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Completed

NCT Number: NCT01550315

Effect of Dietary Sodium Intake on Vascular Endothelium

The investigators will test the hypothesis that markers of vascular endothelial dysfunction will be exaggerated acutely with an extreme high sodium diet compared to an extreme low-sodium diet. The investigators will compare patients with postural orthostatic tachycardia (POTS) to healthy control subjects.

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Key information

Conditions

Postural Tachycardia Syndrome (POTS) Autonomic Nervous System Diseases Nervous System Diseases Orthostatic Intolerance Postural Orthostatic Tachycardia Syndrome Primary Dysautonomias

Age range

18 year–60 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Vanderbilt University Medical Center

Nashville, Tennessee, 37232, United States

About this study

The study will involve a crossover design in which each subject will be assessed (as below) while on a very low-sodium (10 mEq/day) diet compared with a very high-sodium diet. These acute dietary interventions will be part of the parent study ("Dietary Salt in Postural Tachcyardia Syndrome" funded by R01 HL102387) for 4-5 days at the time of the study. Dietary success will be assessed using a 24h urine for sodium and creatinine as a part of the parent study.

Blood will be drawn and collected in a fasting state for future assay and analysis of the following tests:

  • Glucose, Insulin (glucose impairment, insulin resistance)
  • Fasting lipid profile
  • C-Reactive Protein (hsCRP) (inflammatory state)
  • Inflammatory cytokines (inflammatory state)
  • aliquots (future analysis)

Pulsitile Arterial Tonometry (PAT) Protocol Calf Blood Flow in Reactive Hyperemia (CBF-RH) - venous occlusion plethysmography Evaluation of Forearm-Mediated Dilation

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Subjects will be enrolled in the parent study "Dietary Salt in Postural Tachcyardia Syndrome" funded by R01 HL102387 Postural Tachycardia Syndrome
  • Diagnosed with postural tachycardia syndrome by the Vanderbilt Autonomic Dysfunction Center
  • Subjects will be enrolled in the parent study "Dietary Salt in Postural Tachcyardia Syndrome" funded by R01 HL102387
  • Postural Tachycardia Syndrome
  • Diagnosed with postural tachycardia syndrome by the Vanderbilt Autonomic Dysfunction Center
  • Increase in heart rate ≥30 beats/min with position change from supine to standing (10 minutes)
  • Chronic symptoms consistent with POTS that are worse when upright and get better with recumbence Control Subjects
  • Healthy, non-obese, non-smokers without orthostatic tachycardia
  • Selected to match profiles of POTS patients (gender, age)
  • Not using vasoactive medication
  • Age between 18-60 years
  • Male and female subjects are eligible.
  • Able and willing to provide informed consent

Exclusion criteria

  • Overt cause for postural tachycardia (such as acute dehydration)
  • Inability to give, or withdrawal of, informed consent
  • Pregnant
  • Other factors which in the investigator's opinion would prevent the subject from completing the protocol.

Treatment and study plan

Pulsitile Arterial Tonometry (PAT) Protocol

Procedure
  • A blood pressure cuff will be placed on one upper arm (study arm; non-dominant), while the contralateral arm will serve as a control (control arm).
  • RH-PAT probes will be placed on one finger (finger II, III, or IV) of each hand (same finger on both hands). The fingers on either side of the one with the probe will be separated using soft sponge rings.
  • Continuous recording of pulsatile blood volume responses from both hands will be initiated.
  • After a 10-min equilibration period, the blood pressure cuff on the study arm will be inflated to 60 mm Hg above systolic pressure for 5 min. The cuff will then be deflated to induce reactive hyperemia, PAT recording will be stopped.

Other names: EndoPat

Calf Blood Flow in Reactive Hyperemia (CBF-RH)

Device

Calf blood flow (CBF) will be determined using venous occlusion plethysmography and calibrated mercury strain-gauges during reactive hyperemia after a 5 min of ischemia of the distal limb. Strain-gauges will be applied to the widest part of the non-dominant calf (~10 cm below patella). Participants will remain quietly supine for 10 min with legs elevated on foam pads above the right atrium to achieve stable baseline measurements of CBF. The venous occlusion cuff is inflated for 4 seconds at 8 seconds intervals, while monitoring the change in resistance in the system, pressure inside the measuring cuff, and 5-10 determinations are performed

Other names: Hokansan strain guage venous plethysmography

Evaluation of Forearm-Mediated Dilation

Device

The arm will be kept extended and immobilized at heart level. Brachial artery diameter will be measured using a high resolution ultrasonography using a linear array probe with a 5 to 17 MHz frequency range. The brachial artery will be imaged in longitudinal sections, 5-10 cm proximal to placement of an occlusion cuff in the dominant forearm just below the antecubital fossa. The probe will be held with a stereotaxic holder with micrometer movement capabilities.

Other names: Ultrasound

Primary outcomes

  1. FMD (% Change)

    Time frame: FMD was assessed on the morning of day 7, after 6 days of being on either a high salt diet or a low salt diet.

    The primary analysis will involve a non-parametric, paired, Signed Rank test of flow mediated dilation (FMD) between all subjects (POTS & control subjects) on the high sodium diet vs low sodium diet

Sponsors and collaborators

Lead sponsor

Vanderbilt University Medical Center

Other

Collaborators

  • National Heart, Lung, and Blood Institute (NHLBI)
  • National Institutes of Health (NIH)

Registry information

Official study title

A Pilot Study of the Effect of Dietary Sodium Intake on Assessments of Vascular Endothelium

Important dates

Study start
2012
Primary completion
2020
Study completion
2021
First posted
Mar 9, 2012
Registry last updated
Jan 5, 2022

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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