Last June, Doug Bergeson was working on his house in Wisconsin when the nail gun he was holding accidentally went off. The power tool drove a 9 centimeter (3.5 inch) nail into his chest. Bergeson had no idea how serious his injury was until doctors took an X-ray at a local hospital. The image revealed that the nail had punctured his heart. Bergeson says part of the nail was sticking out of his body and jumped in sync with his heartbeat.
Bergeson underwent surgery to remove the nail. It turned out that the piece of metal was lodged less than 2 millimeters (0.08 in.) from a major artery—a blood vessel that carries oxygen-rich blood from the heart to the rest of the body. If the nail had nicked the artery, Bergeson could have suffered uncontrollable internal bleeding and probably would have died.