Dietary Nitrates and Vascular Function in Patients With Peripheral Artery Disease

N/ACompletedNCT01983826

University of Iowa21 enrolled

Overview

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.

Study Type

INTERVENTIONAL

Allocation

RANDOMIZED

Purpose

BASIC_SCIENCE

Masking

DOUBLE

Enrollment

Conditions

Peripheral Artery Disease

Interventions

Eligibility

Sex: ALLMin age: 50 YearsMax age: 85 Years

Medical Language ↔ Plain English

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

Outcomes

Primary Outcomes

Change in Vasodilator Capacity

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).

Time frame: Pre and post 8 weeks of dietary nitrate supplementation

Change in Arterial Stiffness

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).

Time frame: Pre and post 8 weeks of dietary nitrate supplementation

Change in Functional Capacity - Distance Walked in 6 Minutes

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.

Time frame: Pre and post 8 weeks of dietary nitrate supplementation

Dietary Nitrates and Vascular Function in Patients With Peripheral Artery Disease

Overview

Conditions

Interventions

Eligibility

Locations (1)

Outcomes

Primary Outcomes