Italy's controversial former Prime Minister Silvio Berlusconi underwent apparently successful open heart surgery on Tuesday, just over a week after a heart attack his doctor said could have killed him. In a four-hour operation at the San Raffaele hospital in Milan, the 79-year-old tycoon and owner of AC Milan had a faulty aortic valve replaced. "Everything went as expected," Berlusconi's personal doctor, Alberto Zangrillo, told reporters after the surgery while the hospital said there had been no complications in theater. "Everything is okay guys, now I can speak more calmly," said Gianni Letta, a close political ally of the billionaire leader of the center-right political movement Forza Italia. Berlusconi's brother Paolo added: "We were calm before and we are even calmer now. "There is incredible skill involved in open heart surgery but the operation went well, the surgeons did their job in the most professional way possible. "I am confident my brother will overcome this challenge and will soon be back amongst us, with even more strength and determination than before." The flamboyant media mogul and football club owner, who dominated Italian politics for two decades, is expected to spend several days in intensive care and several weeks in hospital in total. Berlusconi's 30-year-old companion, Francesca Pascale, was seen at the window of his hospital room shortly after the operation began, looking tearful and clutching a handkerchief. Italian media reports said some of the twice-divorced Berlusconi's five children were also at San Raffaele hospital. The operation was performed by Ottavio Alfieri, the head of the hospital's cardiac surgery unit. The aging billionaire, notorious for his brushes with the law and his "bunga bunga" sex parties, was admitted for tests at the hospital on June 7 having suffered a minor heart attack a few days earlier. "He arrived at the hospital in a severe state, he risked his life, he risked dying and he knew it," Berlusconi's doctor Zangrillo told a news conference last Thursday. Zangrillo said the fault in the heart valve was "severe" and that without the operation, "the risk of him dying within the year would be 10 percent." But he said he expected Berlusconi to be back to full health within a month, adding that successful surgery would leave him "better than before." The one-time cruise ship singer turned center-right politician suffered a heart attack 10 years ago and had a pacemaker fitted in the United States. The device was replaced at the end of last year. "Naturally, I am concerned," Berlusconi, who has largely dropped off the political radar in Italy, wrote on his Facebook page on Monday. "But I am also very moved by the very many demonstrations of appreciation, support and affection which I have received from everywhere, even from political rivals." Italy's center-left Prime Minister Matteo Renzi wished his rival "good luck." Matteo Salvini, the head of the far-right Northern League — a sometime ally but also rival on the rightwing of Italian politics — sent Berlusconi "best wishes for his quick return to the field."