A senior children's heart surgeon is to leave his post in Belfast next month -- sparking fears the service will be "brought to its knees".
The parent of a toddler with serious heart problems has spoken of his concerns after it was confirmed Professor Fred Wood, one of the two main heart surgeons in Belfast, will leave his job in December.
The health trust has moved to reassure parents that despite his departure children who require cardiac surgery will have access to the care "they require".
However it remains unclear if Prof Wood, who has now taken up a post as the President of Royal College of Surgeons in Ireland, will be replaced.
The development comes amid major fears over the future of paediatric heart surgery in Belfast.
Gerald Clifford from Craigavon said urgent answers are needed about the future of the service which is facing major upheaval.
Mr Clifford (36), whose three- and-a-half-year old son Liam has undergone two surgeries in Belfast, fears the loss of Prof Wood could lead to "crisis point" for children's services in Northern Ireland.
Prof Wood, a retired surgeon with more than 30 years' experience working as a congenital heart surgeon, provided a locum service for the Belfast Trust.
The surgical service for congenital heart disease in Belfast is currently provided by two surgeons employed by the Belfast Trust -- one being Prof Woods -- with support where needed from two further surgeons based at Our Lady's Hospital for Sick Children in Dublin.
His retirement will mean only one surgeon will be employed.
Health Minister Edwin Poots has yet to give his decision on the future of the service following a consultation which ended over a year ago. Heart operations for children are still taking place in the Royal Victoria Hospital. But there are restrictions on the numbers receiving surgery, with complex diagnoses being transferred mainly to Birmingham Children's Hospital in England.
Mr Poots is yet to announce his decision on whether services will remain in Belfast, be shared with Dublin or move to England.
Mr Clifford said this adds more concern to the service being "slowly closed by stealth".
"There is a tipping point come the start of December when Prof Wood leaves to take up a different post.
"And the prophecy will have fulfilled itself by then and there really will be nothing for Mr Poots to rescue."
He added: "The stance Mr Poots is taking has earned him a lot of goodwill from parents regardless of the other issues he has managed to get himself in trouble over.
"But if that goes on he is now starting to lose that good faith.
"The service really has been brought to its knees.
"That is a crisis point for the service. That will only leave one surgeon."
Mr Clifford said accountability over the issue from health chiefs needed to be clarified.
"The restrictions that they have placed are crippling the service while there is no decision being made the service is being weakened and weakened."
A spokeswoman for the Belfast Trust said: "While Professor Woods will be retiring from December, we can reassure parents that any child who requires paediatric cardiac surgery will have access to the care they require and will receive treatment without any undue delay.
"The specific arrangements that will be in place following Professor Woods' retirement are being carefully considered by the Trust, in conjunction with the HSCB/PHA and the Department of Health, Social Services and Public Safety."
A departmental spokesman said: "The department is aware that Professor Woods intends to leave his post next month.
"The Department, Health and Social Care Board and the Belfast Trust are in discussion about securing arrangements to ensure that a safe and quality paediatric congenital cardiac surgical service continues to be available for the population of Northern Ireland.
"An announcement on the next steps will be made as soon as possible.
"The minister has made it clear that his prime concern is to provide a safe and quality service for these vulnerable children," said the spokesman.
Liam Clifford was born in March 2010. He has pulmonary artersia with a VSD which means his artery never developed so the heart can't naturally pump blood to the lungs. When he was six hours old he was rushed to Belfast and had his first surgery when he was just 10 days old. When he was 10 months old he had his second major surgery. The surgical device which acts as the artery will need replaced as he grows -- at least three more operations.