No Pulse: How Doctors Reinvented The Human Heart

This 10,000-rpm, no-pulse artificial heart doesn't resemble an organic heart--and might be all the better for it

By Dan Baum Posted 02.29.2012 at 12:13 pm 37 Comments

Home Made: To make a heart, doctors stripped pumps from commercial LVADs. Other components they bought from Home Depot or stitched by hand. Jack Thompson

The Texas Medical Center is a city within a city. Its 13 hospitals and 21 schools cover a swath of Houston bigger than New York’s Central Park. Navigating its raised sidewalks, light rail and glass towers feels like getting lost on a set for The Jetsons. One hundred thousand people work and study here every day. The place has its own zip code.

Among the towers is the Texas Heart Institute, in which I found Dr. Billy Cohn, a big, fit man in his early 50s with light hair, blue eyes, and an office that would no doubt have exasperated his mother. It looked like the mad scientists’ club at a middle school, every surface covered with sketches, tools, bits of machined metal, wire, statuettes, playing cards and such toys as a Darwinian evolution action-figure set (horseshoe crab, various monkeys and a gray-bearded intellectual). A static-electricity generator flashed lightning bolts, and a three-dimensional model of the human heart loomed over Cohn’s desk. Even his file cabinet looked weird, pimpled with tiny bits of metal.

“Rare-earth magnets!” Cohn cried, straining to pull one free. He put it in my hand. It was the size of a pencil eraser, and when I loosened my grip, it shot like a bullet to the file cabinet with a clang. “Extremely powerful.” Cohn has pioneered the use of rare-earth magnets to move catheters into place deep inside the body. He avoids having to cut patients open by threading the magnets, and their tiny loads, up through arteries. He pawed several sheets of paper off the floor and drew diagrams on their unused backs, launching an hour-long discourse on the instruments and procedures he’s built around miniature magnets.

Building a heart that mimics nature's lub-dub may be as comically shortsighted as Leonardo Da Vinci designing a flying machine with flapping wings.On his wall hung four metal serving spoons of the kind you might see on a cafeteria line. One was intact; the other three had intricate slots cut in them. Years ago, Cohn butchered the spoons in his home garage to solve the problem of holding a heart still while operating on it. The standard way, at the time, was to shut off the heart altogether and put the patient on a heart-lung machine. But that was risky. Cohn’s spoons let surgeons hold a heart in place while still giving them access to the parts they needed to slice or stitch. Through the custom-cut slots, the surface of the heart would emerge and hold still for tinkering, even while the rest of the heart thrashed around under the spoon. Cohn refined the idea and sold it to a medical-devices company, which has marketed the tools worldwide.

Cohn grew up building rockets in the garage with his older brother John, and neither of them ever quite outgrew it. (John is one of 80 IBM fellows, the company’s highest technical rank.) “That there?” Billy Cohn said, pointing to what I’d thought was a scuba diver’s speargun. It hung on the wall beside laminated newspaper clippings about him. “I invented that out of old parts in the garage. It puts a bag, like a big sock, all the way around the heart.” He spent 20 breathless minutes describing why a surgeon would want to do such a thing.

It’s the continuous-flow artificial heart Cohn installed in the chest of Meeko the calf, though, that enthralls him now. Using such turbines to assist sick hearts has been standard practice since the mid-1990s. But along with his research partner, Dr. O.H. “Bud” Frazier, Cohn is experimenting with using them to replace the heart entirely—and doing so with the hands-on ingenuity of the professor on Gilligan’s Island. He rummaged through the detritus on his desk and placed in my hands two gray metal cylinders—turbines, each the size and shape of a saltshaker—connected to each other by white tubing. Also attached to each was a white cone made of a spongy rubberized cloth.

“Dacron polyester,” he said. Because the cones are what get sewn to the remainder of the heart’s atria, their design was tricky. He ticked off the concerns on his long fingers. “The materials needed to be blood-friendly. The structure needed to be resilient to deformation. It had to be formable in a limited space. We needed to be able to sew it, but the needle holes couldn’t let blood leak. And we had to be able to customize it in the OR by cutting it. I bought some ordinary Dacron from the fabric store and RTV silicone from Home Depot to impregnate the outside. I did all this in my garage. My wife calls them dolly dresses.”

The continuous-flow heart solves the biggest problem with artificial hearts: longevity. One little turbine like the ones Cohn showed me has been running continuously in a lab for eight years and shows no sign of wearing out. Another advantage is that it runs on a battery no bigger than a videocassette. The patient can wear it in a kind of shoulder holster—cumbersome, but not as bad as sitting day and night beside a hissing compressor the size of a dishwasher.

It all made sense in theory, sitting in Billy Cohn’s office. But the whole idea of life without a pulse was a little too weird for me to grasp. It seemed like some sort of parlor trick. How could someone be alive without exhibiting the most fundamental sign of life? And how did anybody even dream up such a thing?

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