Doctors then lowered his body temperature by more than 3C and he was sedated and fitted with a pacemaker to slow his heart rate down.
He is now recovering well at home in Easington Colliery, County Durham.
The procedure was carried out by surgeons at Newcastle's Freeman Hospital who kept him in a special blanket filled with chilled air for four days.
Finley's parents Donna Link-Emery and Aaron Burton first became concerned when he failed to put on enough weight at 10 weeks' old.
'Lovely rate'
Checks at the University Hospital of North Durham revealed he had a congenital heart condition which was causing his lungs to work too hard, making him breathless and too tired to eat properly.
He underwent surgery two days later.
Ms Link-Emery, 27, said: "We were told he may have to be in hospital for six weeks so we were stunned when they said he could leave so quickly.
"Now he's doing really well and has already put on lots of weight."
Paddy Walsh, a specialist children's cardiac nurse, said: "When we close off the hole babies start breathing at a lovely rate and they manage to feed beautifully."
