The hospitals that perform child heart surgery are due to learn which will have to stop performing operations.
There are currently 10 units in England, but an official consultation has proposed up to four should cease doing surgery.
The NHS review was carried out amid fears expertise was spread too thinly.
It has already concluded surgery should be concentrated on fewer sites and will announce on Wednesday which will be allowed to continue.
Centres in Leicester, Leeds, Newcastle, Southampton and London are under threat.
Those that are told to stop surgery will still stay open as they will be allowed to continue seeing patients for diagnosis, monitoring and non-surgical treatment.
Safe service
In total, there are four options on the table - each of which involves the ending of surgery at three or four sites.
About 3,600 operations are carried out each year on children born with a range of heart defects.
Most survive to adulthood, but there is widespread agreement among professional bodies that to provide a uniformly high quality and safe service operations must be concentrated in fewer, larger centres to enable surgeons to improve skills and share expertise.
Surgery at one unit - Oxford's John Radcliffe - was stopped as recently as 2010 after a spate of deaths.
But concerns about child heart surgery go back much further with questions being raised ever since the Bristol scandal in the 1990s when children having heart surgery died needlessly.
