More than 130 parents have attended a public meeting as part of a NHS review into the future of a heart surgery unit in Hampshire.
A national review could see some of the 11 centres that provide the specialist treatment stop performing surgery.
Sam Prior, from Locks Heath, whose eight-year-old son needs regular treatment at the unit in Southampton, was one of the people who attended.
The Southampton General Hospital unit carries out 400 procedures a year.
The outcome of the study by the NHS National Specialised Commissioning Group is expected to publish its recommendations early next year.
Ms Prior saidher son, who has a missing left ventricle muscle, had undergone 10 procedures which involved a general anaesthetic, including four heart operations.
"[Using the centre] is not a one-off event for us and they need to recognise this. The treatment will continue for the rest of his life."
"The centre at Southampton is everything it should be and more.
"It's the working model of what they are trying to achieve with the review."
Steve Collins, from the NHS Specialised Commissioning Team, said: "What we're looking at is the care that people with congenital heart problems need and have and where these operations should happen."