Twelve-year-old Hannah Clark is believed to have become the first British patient to have her heart transplant reversed.
Hannah's heart was affected by a muscle disease
What was wrong with Hannah?
She had a condition known as cardiomyopathy.
This is a serious disease of the heart muscle, which causes the organ to expand in size to try to compensate for the fact that its ability to pump blood is compromised.
In Hannah's case, her heart had already doubled in size by the age of just two, and there were real fears it would soon give out completely.
What was her initial treatment?
Ten years ago, doctors at Harefield Hospital, Middlesex, decided to give Hannah a new heart.
The operation they carried out was a "piggy-back", or heterotopic, transplant.
The new organ was inserted into the right side of the chest and attached to Hannah's original heart, which remained in position.
The donor organ took over the job of pumping most of her blood around the body.
The original heart still pumped some of Hannah's blood, but, with most of the pressure relieved by the new organ, was effectively able to rest.
The donor heart was connected in such a way that blood returning from the lungs was able to enter the left-side filling chamber - or left atrium - of either of the two hearts.
But because the donor heart was the more healthy, it took on the lion's share of the work.
The two major blood vessels leaving each heart - the aortas - were merged, to ensure that a unified blood supply to the rest of the body.
However, the circulation of the original heart was not fundamentally changed.
Why did Hannah need follow-up treatment?
She had developed complications related to her immune system.
Hannah's donor heart worked fine until last November, when a routine check-up showed her body was beginning to reject it.
What did the new surgery involve?
Surgeons at London's Great Ormond Street Hospital operated to disconnect the donor heart, leaving Hannah's own heart to take on the sole role of pumping blood around the body.
For ten years the organ had effectively been taking a rest, and the doctors figured that by now it was probably recovered enough to be able to take on a normal function again.
The surgery, believed to be the first of its kind for this purpose in the UK, went smoothly. Although it was scheduled to take eight hours, it was completed in just four.
How is Hannah progressing?
Very well. She made such a good recovery that she was able to come home within five days.
She no longer has to take powerful drugs to suppress her immune system, and hopes soon to go back to school.
Hannah has also been battling lymph cancer for the past few years but is currently in remission after a successful course of chemotherapy in January of this year.
The fact that she no longer requires immuno-suppressive drugs will also help her recovery from the lymph cancer.
Has medicine moved on since Hannah's first operation?
Yes. Experts said a modern approach to the problem would see the enlarged heart rested, while a mechanical heart, known as a ventricular assist device, took over its job temporarily.
Ten years ago such devices were not sufficiently reliable in children, which is why Hannah received a donor heart alongside her own.