Italian surgeons have began a four-hour heart operation on former prime minister Silvio Berlusconi to replace a defective aortic valve, a hospital statement said.
The surgery started at 8 a.m.
The 79-year-old centre-right leader and media mogul was admitted to hospital last week suffering from what his doctors called a cardiac deficiency.
In a post on Facebook, Berlusconi wrote yesterday: "Naturally I am worried, but I have been very much consoled by the outpour of affection and support that have come from many parts, including from so-called political enemies."