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Rebel Heart OPEN ACCESS

How Billy Cohn’s Lifelong Obsession with the Artificial Heart Spawned a Prolific Career As a Medical Device Innovator.

[+] Author Notes

Kayt Sukel is a science and technology writer based in Houston.

Mechanical Engineering 139(09), 42-47 (Sep 01, 2017) (6 pages) Paper No: ME-17-SEP3; doi: 10.1115/1.2017-Sep-3

This article discusses features and advantages of BiVACOR, an artificial heart machine. It also presents a brief overview of medical successes of Billy Cohn, a medical doctor. The BiVACOR heart is a rotary pump with a single moving part that consists of two impellers on a magnetically suspended rotor. Cohn along with his older brother built homemade gadgets, rocket engines, and a variety of incendiary devices in the garage. As Cohn progressed in his medical career, he never stopped tinkering. He was fast becoming one of the finest heart surgeons in the country, yet he spent his free time in his home workshop, prototyping medical devices to assist his operations. Cohn and O.H. ‘Bud’ Frazier, a cardiac surgeon who had performed more than 1000 heart transplants, led the work on AbioCor from the Texas Heart Institute in Houston and worked on a completely novel approach to artificial heart design—continuous flow. The heart, built by the two surgeons, is set out to build would replace those metaphorical flappy wings with fixed ones.

In the video, a team of men in scrubs surround a young, caramel-colored calf as it walks tentatively forward on a treadmill, its attention fixed on a handful of greens just beyond its nose. The calf, sinewy and fit, quickly ups his stride, stretching his mouth toward the tempting treat.

Billy Cohn helps to break ground on the new Johnson & Johnson Center for Device Innovation Building at the Texas Medical Center in Houston.

Grahic Jump LocationBilly Cohn helps to break ground on the new Johnson & Johnson Center for Device Innovation Building at the Texas Medical Center in Houston.

“Just look at that,” said Billy Cohn, sketching out the calf's musculature with his finger to emphasize the beast's health, acting more like a seasoned judge of 4-H livestock competitions than the distinguished cardiac surgeon and medical device inventor that he is.

“That's a goddamn healthy looking cow,” he said. “You’d never know that's an animal with no heartbeat, no pulse.”

Cohn's right—it is a healthy looking animal. Shiny and sleek, with warm, expressive eyes and a strong gait, you might never know that it had its heart replaced with a BiVACOR artificial heart three months earlier.

“Totally normal growth. His hair grew back really fast. No problems whatsoever. And now his cardiac output is 14 liters a minute,” Cohn explained. “It's just a pristine animal, put on 72 pounds of lean muscle in the last few months.

“I know it seems like developing a mechanical heart should be really doable. The heart is just a pump, after all. Not much to it.”

“It's just beautiful.”

It would be easy to assume that Cohn is ascribing such beauty to the calf, which does indeed look like a serious blue ribbon contender. But Cohn is actually referring to the BiVACOR heart, which he calls the first “practical artificial heart on the planet.” A 56-year-old medical doctor with dozens of patents for medical devices under his name, Cohn has a fine appreciation for an exquisite, well-designed machine.

“Magnetically levitated, no mechanical friction or wear, it's the best design we’ve seen,” he said, his voice exhilarated to a tone of boyish wonder. “After decades of work on an artificial heart, we’re on the four-yard line and ready to make that touchdown.”

He pauses and takes a deep breath. “It's about goddamn time.”

Cohn distinctly remembers when he heard about the world's first artificial heart.

It was 1969, and today's preeminent cardiac surgeon was a precocious—and often unruly— grade-schooler. His mother, always clipping articles to inspire him and his siblings, showed him a write-up about the mechanical heart that surgeon Denton Cooley had just placed inside Haskell Karp, a man waiting for a heart transplant. As he read the piece, Cohn was transfixed by the description of the bellows-like device made of polyester and polyurethane.

“It absolutely fascinated me. I mean, the idea that you could put a mechanical heart in someone just seemed crazy,” he said. “I took that article to school with me, I was so excited. I was showing it to someone when the teacher caught me and took it away. But when she saw what it was, she asked me to get up and say something about it to the class. Which, I, of course, did,” Cohn said.

That began Cohn's self-stated “obsession” with the artificial heart. It is an invention that he has followed since childhood—and one he intends to have ready for patients within the next few years.

“I know it seems like developing a mechanical heart should be really doable,” he said. “The heart is just a pump, after all. Not much to it. But we just hadn’t gotten there with the right design. I was convinced I was born in the wrong era. I figured it would be developed while I was in high school or college and I’d have nothing to do with it.”

As it turns out, he could not have been more wrong.

One could argue that Cohn was destined to play a part in the makings of the mechanical heart. When he moved to Houston as a toddler in the early 1960s, the sleepy Texas backwater was transforming itself into a place for progress and innovation. In 1961, NASA selected the city for its manned flight center. Four years later, the very first domed stadium constructed in the United States, the Astrodome, opened to acclaim as the “eighth wonder of the world.” Houston was also the domicile of the Texas Medical Center, the largest medical center in the world, where Cooley and Michael DeBakey earned their reputations as the finest cardiac specialists in the world.

“My Mom used to drive me down by the Medical Center,” he said. “She’d tell me, ‘That's where Dr. DeBakey and Dr. Cooley work.’ And it made a huge impression on me. Between the astronauts, the Astrodome, and these heart surgeons, it really seemed like anything was possible.”

If anyone asked what he wanted to do when he grew up, Cohn would alternate between heart surgeon and astronaut—though he never thought either was a “remote possibility.” Yet he kept dreaming of artificial hearts, resolutely incorporating drawings of pneumatic artificial heart valves in the homemade cards he gave to his mother over the years.

