NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
Effects of standing on cerebrovascular resistance in patients with idiopathic orthostatic intolerancePURPOSE: Patients with idiopathic orthostatic intolerance often have debilitating symptoms on standing that are suggestive of cerebral hypoperfusion despite the absence of orthostatic hypotension. SUBJECTS AND METHODS: We evaluated the effects of graded head-up tilt on cerebral blood flow as determined by transcranial Doppler measurements in 10 patients with idiopathic orthostatic intolerance (nine women, one man, 22 to 47 years) and nine age- and sex-matched control subjects. RESULTS: In patients, mean (+/- SD) arterial pressure at 0 degrees head-up tilt was 90 +/- 11 mm Hg and was well maintained at all tilt angles (90 +/- 11 mm Hg at 75 degrees). In controls, mean arterial pressure was 85 +/- 7 mm Hg at 0 degrees and 82 +/- 11 mm Hg at 75 degrees head-up tilt. There was a substantial decrease in peak velocity with increasing tilt angle in patients (28% +/- 10%) but not in controls (10% +/- 10% at 75 degrees, P <0.001). Similarly, mean velocity decreased 26% +/- 13% in patients and 12% +/- 11% in controls (P = 0.01). With increasing head-up tilt, patients had a significantly greater increase in regional cerebrovascular resistance than controls. CONCLUSIONS: In patients with idiopathic orthostatic intolerance, peak and mean middle cerebral artery blood flow velocity decreased in response to head-up tilt despite well sustained arterial blood pressure. These observations indicate that in this group of patients, regulation of cerebrovascular tone may be impaired and might therefore be a target for therapeutic interventions.
Document ID
20040141968
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Jacob, G.
(Recanati Autonomic Dysfunction Center Haifa, Israel)
Atkinson, D.
Jordan, J.
Shannon, J. R.
Furlan, R.
Black, B. K.
Robertson, D.
Date Acquired
August 22, 2013
Publication Date
January 1, 1999
Publication Information
Publication: The American journal of medicine
Volume: 106
Issue: 1
ISSN: 0002-9343
Subject Category
Aerospace Medicine
Funding Number(s)
CONTRACT_GRANT: HL56693
CONTRACT_GRANT: RR00095
CONTRACT_GRANT: NS33460
Distribution Limits
Public
Copyright
Other
Keywords
Non-NASA Center
NASA Discipline Regulatory Physiology

Available Downloads

There are no available downloads for this record.
No Preview Available