Researchers from the North East are developing a new machine, which could help to identify dozens more donor hearts suitable for transplant.
The new machine restarts the heart and keeps it beating while doctors carry out tests to work out whether it is suitable.
At the moment, when a family agrees to donate their relative's organs, the assessment team will only transplant the heart if they are certain it is suitable, because the risks of making a mistake are too high. Last year, about 600 donors came forward - but only 138 hearts were taken and used.
The researchers from the University of Sunderland, Newcastle University and Newcastle's Freeman Hospital hope the new machine would help to identify many more suitable hearts and could double the number of transplants.
The machine mimics the human body, with devices to oxygenate, cleanse and pressurise blood and a container for the heart.
So far, trials have used hearts from pigs, but approval has now been granted to use a small number of human hearts. It could only be a year or two before the machine is ready for clinical use within operating theatres.