You may have found the fat oozing from a smoker's clogged artery in the current British Heart Foundation advertisement difficult viewing. You may have felt disturbed by Günther von Hagen's televised autopsy when it was shown on Channel 4.

But for publicly edifying real-life gore fests, the live relay at the Science Museum's Dana Centre in London last night of a two-and-a-half hour heart bypass operation takes some beating.

The operation, on a 51-year-old American man who had volunteered to be filmed, took place at Morristown Memorial hospital in New Jersey and was beamed live to a 100-strong audience in London. Broadcasts of this kind have been going on in the US for six years, but this was the first time British people have been able to see an operation live.

From the first incision to the last suture this was a dizzying extravaganza with a variety of camera angles, a coloured ultrasound and an endoscope in the man's arms and a commentary from experts in London and the operating theatre.

It was not for the squeamish. "We're going to saw through the breastbone," said Tim McElroy, director of educational technologies at the Liberty Science centre in the US who acted as facilitator and question master in London.

And, a few thousand miles away they did, prompting groans from some of us. There were more groans, too, when Dr McElroy pointed to the "harvesting" of an artery from the man's arm to be used in the quintuple bypass.

This so-called cardiac classroom was a return to the days depicted in Rembrandt's The Anatomy Lesson of Dr Nicolaes Tulp, when the surgeon was part performance artist, keen to demonstrate technical prowess.

As Günther von Hagens sought to bring the workings of the human body and surgical operations from the theatre to a public audience to serve general enlightenment, this so-called cardiac classroom was aided at educating its audiences to adopt healthier lifestyles and to understand heart disease. "We also want to encourage high-school kids to see the exciting things we're doing and get into science," said John Brown, the chief surgeon, as he sutured something that looked pretty fundamental to my untrained eyes.

"Not that they'll all become doctors and nurses, but it would be great if some did."

More than 4,000 children have seen operations broadcast this way in the US.

"Think about how boring it is to read a pamphlet about heart disease. It just doesn't compare with watching this," said Dr McElroy.

Members of the London audience, which included surgeons, were able to question the operating team as they worked. And the questions varied in technical expertise.

One person asked if it was true that artery grafts used to be taken from women's arms so they didn't ruin the look of their legs during heart bypass operations (apparently there is no foundation for that view).

Another asked if the concentrate of potassium used to arrest the patient's heart was critical. There are both long and short answers to the latter question. The short one is yes.

"Now I've got a question for you," said Dr McElroy. "What colour did you expect the heart to be? Red right?" In fact it was mostly yellow, the colour of the fat that surrounds even the healthiest of hearts.

"There's no correlation between that fat and the fat in blood vessels."

If anything had really gone wrong during the operation Dr Brown was equipped with a foot pedal to end the broadcast and cut to video footage.

It was, insofar as a layperson can judge, a successful operation, but in one particularly worrying close-up Dr Brown seemed to have played up to a section of his British audience by having the words Manchester United written on his surgical gloves, which prompted the question: are we safe in these guys' hands?