Approximately 359,000 patients underwent coronary bypass procedures in the U.S. in 1999. Long term studies have observed an incidence of vein graft occlusion at 19% at 1 year, 25% at 5 years and 50% by 15 years after operation for an overall rate of 2.5% per year after the first year of observation. The consequences of graft failure are as significant as those of primary atherosclerotic disease and include ischemia, myocardial infarction and death.