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Mechanisms of Vasovagal Syncope

NCT01791816 · Status: COMPLETED · Phase: EARLY_PHASE1 · Type: INTERVENTIONAL · Enrollment: 90

Last updated 2025-05-23

No results posted yet for this study

Summary

Vasovagal Syncope (simple postural faint) is the most common cause of acute loss of consciousness. Postural tachycardia syndrome(POTS) is the most common chronic form of postural lightheadedness. Together they afflict many Americans, mostly young women, who are prevented from gainful employ or school attendance. The underlying mechanism is not known. Our past work suggests that a simple molecule, nitric oxide, acts to subvert normal blood flow controls causing blood to pool in the gut when standing. Our proposal will show the mechanism behind this problem and will indicate effective medical treatments. Patients will be compared to healthy control subjects.

Conditions

  • Vasovagal Syncope
  • Postural Tachycardia Syndrome

Interventions

DRUG

Phenylephrine

Phenylephrine dose-response comprises infusion of 0.5, 1, 2, 3, 4 micrograms/kg/min for 10 min at each dose. If bloods pressure increases by 30% or if heart rate decreases below 40 beats per minute we will stop infusion.

DRUG

L-Ng-monomethyl Arginine (L-NMMA)

Systemic L-NMMA is infused as a 500μg/kg/min loading dose for 15 min followed by a 50μg/kg/min maintenance dose for the remainder of the experiment.

Sponsors & Collaborators

  • New York Medical College

    lead OTHER

Principal Investigators

  • Julian M. Stewart, M.D., Ph.D. · New York Medical College

Study Design

Allocation
NA
Purpose
DIAGNOSTIC
Masking
NONE
Model
SINGLE_GROUP

Eligibility

Min Age
14 Years
Max Age
29 Years
Sex
ALL
Healthy Volunteers
Yes

Timeline & Regulatory

Start
2013-02-28
Primary Completion
2022-12-31
Completion
2022-12-31

Countries

  • United States

Study Locations

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Read the full study record

This page highlights key information. For complete eligibility criteria, study locations, investigator contacts, and the full protocol, visit the original record on ClinicalTrials.gov.

View NCT01791816 on ClinicalTrials.gov