Heart surgery. Harvested vein (red) being tested for leaks before being grafted to the heart (seen in background). This is coronary artery bypass graft (CABG) surgery. The vein has been removed from elsewhere in the body (normally the legs) and one end will be attached to the aorta (the main body artery). The other end of the vein will be attached to one of the coronary arteries that normally supply blood to the heart. The grafted vein will then bring blood to the heart, bypassing a blockage in the coronary artery. Such blockages arise from atherosclerosis, the build-up of fatty deposits, including cholesterol, on the lining of the arteries.