Non-invasive measurement of baroreflex during Valsalva maneuver: Evaluation of alpha and beta-adrenergic components

Objective: To evaluate alpha and beta components of adrenergic baroreflex sensitivity (BRSa) in Valsalva maneuver (VM). Methods: BRSa was studied in 89 healthy subjects aged 30 +/- 13 [16-75] years. Subjects were divided into three groups per blood pressure (BP) patterns associated with relatively balanced or increased alpha-adrenergic modulation: (1) BAR (n = 43) - Balanced Autonomic Response with a BP dip below baseline in late phase II (IIL) and recovery in phase IV; (2) SAR (n = 16) - Suppressed Autonomic Response with a non-dipping BP; and (3) AAR (n = 30) - Augmented Autonomic Response with a BP recovery in phase IIL. Discrete (alpha and beta) BRSa formulae were produced using alpha- or beta-adrenergic phases: alpha-BRSa (phase IIL) and beta-BRSa (phase IV), respectively. Discrete BRSa were studied to determine potential correlations to BRSa(1) (validated BRSa evaluation) and evaluated for reliability. Results: Patterns with higher alpha-adrenergic influence showed correlation between alpha-BRSa and BRSa(1) (AAR: r = 0.447, p < 0.05; SAR: r = 0.774, p < 0.01). BAR showed correlation between beta-BRSa and BRSa(1) (r = -0.566, p < 0.01), and alpha- and beta-adrenergic coefficients (r = -0.381, p < 0.05). Discrete BRSa were more reliable than BRSa(1) (n = 33; p < 0.05). Conclusions: Discrete BRSa are reproducible and correlated with BRSa(1). Significance: If validated, discrete BRSa may differentiate physiologic variances and vague dysautonomia. (C) 2015 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.