Performing the Valsalva maneuver causes an increase in intrathoracic pressure, leading to a reduction in preload to the heart. Cardiovascular changes occur during and after this maneuver due to baroreflex and other compensatory reflex mechanisms that are initiated by decreased preload.

What is the effect of Valsalva maneuver?

The Valsalva maneuver reduces cardiac output, which is the amount of blood that the heart puts out with every beat. The individual may feel lightheaded or dizzy as a result. Once the baroreceptor senses the decrease in heart rate and blood pressure, it will stimulate the sympathetic nervous system.

Does Valsalva decrease cardiac output?

Phase 2 of the Valsalva maneuver begins with decreased venous return (because of increased intrathoracic pressure) and decreased stroke volume, cardiac output, and blood pressure (phase 2 early), followed by sympathetically mediated peripheral vasoconstriction and an increase in blood pressure and heart rate (phase 2 ...