The threat model could be a freak heart stabbing. In which case a backup heart somewhere else (and some truly earthshattering breakthroughs in fast clotting) might make sense.
My dream technology would be a way to make my body just ... stop, if Something Bad happened, like all my blood falling out, until someone stumbled upon my non-rotting corpse, patched the holes, and filled it back up.
It's such bullshit that if I stop living for even a little bit my body melts into useless slag like an engine running without oil.
