Study Results
The study team has not published outcome measurements, participant flow, or safety data for this trial yet. Check back later for updates.
Basic Information
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ENROLLING_BY_INVITATION
NA
58 participants
INTERVENTIONAL
2016-02-29
2026-12-31
Brief Summary
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Detailed Description
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The present study is designed to test the hypothesis that patients with POTS harbor functional autoantibodies to adrenergic receptors that lead to an excessive tachycardia characteristic of POTS. For this purpose, this study will define the prevalence, burden, and the in vivo physiological significance of these adrenergic antibodies in a well-phenotyped and representative cohort of patients with POTS and a matched cohort of healthy control subjects, and will characterize the stability of these autoantibodies over time in affected POTS patients.
Conditions
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Keywords
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Study Design
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NA
SINGLE_GROUP
OTHER
NONE
Study Groups
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Autonomic and Antibody Assessments
On up to 3 study days, POTS patients and control subjects will have several tests to assess autonomic function and to detect the presence of autoantibodies to adrenergic receptors. The following tests will de done but in some participants it may not be necessary to do all of them. The investigator will discuss with each participant which particular tests will be done in each particular case:
* Posture study with blood samples for autoantibody testing
* 24-hour heart rhythm and blood pressure monitoring
* autonomic function tests
* Quantitative Axonal Sudomotor Reflex Testing
* Total blood volume assessment
* Pharmacologic testing with phenylephrine
* Pharmacologic testing with isoproterenol
* Cardiac output with rebreathing
* Assessment of splanchnic capacitance
* Microneurography
phenylephrine
Phenylephrine is a selective α1-adrenergic receptor agonist. It will be given in IV bolus injections starting from 12.5 ug. Incremental doses will be given every \~3 min up to 800 ug or until systolic blood pressure increases by 25 mmHg
isoproterenol
Isoproterenol is non-selective beta-adrenergic agonist. It will be given in IV bolus injections starting from 0.025 ug. Incremental doses will be given every \~3 min until heart rate increases by 25 bpm. This intervention is optional.
25 micro-Ci of radiation
Using injection of iodinated I-131 tagged human serum albumin nominally 25 micro-Ci of radiation, blood samples are drawn before and 30 minutes after injection.
Posture study with blood samples
Blood pressure and heart rate will be measured while supine and then while standing for up to 30 minutes. Blood will be drawn in each position to measure hormones that regulate blood pressure and blood volume. An additional sample will be collected in the supine position for the autoantibody assessment.
24-hour heart rhythm and blood pressure monitoring
Blood pressure, heart rate and ECG monitoring for 24 hours
Quantitative Axonal Sudomotor Reflex Testing
The QSART assesses the ability of sympathetic nerve terminals in the skin to release acetylcholine and increase sweat production. The test is performed at 4 sites over the forearm, proximal lateral leg, medial distal leg and proximal foot.
Autonomic function tests
The autonomic function tests will determine how well the autonomic nervous system regulates blood pressure and heart rate. These tests include breathing deeply for two minutes, breathing fast for 30 seconds, maintaining a handgrip for 3 minutes, breathing against pressure for 15 seconds, and placing the hand in ice water for 1 minute. In addition, participants will be tilted up on a tilt table for up to 10 minutes while recording their heart rate, blood pressure and cardiac output.
Rebreathing test
Cardiac output will be measured using the rebreathing technique (Innocor)
Assessment of splanchnic capacitance
Splanchnic capacitance will be assessed using cpap and body impedance to construct pressure volume curves
microneurography
microneurography will be measured in the peroneal nerve to assess sympathetic activity.
Interventions
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phenylephrine
Phenylephrine is a selective α1-adrenergic receptor agonist. It will be given in IV bolus injections starting from 12.5 ug. Incremental doses will be given every \~3 min up to 800 ug or until systolic blood pressure increases by 25 mmHg
isoproterenol
Isoproterenol is non-selective beta-adrenergic agonist. It will be given in IV bolus injections starting from 0.025 ug. Incremental doses will be given every \~3 min until heart rate increases by 25 bpm. This intervention is optional.
