Coronary artery bypass graft surgery (CABG) creates new pathways around narrowed or blocked coronary arteries so that more blood and oxygen reaches the heart muscle. This surgery uses segments of veins or arteries taken from another part of the body and attaches, or grafts, them into place to divert blood flow around a blockage. Once in place, blood flows freely through the graft, bypassing the blockage. Figure 1: Coronary arteries of the heart. Figure 2: Coronary artery disease with atherosclerotic plaque block blood flow.   Figure 3: Coronary bypass graft using a vein segment that allows blood to flow from the aorta to the artery, bypassing the blockage.