 Prior to angiography they will be asked to complete an ankle brachial index evaluation, baseline six minute walk test and walking impairment questionnaire. Arterial access should be obtained in the contralateral common femoral artery to the symptomatic limb if feasible. Angiographic images are to be obtained, interpreted and clinical decisions regarding endovascular treatment are to be made per treating physicians discretion prior to obtaining translesional pressure gradients. In patients whose angiogram does not meet exclusion criteria and do not have a chronic total occlusion CTO a baseline TLG will be obtained. A 0.014 pressure wirecatheter to measure pressure will be inserted. After baseline calibration in the superficial femoral artery, the wire will be inserted past the narrowest lesion into the popliteal vessel. Intra-arterial adenosine 100-200 mcg will be given for hyperemia and measurements are to be recorded. If an intervention is planned, repeat measurements are to be obtained at the end of the procedure. If no intervention is planned this will be the residual or final TLG recorded. If baseline measurement are unable to obtained due to a CTO then only a post intervention residual TLG will be obtained and included in analysis. The operator will be blinded to the pre and post TLG measurements by turning the display monitor away from the procedure table and towards the recorder situated in the procedure room when measurements are being obtained. 