Changes in left ventricular ejection during the valsalva maneuver evaluated by Doppler echocardiography

To characterize left ventricular hemodynamic changes during the Valsalva maneuver, continuous-wave Doppler was used to study 18 normal young adults as they performed forced expiration against 40 cm H₂0 for 20 s. Aortic root size and Doppler velocities were recorded from the suprasternal notch. Cycle length, ejection time, and mean velocity during ejection were measured. Heart rate, stroke volume, and cardiac output were calculated from these data. The values were averaged over every 5-second interval, beginning 5 s before and ending 15 s after completion of the Valsalva maneuver. Changes relative to pre-Valsalva values were assessed using repeated-measures analysis of variance. During the strain phase the heart rate rose a mean of 18 ± (SEM) 3%, with a 34 ± 3% decrease in cardiac output due to a 43 ± 3% fall in stroke volume. Both a 25 ± 3% decrease in ejection velocity and a 24 ± 2% decrease in ejection time contributed to the fall in stroke volume. Although the stroke volume during recovery increased 5 ± 3% relative to baseline, the cardiac output fell 8 ± 3% due to a 12 ± 2% decrease in heart rate. Doppler echocardiography is a simple, noninvasive method to evaluate the multiple alterations of left ventricular output occurring during the Valsalva maneuver.