Vagal Stimulation in POTS

Study Overview
=================
Brief Summary
-----------------
The purpose of this study is to investigate how the electrical stimulation of a nerve in the skin of the earlobe (transcutaneous vagal nerve stimulation), alone or in combination with two medications (galantamine and pyridostigmine), affects the way the autonomic (involuntary) nervous system controls heart rhythm, symptoms on standing, and inflammatory markers in female patients with postural tachycardia syndrome (POTS). The study consists of 2 parts: a screening (1-2 study days), and 3 testing days. The study will take 5 days total and about 16 participants will be screened for the study. The investigators estimate 13 will be eligible to participate in all of the study days.

Detailed Description
-----------------
This study will test the hypothesis that impairment of the parasympathetic nervous system contributes to the symptoms of POTS and that stimulation of this part of the nervous system improves the excessive increase in heart rate, standing tolerance and inflammation in patients with POTS. For this purpose, the investigators will use electrical stimulation of a nerve in the skin of the earlobe (transcutaneous vagal nerve stimulation) and two medications that increase the levels of acetylcholine (a neurotransmitter) in the central or peripheral nervous system (galantamine and pyridostigmine, respectively) to increase the activity of the parasympathetic nervous system. Screening Procedures: Potential participants will be screened in the Vanderbilt Autonomic Dysfunction Center (ADC). Medications affecting heart rate, blood pressure, blood volume, inflammatory markers and the autonomic nervous system will be withdrawn for at least five half-lives before studies. Patients will undergo a complete history and physical examination, ECG, routine clinical laboratory analyses and a blood pregnancy test for women of childbearing potential. Autonomic testing including a posture study with plasma catecholamines is then performed to determine if they meet the inclusion/exclusion criteria. Eligible participants will be studied on three separate days in a randomized, double-blind, crossover fashion. On each testing day, patients will be given one dose of the study medication (either pyridostigmine, galantamine or placebo pill), and then will have two tilt table tests (a motorized table with a footboard that moves to an upright position): one with the vagal stimulation and one with sham electrical stimulation. Heart rhythm, blood pressure and the amount of fluid in the body (body impedance) will be monitored during studies. Blood samples (up to a total of 2 tablespoons per study day) will also be collected. The order of the study days and tilt tests will be decided at random, like the toss of a coin. Each study day will last about 5 hours.

Official Title
-----------------
Vagal Stimulation in POTS - The Autonomic Inflammatory Reflex (Pilot 3)

Conditions
-----------------
Postural Tachycardia Syndrome

Intervention / Treatment
-----------------
* Drug: placebo sugar pill
* Drug: Pyridostigmine Pill
* Drug: Galantamine Pill
* Device: Vagal stimulation
* Device: Sham vagal stimulation


Participation Criteria
=================
Eligibility Criteria
-----------------
Inclusion Criteria: Female subjects of 18-45 years, with Postural Tachycardia Syndrome (POTS) as defined by a heart rate increase ≥30 bpm from supine within 10 min of standing or head-up tilt in the absence of orthostatic hypotension, with chronic symptoms (> 6 months), and in the absence of other acute cause of orthostatic tachycardia. Subjects able and willing to provide informed consent Exclusion Criteria: Pregnancy. Medical conditions that can explain postural tachycardia (e.g., dehydration, medications). Patients who are bedridden or chair-ridden Subjects taking any medication known to affect autonomic function or inflammatory markers (e.g. corticosteroids) who could not discontinue them before study participation. Conditions associated with chronic inflammatory processes which in the investigator's opinion would affect the interpretation of the results. Examples may include smoking, diabetes, BMI>30 kg/m2, current infections or cancer. Other factors which in the investigator's opinion would prevent the subject from completing the protocol.

Ages Eligible for Study
-----------------
Minimum Age: 18 Years
Maximum Age: 45 Years

Sexes Eligible for Study
-----------------
Female

Accepts Healthy Volunteers
-----------------
No

Study Plan
=================
How is the study designed?
-----------------

Design Details

Primary Purpose: Basic Science
Allocation: Randomized
Intervention Model: Crossover Assignment
Interventional Model Description: Randomized, double-blind, crossover
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Placebo pill with vagal/sham stimulation<br>Patients will receive a single oral dose of placebo sugar pill, and 1.5-2 hours later they will have two tilt table tests: one with vagal stimulation and one with sham vagal stimulation | Drug: placebo sugar pill<br>* placebo single oral dose<br>* Other names: placebo;Device: Vagal stimulation<br>* Vagal stimulation will be given at 50 Hz during the tilt table tests<br>* Other names: Transcutaneous vagal nerve stimulation;Device: Sham vagal stimulation<br>* Sham vagal stimulation will be given at 0.01 mA during the tilt table tests<br>|
| Experimental: Pyridostigmine with vagal/sham stimulation<br>Patients will receive a single oral dose of pyridostigmine pill 30 mg, and 1.5-2 hours later they will have two tilt table tests: one with vagal stimulation and one with sham vagal stimulation | Drug: Pyridostigmine Pill<br>* pyridostigmine bromide 30 mg single oral dose<br>* Other names: Mestinon;Device: Vagal stimulation<br>* Vagal stimulation will be given at 50 Hz during the tilt table tests<br>* Other names: Transcutaneous vagal nerve stimulation;Device: Sham vagal stimulation<br>* Sham vagal stimulation will be given at 0.01 mA during the tilt table tests<br>|
| Experimental: Galantamine with vagal/sham stimulation<br>Patients will receive a single oral dose of galantamine pill 8 mg, and 1.5-2 hours later they will have two tilt table tests:one with vagal stimulation and one with sham vagal stimulation | Drug: Galantamine Pill<br>* Galantamine hydrobromide 8mg single oral dose<br>* Other names: Razadyne;Device: Vagal stimulation<br>* Vagal stimulation will be given at 50 Hz during the tilt table tests<br>* Other names: Transcutaneous vagal nerve stimulation;Device: Sham vagal stimulation<br>* Sham vagal stimulation will be given at 0.01 mA during the tilt table tests<br>|

What is the study measuring?
-----------------
Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| High frequency variability of heart rate | Average of high frequency variability of heart rate during the head up tilt | Up to 15 min of head up tilt | 

 Terms related to the study
=================
Keywords Provided by Centre Hospitalier Valida
-----------------
vagal stimulation, POTS, galantamine, pyridostigmine