Effect of Dietary Sodium Intake on Vascular Endothelium

This study is currently recruiting participants. (see Contacts and Locations)
Verified January 2013 by Vanderbilt University
Sponsor:
Information provided by (Responsible Party):
Satish R. Raj, Vanderbilt University
ClinicalTrials.gov Identifier:
NCT01550315
First received: March 2, 2012
Last updated: January 7, 2013
Last verified: January 2013
  Purpose

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.


Condition Intervention
Postural Tachycardia Syndrome (POTS)
Procedure: Pulsitile Arterial Tonometry (PAT) Protocol
Device: Calf Blood Flow in Reactive Hyperemia (CBF-RH)
Device: Evaluation of Forearm-Mediated Dilation

Study Type: Interventional
Study Design: Allocation: Non-Randomized
Intervention Model: Crossover Assignment
Masking: Open Label
Primary Purpose: Basic Science
Official Title: A Pilot Study of the Effect of Dietary Sodium Intake on Assessments of Vascular Endothelium

Resource links provided by NLM:


Further study details as provided by Vanderbilt University:

Primary Outcome Measures:
  • RH-PAT Index [ Time Frame: On steady state (after 5 days) low and high sodium diets ] [ Designated as safety issue: No ]
    The primary analysis will involve a non-parametric, paired, Signed Rank test of RH-PAT between all subjects (POTS & control subjects) on the high sodium diet vs low sodium diet


Secondary Outcome Measures:
  • fasting glucose and insulin levels [ Time Frame: after steady state has been reached (>5 days) on low and high sodium diets ] [ Designated as safety issue: No ]
    Secondary analyses will include non-parametric paired comparisons between low sodium and high sodium diets of continuous outcome measures (outlined in section 7.3). Secondary comparisons might also assess differences in the dietary sodium induced changes between POTS patients and control subjects.


Estimated Enrollment: 50
Study Start Date: April 2012
Estimated Study Completion Date: March 2017
Estimated Primary Completion Date: March 2017 (Final data collection date for primary outcome measure)
Arms Assigned Interventions
Active Comparator: High Sodium - POTS & Controls
Subjects will receive a high sodium diet for 4-5 days prior to study day. Procedures include: blood work, urine collection, Pulsitile Arterial Tonometry (PAT), PAT analysis, Calf Blood Flow in Reactive Hyperemia (CBF-RH), & evaluation of forearm-mediated dilation.
Procedure: Pulsitile Arterial Tonometry (PAT) Protocol
  • 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 Name: EndoPat
Device: Calf Blood Flow in Reactive Hyperemia (CBF-RH)
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 Name: Hokansan strain guage venous plethysmography
Device: Evaluation of Forearm-Mediated Dilation
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 Name: Ultrasound
Low Sodium Diet (POTS & Controls)

Participants will consume a very low sodium diet (10 mEq/day) for 4-5 days prior to study day.

Procedures include: blood work, urine collection, Pulsitile Arterial Tonometry (PAT), PAT analysis, Calf Blood Flow in Reactive Hyperemia (CBF-RH), & evaluation of forearm-mediated dilation.

Procedure: Pulsitile Arterial Tonometry (PAT) Protocol
  • 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 Name: EndoPat
Device: Calf Blood Flow in Reactive Hyperemia (CBF-RH)
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 Name: Hokansan strain guage venous plethysmography
Device: Evaluation of Forearm-Mediated Dilation
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 Name: Ultrasound

Detailed Description:

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

  Eligibility

Ages Eligible for Study:   18 Years to 60 Years
Genders Eligible for Study:   Both
Accepts Healthy Volunteers:   Yes
Criteria

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.
  Contacts and Locations
Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the Contacts provided below. For general information, see Learn About Clinical Studies.

Please refer to this study by its ClinicalTrials.gov identifier: NCT01550315

Contacts
Contact: Satish R Raj, MD, MSCI 615-322-2931 adcresearch@vanderbilt.edu
Contact: Victor Nwazue, MD, ChB 615-322-3304 adcresearch@vanderbilt.edu

Locations
United States, Tennessee
Vanderbilt University Medical Center Recruiting
Nashville, Tennessee, United States, 37232
Principal Investigator: Satish Raj, MD, MSCI         
Sub-Investigator: Victor Nwazue, MD, ChB         
Sub-Investigator: Alfredo Gamboa, MD         
Sponsors and Collaborators
Vanderbilt University
Investigators
Principal Investigator: Satish R Raj, MD MSCI Vanderbilt University
  More Information

Publications:
Vital signs: prevalence, treatment, and control of hypertension- United States 1999-2002 and 2005-2008. MMWR Morb Mortal Wkly Rep 2011 February 4;60(4):103-8

Responsible Party: Satish R. Raj, MD, Assistant Professor, Vanderbilt University
ClinicalTrials.gov Identifier: NCT01550315     History of Changes
Other Study ID Numbers: 111577
Study First Received: March 2, 2012
Last Updated: January 7, 2013
Health Authority: United States: Institutional Review Board

Keywords provided by Vanderbilt University:
POTS
endothelial function
high salt vs low salt diet
PAT protocol
Calf blood flow
forearm mediated dilation

Additional relevant MeSH terms:
Tachycardia
Postural Orthostatic Tachycardia Syndrome
Arrhythmias, Cardiac
Heart Diseases
Cardiovascular Diseases
Pathologic Processes
Orthostatic Intolerance
Primary Dysautonomias
Autonomic Nervous System Diseases
Nervous System Diseases

ClinicalTrials.gov processed this record on July 31, 2014