As part of a series of articles BBC News Online reporter Jane Elliott looks behind the scenes of the NHS.
Jonathan was not fit enough for transplant
This week we focus on the story of a transplant patient who was given a new lease of life when his donor heart failed.
When Jonathan Cropper's donor heart started to fail at the age of 32 he feared the worst.
Tests revealed that his kidneys had been badly damaged and his body was not strong enough for another transplant.
So when doctors suggested he could be suitable for an artificial heart, to give his organs time to recover enough to face another transplant, the father-of-two was keen to give it a try.
Jonathan had originally needed a transplant after developing a condition called familial dilated cardiomyopathy, which had resulted in his heart becoming enlarged and weakened.
His father and a cousin have also had heart transplants and an aunt died while on the waiting list for her new heart.
But as Jonathan's condition developed there was no indication that he was at risk until he collapsed at the age of 21. Doctors then delivered the devastating news that he needed a transplant.
"It was just after Christmas and I noticed I was struggling walking to the pub. One morning I was running around to get to work and I collapsed. The hospital diagnosed me with cardiomyopathy.
"They later found out it was a hereditary genetic fault, but they have screened my two kids and say that they think that they are both OK."
For nearly ten years Jonathan's new heart worked well, but then in May this year he started to notice problems and became the first Harefield Hospital patient to be fitted with the Jarvik artificial heart.
"I knew it was not right, but I didn't want to admit that I was having problems, because I knew what was coming up and I knew what was going to happen and I kept thinking what are they going to be able to do.
"They said that my kidneys were not in good enough shape to have another transplant so this is going to help them repair."
Doctors fitted Jonathan, from Bedfordshire, with his artificial heart and he hopes to soon be able to be fit enough to go back to work.
"It really has improved my life even though it has been fitted for the shortest time.
"They don't know how long the device can be used for because it is so new, but they think it could give me a breathing space of about three to five years to help my body recover enough to have a transplant.
Dr Christopher Bowles, co-ordinator of the artificial heart programme said the artificial hearts were producing some exciting results.
"In the past we have mainly used artificial hearts to sustain the lives of patients until they received a heart transplant although ultimately they should become suitable for permanent use.
"This is the first time in the world that this device has been used to support the circulation of a patient whose transplanted heart has started to fail.
"We are very satisfied with Jonathan's progress.
"For our early experience, we noticed that the heart function of some patients improved spontaneously during artificial heart support."
Dr Bowles said they had carried out clinical trials at the hospital using novel combinations of drugs to help increase the performance of the heart muscle with the aim of allowing the removal of the artificial heart.
"The drug therapy really seems to help the heart become stronger. Our results in the "Bridge to Recovery" trial are better than at any other hospital. We really think we have something exciting here."