- ICH GCP
- US Clinical Trials Registry
- Clinical Trial NCT01210430
Local Vasoconstriction in Postural Tachycardia Syndrome
Study Overview
Status
Conditions
Intervention / Treatment
Detailed Description
Chronic orthostatic intolerance due to the postural tachycardia syndrome (POTS) severely impairs daily life in over a million Americans, mostly young women. POTS is defined by symptoms of orthostatic intolerance associated with excessive upright heart rate. While there is general agreement that abnormalities in vascular regulation and autonomic activity account for the tachycardia and symptoms of POTS, its pathophysiology is heterogeneous and only partially characterized.
The key feature of POTS is symptoms which are most prominent when standing. However, in some, findings are present supine (lying down) but worsened standing. Symptoms of POTS include dizziness in all patients, exercise provoked symptoms and thus exercise intolerance, excessive fatigue, nausea and abdominal pain, headache, shortness of breath and deep breathing, weakness, shakiness and postural anxiety, pallor, and neurocognitive loss (difficulty thinking). These occur on a day-to-day basis. The symptoms overlap with the case definition of chronic fatigue syndrome (CFS) and POTS is often found in CFS in the young. Fainting is relatively uncommon during daily life.
A major subset of POTS has increased peripheral resistance and low blood flow(LFP) related to increased angiotensin-II (Ang-II), and decreased nitric oxide (NO). NO deficits are reversed by Ang-II type-1 receptor (AT1R) blockade, ascorbic acid (AA) and tetrahydrobiopterin in skin suggesting the importance of oxidative stress. Preliminary data also suggest that the coupling of sympathetic nerve activity to blood vessel contraction is enhanced via ↑Ang-II and ↓NO. We hypothesize that this is due to activation of reactive oxygen species (ROS) including superoxide, which scavenges NO to generate peroxynitrite, and hydrogen peroxide. Combined measurements in the skin and the systemic circulation will be combined with local measurement of ROS production and sympathetic nerve activity will enable us to determine precisely how the autonomic nervous system is affected by the illness. Methods include cutaneous microdialysis to measure ROS, skin biopsy and blood tests to measure gene expression of nitric oxide synthase and Ang-II receptors, and peroneal microneurography to measure muscle sympathetic nerve activity (MSNA). Combined with ultrasonic femoral artery blood flow this will yield assessment of the interactions of nerves with the blood vessels that they control.
If we discover specific biochemical mechanisms of POTS in patients, then we may be able to specifically treat the defect.
Study Type
Enrollment (Actual)
Phase
- Early Phase 1
Contacts and Locations
Study Locations
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New York
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Hawthorne, New York, United States, 10532
- New York Medical College/Bradhurst building
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Participation Criteria
Eligibility Criteria
Ages Eligible for Study
Accepts Healthy Volunteers
Genders Eligible for Study
Description
Inclusion Criteria:
Cases will be between the ages of 14 and 29 years old referred for evaluation of orthostatic intolerance with 3 or more of the following symptoms for at least 3 months:
- dizziness
- nausea and vomiting
- palpitations
- fatigue
- headache
- exercise intolerance
- blurred vision
- abnormal sweating heat.
- Cases will have the diagnosis of symptomatic postural tachycardia made during a screening tilt table test.
- Cases will have normal physical examination, and normal electrocardiographic and echocardiographic evaluations.
- Only those free from heart disease, and from systemic illness will be eligible to participate.
- This excludes patients with illnesses and disease states known to be associated with endothelial cell dysfunction such as diabetes, renal disease, congestive heart failure, systemic hypertension, acute and chronic inflammatory diseases, neoplasm, immune mediated disease, trauma, morbid obesity and peripheral vascular disease.
- At the time of testing all patients and control subjects must refrain from vasoactive drugs for two weeks. Please check with us about any medication that you are taking.
Exclusion Criteria:
- Criteria for initial exclusion will include a condition known to be associated with endothelial dysfunction
- An active medical condition that may explain the diagnosis
- A previous medical condition with undocumented resolution that may explain the diagnosis
- Past or present major psychiatric disorder
- Substance abuse within 2 years before onset of symptoms.
Study Plan
How is the study designed?
Design Details
- Primary Purpose: Diagnostic
- Allocation: Randomized
- Interventional Model: Crossover Assignment
- Masking: Double
Arms and Interventions
Participant Group / Arm |
Intervention / Treatment |
---|---|
Placebo Comparator: Normal Saline
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Subjects will receive 60mg/kg of normal saline over 20 minutes followed by a maintenance infusion of 20mg/kg of normal saline.
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Active Comparator: Losartan
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Subjects will receive placebo or losartan for 4 weeks.
Days 1-7, subjects will receive 12.5mg of Losartan or placebo.
Days 7-14, subjects will receive 25mg of Losartan or placebo.
Days 14-28, subjects will receive 50mg of Losartan or placebo.
|
Active Comparator: Ascorbic Acid (VItamin C)
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Subjects will receive 60mg/kg of Ascorbic Acid over 20 minutes followed by a maintenance infusion of 20mg/kg.
Other Names:
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What is the study measuring?
Primary Outcome Measures
Outcome Measure |
Time Frame |
---|---|
Orthostatic tolerance measured by the heart rate and blood pressure response to upright tilt
Time Frame: 2 months
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2 months
|
Secondary Outcome Measures
Outcome Measure |
Time Frame |
---|---|
Sympathetic activation and blood flow measured by sympathetic nerve recordings and Doppler blood flow in the leg
Time Frame: 2 months
|
2 months
|
Collaborators and Investigators
Sponsor
Investigators
- Principal Investigator: Julian M Stewart, MD, PhD, New York Medical College
Publications and helpful links
Helpful Links
Study record dates
Study Major Dates
Study Start
Primary Completion (Actual)
Study Completion (Actual)
Study Registration Dates
First Submitted
First Submitted That Met QC Criteria
First Posted (Estimate)
Study Record Updates
Last Update Posted (Actual)
Last Update Submitted That Met QC Criteria
Last Verified
More Information
Terms related to this study
Keywords
Additional Relevant MeSH Terms
- Pathologic Processes
- Heart Diseases
- Cardiovascular Diseases
- Nervous System Diseases
- Disease
- Arrhythmias, Cardiac
- Cardiac Conduction System Disease
- Autonomic Nervous System Diseases
- Primary Dysautonomias
- Orthostatic Intolerance
- Syndrome
- Tachycardia
- Postural Orthostatic Tachycardia Syndrome
- Physiological Effects of Drugs
- Molecular Mechanisms of Pharmacological Action
- Anti-Arrhythmia Agents
- Antihypertensive Agents
- Protective Agents
- Micronutrients
- Angiotensin II Type 1 Receptor Blockers
- Angiotensin Receptor Antagonists
- Antioxidants
- Losartan
- Vitamins
- Ascorbic Acid
Other Study ID Numbers
- 2R01HL074873-06A2 (U.S. NIH Grant/Contract)
This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.
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