SIX months after Hongkong's first heart transplant, surgeons received a second heart donation - but could not use it because it was of the wrong blood group. Dr Tse Tak-ming, senior medical officer at Grantham Hospital, which carried out the first transplant last December, said doctors were disappointed not to be able to use the heart, which was donated about a month ago, but felt it would be too risky. The woman donor was blood group O, which did not match any of the patients awaiting transplants. While it was theoretically possible to transplant a heart of a different blood group to the patient's, there were other factors which prompted doctors to reject the heart. The donor, who died in a traffic accident, was in her 50s. ''That made us a little bit worried there is a possibility that the heart itself has some minor complications of coronary heart disease which we wouldn't know about until we had transplanted it,'' he said. The patient who would probably have received the heart - Grantham has five or six patients waiting for a transplant - was in his early 30s, so a younger heart was preferred, Dr Tse said. Another problem was that the donor had suffered from low blood pressure for almost a week due to multiple fractures caused by the traffic accident. Liver and kidney teams also rejected her organs for this reason. The heart was offered to other heart units in Hongkong, but was not taken up. Dr Tse said the case highlighted doctors' difficulty in deciding when to approach a patient's relatives for organ donation. ''The problem is, if you talk to the relatives too early, the relatives will be more suspicious of the doctors, although this is when the transplant teams are more interested in the organs,'' he said. ''But if you talk to them at a very late stage, then you potentially compromise the organs. It's a very fine dividing line.'' Although the success of Hongkong's first heart transplant last December raised hopes of more donations, Dr Tse said surgeons were still finding it ''very tough'' to obtain organs. ''The Chinese people still think the soul resides in the heart and if the heart is still beating, you're not dead,'' he said. ''Nothing has changed.'' Professor Mok Che-keung, who conducted Hongkong's first heart transplant, said he felt disappointed that no more suitable donors had been found. But he said Hongkong's second heart transplant could happen at any time. ''I remember about 11/2 years ago, we had three donors in 11/2 months,'' he said. ''But at that time our line-up recipients had all perished while waiting for the transplant.'' Dr Tse said patients awaiting transplants were still optimistic. They were all still walking. ''They're still pretty good,'' he said. Dr Tse said heart doctors planned to meet transplant co-ordinators to review the situation.