VENOUS CHANGES OCCURRING DURING THE VALSALVA MANEUVER - EVALUATION BY INTRAVASCULAR ULTRASOUND

The Valsalva maneuver, originally described in 1704, is a widely used physiologic technique for the non-invasive evaluation of heart murmurs and ventricular function.1-3 The maneuver consists of forceful expiration against a closed glottis, resulting in an increase in intrathoracic pressure and a decrease in venous return to the heart. Although the hemodynamic changes occurring during the various stages of the maneuver have been well documented, the associated venous changes have not been precisely described. Intravascular ultrasound allows for the accurate evaluation of the dimensions of vascular structures.4,5 In this study, we assessed the changes in area and circumference that occurred in an intrathoracic vein, the superior vena cava, and an extrathoracic vein, the right internal jugular, during the strain phase (phase 2) of the Valsalva maneuver. From these measurements, we wished to determine whether the decrease in venous flow to the heart during the Valsalva maneuver was due to the elevated pressure in the right atrium secondary to the elevated intrathoracic pressure, or to direct external compression of the superior vena cava by the elevated intrathoracic pressure. © 1994.