Multiple sources tell TMZ, Joan Rivers ‘ personal doctor who was working on Joan when she stopped breathing is Dr. Gwen Korovin , who treats the biggest celebs in the world. The sources said, Dr. Korovin was not authorized to practice medicine at Yorkville Endoscopy center. Her patients include Celine Dion , Lady Gaga , Hugh Jackman , John Mayer , and Brooke Shields . Dr. Korovin’s Facebook page has a pic of the doc in her office with pics of her celeb patients lining the walls.
