Arnold Schwarzenegger has lived up to his famous catchphrase, 'I'll be back.'

According to The Terminator star's representative, his first words after waking up from emergency open-heart surgery were, 'I'm back.'

Daniel Ketchell tweeted on Friday that the 70-year-old actor is awake and is in good spirits following a valve replacement procedure, it was revealed this afternoon.

TMZ, which broke the news, said the former governor of California went to Cedars-Sinai Medical Center in Los Angeles on Thursday to have a scheduled catheter valve replacement.

The procedure is said to be risky, and the seven-time Mr Olympia winner developed complications, leading to an emergency open-heart surgery that reportedly lasted several hours.

Arnold Schwarzenegger, pictured on March 18, has undergone an emergency open-heart surgery after a failed valve replacement procedure

Latest sighting: Puffing on a cigar, Schwarzenegger and a friend are seen leaving the Waldorf Astoria Hotel after having lunch with his son Patrick Schwarzenegger in Beverly Hills on Wednesday, a day before his procedure

A statement released on Twitter by Schwarzenegger's spokesman addressing his health scare

The scheduled catheter valve replacement was carried out on Thursday at Cedars-Sinai Medical Center in Los Angeles

EXPLAINED: ARNOLD SCHWARZENEGGER'S HEART OPERATION DESIGNED FOR HIGH-RISK PATIENTS Arnold Schwarzenegger, 70, underwent a transcatheter pulmonary valve replacement on Thursday. However, he suffered complications which led to emergency open heart surgery. He is now stable. WHO NEEDS A TRANSCATHETER PULMONARY VALVE REPLACEMENT (TPVR)? There are four valves which control the heart's blood flow. One of those if the pulmonary valve. It opens when the right ventricle of the heart contracts, allowing oxygen-parched blood into the lungs for oxygen. Any issues with this valve can impact blood flow to the entire body. Many can go years without pulmonary heart valve issues being spotted, since the symptoms of fatigue, arrhythmia and shortness of breath. WHY A TPVR INSTEAD OF SURGERY? TPVR operations are associated with shorter hospital stays compared to open surgery, but produce near-identical results. This strategy is often used as a safer bet for people who may have risks with their hearts. This includes people who have already undergone a valve replacement, as Schwarzenegger did in Mexico in 1997. At the time, he told reporters he'd had no symptoms but elected to get operated in an abundance of caution. The high-risk bracket also includes patients who show severe symptoms of aortic stenosis. Severe symptoms suggest the person has a high risk of succumbing to their condition if not operated on soon. Finally, doctors will also endorse a TPVR over open surgery if the patient suffers from other debilitating conditions, like lung disease and kidney disease. WHAT ARE THE RISKS? Though the operation is minimally-invasive, it carries a high risk of death, largely because it is performed on high-risk patients: Bleeding

Blood vessel complications

Problems with the replacement valve, such as the valve slipping out of place or leaking

Stroke

Heart rhythm abnormalities (arrhythmias)

Kidney disease

Heart attack

Infection

Death Advertisement

As of late Friday afternoon, his condition following the operation was described as stable.

DailyMail.com reached out to Creative Artists Agency seeking comment from Schwarzenegger's publicist and was awaiting a reply.

The veteran action star traveled to Mexico in 1997 to undergo surgery to replace a pulmonary valve. According to the American Heart Association, the valve closes off the lower right chamber and opens to allow blood to be pumped from the heart to the lungs (through the pulmonary artery) where it will receive oxygen.

It was reported earlier that the procedure was to replace an aortic valve.

'I've never felt sick or had any symptoms at all, but I knew I'd have to take care of this condition sooner or later,' Schwarzenegger said in a statement after the operation, according to the Los Angeles Times. 'I said to the doctors, "Let's do it now, while I'm young and healthy." They agreed this was the way to go.'

Pulmonary valve replacement is a procedure in which a patient's leaky, or partially blocked, pulmonary valve is replaced with an artificial heart valve.

The actor's spokesperson said at the time that he had a congenital heart defect that had nothing to do with steroids, which Schwarzenegger had admitted to using during his time as a world-class bodybuilder.

On Friday, Schwarzenegger's representative released a statement saying the replacement valve from 1997 was never meant to be permanent and has outlived its life expectancy, so he chose to replace it on Thursday through the less invasive catheter valve procedure.

A team of surgeons at Cedars-Sinai were on standby in case an open-heart surgery had to be performed, which ended up being the case.

Daniel Ketchell, the actor's spokesman, said that the valve was successfully replaced during the open-heart surgery.

Schwarzenegger presents Byoung Chan of Korea with the winners trophy for the Arnold Amateur Bodybuilding event, during the Arnold Sports Festival Australia at The Melbourne Convention and Exhibition Centre on March 18

Young and buff: Schwarzenegger poses during the 38th Cannes film festival (left), where he presented the documentary Pumping Iron. Pictured right: Schwarzenegger poses for a portrait on Venice Beach in August 1977

He'll be back: Schwarzenegger became a household name after he appeared in James Cameron's futuristic blockbuster The Terminator in 1984

Schwarzenegger's latest sighting was in Beverly Hills on Wednesday, when he was spotted puffing on a cigar in a friend's car while leaving the Waldorf Astoria Hotel after having lunch with his son Patrick in Beverly Hills.

The outspoken actor and politician appeared on CNN last weekend to talk about the future of the Republican Party in the age of Donald Trump, saying that the GOP is 'dying at the box office.'

The previous Sunday, the Austrian-born Predator star made an appearance at an amateur bodybuilding competition as part of the 2018 The Arnold Sports Festival in Melbourne, Australia.

A day before Schwarzenegger's procedure, his ex-wife Mariah Shriver took to Instagram to promote the documentary The Heart of Nuba, which focuses on the work of Dr Tom Catena, a Catholic missionary

Father-son quality time: Schwarzenegger is often photographed with his actor son Patrick. In January, the pair donned lederhosen during a visit to Austria (left). In an Instagram post on July 30, 2017, Patrick wished his famous dad happy 70th birthday (right)

Twinning: Arnold and Patrick Schwarzenegger are pictured during the GQ Men of the year Award 2017 at Komische Oper on November 9, 2017 in Berlin

Schwarzenegger appeared buff and well-tanned, and happily posed with fans for pictures.

In a recent interview he gave in Australia, Schwarzenegger said his age is just a number to him.

'I don't even think that I'm 70, I know I'm 70, but so what?' he told The Project. 'It's only on my passport or my driver's licence, but I feel the same way as I did 20 years ago.'

'I feel good about myself. I work out. I make my movies. Life is great. I feel useful and productive,' he added.

According to Schwarzenegger's IMDB page, the Hollywood heavyweight has a half-dozen film and TV projects in the works, including the action flick Viy 2: Journey to China co-starring Jackie Chan and an untitled Terminator reboot.

The divorced Conan the Barbarian alum has five children, including his son Patrick, who has followed his father's footsteps into acting and is currently starring in the new drama Midnight Sun opposite Bella Thorne.