A British girl is thought to have become the first heart transplant patient in the UK and possibly the world to have had her donor organ removed and her own heart re-started, a London hospital said on Thursday.

Hannah Clark from south Wales had a heterotopic transplant operation - known as a “piggyback” because the donor heart is placed next to the original organ - 10 years ago.

However, complications arose after her body recently started reacting badly to the drugs she had to take to stop her body rejecting the new heart and surgeons took the decision to remove the donor organ.

“We discovered that actually her old heart was now working quite well,” said a spokesman from London’s Great Ormond Street Hospital for Children.

“So we removed the transplant heart, we were able to take her off the anti-rejection drugs and reconnected her old heart back up again and it worked. She’s doing very well.”

He added: “We would be surprised if anybody came up with another case. Maybe it’s a world first.”

Sir Magdi Yacoub, the Egyptian-born surgeon who performed Clark’s original transplant, advised surgeons during the February 20 operation. He said he was delighted that the girl’s heart had recovered so well.

“Her (original) heart recovered almost completely,” he told BBC Radio. “It is now a normal heart. This is a very happy ending.”

Medical experts said the operation was an important development in treating people suffering from cardiomyopathy, whereby the heart becomes inflamed and functions poorly.

“Surgeons like Magdi Yacoub have thought for some time that if a heart is failing because of acute inflammation, it might be able to recover if rested,” said Professor Peter Weissberg, Medical Director of the British Heart Foundation.

“This seems to be exactly what has happened in this case. The piggyback heart allowed the patient’s own heart to take a rest.”

He said the modern approach to Clark’s problem would be to install a temporary mechanical device, which could be removed after a few months, but that such a method had not been available 10 years ago.

“This is a great example of how a pioneering and novel approach to a medical problem can lead to surprising results that tell us a lot about how some heart diseases progress,” he said.