'I'm back!': Arnold Schwarzenegger returns to Twitter after emergency open-heart surgery

"It’s true: I’m back!" Arnold Schwarzenegger, 70, tweeted Monday, quoting his famous Terminator catchphrase after undergoing emergency open-heart surgery Thursday.

"I went to sleep expecting to wake up with a small incision and woke up with a big one — but guess what? I woke up, and that’s something to be thankful for," he wrote. "Thank you to the doctors & nurses. And I’m truly filled with gratitude for all of the kind messages." 

Daniel Ketchell, a spokesman for the Terminator star and former California governor, confirmed Friday that doctors at Cedars-Sinai Medical Center in Los Angeles had planned to put in a new pulmonic valve (replacing the old one he received in 1997) via a less-invasive catheter procedure but ended up cracking his chest and replacing it by open-heart surgery.