A 16-year-old girl from Wales who made history when she had a donor heart grafted onto her own as a baby has made a full recover, BBC reported.
Doctors say Hannah Clark's own heart is now in perfect working order three-and-a-half years after her "piggy-back" donor heart was removed.
Sir Magdi Yacoub, the pioneering surgeon who performed Hannah's original transplant when she was two, said he was "surprised and delighted".
The Lancet journal tells her story.
The original operation in 1995 saved Hannah's life because she had cardiomyopathy - a condition which made her heart double in size and risk giving out within a year.
The donor heart was able to take over most of the role of pumping blood around Hannah's body, effectively allowing her own beating heart to rest.
But 10 years later, at the age of 12, Hannah, from Mountain Ash, in Rhondda Cynon Taf, was experiencing serious health problems as a side effect of the immunosuppressant drugs she was taking to prevent rejection of the donor organ.
Hannah had developed tumours that had begun to spread and needed chemotherapy treatment.
For this to work, the doctors had to reduce Hannah's immunosuppressants. But this led to her body rejecting the donor heart.
Doctors at London's Great Ormond Street Hospital decided the only option was to disconnect the donor organ.
They found Hannah's own heart had recovered enough to cope on its own and without daily medication.
Three years on, Hannah has made a complete recovery, say her surgeons Sir Magdi and Mr Victor Tsang.
Sir Magdi described the recovery of Hannah's heart as "magic".
"We did not expect her heart to recover but when it did begin to recover we were absolutely delighted.
"A heart that was not contracting at all now is functioning normally.
"It shows the possibility of recovery of the heart."
Hannah said she felt lucky to be alive. "I would not have been here today if it wasn't for the donor and the surgeons who did my operation. I'm really grateful.
"I don't have to take any medicines now except an inhaler for my asthma. And I am really excited about starting a job working with animals. I couldn't do that before because the fur could have affected my chest."
Professor Peter Weissberg, of the British Heart Foundation, said cardiologists have long wondered whether a heart which is failing because of cardiomyopathy might be able to recover if rested.
"This seems to be exactly what has happened in Hannah's case in which the donor heart allowed her own heart to take a rest and recover.
"This is an exciting discovery since it proves that, in some instances, a weakened heart has the capacity to recover - if it can be helped."
He said experts were working to perfect a mechanical heart, called a ventricular assist device, that can be used in children temporarily to take over the work of a weak heart while it recovers.
A similar device already exists for adults with heart failure awaiting a donor transplant.