Endothelial Function in Lower Extremity Bypass Grafts

Endothelial Function in Lower Extremity Bypass Grafts

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.

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