The most extraordinary story was in the news recently. Stan Larkin of Michigan, age 25, has led a fairly normal life - except that for nearly two years, he didn't have a heart in his body. Last month, he finally received a heart from a donor. But for over a year and half before that, he had no human heart at all! Instead, he had a pump, connected to a machine that he carried around in a backpack, which circulated his blood.