As part of a series of articles BBC News Online reporter Jane Elliott looks behind the scenes of the NHS.
Carl has broken numerous records
This week we focus on the story of an athlete who first took up serious sport following a heart transplant.
Carl Whittaker has taken part in every British and World Transplant Games since 1985 and was the world 100 metres champion in 1995.
He competed in his first games just seven months after his transplant, when he shocked himself by running the 100 metres in just 13.3 seconds.
Now aged 43 Carl, who has a host of medals and trophies, is thinking of retiring from the world athletics stage but says he has thoroughly enjoyed the challenge.
"I am going to hang up my boots, I have won nearly everything I wanted to. I was the world champion.
"I have got records which nobody else has and if people know they are going to have to race me, they are worried."
But Carl explained he had stumbled into the world of athletics by accident.
Just months after his heart transplant a man approached him at a check-up and asked him to take part in the games.
"This man came up to me and said 'you look fit enough'. He asked me if I had heard about the transplant games and I said I didn't know anything about it. He said he was sure I could run, but at that time I could hardly walk."
Before his transplant Carl had been terminally sick. He'd started having problems in his late teens, but no-one knew what was wrong.
Then one day he suddenly he collapsed, while climbing the stairs
"My sister noticed that my heart was going very fast. They took me by ambulance to Northwick Park and they took me to accident and emergency.
"They asked me if I smoked or took drugs.
"They had me on one of the wards and I fell sick and fainted and then I woke up in intensive care and I was all attached to these tubes.
"I woke up and the priest was giving me the last rites."
Two years later doctors said Carl, who had cardiac myopathy, needed a transplant to stand any chance of surviving.
"They told me they had found a heart and my parents and I were crying we were overjoyed.
"If I had not had the transplant I would have been sent home to die."
Sherrie Panther, senior sister at Harefield Hospital, where Carl had his transplant, said his continuing success acted as beacon of hope for people on the waiting list for organ transplants.
She said that people could look at Carl, whom she has nursed since he was first admitted in his early 20's, and see how well he had coped and how fit he is and gain hope about their own future health.
"At the time it was said he was going to die. He had cardiac myopathy. His heart was diseased and enlarged, if only people out there could see there are people who are doing so well.
"It is not all doom and gloom.
"Carl inspired me to go into transplants. If you see somebody who is so sick and then they become so well it does inspire you."
She said that the transplants gave patients a new lease of life, allowing them, like Carl, to explore avenues they had never previously considered.
"They may be able to walk down the aisle to get married or carry out their life long ambitions like flying a plane."
"If Carl had not had the transplant he would not be doing the Olympics and doing good things."