Tony Stark's heart
Tony Stark's Artificial Heart is a machine to keep Tony's injured heart functioning.
Overview
Tony Stark has a damaged heart from the plane crash that the Mandarin caused, because of that he has an implant made by Dr. Ho Yinsen that keeps it beating.
His implant is made out of a stabilized form of Kylight, a metal that is found in the abandoned Stark outpost in the Arctic.
After Tony took the Extremis serum, it repaired his heart and discarded the implant, making it unnecessary for his health.It is unknown of what happenned to it after it discarded from his body.