After undergoing a major heart surgery in Mumbai at Asian Heart Institute, Assam Chief Minister Tarun Gogoi is doing fine and will be in the intensive care unit for four to five days, according hospital sources.The 74-year-old Chief Minister yesterday underwent a bypass in addition to aortic valve replacement and enlargement of the aorta procedure.Dr Vijay D Silva, Medical Director said that Gogoi is expected to be in the hospital for 10-12 days and should be able to fully take over his duties in four weeks from now.He was taken off the ventilator (breathing machine) at 11 pm yesterday. He is communicating normally with his care givers.