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Certain cardiovascular indices predict syncope in the postural tachycardia syndromePatients with postural tachycardia syndrome (POTS) represent a patient population with orthostatic intolerance; some are prone to syncope, others are not. The underlying neurocardiovascular mechanisms are not completely understood. The current study was undertaken to assess if certain cardiovascular indices are predictive of syncope in POTS. We compared the response to tilt-up and the Valsalva maneuver in four groups: POTS patients who fainted (POTS-f; n = 11;31 +/- 11 years): POTS patients who did not faint (POTS-nf; n = 9; 29 +/- 9 years); normal controls (NLS; n = 13; 39 +/- 11 years); patients with generalized autonomic failure with orthostatic hypotension and syncope (n = 10; 59 +/- 14 years). Beat-to-beat heart rate (HR), systolic arterial pressure, diastolic arterial pressure (DAP) and pulse pressure (PP) were monitored using Finapres. Cardiac output, stroke volume (SV) and end-diastolic volume (EDV), and calculated total peripheral resistance (TPR) were recorded using thoracic electrical bioimpedance. An autonomic reflex screen which quantitates the distribution and severity of autonomic failure was also done. With the patient supine, all POTS patients (POTS-nf; POTS-f) had increased HR (p < 0.001) and reduced SV/EDV (p < 0.001) when compared with NLS. On tilt-up, POTS-f patients were significantly different from both NLS and POTS-nf patients; the most consistent alteration was a fall instead of an increase in TPR; other changes were a greater reduction in PP, a reduction (instead of an increment) in DAP, and a different pattern of changes during the Valsalva maneuver (excessive early phase II, attenuated or absent late phase II). Our results suggest alpha-adrenergic impairment with increased pooling or hypovolemia in POTS-f patients. We conclude that it is possible to identify the mechanism of syncope in POTS patients, and perhaps other patients with orthostatic intolerance and an excessive liability to syncope.
Document ID
20040173166
Document Type
Reprint (Version printed in journal)
Authors
Sandroni, P.
(Mayo Clinic Rochester, MN 55905, United States)
Opfer-Gehrking, T. L.
Benarroch, E. E.
Shen, W. K.
Low, P. A.
Date Acquired
August 22, 2013
Publication Date
August 1, 1996
Publication Information
Publication: Clinical autonomic research : official journal of the Clinical Autonomic Research Society
Volume: 6
Issue: 4
ISSN: 0959-9851
Subject Category
Aerospace Medicine
Funding Number(s)
CONTRACT_GRANT: PO1 NS32352
Distribution Limits
Public
Copyright
Other
Keywords
NASA Discipline Number 14-10
Clinical Trial
Non-NASA Center
NASA Discipline Cardiopulmonary
NASA Program Space Physiology and Countermeasures
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