Document Detail

Certain cardiovascular indices predict syncope in the postural tachycardia syndrome.
MedLine Citation:
PMID:  8902319     Owner:  NLM     Status:  MEDLINE    
Patients 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.
P Sandroni; T L Opfer-Gehrking; E E Benarroch; W K Shen; P A Low
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Publication Detail:
Type:  Clinical Trial; Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Clinical autonomic research : official journal of the Clinical Autonomic Research Society     Volume:  6     ISSN:  0959-9851     ISO Abbreviation:  Clin. Auton. Res.     Publication Date:  1996 Aug 
Date Detail:
Created Date:  1997-02-19     Completed Date:  1997-02-19     Revised Date:  2007-11-15    
Medline Journal Info:
Nlm Unique ID:  9106549     Medline TA:  Clin Auton Res     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  225-31     Citation Subset:  IM; S    
Department of Neurology, Mayo Clinic, Rochester, MN 55905, USA.
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MeSH Terms
Blood Pressure / physiology
Cardiac Output / physiology
Heart Rate / physiology
Hemodynamics / physiology*
Posture / physiology*
Sympathetic Fibers, Postganglionic / physiology
Syncope / physiopathology*
Tachycardia / physiopathology*
Tilt-Table Test
Vagus Nerve / physiopathology
Valsalva Maneuver
Vascular Resistance / physiology
Grant Support
P A Low / Mayo Clinic, Rochester, MN

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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