Actor Arnold Schwarzenegger is in stable condition after undergoing heart surgery in Los Angeles, California.

"I'm back," Schwarzenegger said immediately after awakening from the procedure, according to his spokesman, Daniel Ketchell, reports tmz.com.

The former governor of California underwent emergency open-heart surgery on Thursday but Ketchell released a statement on Twitter that the procedure was planned.

"Update: Schwarzenegger is awake and his first words were actually ‘I'm back,' so he is in good spirits," Ketchell tweeted.

Update: @Schwarzenegger is awake and his first words were actually “I’m back”, so he is in good spirits. https://t.co/bJ4pxqS8l6

— Daniel Ketchell (@ketch) March 30, 2018

Schwarzenegger, 70, went to Cedars-Sinai Medical Center to replace a pulmonic valve that was originally changed in 1997 due to a congenital heart defect.

"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," Ketchell said.

Ketchell added that an open-heart surgery team was on hand as part of standard procedure, but was not needed.

"They frequently are in these circumstances, in case the catheter procedure was unable to be performed," Ketchell said. "Governor Schwarzenegger's pulmonic valve was successfully replaced and he is currently recovering from the surgery and is in stable condition."

My statement on Governor @Schwarzenegger’s procedure. pic.twitter.com/7RoVtHN43c

— Daniel Ketchell (@ketch) March 30, 2018

Schwarzenegger, who served as governor of California from 2003-2011, is set to return to the "Terminator" franchise for the sixth film in the series, which is scheduled for release next year.