GREY'S ANATOMY - "Beat Your Heart Out" - Now that Derek has the engagement ring, he searches for the perfect way to propose to Meredith, as Lexie demands that Mark go public with their relationship, and Bailey, encouraged by her work on recent cases and by Dr. Dixon, considers a new direction for her medical career, on "Grey's Anatomy," THURSDAY, FEBRUARY 5 (9:00-10:02 p.m., ET) on the ABC Television Network. (ABC/RANDY HOLEMES) PATRICK DEMPSEY