This study will seek to determine whether non-invasive measures of endothelial function have utility as surrogate markers of cardiovascular risk in patients with peripheral arterial disease undergoing vascular surgery. Measurements of endothelial function will be made before and after initiation of atorvastatin, ascorbic acid, or placebo therapy during the pre-operative period. We will then examine cardiovascular events following surgery. We hypothesize that patients who have no improvement in endothelial function will have increased cardiovascular risk compared to patients with improvement in endothelial function.