Recruiting

Observational Study

Sponsor:

New York Medical College

Code:

NCT05923840

Conditions

Postural Orthostatic Tachycardia Syndrome

Hypocapnia

Hyperventilation

Eligibility Criteria

Sex: Female

Age: 15 - 39

Healthy Volunteers: Accepted

Interventions

Chemoreflex Testing

Baroreflex testing

Orthostatic stress testing

Study Details

Brief summary:

Postural tachycardia syndrome (POTS) is the most common chronic cause of postural lightheadedness, and upright confusion afflicting many Americans, mostly young women. Many POTS patients hyperventilate by increasing their depth of breathing that produces tachycardia, alters blood flow and blood pooling in the body and importantly reduces brain blood flow causing "brain fog". In this proposal the investigators will demonstrate in young women that abnormal repeated brief impairment of blood pressure and brain flow just after standing sensitizes the body's oxygen sensor in POTS to respond as if it were in a low oxygen environment causing hyperventilation and its consequences. In this project the investigators will use various drugs that will help to understand the mechanisms that cause POTS in this unique subset of POTS patients who hyperventilate.

Conditions

Postural Orthostatic Tachycardia Syndrome

Hypocapnia

Hyperventilation

Study ID

NCT05923840

Start date

Sep 23, 2022

Status verified date

Jun, 2023

Completion date

Aug 31, 2024

Anticipated

Primary completion date

Aug 31, 2023

Anticipated

Eligibility Criteria

Eligibility Criteria

Sex: Female

Age: 15 - 39

Healthy Volunteers: Accepted

Inclusion Criteria:

  • The investigators will recruit female POTS cases (N=80) and healthy female control subjects (N=40) aged 15-39 years, matched for BMI. POTS is a disease in which 80-90% are females. Therefore, the investigators will only recruit female POTS patients and controls.

Exclusion Criteria:

  • Any subjects with systemic disease or who cannot stop taking prescribed medications for at least 2 weeks prior to study.

Study Design

Enrollment

30 participants

Anticipated

Allocation

Non randomized

Intervention Model

Parallel Assignment

Primary purpose

Basic Science

Interventions and Outcome Measures

Arms

active comparator: Female Postural Tachycardia Syndrome (POTS) patients without orthostatic hyperpneic hypocapnia

Female POTS patients without orthostatic hyperpneic hypocapnia identified by tilt table testing and respiratory monitoring.

active comparator: Female POTS patients with orthostatic hyperpneic hypocapnia

Female POTS patients without orthostatic hyperpneic hypocapnia identified by tilt table testing and respiratory monitoring.

active comparator: Healthy Female vounteers

Healthy Female vounteers

Interventions

Chemoreflex Testing

The carotid body chemoreflex can be tested by holding carbon dioxide (CO2) constant (isocapnic) and applying hypoxia and hyperoxia. Measurements are then made of expiratory minute volume and of sympathetic activity. The central chemoreflex measures isocapnic and hypercapnic responses in the presence of hyperoxia to suppress the carotid body chemoreflex.

Baroreflex testing

Baroreceptors are measured by the change of heart rate (HR) and sympathetic activity with changing blood pressure using the modified Oxford technique. Blood pressure is lowered an amount by a bolus of sodium nitroprusside and then raised by a bolus of phenylephrine. When standing baroreflexes are activated and the investigators will measure chemoreflex activity upright to see how baroreflex effects the chemoreflexes. Similarly chemoreflexes affect the baroreflexes best observed when the patients are supine.

Orthostatic stress testing

Orthostatic Stress tests are administered in two forms: a standing test to evoke the initial orthostatic hypotensive response that sensitizes and triggers the carotid body chemoreflex by intermittent stagnant ischemia. And the 70 degree upright tilt test that best identifies causal changes in regional blood volumes and flows and in respiratory patterns of hyperpneic hypocapnia.

Primary outcome measure

  • Orthostatic tachycardia [ Time Frame: Baseline in all subjects ]
  • Orthostatic Blood Pressure Changes [ Time Frame: Baseline in all subjects ]
  • Orthostatic Changes in Systemic Vascular Resistance [ Time Frame: Baseline in all subjects ]
  • Orthostatic Blood Volume Changes [ Time Frame: Baseline in all subjects ]
  • Orthostatic Changes in Segmental Blood Flow [ Time Frame: Baseline in all subjects ]
  • Orthostatic Changes in Cerebral Blood Flow [ Time Frame: Baseline in all subjects ]
  • Orthostasis Induced Rate of Breathing [ Time Frame: Baseline in all subjects ]
  • Orthostasis Induced Depth of Breathing [ Time Frame: Baseline in all subjects ]
  • Measurement of chemoreflex sensitivity carotid body chemoreflex and central chemoreflex [ Time Frame: Baseline in all subjects ]
  • Effects of chemoreflex activation on baroreflexfunction and the effects of baroreflex on chemoreflex sensitivity [ Time Frame: Baseline in all subjects ]

Central Contacts and Locations

Central contacts

Marvin S Medow, Ph.D.

914-594-2848marvin_medow@nymc.edu

Julian M Stewart, M.D., Ph.D.

914-594-2849julian_stewart@nymc.edu

Locations

NewYork Medical College

Recruiting

Hawthorne, New York, United States, 10532

Contacts

Marvin S Medow, Ph.D.

914-594-2848marvin_medow@nymc.edu

Julian M Stewart, M.D.,Ph.D.

914-594=2849julian_stweart@nymc.edu

Principal Investigator:

Marvin S. Medow, Ph.D.

More Information

Sponsor

New York Medical College

Last update posted

Jun 28, 2023

Last verified

Jun, 2023

Keywords

  • Postural Tachycardia Syndrome (POTS)
  • Young Females
  • Tilt Table Testing
  • Initial Orthostatic Intolerance

Trial information was received from ClinicalTrials.gov and was last updated on 2026-09-10. This information was provided to ClinicalTrials.gov by New York Medical College on 2023-06-28.