For much of her working life, psychologist Diana Sanders has been helping patients to deal with what life has thrown at them. But few of those she has helped could even begin to imagine Diana's own long struggle for life, which began almost from the moment she was born with a congenital heart condition.

It reached its culmination four years ago, when she underwent a heart-and-lung transplant. Not only did Diana, who lives in Stapleton Road, Headington, with her husband Mo, successfully come through the nine-hour operation to begin a new life, she has written a book describing the journey through her transplant.

Will I Still Be Me? was written because she believes that the rest of us have little idea what it is like to undergo what she calls "the equivalent of a controlled road-traffic accident" or to live with someone else's heart and lungs inside your chest.

It is also being published to help focus attention on National Transplant Week, which begins on Monday.

"I wrote the book in response to the lack of information for patients going through transplants," said Diana, 50, who works at the John Radcliffe Hospital, Oxford.

She recalled the journalist John Diamond, in the preface to his book about his cancer, describing it as "an attempt to write the book I was looking for the night I got bad news".

Diana said: "This is the book I wanted when I realised that a transplant was the only option to save my life. I needed to know how I was going to deal with it all, how I would survive such a huge onslaught on my body both emotionally and physically.

"I have this huge part of someone else inside me and for a long time I didn't feel I was me anymore."

The trauma of the surgery, fighting through the first few months, swallowing 35 pills a day to stop her body rejecting the new organs, is vividly described.

But so are the details of the moment the call from Papworth Hospital, in Cambridgeshire, finally came on June 8, 2002 to inform her that there was a donor for her.

Diana and Mo had settled down to watch Casualty on BBC 1, as they always do on Saturday evenings. Normally, the answerphone would have been on to avoid her favourite programme being interrupted, but on this occasion some instinct made her answer.

On a previous occasion they had received a similar call and rushed to the Papworth, only to find that the organs were not after all suitable. But this time the months of waiting were to end.

She frantically began packing, even finding time to set up the video recorder. Then sitting on the loo, painting her toe nails, she telephoned her friend Jacky, who lives in Binsey to ask her to throw some money into the St Frideswide's well, the place of pilgrimage in medieval times which became Lewis Carroll's treacle-well in Alice in Wonderland. After about an hour the doorbell rang, the vehicle had arrived, her carrier to the next world, she wondered.

"I remember feeling mildly sick," she recalled, "trying not to get my hopes up, but hoping too that this would be another abortive journey, since the alternative seemed too big to contemplate."

By the time she had been assessed for a heart-and-lung transplant two years previously, she knew there were no other options. But even for a woman who for much of her life did not expect to see out the next ten years, it proved a difficult decision: die young or go through life-threatening surgery for an uncertain recovery and a future full of medication.

The condition she was born with meant her heart did not pump enough oxygen around her body. Yet her mother, Barbara, who worked for Cancer Research, and father, John Sanders, the first physics tutor at Oriel College, Oxford, had struggled to find a doctor to take their concerns seriously about their scrawny baby girl, who was continually vomiting and refusing to grow. Finally, they were referred to Dr Victoria Smallpiece who took one look at her and diagnosed renal failure. At the age of one she had an operation to remove a diseased left kidney, but it also became clear there was something wrong with her heart.

"Today, babies with my congenital heart condition are operated on soon after birth, thanks to the pioneering work of Prof Sir Magdi Yacoub," Diana writes. "In the 1950s and 1960s the technology was not available, so I had to put up with my heart." Any exercise was always hard work. Even laughter could leave her gasping for breath, with her mouth and fingers turning blue, which became something of a party trick to entertain friends.

From an early age, she had always been certain that her life would be short. "It is something that I have always carried around with me. No matter how much my parents concealed their anxiety, some of it must have rubbed off quite young."

Later came the devastating news that she would be unable to have children. Then, by the age of 39, she began to experience serious heart problems. Eventually she would find herself too physically unfit to walk up a flight of stairs, eventually becoming dependent on oxygen, stair lift and wheelchair.

