Assessment of Vascular Endothelial Function in Postural Tachycardia Syndrome

Study Overview
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Brief Summary
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The purpose of this study is to see if people with Postural Tachycardia Syndrome (POTS) have different levels of certain chemicals in their blood than people who don't have POTS. This study will test whether the blood vessels of people with POTS will react differently to certain tests than people without POTS. The hypothesis of the study is: Patients with POTS will have vascular endothelial dysfunction compared with control subjects.

Official Title
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Assessment of Vascular Endothelial Function in Postural Tachycardia Syndrome (POTS)

Conditions
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Postural Tachycardia Syndrome

Intervention / Treatment
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* Device: Blood Pressure and Blood Flow


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: ALL: Ages between 18-60 years old Male and female subjects are eligible Able and willing to give informed consent Additional criteria for POTS: Diagnosed with postural tachycardia syndrome by the Vanderbilt Autonomic - Dysfunction Center (1. increase in heart rate >/= 30 beats/minute with position change from supine to standing for 10 minutes and/or 2. Chronic symptoms consistent with POTS that are worse when upright and get better with recumbence. Additional criteria for Control subjects: Healthy, non-obese, non-smokers without orthostatic tachycardia Selected to match profiles of POTS patients (gender, age) Not using vasoactive medications Exclusion Criteria: Overt cause for postural tachycardia (such as acute dehydration) Inability to give, or withdraw informed consent Pregnancy Other factors in the investigator's opinion would prevent the subject from completing the study

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 60 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| POTS & Controls<br>Participants will have a physical prior to the study day and collect urine for 24 hours. On the study day the following procedures take place: After blood samples taken (about 2 tbsp), the subject will lie down. A blood pressure cuff will be placed on one arm and small probes on one finger on both hands. The arm blood pressure cuff will be inflated 60 points above the highest number on your normal blood pressure for five minutes. The blood pressure and forearm blood flow will be recorded. At the end of 5 minutes, the cuff will be released and the measurements of blood pressure and calf blood flow will be repeated. The brachial artery diameter and flow will be measured at baseline, during cuff inflation and for 3 minutes after deflation. The study lasts about 2 hours. | Device: Blood Pressure and Blood Flow<br>* A blood pressure cuff will be placed on one arm and small probes on one finger on both hands. The probes also measure blood pressure. After 10 minutes, the arm blood pressure cuff will be inflated. The cuff will stay inflated for 5 minutes, then the air will be let out. A cuff will be place above the left calf and the left knee. The subject will lie quietly for 9 minutes, then blood pressure and calf blood flow will be measured for one minute. the lower leg cuff will be inflated after 1 minute, then the cuff will be deflated. The blood pressure and forearm blood flow will be recorded. Next, the cuff on the upper leg will be inflated for 5 minutes then, it will be released and the measurements of blood pressure and calf blood flow will be repeated. The study lasts about 2 hours.<br>* Other names: Pulsitile Arterial Tonometry Protocol (PAT);|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| RH-PAT index | The primary analysis of RH-PAT will involve a non-parametric, Mann Whitney U test of RH-PAT between POTS patients and Control subjects. | The study will be complete in approximately 2 hours. There is no follow-up to this study. | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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POTS, Vascular Endothelial Function