Arterial bypass. Coloured 3D computed tomography (CT) angiogram of the iliac and femoral arteries of the patient with high blood pressure who has undergone double arterial bypass surgery to restore blood flow to the arteries that had become blocked as a result of arteritis (inflammation of the blood vessel walls). Here, the kidneys (large, red) are visible at top. In arterial bypass surgery, a synthetic tube or section of healthy vein is grafted to the damaged artery in order to re-route the blood flow and bypass the damaged section.