or reversed (-13 ± 6 cm, p < 0.001) with phase I of the maneuver. During the maintenance phase (phase 11), the flow velocity integral increased significantly (31 ± 2 cm p = 0.05 vs baseline and phase 1) and was associated with a decrease in superior vena cave lumen diameter at the time of Valsalva and continuing throughout the strain. With release of the maneuver (phase 111), there was a sudden significant increase In flow velocity integral (61 ± 2 cm, p = 0.005 vs phase 11) and superior vena cave lumen diameter. Subsequently, superior vena cave flow velocity integral returned to baseline values. This study suggests that one of the ways in which the Valsalva maneuver leads to decreased venous return may be by direct external compression of the superior vena cave. © 1990.