An independent review panel is visiting the Children's Heart Unit at the Freeman Hospital in Newcastle later.
They are investigating a decision, made earlier this year, to close some hospitals and create centres of excellence.
It is part of a move to improve the service and concentrate expert surgeons in bigger units.
The panel was ordered to carry out the review by the Department of Health.
More top news
Kerrie Gosney brings you Sunday night's forecast
Rain moving through on Sunday evening, but Monday looks like one of the better days of the week ahead
The stakes are high for the Labour leader, writes Chris Ship - will another general election be on the cards in the coming months?