This study will determine whether or not saphenous vein \[arterial\] bypass grafts in the leg relax in response to increases in blood flow.
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.
Study Type
INTERVENTIONAL
Allocation
NA
Purpose
BASIC_SCIENCE
Masking
SINGLE
Enrollment
19
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.
Brigham and Women's Hospital
Boston, Massachusetts, United States
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.
Time frame: Single visit study
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