Endothelial Function in Lower Extremity Bypass Grafts

Study Overview
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Brief Summary
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This study will determine whether or not saphenous vein [arterial] bypass grafts in the leg relax in response to increases in blood flow.

Detailed Description
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Subjects who have undergone saphenous vein [arterial] bypass grafts from the femoral to above-knee popliteal artery will undergo ultrasound imaging at rest, and again after 5 minutes of blood pressure cuff occlusion of the calf. (at 1 minute and 15 minutes) Subjects will then be given sub-lingual nitroglycerin, and repeat ultrasound will be performed 3 minutes later. Following 10 minutes of rest, subjects will be given intravenous L-NMMA, a specific nitric oxide inhibitor, to help determine the responsible agent of the vein graft flow mediated dilation.

Official Title
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Endothelial Function in Lower Extremity Bypass Grafts

Conditions
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Peripheral Arterial Disease

Intervention / Treatment
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* Drug: L-N^G monomethyl arginine (L-NMMA)


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Adults who have undergone femoral artery to above-knee popliteal artery saphenous vein bypass grafts Exclusion Criteria: Amputation beyond the toes Critical limb ischemia defined as rest pain, non-healing ulceration or gangrene Pregnancy

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Intervention Model: Single Group Assignment
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: 1<br>ultrasound imaging of saphenous vein bypass graft following an ischemic stimulus, administration of sublingual nitroglycerin and intravenous administration of L-NMMA. | Drug: L-N^G monomethyl arginine (L-NMMA)<br>* L-NMMA was infused at a dose of 1 mg/kg over 10 minutes to competitively inhibit the production of nitric oxide. Ultrasound imaging of the saphenous vein [arterial] bypass at baseline, and following an ischemic stimulus, administration of sublingual nitroglycerin, and intravenous administration of L-NMMA.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change From Baseline in Saphenous Vein Bypass Graft Vasodilation | Flow-mediated, endothelium-dependent vasodilation was determined by comparing baseline vein graft diameter with vein graft diameter as measured after deflation of a 2.5-inch wide sphygmomanometric cuff that had been inflated to suprasystolic pressure for 5 minutes. The cuff was never placed directly over the graft. Vasodilation of the vein graft was determined by acquiring images at 1 minute after cuff deflation. | Single visit study | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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saphenous vein bypass grafts, flow-mediated vasodilation