Dietary Nitrates and Vascular Function in Patients With Peripheral Artery Disease

Not Applicable

Completed

Conditions: Peripheral Artery Disease

Interventions: Dietary Supplement: Sodium Nitrate
Other: Placebo

Registration Number: NCT01983826

Lead Sponsor: University of Iowa

Brief Summary: 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.

Detailed Description: Not available

Recruitment & Eligibility

Status: COMPLETED

Sex: All

Target Recruitment: 21

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

Study & Design

Study Type: INTERVENTIONAL

Study Design: PARALLEL

Arm && Interventions

Group	Intervention	Description
Sodium Nitrate	Sodium Nitrate	Sodium Nitrate (1g/day) for 8 weeks
Placebo capsule	Placebo	Microcrystalline cellulose (daily) for 8 weeks

Primary Outcome Measures

Name	Time	Method
Change in Vasodilator Capacity	Pre and post 8 weeks of dietary nitrate supplementation	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	Pre and post 8 weeks of dietary nitrate supplementation	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 - Distance Walked in 6 Minutes	Pre and post 8 weeks of dietary nitrate supplementation	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 after 8 weeks of dietary nitrate supplementation.