There isnt an artery you can lose in your leg for a bypass, but the body can cope with losing a few
veins. Arteries are much stronger than
veins and
veins have tiny flaps in them which act as one way valves. When these break down, the vein wall weakens making it swell and varicose.
So, due to their superior quality and strength, arteries are the favoured vessels for a bypass. They can use one of a pair from the left side of the chest and one from a pair on the right side of the chest.