Boris Yeltsin, who ran Russia on half a heart, at last puts his fate in the hands of surgeons

Crucial decision in next few days as team gambles on whether to take president off respirator

Boris Yeltsin has entered a critical 48-hour period when surgeons will get a clearer idea of the success of the multiple heart bypass operation on which his presidency, and the future of Russia, depends.

Doctors will today decide whether they can take him off a respirator following the seven-hour operation, during which they stopped the President's heart for 68 minutes. Then comes another crucial moment - discovering if he can control his own breathing.

Five hours after the the operation the President, 65, recovered consciousness and opened his eyes, said Yevgeny Chazov, who for years treated Leonid Brezhnev. The announcement came after a day in which, for the first time, the world was given information about a complex operation on a Russian leader, and heard from surgeons who worked on the organ that has obsessed so many for so long.

Renat Akchurin, head of the 12-strong team, said the operation had gone well but a US surgeon who was present said it involved five bypasses, more than had been thought neccessary. Professor George Noon told Reuters: "The vessels that were diseased were bypassed and it ended up with the number five." He said that a couple of Yeltsin's arteries had sections which were completely blocked.

Mr Yeltsin still faces the very important stage of post-operative treatment. The first few days after a coronary bypass are critical, as they establish whether any damage to other organs has been inflicted during surgery. But Dr Akchurin said that, "touch wood", Mr Yeltsin may decide to sign a decree today or tomorrow taking back the powers he temporarily transferred to his Prime Minister, Viktor Chernomyrdin.

Michael DeBakey, the American cardiologist who led US and German advisers, said the operation was a "complete success" and predicted Mr Yeltsin would be able to perform his duties in a "perfectly normal fashion". He may be active long after his second term expires in 2000 - most studies show almost three-quarters of bypass patients are leading a normal life 10-15 years after the operation, said the surgeon.

For Mr Yeltsin's government and supporters in the West, the operation was not before time. It followed 15 months in which he had two and probably three, heart attacks. In his absence, his entourage jockeyed for power, while the country was buffeted by political and financial crises. Yesterday saw evidence of that when hundreds of thousands took to the streets for a day of strikes and rallies, largely over wage arrears.

But it will be some time before Mr Yeltsin can tackle these issues. Although Dr Akchurin said he may be able to begin work as soon as next week, he will be, at best, a part-time president until Christmas.

The first sign that the operation was pending came early yesterday, when the President's motorcade left the sanatorium where he was staying and headed for the Moscow Cardiological Centre.

It was exactly two months after he confirmed to television viewers what had long been suspected: he had heart disease and needed surgery. Doctors later diagnosed one blocked and three partially blocked arteries.

His surgeons said they decided to go ahead when he was in "optimum" condition - rid of early problems with an over-active thyroid, internal bleeding and anaemia. But its timing, on the day of the US election, was stage- managed, as was media coverage. The surgeons' conference was restricted to what aides called a "golden group" of 100 correspondents, a fraction of those in Moscow.

To the indignation of the President's staff, the world was denied news of the start of the operation for 30 minutes, because Russian agencies distrusted the initial announcement and wanted to check. But the operation's progress was then reported by Russian media throughout the day.

Mr Yeltsin's spokesman said he joked with doctors as he went into the operating theatre. But last night, as they awaited the outcome, their mood was more subdued. A number of critical questions remain. For instance, has the operation caused any brain damage? Such issues will be preying on the mind of Mr Yeltsin's wife, Naina: "Pray God that it will work out okay," she said after the operation.

She was, she said, "very worried, of course".