The Pope had a pacemaker fitted less than three months before the announcement of his resignation, in an operation that had remained a secret until Tuesday.
SPECULATIONS about Pope Benedict XVI's declining health and the bitter power struggles in the Vatican gripped the world following the shock news of the pontiff's resignation.
It emerged that the 85-year-old Benedict--who abdicated on health grounds--visited a Rome hospital just three months ago to have a new pacemaker fitted.
Father Federico Lombardi, the Vatican's chief spokesman, confirmed the report, saying: "It is correct that (the pace-maker) was substituted but it is not relevant to the Holy Father's decision to stand down."
Fr. Lombardi told journalists "no specific illnesses" were behind Pope Benedict's decision, in an attempt to squash speculation that he was suffering from a terminal illness.
Italy's leading daily broad-sheet, Corriere della Sera, suggested instead that the abdication was motivated by the "Vatileaks" scandal, which saw confidential papers stolen by Benedict's butler, Paolo Gabriele, and disclosed to the press last year. Gabriele, who was jailed and then pardoned by the Pope in December, claimed he was trying to expose corruption at the Holy See and unmask individuals who were attempting to manipulate the pontiff.
It was the first time that Benedict's need for the device had been revealed by the Vatican.
But officials insisted that the Pope's heart condition had nothing to do with his decision to step down after eight years in office, just as they have maintained that the dramatic step was not motivated by the scandal and intrigue that buffeted Benedict's eight-year papacy.
The pacemaker was a re-placement for one which had been fitted about 10 years ago, before he was elected John Paul II's successor in 2005.
The fitting of the new pace-maker was carried out by heart surgeons at the Pius XI medical clinic in Rome.
The operation went so well that the Pope made a speedy recovery and did not even miss his weekly Angelus address, which is held each Sunday.
Benedict commissioned three of his most loyal cardinals to write a report into the affair, which some are now claiming was the tipping point in his decision to step aside. Experts have suggested that the report--which was immediately shelved by the Pope--may have revealed a major conspiracy to discredit his papacy and also smear his unpopular de facto Prime Minister, Tarcisio Bertone.
Benedict's tenure was a turbulent one, even by Vatican standards. Relatively liberal comments by the new Minister for the Family, Archbishop Vincenzo Paglia, which were reported just last week, underlined the battle between ultra-conservative figures such as Benedict and more progressive elements in the Church.
Archbishop Paglia appeared to back calls for civil partner-ships for gays and called for an end to discrimination at the most recent International Meeting on the Family in Milan.
Fr. Lombardi claimed the archbishop's comments were entirely consistent with the Church's position on the issue, despite Benedict's notoriously conservative declarations on the subject.
Another veteran of the Holy See, John Thavis, author of the forthcoming book, Vatican Diaries, told The Independent he thought Benedict was happy to go "because he has achieved every major thing he's set out to do. He is feeling frailer. You could see it at Christmas, he was obviously weaker. And he thinks he had achieved his main objectives: the series of three books on the life of Jesus of Nazareth and the launch of the New Evangelisation campaign."
Mr. Thavis said, however, that the resignation might have lasting repercussions. "This Pope has resigned at 85. The next one might resign at 75. Maybe the Church will feel compelled to elect younger popes from now on."
Benedict will continue his ordinary duties until February 28. At 8.00 p.m. that day he will cease to be Pope. He will remove his pontifical ring, which will be destroyed. The Catholic world will have to wait for a new pontiff to be elected by papal conclave of cardinals, which is expected to meet within about two weeks of his resignation.
Fr. Lombardi said the exact date of the conclave was still being decided, because the rarity of a papal resignation meant Vatican experts were still interpreting canonical law in order to decide when to hold it.