Research Studies

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The Studies Mechanisms of Vasovagal Syncope ] Local Vasoconstriction and Sympathoexcitation in Postural Tachycardia Syndrome ] Brain Fog in CFS and POTS ] Vascular Dysfunction in the Chronic Fatigue Syndrome ] Hyperpnea in Postural Tachycardia ]

Currently we are funded by the National Heart Lung and Blood Institute (NHLBI) of the National Institutes of Health to perform research studies investigating the role of circulatory dysfunction in postural tachycardia syndrome (POTS) and in Postural Vasovagal Syncope. Further funding has been obtained from the CFIDS Society to study neurocognitive deficits ("Brain Fog") in patients with the Chronic Fatigue Syndrome (CFS) and with POTS. 

We have solicited patients for this and an earlier POTS study since September 2004. The study is on-going although the precise experiments have changed to include basic mechanisms of central nervous system control of blood pressure in subsets of POTS patients. Moreover neurocognitive deficits (lightheadedness, brain fogi, memory loss0 have taken center stage and may be intimately related to altered relationships between cerebral blood flow and blood pressure. 


NIH Studies: 

Local Vasoconstriction in Postural Tachycardia Syndrome (July 2010 -2015, Patient Enrollment Opened September 1, 2010)

Mechanisms of Vasovagal Syncope (March 2013-2017), Patient Enrollment Open in April 2013


CFIDS Society: 

Brain Fog in Chronic Fatigue Syndrome


Completed Studies

Vascular Dysfunction in Chronic Fatigue Syndrome (April 2008-April 2013)Patient Enrollment Opened July 1, 2008). This study is now closed.

Hyperpnea in Postural Tachycardia Syndrome. This study is closed as an NIH study but is continuing to recruit several patients per year. 





Home ] Julian M. Stewart, M.D., Ph.D. ]


Orthostatic Stress  Testing & instrumentation
Circulatory Measurements
Circulatory Autonomic Testing
Initial Orthostatic Hypotension
Research Studies
Fainting and Related Phenomena a Lay Review
Orthostatic Intolerance
Orthostatic Hypotension