Time-frequency assessment of heart rate variability under Valsalva and Mueller maneuvers

Mueller and Valsalva maneuvers are antagonist in nature, but autonomic response to Mueller's has not been clearly established. In order to assess their autonomic balance by heart rate variability analysis, we used the time-frequency distribution of Born-Jordan. We measured the RR time series from ten ECG records for each maneuver, each pair measured in the same individual. The Mueller maneuver showed an increment of the heart rate in the first half of the maneuver, which evolved to bradycardia at the end and during recovery, while Valsalva maneuvers presented tachycardia during the entire recording and bradycardia was only observed in the recovery stage. Consistently, the high frequency component of the RR intervals for Mueller maneuver was higher during and after the maneuver than the corresponding Valsalva values. In this way, the Mueller maneuver presented an increased vagal modulation.