During a coronary surgery, typically called coronary artery bypass or coronary bypass, arteries are taken from other parts of the patient's body and fused with (or replace) the malfunctioning coronary artery. Doctors have a couple options in this artery replacement. First, they can use an artery from the patient. Second, the doctor can use a harvested artery from another person.
One advantage of using the surgical patient's own artery is that it is a part of his or her own body. The body, then, is less likely to react to it (somewhat like a rejection). On the other hand, the patient's own arteries may not be strong enough to handle the stress the heart places on them. (For example, they could have PAD-peripheral artery disease.) If a weakened artery is used, it would not work as a suitable replacement.