Torn by conflict, corporate greed and the deaths of innocents turned Dr. Wirtham into the man he is today: the vigilante Cardiac. Dr. Elias Wirtham was a dedicated physician who, while still a child, lost his older brother to a rare and incurable disease. With that, Elias vowed to become a physician. Graduating from medical school, he went on to build the most powerful medical and biological research empire on the East Coast. Acquiring an older chemical company, he learned that it had produced a drug that could have saved his brother, but kept it off market until the economic climate was more favorable. Enraged and embittered, he vowed to strike at those individuals whose positions or technicalities protected them from the law.
In order to undertake this crusade, Elias underwent a series of extremely painful operations that replaced his heart with a compact beta-particle reactor and encased his entire body within a layer of Vibranium-mesh pseudoskin, specifically designed to channel beta particles into his muscles. He became Cardiac, the cyborg-vigilante.
Cardiac's first target was Sapridyne Chemicals, who supposedly manufactured legal chemicals needed to process cocaine, and were being exported to South America. Spider-Man came to take pictures and expose the company to the public, but Cardiac came to completely and utterly destroy the place. Spider-Man (working for Silver Sable at the time), the Rhino (working for Justin Hammer, who had stocks invested in the company), and Boomerang (working for Hammer as well) failed to stop Cardiac.
Since then, Cardiac has gone on vigilante raids against Albert Brukner (a corrupt S&L broker), a subsidiary of Stane International that produced dangerous dolls for children, William Gant and his movie studio (he produced documentaries on human suffering), and New York's Code: Blue (a branch of the NYPD devoted to stopping superhuman threats). During his attack on Gant, he ran into Styx and Stone, Gant's bodyguards. At first, Cardiac pretended to befriend the pair, but betrayed them and would have killed Styx if Spider-Man had not intervened.
Cardiac knows that he doesn't live in a perfect world. He wants to save lives, but often has to take them, and is haunted by every death he causes. But he cannot stop his crusade—his compassion makes him ruthless, and his desire for justice compels him to break the law.
In all probability, Cardiac continues his vigilante war.