The parents of baby Carter Cookson have said they may only have three days to find him a heart.
Speaking to ITV News Tyne Tees, Carter's mum Sarah, said "the machine that's keeping him alive" has "run it's course".
Carter was born on Boxing Day, but suffered three cardiac arrests hours after his birth.
Since then he has been assisted by a special machine called an "Ecmo", which enables his heart to pump blood around his body.
The Ecmo machine carries with it a high chance of infection or blood clots forming within the circuit, so on a day-to-day basis consultants have to make sure no clots are found in the circuit and the circuit is free of infection.
Carter's parents said due to complications with Carter's connection to the machine, surgeons may be unable to change the Ecmo again if anymore clots form in the circuit, meaning they have a race against time to find a heart.
He’s at quite a good place to actually be ready for a transplanted heart so it’s not like he’s given up, it’s just the fact that the machine has run its course and you can only change it so many times, because the canulars are at risk of just him bleeding to death, so we’re kind of stuck in the situation where he, we hope, would survive a transplant, but unfortunately it’s the machine that’s keeping him alive that is going to stop him from getting it, if we don’t get a heart.
Carter's parents earlier renewed their appeal, through the Facebook campaign page 'Find a Heart for Carter', for a new heart to be donated so it can be used in a life saving transplant.
The post said:
Experts from NHS Blood and Transplant told ITV News finding a heart donor for babies is extremely difficult.
The size needs to size match with the recipient and not many children do die in the UK in a way that they can donate their organs, but when they do we encourage the families to think about donation and if they make that decision, support them through that donation process.
It was announced earlier this month that proposals for a change in the law on organ donation in England, which will presume consent unless people opt out, is set to be named after a little girl from Devon and a boy who received one of her organs.
Nine-year-old Keira Ball died on 30 July 2017, after suffering head and neck injuries in the crash on the A361 near West Buckland, Devon.
Her organs were donated and she saved the lives of four other children.
Her mum, Loanna Ball, told ITV News the decision to donate was "a beautiful thing" and helped her through the grieving process.
We found there is comfort to be had in donating organs in your darkest of times, when things can’t get any worse, there has been a slight silver lining for us that she has gone on and saved other people.