The doctors are supposed to clear the blockage in his heart and put a stent there, Thomas told the website.
Sky News reported that Ragland received VIP treatment.
A spokeswoman for the prince declined to comment directly on the TMZ report or to say whether Markle's father would be at the wedding.
The bride's mum Doria Ragland will be staying with her daughter at Cliveden House Hotel the night before the wedding and is accompanying her daughter to the church on the morning of Saturday 19 May.
Big day looming Meghan and Harry
Who will walk Megan down the aisle then?
With the mother and daughter being so close, it's hardly surprising that Doria has a special role on the day, set to stay with Meghan in Windsor the night before the wedding and then ride in the auto to the church with her.
Markus Anderson is Ms Markle's closest male confidant and she has described him as a "loving, supportive, and endlessly fun friend". Jason Knauf, communications secretary to Prince Harry, said, "She has a very close knit group of friends and did not want to choose one over the other".
But on Monday, Thomas Markle told TMZ that he was no longer planning to attend the wedding, several days after he had suffered a heart attack and confirmed that he'd taken staged paparazzi photos of himself getting ready for the weekend.
The pictures - in which he was being measured for a suit and admiring a photo of the future royal couple on his computer - sold for $100,000 (83,000 euros), according to British tabloid the Daily Mirror.
Mother's shout scares bear into dropping her 5-year-old daughter
The bear will be euthanized if caught, and then sent to Fort Collins facility for necropsy. This is the paw of the bear that may have attacked a 5-year-old in Grand Junction.
Fellow passenger Christiane Jennings, who has taken the tour as part of a 40th-birthday celebration with her daughter, is full of praise for Markle.
Truthfully, we won't know for sure whether Thomas will attend the royal wedding or not until the actual royal wedding.
She said her father had "suffered at the hands of the media" who had presented him "in the most disgusting ways".
"Because the media were so unfairly portraying him in a negative light".
May 4: Kensington Palace announces Thomas will walk Meghan down the aisle.
Dr Mahathir to remain in power one to two years
He reiterated his full support for Mahathir's leadership and said their political feud has always been buried. He was Mahathir's deputy in the 1990s but fell out with his mentor during the Asian financial crisis.
But she won't be called "Princess Meghan" alone - as only those born into the Royal Family are bestowed the privilege of having Princess at the start of their name.
Asked whether she would be happy for Ms Markle to return to the school, Ms Diekmann said: "That would be great".
A cardboard cut-out display of Prince Harry and his fiance USA actress Meghan Markle sits outside a card shop ahead of the couple's wedding.
Sam Allardyce expected to part ways with Everton next week
Moshiri is now expected to reach a settlement on the final year of Allardyce's deal before moving quickly to appoint his successor.
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