The 74-year-old was admitted to Gleneagles Global hospital in Chennai.
"Natarajan Maruthappa was admitted to the intensive care unit (ICU), Gleneagles Global (Hospital), on March 16 with severe chest infection," the hospital said in a statement today.
Mr Natarajan is on ventilator support and his condition is critical," the hospital's chief operating officer, Shanmuga Priyan, said.
In October last year, Mr Natarajan was admitted to the hospital, where he underwent a liver and kidney transplant.
He was discharged after having completely recovered from the operation with good liver and kidney graft function.
Mr Natarajan had worsening liver and kidney failure and lung congestion, ahead of the twin organ transplant.
Tracheostomy was performed on October 6, 2017, and he was on ventilator support for sometime, the hospital had said then.
(This story has not been edited by NDTV staff and is auto-generated from a syndicated feed.)
Get the latest election news, live updates and election schedule for Lok Sabha Elections 2019 on ndtv.com/elections. Like us on Facebook or follow us on Twitter and Instagram for updates from each of the 543 parliamentary seats for the 2019 Indian general elections.