25 micro-Ci of radiation
Using injection of iodinated I-131 tagged human serum albumin nominally 25 micro-Ci of radiation, blood samples are drawn before and 30 minutes after injection.
Posture study with blood samples
Blood pressure and heart rate will be measured while supine and then while standing for up to 30 minutes. Blood will be drawn in each position to measure hormones that regulate blood pressure and blood volume. An additional sample will be collected in the supine position for the autoantibody assessment.
24-hour heart rhythm and blood pressure monitoring
Blood pressure, heart rate and ECG monitoring for 24 hours
Quantitative Axonal Sudomotor Reflex Testing
The QSART assesses the ability of sympathetic nerve terminals in the skin to release acetylcholine and increase sweat production. The test is performed at 4 sites over the forearm, proximal lateral leg, medial distal leg and proximal foot.
Autonomic function tests
The autonomic function tests will determine how well the autonomic nervous system regulates blood pressure and heart rate. These tests include breathing deeply for two minutes, breathing fast for 30 seconds, maintaining a handgrip for 3 minutes, breathing against pressure for 15 seconds, and placing the hand in ice water for 1 minute. In addition, participants will be tilted up on a tilt table for up to 10 minutes while recording their heart rate, blood pressure and cardiac output.
Rebreathing test
Cardiac output will be measured using the rebreathing technique (Innocor)
Assessment of splanchnic capacitance
Splanchnic capacitance will be assessed using cpap and body impedance to construct pressure volume curves
microneurography
microneurography will be measured in the peroneal nerve to assess sympathetic activity.
Other Intervention Names
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Eligibility Criteria
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Inclusion Criteria
* Postural Tachycardia Syndrome: Heart rate increase \>30 bpm from supine within 10 min of standing, in the absence of orthostatic hypotension (\>20/10 mmHg fall in blood pressure), with chronic symptoms (\> 6 months), and in the absence of other acute cause of orthostatic tachycardia.
* Able and willing to provide informed consent
* Female premenopausal subjects must utilize adequate birth control and willingness to undergo serum beta-hCG testing
* The subject must understand and be able to comply with the study procedures and restrictions.
Exclusion Criteria
* Orthostatic hypotension (consistent drop in blood pressure \>20/10 mmHg with 10 min stand)
* Pregnancy
* Cardiovascular disease, such as myocardial infarction within 6 months, angina pectoris, significant arrhythmia (sinus tachycardia is not excluded), deep vein thrombosis, pulmonary embolism
* History of serious neurologic disease
* History or presence of significant immunological or hematological disorders
* Clinically significant gastrointestinal impairment that could interfere with dietary compliance or drug absorption
* Impaired hepatic function (aspartate amino transaminase and/or alanine amino transaminase \>1.5 x upper limit of normal range)
* Impaired renal function (serum creatinine \>1.5 mg/dL)
* Hematocrit \<28%
* Current or concurrent disease that could affect the absorption, action or disposition of the drug, or clinical or laboratory assessments.
* Any underlying or acute disease requiring regular medication that could possibly pose a threat to the subject or make implementation of the protocol or interpretation of the study results difficult
* Inability to comply with the protocol
Healthy control subjects will be healthy, non-smoking and on no chronic medications at the time of the study. Healthy control subjects will be group-matched to the POTS patients for age and gender. We will attempt to study female patients in the first half of their menstrual cycle to minimize cyclical variability.
18 Years
50 Years
ALL
Yes
Sponsors
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University of Oklahoma
OTHER
Vanderbilt University Medical Center
OTHER
Responsible Party
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Luis E Okamoto
Research Instructor
Principal Investigators
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Luis Okamoto, MD
Role: PRINCIPAL_INVESTIGATOR
Vanderbilt University Medical Center
Locations
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University of Oklahoma Health Sciences Center
Oklahoma City, Oklahoma, United States
Autonomic Dysfunction Center
Nashville, Tennessee, United States
Countries
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Other Identifiers
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151791
Identifier Type: -
Identifier Source: org_study_id