One innovation involves biocompatible machinery. To understand how it helps, you have to know a little more about the surgery. During bypass surgery, a machine performs the role of the heart and lungs so the heart can be stopped during the operation. The machine pumps the patient's blood in and out and gives it oxygen. But the blood doesn't react naturally in plastic tubes.
Blood does the same thing that it does when it senses a wound.
It begins to clot. It causes inflammation. As a result, doctors must give patients anti-clotting medicine during the operation to thin the blood. This process creates a small percentage of risk to the patient. Most injuries are temporary and self-limited, but some lead to a delayed recuperation.