Arterial bypass. Coloured 3D computed tomography (CT) angiogram of the iliac and femoral arteries of the legs of a 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). 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.