Alex Ferguson last night insisted neither his long-term commitment to rebuild Manchester United nor his short-term pursuit of Arsenal in the English Premiership would be affected by the heart complaint which has required him to be fitted with a pacemaker.

The Scot, who turned 62 last New Year's Eve, underwent surgery last week to have the device fitted to combat the effects of supraventricular tachycardia, a disturbance of his heart rhythm which first flared up last December and necessitated "electrozap" treatment - as was given to Tony Blair last October.

An irregular heartbeat is considered a minor cardiovascular complaint, with Ferguson back to take training the following day and bullish yesterday in his insistence that it was "business as usual" at Carrington as United prepared for tomorrow's Manchester derby at City.

Confirmation that United's manager of 18 years required the pacemaker, however, has added to the sense of uncertainty that has engulfed Old Trafford in recent weeks.

"The club knew I was having it done," said Ferguson, who underwent 90 minutes of surgery under a local anaesthetic last week to have the electrical gadget fitted. "I informed (the chief executive) David Gill a while ago. This was always an option for me. It follows on from the little blip I had at the end of last year and there are no long-term worries.

"The advice I got was I should get it done because it was a simple, easy procedure which made the problem controllable. It doesn't affect the job.

"I feel better with it, I must say. Much better. There are absolutely no long-term health implications and the board have no problem with it at all."

Ferguson appeared relaxed, even cheerful, yesterday despite the downturn in United's fortunes which has arguably left him enduring his most traumatic spell of recent years, with Tuesday's Champions League elimination to Porto coming hard on the heels of the feud with shareholder John Magnier.

That conflict has now been resolved, though the Scot complained of huge intrusions into his private life while the legal dispute rumbled on. Indeed, he stressed that he had only revealed details of his condition after learning that details of his medical records had been leaked.

"I thought I'd be open about it in view of one tabloid planning to run a story to sensationalise it," explained Ferguson, who signed a new one-year rolling contract in January to choke speculation about his potential retirement. "I wanted to give my version of why I've had it fitted."