Heart transplants have fallen by almost half in ten years and there are now not enough being carried out to maintain surgeons' skills, doctors warn today.

The 46 per cent fall in UK heart transplants has puzzled specialists as it has not happened in Europe they say.

Guy Macgowan, consultant cardiologist at the Freeman Hospital, Newcastle on Tyne who with colleagues highlights the fall in the British Medical Journal said one factor was a change in the nature of organ donors.

In the past, organs have been taken principally from donors declared brain dead, where there is no electrical activity in their brains.

In practice this restricted potential donors to patients being cared for in intensive care units, where measurement of brain electrical activity is routine.

In recent years, to boost organ donation rates, hospitals have also selected patients whose hearts have stopped beating.

These are just as valuable as donors of organs such as kidneys, liver, pancreas and intestines but they cannot be used to source a heart.

"The new strategy has increased the overall supply of organs, which is good, but hearts have been disadvantaged," Dr MacGowan said.

Heart transplants are effective. A patient with heart failure has a 50 per cent chance of dying within a year while one undergoing a heart transplant has a 50 per cent chance of surviving ten years.

Dr MacGowan said the answer to the shortage of organs was to offer patients artificial hearts - mechanical pumps - inserted inside the chest instead.

These had greatly improved in the last decade and new versions were better than a transplant over two years though it was not known how well they would perform over a longer period.

"We are pessimistic about increasing the number of donor hearts for transplant. It doesn't seem to be happening. So we are saying the few heart transplants being done should be prioritised for those who cannot have mechanical heart pumps, such as those with congential heart problems, so that as many people are helped as possible."

"And it is time to consider reducing the number of heart transplant units from the present six, so surgeons have enough patients to operate on to maintain their expertise."

The Department of health was planning a review, he said.

The British Heart Foundation said fewer but bigger centres provided the best care for patients. "These centres of excellence can see a wide range of patients on a regular basis ensuring that medical staff maintain and improve their skills, and are able to train up new recruits," Professor Peter Weissberg, medical director, said.