ultrasound imaging of saphenous vein bypass graft following an ischemic stimulus, administration of sublingual nitroglycerin and intravenous administration of L-NMMA.

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.

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.

All 19 study subjects had continuously patent femoral-to-popliteal arterial bypass with autogenous greater saphenous vein. Ultrasound imaging of saphenous vein bypass graft followed an ischemic stimulus and administration of sublingual nitroglycerin. In the last 6 consecutive subjects, L-N^G monomethyl arginine (L-NMMA) was administered intravenously.

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.

All 19 study subjects. Each subject qualified for the study on the basis of a continuously patent femoral-to-popliteal arterial bypass with autogenous greater saphenous vein.