Dietary Nitrates and Vascular Function in Patients With Peripheral Artery Disease

This study is currently recruiting participants. (see Contacts and Locations)
Verified May 2016 by University of Iowa
Information provided by (Responsible Party):
University of Iowa Identifier:
First received: October 28, 2013
Last updated: May 10, 2016
Last verified: May 2016
The overarching question addressed in the current project is: Does dietary nitrate supplementation (8 weeks) improve physiological function in patients with peripheral arterial disease (PAD)? The investigators will specifically address whether dietary nitrate supplementation enhances blood vessel function, blood pressure regulation, and exercise capacity. The proposed project uses an array of clearly defined measurements which will allow investigators to quantify blood vessel function (vasodilator responsiveness and arterial stiffness), blood pressure (variability and responsiveness to stress), and functional capacity before and after 8 weeks of dietary supplementation.

Condition Intervention
Peripheral Artery Disease
Dietary Supplement: Sodium Nitrate
Other: Placebo

Study Type: Interventional
Study Design: Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Double Blind (Subject, Investigator)
Primary Purpose: Basic Science
Official Title: Dietary Nitrates and Vascular Function in Patients With Peripheral Artery Disease

Resource links provided by NLM:

Further study details as provided by University of Iowa:

Primary Outcome Measures:
  • Change in Vasodilator capacity [ Time Frame: Pre and post 8 weeks of dietary nitrate supplementation ] [ Designated as safety issue: No ]
    Forearm and calf blood flow will be measured independently by venous occlusion plethysmography using mercury-in-silastic strain gauges. Plethysmographic measurements will be made at rest and following 5 minutes of ischemia (reactive hyperemia) of the distal limb (forearm and calf). Peak blood flow will be determined as the highest flow recorded during the post deflation period. Total blood flow will be measured as the area under the time-curve after resting flow is subtracted. Vascular conductance will be calculated using blood flow/mean arterial pressure (via finger plethysmograph).

  • Change in Arterial Stiffness [ Time Frame: Pre and post 8 weeks of dietary nitrate supplementation ] [ Designated as safety issue: No ]
    ECG gated arterial waveforms will be obtained via applanation tonometry from the carotid and femoral arteries. The pulse wave velocity (PWV; index of arterial stiffness) will be determined between the carotid and femoral measurement sites (cfPWV). The time (t) between the feet of recorded pressure waves will be determined as the mean of 10 consecutive cardiac cycles. PWV is calculated from the distance (D; meters) between measurement points and the measured time delay (t): PWV = D/Δt (m/s).

  • Change in Functional Capacity [ Time Frame: Pre and post 8 weeks of dietary nitrate supplementation ] [ Designated as safety issue: No ]
    6-minute walk tests will be performed before and after treatment to assess functional capacity. The main comparisons will be changes distance walked in 6 minutes and time to claudication after 8 weeks of dietary nitrate supplementation.

Estimated Enrollment: 30
Study Start Date: November 2013
Estimated Primary Completion Date: October 2016 (Final data collection date for primary outcome measure)
Arms Assigned Interventions
Experimental: Sodium Nitrate
Sodium Nitrate (1g/day) for 8 weeks
Dietary Supplement: Sodium Nitrate
Sodium Nitrate (1g/day) for 8 weeks
Placebo Comparator: Placebo capsule
Microcrystalline cellulose (daily) for 8 weeks
Other: Placebo
Microcrystalline cellulose (daily) for 8 weeks


Ages Eligible for Study:   50 Years to 85 Years
Genders Eligible for Study:   Both
Accepts Healthy Volunteers:   No

Inclusion Criteria:

  • Documented peripheral artery disease
  • Ankle-Brachial Index (ABI) < or = to 0.90

Exclusion Criteria:

  • Non-atherosclerotic vascular disease
  • Critical limb ischemia
  • Active ischemic ulceration
  • Recent (within one year) revascularization
  • Symptomatic coronary artery disease (angina pectoris)
  • Heart failure
  • Resting systolic blood pressure > 180 mmHg or diastolic pressure > 100 mmHg
  • Hypotension (resting systolic BP < 90 mmHg)
  • Smoking or history of smoking within past one year
  • Use of phosphodiesterase V inhibitor drugs
  • Women with history of hormone replacement therapy within the past 6 months
  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 identifier: NCT01983826

Contact: Darren P Casey, Ph.D. 319-384-1009

United States, Iowa
University of Iowa Recruiting
Iowa City, Iowa, United States, 52242
Sponsors and Collaborators
University of Iowa
Principal Investigator: Darren P Casey, Ph.D. University of Iowa
  More Information

Responsible Party: University of Iowa Identifier: NCT01983826     History of Changes
Other Study ID Numbers: 13GRNT16490002  13GRNT16490002 
Study First Received: October 28, 2013
Last Updated: May 10, 2016
Health Authority: United States: Institutional Review Board

Keywords provided by University of Iowa:
blood flow
vascular function

Additional relevant MeSH terms:
Peripheral Arterial Disease
Arterial Occlusive Diseases
Cardiovascular Diseases
Peripheral Vascular Diseases
Vascular Diseases processed this record on May 26, 2016