Surgical bypass treats your narrowed arteries by creating a bypass around a section of the artery that is blocked. Your arteries are normally smooth and unobstructed on the inside but they can become blocked through a process called atherosclerosis, which means hardening of the arteries. As you age, a sticky substance called plaque can build up in the walls of your arteries. Cholesterol, calcium, and fibrous tissue make up the plaque. As more plaque builds up, your arteries can narrow and stiffen. Eventually, as the process progresses, your blood vessels can no longer supply the oxygen demands of your organs or muscles and symptoms may develop.

During a bypass, your vascular surgeon creates a new pathway for blood flow using a graft. A graft is a portion of one of your veins or a man-made synthetic tube that your surgeon connects above and below a blockage to allow blood to pass around it.