Chris Cairns' wife Melanie has spoken out over her husband's condition as the New Zealand cricket great recuperates in an Australian hospital following heart surgery.

It's understood Cairns, 51, collapsed, having suffered a massive heart attack last week in Canberra - resulting in an aortic dissection, a tear in the inner layer of the body's main artery.

Melanie Cairns confirmed on Wednesday that her husband has been transferred to a Sydney hospital to undergo further surgery.

"As has now been widely reported in the media, Chris suffered a major medical event in Canberra late last week. He initially underwent surgery in Canberra, but the seriousness of his condition is such that he has now been transferred to St Vincent's hospital in Sydney, where he has undergone further cardiovascular surgery," Melanie Cairns said in a statement.

"Chris' family and friends are heartened by the respectful and warm manner in which this terrible news has been reported, and received by the public, both in New Zealand and around the world, and thanks everyone for their warm wishes, prayers, and kind words.

"For now, no further statements will be made regarding Chris' situation, and the Cairns family asks that people continue to respect their privacy as they deal with this difficult, upsetting and concerning situation."

New Zealand Cricket CEO David White said in a statement: "We're deeply concerned to hear of Chris Cairns' medical emergency. Our thoughts are with his family in Australia and here in New Zealand. Chris is a much loved husband, father, and son - and remains one of our finest all-rounders. We hope he's able to make a full recovery."

Cairns, the son of Black Cap legend Lance Cairns, was a right-hand batsman and fast-medium bowler. He was known as one of the finest all-rounders of his generation.

Cairns has been living and working in Canberra with his wife and their children for several years.

Chris Cairns and his wife Melanie in 2014. (Photo / Getty)

He has been the chief executive of SmartSportz, a company specialising in virtual sport.

Cairns had to rebuild his life after walking out of Southwark Crown Court in London in 2015 after being found not guilty of perjury and perverting the course of justice charges in relation to match-fixing allegations.

The allegations took a huge toll on the cricketer's life.

He described his reputation as "completely scorched" from the saga and spoke of going through "hell" during the perjury trial.

He was first named as one of 11 "tainted" cricketers in the now defunct Indian Cricket League in a 2009 email between International Cricket Council investigators.

Cairns took part in the ICL, which ran for two seasons in India from 2007 to 2009.

But in 2010, Indian millionaire businessman Lalit Modi, a former boss of the Indian Premier League, posted a tweet saying Cairns had been removed from the player auction for the IPL due to a "past record of match fixing".

Cairns quickly launched a defamation case against Modi in London.

Two years later in 2012, Cairns won the libel trial and was awarded damages from Modi.

Yet his troubles weren't over as he faced allegations from fellow New Zealand cricketers Lou Vincent and Brendon McCullum that he had tried to recruit them to fix matches.

It was not until Cairns was found not guilty of perjury in relation to match fixing allegations in 2015 in a London court that he was able to finally clear his name.

Brendon McCullum leads tributes of support

Chris Cairns and Brendon McCullum. (Photo / Photosport)

Former Black Caps captain Brendon McCullum was among the many to send messages of support to Cairns and his family.

McCullum testified against his former teammate in the 2015 perjury trial at Southwark Crown Court in London, during which Cairns was found not guilty of charges relating to alleged match-fixing.

"It's a difficult subject to obviously talk about. We haven't seen each other for quite a long time," McCullum said on his SENZ Breakfast show.

"We've been reflecting on just how fine a cricketer he was when the news came through and what he did for the game and New Zealand cricket throughout his career as well. Our relationship is unimportant in the whole thing, the fact is that Chris is a father and also a son to Lance and Sue. They've already had such tragedy in their life with the loss of Chris' sister a long time ago as well.

"It's a really difficult time for those people and I know the cricket community and all those who support the Cairns family will be suffering right now. Today my family and myself are thinking of those people who are suffering."

Former Black Caps teammate Andre Adams said on social media his "thoughts and prayers are with Chris and his family".

"Horrid situation and hoping for the best," he wrote on Twitter.

Fans were quick to share their support for Cairns, with many wishing him a speedy recovery and reminiscing about his memorable moments for New Zealand.

"Oh no. This is awful. Chris Cairns is responsible for one of my most treasured cricket memories: NZ v RSA at the Gabba for my 15th birthday.

"We were on the brink of defeat and he blasted an unbeaten century. And I admire the work he did for rail safety after his sister died," one wrote.

Australian journalist Brendan Bradford added: "Ah man this is awful. Chris Cairns was an absolute icon when I was growing up. A genuine superstar. Hope he pulls through this."

NRL journalist Brad Walter wrote: "Terrible news. I used to love watching Chris Cairns bat and bowl. He was the Kiwi version of Gary Gilmour."