A 12-year old girl has been given a groundbreaking operation, reversing a heart transplant done ten years ago, and restoring not only her original heart, but her quality of life. 12-year old Hannah Clark from Mountain Ash, South Wales, has suffered a significant portion of illness in her short life. In 1996, then aged only two, she was given a life-saving heart transplant by prominent heart surgeon Professor Sir Magdi Yacoub. Hannah suffered from a rare form of cardiomyopathy, where the heart was twice the size it should have been but severely weakened, making her perpetually ill. Without the initial transplant, she would have died. Hannah's original operation involved attaching the donor heart 'piggyback' onto the diseased heart. The donor heart then took most of the pumping work away from the diseased heart, which continued to be connected to Hannah, leaving her with two hearts beating inside her small body. Since that initial operation, Hannah has suffered a string of illnesses unrelated to the transplant, including pneumonia, kidney failure and lymph cancer, for which she was successfully treated with chemotherapy in January. All the while, Hannah had to take drugs to stop her body rejecting the donor heart. However, more bad news came in November, when a routine check-up found that Hannah had started to reject her donor heart. The resulting operation could easily provide fuel for a Hollywood film. The solution was to remove the donor heart and re-attach Hannah's original heart, reversing the initial transplant. The original surgeon, Professor Sir Magdi Yacoub, came out of retirement to advise a new team on the operation, which took place at the world famous Great Ormond Street children's hospital in London on 20 February. 'There was an outside possibility that her heart would recover,' said Professor Sir Yacoub in an interview with the BBC. Realistically, this was Hannah's only choice.' The operation was a journey into the unknown, and Hannah's mother, Elizabeth Clark, was warned that the operation would be long, and that Hannah could expect to spend weeks or months in intensive care. The advice was vague simply because the operation had not been done before, and the consequences were unknown. In the end, the operation took only four hours, and Hannah was allowed to go home within five days. 'It worked out. It's really wonderful,' said Professor Sir Yacoub. Elizabeth Clark says that Hannah was now looking forward to returning to school. 'We would not be sat here today if it wasn't for that donor,' she told the BBC. 'We really need people to know that they need more donors on the transplant list.' Ironically, after this groundbreaking operation, Hannah is in better health than ever, and no longer needs to take the anti-rejection drugs that were essential before the operation. Professor Peter Weissberg is Medical Director of the British Heart Foundation. 'This is an exciting and important event. Surgeons like British Heart Foundation Professor Sir 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. 'This seems to be exactly what has happened in this case,' he said. 'The piggy back heart allowed the patient's own heart to take a rest. Today the approach would be to implant a mechanical heart, called a ventricular assist device, to take over the work of the inflamed heart in the hope that the heart will recover and the device can be taken out after a few months. 'Ten years ago such devices were not sufficiently reliable, which is why Hannah received a donor heart along side her own. 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. In the past, patients with inflamed hearts either died or were transplanted before their own hearts had any chance of recovery,' he said.