There’s no safe way to get a close-up view of the human heart as it goes about its work: you can’t just pop it out, take a look, then slot it back in. Scientists have tried different ways to get around this fundamental problem: they’ve hooked up cadaver hearts to machines to make them pump again, attached lab-grown heart tissues to springs to watch them expand and contract. Each approach has its flaws: reanimated hearts can only beat for a few hours; springs can’t replicate the forces at work on the real muscle. But getting a better understanding of this vital organ is urgent: in America, someone dies of heart disease every 36 seconds, according to the Centers for Disease Control and Prevention.
