Autonomic Determinants of POTS - Pilot1

Autonomic Determinants of Postural Tachycardia Syndrome (Acute Pilot Study 1)


Lead Sponsor: Vanderbilt University Medical Center

Collaborator: National Heart, Lung, and Blood Institute (NHLBI)

Source Vanderbilt University Medical Center
Brief Summary

Postural tachycardia syndrome (POTS) is a relatively common condition affecting mostly otherwise healthy young women. It is the cause of significant disability and an impairment in quality of life. These patients have high heart rate and symptoms during standing. Many of these patients are disabled and have a poor quality of life. The sympathetic nerves are part of the nervous system that helps to maintain normal blood pressures and heart rates during activities of daily life. The purpose of this study is to determine the importance of sympathetic activation as a cause of orthostatic symptoms. The investigators will assess the effects of a blood pressure medication (Moxonidine) on the symptoms during standing. Moxonidine lowers sympathetic activity. The investigators believe patients with high resting sympathetic activity might benefit from Moxonidine. It might reduce high heart rate and improve symptoms during standing. This study should help clinicians and the growing population of patients with POTS gain a better understanding of this disorder and find more personalized treatment.

Detailed Description

Postural tachycardia syndrome (POTS) is a relatively common condition affecting mostly otherwise healthy young women. It is the cause of significant disability and an impairment in quality of life of a magnitude comparable to patients with chronic obstructive pulmonary disease or congestive heart failure. It is characterized by sympathetic activation with an exaggerated orthostatic tachycardia that responds to low doses of beta-blockers. The underlying pathophysiology of this disorder and the nature of this sympathetic activation is not clear and is likely heterogeneous. In many patients this sympathetic activation could be an appropriate compensatory response to hypovolemia, deconditioning or partial neuropathy. The investigators have identified a subset of patients in whom sympathetic activation appears to be a primary phenomenon. These patients are characterized by high central sympathetic outflow, as determined by muscle sympathetic nerve activity (MSNA) above the upper 95% confidence interval for the group. This "hyperadrenergic" phenotype is associated with a paradoxical increase in blood pressure on standing and exaggerated pressor response to the vasoconstrictive phase of the Valsalva maneuver, and clinical observations suggest they improve clinically when treated with central sympatholytics. The investigators propose to test the hypothesis that there is a subset of POTS patients with a central sympathetic activation as the primary pathophysiology. In an acute double blind, placebo-controlled, randomized study, the investigators propose that administration of the central sympatholytic moxonidine will improve orthostatic symptoms and abnormalities in orthostatic hemodynamics, as well as sympathetic outflow.

Overall Status Recruiting
Start Date 2019-08-27
Completion Date 2025-12-31
Primary Completion Date 2024-07-31
Phase Early Phase 1
Study Type Interventional
Primary Outcome
Measure Time Frame
Change in Orthostatic Symptom Burden [delta (delta VOSS)] after 30 min supine to after 15 min upright (delta VOSS), 2-3 hours after placebo or moxonidine intake [delta (delta VOSS)].
Secondary Outcome
Measure Time Frame
Change in Orthostatic Change in Heart Rate [delta (delta HR)] after 30 min supine to after 15 min upright (delta HR), 2-3 hours after placebo or moxonidine intake [delta (delta HR)].
Enrollment 48

Intervention Type: Drug

Intervention Name: Moxonidine

Description: active drug given as 1 dose

Arm Group Label: Moxonidine

Other Name: Physiotens

Intervention Type: Drug

Intervention Name: Placebo

Description: placebo pill given as 1 dose

Arm Group Label: Placebo

Other Name: inactive pill



Inclusion Criteria: - female/male subjects, age 18-55 years, - criteria for postural tachycardia syndrome (POTS): 1. a heart rate increase of ≥30 beats/min within 10 minutes of upright posture; 2. lack of orthostatic hypotension (blood pressure fall ≥ 20/10 mmHg within 10 minutes of standing); and 3. chronic symptoms during upright posture over at least 6 months, in the absence of any other acute cause. - in the follicular phase of the menstrual cycle (day 5-13 of a 28-day cycle) - POTS with primary central sympathetic activation (psPOTS) as defined as having resting muscle sympathetic nerve activity (MSNA) greater than or equal to 25 bursts/min - able and willing to provide informed consent. Exclusion Criteria: - pregnancy, - smoker, - BMI>30 kg/m2, - deconditioned status (if available VO2max<80% of predicted) - unable to withdraw from medications known to affect autonomic function, blood pressure or blood volume - systemic illnesses known to produce autonomic neuropathy, including but not limited to diabetes mellitus, amyloidosis, monoclonal gammopathies, and autoimmune neuropathies. - Arteriosclerotic disease of carotid artery. History of neck surgery. - conditions associated with inflammatory processes, such as coronary artery disease, hypertension, smoking, hypercholesterolemia (or on statin therapy), rheumatoid arthritis, diabetes - treatment with oral corticosteroids, current infections (e.g., urinary tract infection), or use of non-steroidal anti-inflammatory drugs - other factors which in the investigator's opinion would prevent the subject from completing the protocol including clinically significant abnormalities in clinical, mental or laboratory testing.



Minimum Age:

18 Years

Maximum Age:

55 Years

Healthy Volunteers:

Accepts Healthy Volunteers

Overall Official
Last Name Role Affiliation
André Diedrich, MD Principal Investigator Vanderbilt University Medical Center
Overall Contact

Last Name: Emily C Smith, RN

Phone: 615 875-1516

Email: [email protected]

Facility: Status: Contact: Investigator: Vanderbilt University Medical Center Emily C Smith, RN 615-875-1516 [email protected] Andre Diedrich, MD Principal Investigator
Location Countries

United States

Verification Date


Responsible Party

Type: Principal Investigator

Investigator Affiliation: Vanderbilt University Medical Center

Investigator Full Name: Andre' Diedrich

Investigator Title: Research Professor of Medicine

Has Expanded Access No
Condition Browse
Number Of Arms 2
Arm Group

Label: Moxonidine

Type: Experimental

Description: Patients will receive a single oral dose of moxonidine 0.4 mg.

Label: Placebo

Type: Placebo Comparator

Description: Patients will receive a single oral dose of placebo.

Patient Data No
Study Design Info

Allocation: Randomized

Intervention Model: Crossover Assignment

Intervention Model Description: Randomized, double-blind, placebo-controlled crossover

Primary Purpose: Other

Masking: Double (Participant, Investigator)

Masking Description: Subject and investigator will be blinded. The randomization will be generated by the pharmacy. A staff member of the Autonomic Dysfunction Center who is not involved in the study will keep secretly the randomization blinding table for emergencies. Blinding will be broken for intermediate data analysis and in case of emergencies if necessary. The blinding will be broken at the end of statistical analysis for interpretation of results.

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