GREY'S ANATOMY - &quot;Heart-Shaped Box&quot; - The doctors become nostalgic when George O'Malley's mother, Louise, returns to Seattle Grace for medical help after a botched surgery at a neighboring hospital; the residents are inspired by a medical miracle when they witness a harvested heart that continues to beat outside the body; a new pediatric fellow excites Arizona and makes Alex feel threatened; Jackson lets his suspicions about Mark and Lexie interfere with his work; and Henry and Teddy have their first marital fight when he expresses interest in pursuing medical school, on &quot;Grey's Anatomy,&quot; THURSDAY, NOVEMBER 3 (9:00-10:02 p.m., ET) on the ABC Television Network. (ABC/RANDY HOLMES)PATRICK DEMPSEY, CHYLER LEIGH