Presenter Chris Tarrant was rushed from Heathrow Airport to Charing Cross Hospital in London after suffering what doctors are calling a “mini-stroke”.
The Who Wants to Be a Millionaire host was taken ill during an 11-hour flight from Thailand a week last Saturday, after filming a fishing show in Burma.
Medical staff initially though Tarrant was in the midst of a severe asthma attack but further investigation revealed a blood clot in his leg and he underwent emergency surgery to break it up before it could cause a full-scale stroke.
"The doctor describes it as a mini stroke, probably brought on by the asthma and bronchitis on the plane,” said Tarrant’s manager Paul Vaughan.
"They found a clot which they managed to break up. It was a clot in the leg and that can immediately go to the brain or lungs.
"He is determined to leave hospital. But he’s not going back to work," Vaughan told The Sun, adding "This is a nasty wake-up call."
Tarrant, 67, is reportedly under the supervision of the same specialist who treated BBC political commentator Andrew Marr, and since his surgery has begun to leave the hospital during the day, returning each evening.
Tarrant hosted the last edition of Who Wants to Be a Millionaire in February, more than 15 years after it debuted on ITV.