Ever left lettuce in the freezer by accident? When you thaw it out, instead of crisp leaves you get limp mush. That's because when water freezes, it expands into ice crystals that act like microscopic knives, slicing through cell membranes. Now imagine that same problem, but with something as complex as a human heart. You might think "well, that's why we have freezers that go colder - surely at some temperature it would freeze so fast the ice crystals wouldn't form?" Dr. Yoed Rabin at Carnegie M...