Then read this.
And this doesn't even broach the question of whether 'brain death' is a genuine diagnosis of death. Which it isn't because people can recover from 'brain death' and by definition you don't recover from death (except by divine intervention).
Life is increasingly imitating Monty Python.
'But you can only have my liver in the event if my death!'
'No-one has ever survived us taking out his liver!'