“I want to reassure fans that everything is okay, I feel fine,” said the 62-year-old Scot, whose side face Manchester City at Eastlands on Sunday.

“It was an option for me to get this done. The club knew about it and I feel great, so it’s business as usual.”

Fears about Ferguson’s health were first raised in December when it was revealed that he had been forced to enter hospital to have a heart irregularity corrected.

At the time, as now, he insisted it would not have any effect on his job.

“I enjoy the work I do and it will continue,” he said.

Ferguson informed chief executive David Gill of his plans before having the operation, which lasted for 90 minutes.

Although the procedure is now seen as routine, the news is bound to concern some United fans, who have seen their illustrious manager pitched into one of the most stressful periods of his 18 years at the Old Trafford outfit.

Aside from the poor on-pitch performances since the turn of the year, culminating in Tuesday’s stunning Champions League exit to Porto, Ferguson has also had to cope with huge intrusion into his private life.

He revealed last month his torment at finding son Jason was having his mail stolen, a situation Ferguson believed had been brought about because of his legal dispute with United’s major shareholder John Magnier.

That battle is now over but Ferguson was equally outraged by questions being raised over his involvement in a series of transfer deals that were highlighted amid the 99 corporate governance questions posed of the United board by Magnier and his business partner JP McManus.

If that was not enough, he has also been heavily involved in Rio Ferdinand’s battle against an eight-month suspension for a failed drugs test and had a huge row with the Football Association in the aftermath of the ‘Battle of Old Trafford’ with Arsenal.

Even for a man used to a punishing workload that would exhaust most men within a week, the extra pressure is bound to have an effect and Ferguson is more aware than most about the health pressures soccer management can bring.

He is still haunted by the memory of Jock Stein collapsing of a heart attack alongside him in the Scotland dug-out during a World Cup tie in Cardiff in 1985.

He went some way to removing part of his professional burden by bringing old friend Walter Smith in as his assistant until the end of the season after spending the first six months of the campaign without a recognised number two, although, until his team start producing consistent winning performances the pressure of his high-intensity position will continue to be an onerous one.