I thought that cardiac death didn't allow for all of the same organs to be usable post-death?
I think I heard this in high school many years ago and never got it corraborated, but it went something like this:
When someone is brain dead, their organs are still being perfused blood, so the person can donate those organs that get regular amounts of blood (like heart, lungs, liver, kidney, etc.)
While in cardiac death, those organs will lose blood supply and start to necrose before they can be ripped out of the patient, thus making them ill-advised transplant options. I have heard that corneas can be harvested from cardiac deaths, however?
I don't know if I'm way off base in these ideas, so if anyone can confirm/deny, that'd be useful.