The 51-year old Uddhav, who will celebrate his birthday July 27, was rushed and admitted for a day to the Lilavati Hospital last Monday after he complained of chest pain.
Though details of his proposed operation are not officially available, it is learnt that an angiography and other tests conducted on Uddhav revealed at least three blockages in his cardiac blood vessels.
Maharashtra Navnirman Sena chief and cousin Raj Thackeray Thursday went to the Thackeray residence Matoshri in Bandra East to enquire after Uddhav's health and his surgery, the party official said. He is likely to remain present at the hospital during the surgery.
Uddhav had been suffering from chest pains since last Friday but it is not known whether he had been on medication prior to his daylong sojourn in the hospital last Monday.
His health condition had apparently been kept under wraps since even top party leaders were taken completely unawares when he was hospitalised.
He has been under the care of a team of cardiologists Samuel Mathew, Jalil Parkar, Ajit Menon, Omprakash Jaiswal, Prakash Jindani and Samad Ansari.
Uddhav's health condition has been a matter of concern within the Shiv Sena, its allies Bharatiya Janata Party, Republican Party of India and the state political circles.