Without a new heart my son will die.

That’s the warning from Houghton mum, Kate Lewis, whose four-year-old son James has a rare, incurable heart condition – he desperately needs a transplant and has been on the waiting list for a year.

Last July James was diagnosed with restrictive cardiomyopathy – a condition which affects one in a million children in which the muscles in the wall of the heart are rigid and stop it from filling up with blood normally.

Doctors at Southampton General Hospital told Kate and her husband, David, that James’s heart could fail at any time.

They have also told them that James is unlikely to live past his sixth birthday if he does not get a new heart soon.

His parents are backing the Live Life Then Give Life campaign highlighting the chronic shortage of transplant organs for children in the UK.

His mum said: “Sometimes I go and check on James in bed and put my hand or my head on his chest to check his heart is still beating. It always feels very slow. I worry one day I will go in and it won’t beat.

“It feels like we are living on borrowed time and we really don’t know how long we will have with James.”

Besides James the couple have a 10 year-old daughter, Amelia and another son, Charles, aged eight.

Kate, 44, added: “We were told our only hope was a heart transplant. We felt like the bottom dropped out of our world. It was unbelievable news.

“They say the average wait for a heart is 12 months but I expect that could be longer. I’ve been told there are more children than ever waiting. It does feel like we have to make the most of our time we have with him and we’ve learnt to live with that, but it’s taken a long time to accept it.”

James is now on daily medication and experts at Southampton General and Great Ormond Street Hospitals are monitoring his condition closely.

He can go on a blood pumping machine known as a Berlin Heart which would help keep him alive for a year while waiting for a transplant but there is also long waiting list for this equipment. “If people signed up to the organ donor register it would be amazing. Children are dying needlessly all the time and there are not enough organs to go around,” said Kate.

“But what I can do is be with him every step of the way and at least by raising awareness of the child organ donor shortage I feel I can do something positive in such a trying time,” concluded Kate who is also raising cash for the Love Hearts appeal.

Romsey MP, Caroline Nokes who has met the family said: “Clearly the last 12 months have been very difficult for them as a family, but you cannot help but be impressed at the way they have thrown their energies into Live Life Then Give Life and promoting the need for more child donors. This is a matter of life and death to James and children like him. I sincerely hope that a donor heart for James is found in time so that this little boy can overcome this terrible condition."