A baby has become the first person in the world to receive a combined heart and thymus transplant — offering hope to millions of patients.

Easton Sinnamon was born with a weak heart and immune system and spent his first seven months in hospital.

He needed numerous heart operations as well as treatment for recurrent infections his body was unable to fight on its own.

His doctors, from Duke University in the US, requested approval for an experimental type of transplant that hadn’t been done in combination in humans before.

As well as a new heart, they believed he needed a transplant for his thymus — a gland in the chest which makes white blood cells called T cells.

When our immune system detects a foreign body it can send these white blood cells to respond to what is believed to be an infection.

Experts thought that by transplanting a heart and thymus tissue from the same donor, the thymus would be less likely to identify the new heart as a foreign body.

They received approval and, at just six months old, Easton received his heart transplant followed by the thymus tissue implant two weeks later.

Now, at the age of one, he is said to be ‘thriving’ following the procedure, which has the potential to change the future of organ transplants.

Most people who receive a transplant need to take lifelong immune-suppressing drugs to prevent their immune system from rejecting the new organ.

But taking these drugs over a long period can weaken their immune system and make them highly vulnerable to even mild infections.

Easton continues to be monitored and it is hoped in the future he will be taken off the anti-rejection drugs.

And doctors think thousands of patients could potentially benefit if it is found to be successful.

Dr Joseph Turek, Duke’s chief of paediatric cardiac surgery and a member of the surgical team that performed the landmark procedure, said: ‘This has the potential to change the face of solid organ transplantation in the future.

‘If this approach proves successful — and further validation is contemplated — it would mean transplant recipients would not reject the donated organ and they would also not need to undergo treatment with long-term immune-suppressing medications, which can be highly toxic, particularly to the kidneys.

‘This concept of tolerance has always been the holy grail in transplantation, and we are now on the doorstep.’ He added that in the future this type of transplant could potentially benefit ‘thousands and thousands’ of patients.

Kaitlyn Sinnamon, Easton’s mother, said: ‘It was one of those things where it could help him, and if it works, it not only helps him, but it could help thousands of other people as well with their children who need transplants.

‘When we talked about it, it was like “Why would we not do it when we can make a difference for all these other people?”