Autoimmune Basis for Postural Tachycardia Syndrome

Summary

The purpose of this study is to see if some people with postural tachycardia syndrome (POTS) have higher levels of immune proteins (autoantibodies) directed against receptors of the autonomic nervous system, and if these autoantibodies make a difference in their POTS symptoms. The investigators also want to see if the levels of these autoantibodies stay the same over time.

Conditions

• Postural Orthostatic Tachycardia Syndrome
• Postural Tachycardia Syndrome
• Tachycardia
• Arrhythmias, Cardiac
• Autonomic Nervous System Diseases
• Orthostatic Intolerance
• Cardiovascular Diseases
• Primary Dysautonomias

Interventions

OTHER

Assessment of splanchnic capacitance

Splanchnic capacitance will be assessed using cpap and body impedance to construct pressure volume curves

PROCEDURE

microneurography

microneurography will be measured in the peroneal nerve to assess sympathetic activity.

DRUG

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

DRUG

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.

RADIATION

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.

PROCEDURE

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.

PROCEDURE

24-hour heart rhythm and blood pressure monitoring

Blood pressure, heart rate and ECG monitoring for 24 hours

PROCEDURE

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.

PROCEDURE

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.

OTHER

Rebreathing test

Cardiac output will be measured using the rebreathing technique (Innocor)

Sponsors & Collaborators

• University of Oklahoma

  collaborator OTHER

• Vanderbilt University Medical Center

  lead OTHER

Principal Investigators

• Luis Okamoto, MD · Vanderbilt University Medical Center

Study Design

Allocation

NA

Purpose

OTHER

Masking

NONE

Model

SINGLE_GROUP

Eligibility

Min Age

18 Years

Max Age

50 Years

Sex

ALL

Healthy Volunteers

Yes

Timeline & Regulatory

Start

2016-02-29

Primary Completion

2026-10-31

Completion

2026-12-31

Countries

• United States

Study Locations