Hearts were repaired in the Freeman Hospital surgery

He has performed coronary bypasses and replaced valves on hearts so they can be reused.

He told BBC News Online that he first carried it out when he had a patient desperately needing an organ, and a heart which had just a minor defect.

"I had a very sick patient. We had a donor heart, and there was a little bit of disease in one of the arteries on the front of the heart.

He said, aside from that minor defect: "It occurred to me that this heart was functioning perfectly well."

The work on the hearts adds just 10 - 15 minutes onto a four -hour transplant operation, and is carried out when the organ is in the recipient's body.

Three of the five hearts which have been repaired have needed coronary bypasses - in which a narrowed or blocked artery is bypassed using a section of vein.

Transplant dilemma

Professor Dark says the issue of using organs which might be classed as less than perfect has to be addressed.

He said one of the main issues was asking a potential recipient if they are happy to receive such an organ.

Professor Andrew Bradley, president of the British Transplant Society said: "There are occasions where the organs are sub-optimal [less than perfect], but nevertheless at the end of the day, the balance of risk is that the transplant should go ahead."

John Evans of the British Organ Donor Society said he thought people would take such an organ.

"If it was a scenario where the patient might die in the next 24 - 48 hours, or having a transplant, you would have a transplant

But he said increased awareness of the need for organ donors, through government campaigns, and other sources of information were the key to increasing donor numbers.

In February, Health Secretary Alan Milburn announced a �3m scheme to double the number of people on the organ donation register.

Following a "transplant summit", he also set targets of doubling the number of kidney transplants, and increasing the number of heart, lung and liver transplants by 10% over the next five years.