WENN

Arnold Schwarzenegger proved he was in "good spirits" as he woke up from emergency heart surgery on Thursday by referencing his trademark Terminator phrase.

The ageing action man and former Governor of California hit headlines on Friday after he reportedly suffered complications during a catheter valve replacement operation at Los Angeles' Cedars-Sinai Medical Center, prompting doctors to perform urgent open heart surgery.

Arnold's spokesman, Daniel Ketchell, has since assured fans the actor is recovering well, claiming the procedures were nothing out of the ordinary, and were related to a previous operation he had undergone 21 years ago.

"Yesterday, Governor Schwarzenegger underwent a planned procedure at Cedars-Sinai to replace a pulmonic valve that was originally replaced due to a congenital heart defect in 1997," Ketchell wrote in a statement posted on Twitter.

"That 1997 replacement valve was never meant to be permanent, and has outlived its life expectancy, so he chose to replace it yesterday through a less-invasive catheter valve replacement. During that procedure, an open-heart surgery team was prepared, as they frequently are in these circumstances, in case the catheter procedure was unable to be performed.

"Governor Schwarzenegger's pulmonic valve was successfully replaced and he is currently recovering from the surgery and is in stable condition."

Ketchell went on to express his thanks to Schwarzenegger's "entire medical team for their tireless efforts", and in a follow-up tweet, he revealed the 70-year-old's sense of humor remains fully intact, as he uttered a line similar to his famous Terminator catchphrase, "I'll be back".

Returning to Twitter shortly after posting his full statement, Ketchell wrote, "Update: @Schwarzenegger is awake and his first words were actually 'I'm back', so he is in good spirits."