A girl from Wales is believed to be the first patient in the United Kingdom – and possibly the world – to have her heart transplant reversed, doctors said Thursday.

Doctors at London's Great Ormond Street Hospital removed Hannah Clark's donated heart after her body rejected it. They then restarted her own heart, which had never been removed.

Hannah Clark got a heart transplant at age 2, but her own heart was left in her chest and continued to beat. (Barry Batchelor/AP)
Hannah Clark got a heart transplant at age 2, but her own heart was left in her chest and continued to beat. (Barry Batchelor/AP)

The 12-year-old, who comes from south Wales, had a heterotopic transplant operation 10 years earlier.

The procedure is called a "piggyback" because the donor organ is placed next to the patient's original heart.

At two years old, Hannah had cardiomyopathy, a condition that causes the heart to become inflamed and to function poorly. Her heart doubled in size and Hannah was at risk for heart failure.

She was given a new heart and it took over pumping blood while her own heart rested while still continuing to beat.

Her new heart worked fine until November 2005 when doctors found that her body was rejecting it.

They decided to remove the heart and, during the operation on Feb. 20, they found that her own heart was working quite well.

After removing the donor heart, they reconnected her original heart and it took over pumping blood.

'This is a very happy ending'

Dr. Magdi Yacoub, the surgeon who performed Hannah's original heart transplant, advised surgeons who removed the donor heart.

"Her [original] heart recovered almost completely," he told BBC Radio. "It is now a normal heart. This is a very happy ending."

Prof. Peter Weissburg, medical director of the British Heart Foundation, said the transplant reversal was an important event in the understanding of how heart diseases progress.

He said the modern treatment for Hannah's condition would be to install a ventricular assist device, a temporary mechanical aid that would be removed after a few months.

Such devices were not considered reliable enough 10 years ago, which is why Hannah received a new heart.