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Mechanisms of blood pressure alterations in response to the Valsalva maneuver in postural tachycardia syndromeThe postural tachycardia syndrome (POTS) is characterized clinically by orthostatic lightheadedness and tachycardia. When these patients perform a Valsalva maneuver, there is an excessive blood pressure increment after cessation of the maneuver (phase IV) that is sometimes associated with headaches. It is not known whether excessive phase IV is due to excessive peripheral vascular tone (an alpha-adrenergic mechanism) or is a manifestation of increased beta-adrenergic tone (hyperadrenergic state). The authors undertook a pharmacologic study evaluating the effect of intravenous phentolamine (alpha-adrenergic antagonist) and propranolol (beta-adrenergic antagonist) on the different phases of the Valsalva maneuver in a group of patients with POTS and age-matched normal control subjects. Patients with POTS had mean phases, when compared with controls, that were characterized by more negative II_E (p = 0.07), smaller II_L (p = 0.04), and significantly larger phase IV (p = 0.001). The effect of phentolamine was qualitatively and quantitatively different in POTS when compared with controls. Ten mg phentolamine in controls resulted in a significant accentuation of phase II_E (p = 0.001), attenuation of phase II_L (p = 0.002), and increase of phase IV (57.6 vs 30.7 mm Hg; p = 0.025). These changes resembled those of patients with POTS at baseline. In patients with POTS, the phase II abnormalities, already present, were further accentuated (p <0.001), and phase IV became smaller (50.6 vs 73.8 mm Hg; p = 0.09). Propranolol had no significant effect on phases II_E and II_L, but significantly reduced phase IV in both controls (p <0.05) and in patients with POTS (p <0.001) and improved the headache symptoms, when present, during and after phase IV. The authors conclude that phase IV is mainly under beta-adrenergic regulation and that the exaggerated phase IV in POTS is a result of a hyperadrenergic state.
Document ID
20040141617
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Sandroni, P.
(Mayo Clinic Rochester, Minnesota 55905, United States)
Novak, V.
Opfer-Gehrking, T. L.
Huck, C. A.
Low, P. A.
Date Acquired
August 22, 2013
Publication Date
February 1, 2000
Publication Information
Publication: Clinical autonomic research : official journal of the Clinical Autonomic Research Society
Volume: 10
Issue: 1
ISSN: 0959-9851
Subject Category
Aerospace Medicine
Funding Number(s)
CONTRACT_GRANT: M01 RR00585
CONTRACT_GRANT: PO1 NS32352
Distribution Limits
Public
Copyright
Other
Keywords
Non-NASA Center
NASA Discipline Cardiopulmonary
NASA Program Biomedical Research and Countermeasures

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