Ultimately, she says the key factor in making her mind up to go for a transplant, after initial reluctance, was quality of life.

"I wanted to stay alive, yes, but not at any cost," she said. There was also her desperate wish not to die before her parents. "I especially hated the idea of my mother having to bury me. She had carried around the responsibility for my health since my birth; although not in any way her fault, she still felt responsible."

Diana went into the operating theatre all too well aware that one person out of ten people does not survive such an operation. She does not spare the reader in describing her state following the operation. Strangely, it is not pain she feels, but profound discomfort.

"I do not even have words or images or memories to describe how I feel," she writes. "Terrible, toxic, tight, unable to breathe the closest is to say I feel poisoned. Every cell in my body feels strange. The sensations in my skin are all wrong. My breathing is different, extraordinary, like someone has sewn up my diaphragm and I am breathing against a great weight.

"My head has been shaken and twisted and put back on the wrong way round so that thoughts and words come out backwards. My body is in constant motion, trembling deep inside, terrible agitation, inside and outside."

Initially, she was to fear that when they took out her heart, they had taken her fighting spirit with it. For she found herself overwhelmed with grief and loss and at one point demanded: "Put them back. I want my heart back. My lungs, my poor lungs, I want them back."

At home she was to suffer months of intermittent sickness and depression, a subject she knew much about through her work. "I could neither recognise it in myself, nor summon the strength or wisdom to do anything about it," writes Diana. "Gradually, my mind became consumed with ways of ending it all. I felt deeply guilty for feeling like this after all, my donor was dead and had never had a choice. How would my donor's family feel if they knew what I was thinking. Knowing that only made me feel worse, feel less and less worthy. I was in fact suffering from shock and the effects of steroids." Mo, who works for the wildlife trust BBOWT, can recall his wife waking him early one Sunday morning complaining of banging and demanding to know who was doing DIY at such a time. Unable to hear anything, he was slightly bemused. Only when Diana began tapping the rhythm on the bedroom table, did they realise it was the sound of her new foreign, unfamiliar heart. It would be several weeks before her brain accepted the new noise as normal and screened it out, in the way those living near busy roads eventually cease to hear the traffic.

Yet four years on Diana believes she is more alive and well than she has ever been before. With no more breathlessness she and Mo began walking like "maniacs" in Oxfordshire, Devon, Scotland and later in Switzerland. But the greatest pleasure was being able to do ordinary things such as being able to use a vacuum cleaner or lift a casserole into the oven without gasping.

She has fulfilled many of the goals formulated in her sick bed, including getting back to work, travelling to New Zealand and holding a first birthday party to thank her family and friends.

There are about 17 tablets to take at different times of the day, while her scars have healed, leaving a thin 18cm long slightly raised pink line down her front and a mark on her neck from the intravenous line.

"I do not try to hide the scars but wear them with pride," she says.

With 8,000 people each year in the UK waiting for transplants, of whom only 2,500 are successful, her book makes a strong appeal for new donors to come forward.

"Black and Asian people, for example, are more likely than white people to need a transplant, due to higher rates of kidney disease and diabetes," she writes. "But despite needing more transplants, these groups are less likely to register as organ donors."

The message will be underlined at the official launch of her book, where she will be joined by Sir Terence English, the distinguished cardiac surgeon and the former master of St Catharine's College, Cambridge, who will talk about the future of transplants, and Dr Ann McPherson, the Oxford GP who helped pioneer DUPLEX, the database of patients' experiences.

Her father did not live to see Diana's book published, but its launch on Tuesday will be at Oriel College, where he had been such a familiar figure.

But as well as her father, Diana will also be remembering a brave and generous 35-year-old woman, whose heart is now hers, and whose example is there for all of us.

  • Will I Still Be Me? A Journey Through A Transplant by Diana Sanders (Day Books) is priced at £8.99. It is available from www.dianasanders.net