Cohn also grew up a tinkerer. Egged on by his older brother, John, now an IBM Fellow, the boys built homemade gadgets, rocket engines, and a variety of incendiary devices in the garage.

“It's amazing we still have our eyes and fingers,” Cohn said, a wide smile breaking across his face. “I just love tinkering. I love getting Super Glue all over me, the smell of burning metal chips. There's nothing like it.”

Along with his appetite for tinkering, Cohn also cultivated a passion for trombone and bass guitar. By the time he graduated high school, despite the advances being made on the Jarvik artificial heart—the greatest mechanical heart of its time—he decided to study music at Oberlin College. Cohn fell in love with the early punk rock vibe at Oberlin. It spoke to his rebel nature.

Yet Space City and that telltale artificial heart continued to beckon. After two years and a summer job as a hospital orderly, the possibility of becoming a heart surgeon didn’t seem quite as remote as before—especially when compared to trying to build a career as a professional musician.

“I loved music—I still love music—it's great fun,” he said. “When I grew up, I didn’t think that just anybody could decide to be a heart surgeon and just do it.

“But after being in school for a while and talking to doctors, I realized reaching a goal is about following the steps and making the kind of decisions that lead you closer to your goal instead of away from it. Eighty percent of life is showing up, right? I decided I wanted to show up and become a surgeon,” he said.

Cohn may feel most at home in his garage workshop, where he glues, solders, bends, and drills new medical device prototypes made from kitchen implements and spare parts.

Grahic Jump LocationCohn may feel most at home in his garage workshop, where he glues, solders, bends, and drills new medical device prototypes made from kitchen implements and spare parts.

The BiVACOR heart is a rotary pump with a single moving part that consists of two impellers on a magnetically suspended rotor.

Grahic Jump LocationThe BiVACOR heart is a rotary pump with a single moving part that consists of two impellers on a magnetically suspended rotor.

Cohn switched majors, graduated with a bachelor's degree in biology, and returned to Houston to attend Baylor College of Medicine. He was one of the few selected to join the institution's famed heart surgery program, and eventually was chosen as the last chief resident of his childhood idol, Michael DeBakey.

As Cohn progressed in his medical career, he never stopped tinkering. He was fast becoming one of the finest heart surgeons in the country, yet he spent his free time in his home workshop, prototyping medical devices to assist his operations. Although he never took an official engineering course, he describes himself as a “frustrated mechanical engineer.”

“I get so much satisfaction from working with tools and working with my hands,” he said. “I do see it as a form of play and self-entertainment. Heading to Home Depot and picking up a bunch of stuff to build something I have in mind is fun. And if it doesn’t work, then figure out what I overlooked and remake it, maybe more than a few times. When I can make something that improves what I use in surgery, that's even better. Because in doing so, I’m not just helping one patient, but lots of other patients down the line.”

At current count, Cohn holds an astonishing 90 patents. This includes the 1997 Cohn Cardiac Stabilizer, a device he invented that helps surgeons perform coronary bypass surgeries while a patient's heart is still beating.

Twenty years ago, patients undergoing bypass surgery needed to be hooked up to a heart-lung machine that pumped blood so physicians could still the heart for surgery. However, sometimes the pump caused infections and blood clots.

Johns Hopkins researchers solved that problem with a salad tongs-like device that surgeons inserted into the chest through a small incision. It enabled them to work on a slowed but still beating heart, but Cohn found it challenging to stitch the bypass grafts securely to the heart.

He thought he could do better, and bought out the local supermarket's stock of metal soup ladles. After twisting them into a variety of angles, surfaces, and openings, he created a device that allowed surgeons to press against the diseased artery and stitch the graft into place through a square cutout. Surgeons have used the stabilizer in more than 200,000 operations worldwide.

That was just one of Cohn's many inventions. Some were innovative gadgets designed to make surgery easier. Others improved upon traditional surgical retractors, catheters, and suturing devices. Many started as homemade prototypes and are now used today by surgeons all over the world. When he sees a need, he heads to his workshop to try to answer it.

By the turn of the century, Cohn was working at Harvard Medical School. Although he had a growing reputation as a device innovator, he had not contributed anything to the design of a mechanical heart. Then he began hearing about a local startup, AbioMed, which was preparing its AbioCor heart for human trials. The news rekindled Cohn's childhood obsession.

“It was a brilliant design,” he recalled. “It had this internal clockwork system that drove silicone oil from left to right and right to left, compressing a flexible bladder that had in and out valves—entry valve, chamber, exit valve—all molded out of this water-insoluble material that would dump in the blood and then spin it so it wouldn’t accumulate anywhere.”

O.H. “Bud” Frazier, a cardiac surgeon who had performed more than 1,000 heart transplants, led the work on AbioCor from the Texas Heart Institute in Houston. Cohn, in Boston, felt left on the sidelines.

Then serendipity stepped in. Frazier and Cohn met at several surgical meetings. Their discussions inevitably turned to new ways to improve upon AbioCor's design. Ultimately, Frazier invited Cohn to return to Houston to work with him on a completely novel approach to artificial heart design—continuous flow.

Conceptually, Cohn explained, it was the difference between the first aspiring aviators, who tried to mimic the flapping wings of birds, and the Wright Brothers, who figured out how to achieve lift with much simpler fixed wings. The AbioCor heart, Cohn said, was the “best heart with flappy wings.”

The heart he and Frazier set out to build would replace those metaphorical flappy wings with fixed ones. It would not beat. Instead, it would use two gray metal turbines connected with white tubing and polyester cones sewn onto the heart's atria to pulse blood through the body.

The two designed, iterated, and then tested a prototype. And in 2011, they implanted their Frazier-Cohn heart into a dying 55-year-old man named Craig Lewis. He lived for an additional five weeks following the surgery before dying of liver and kidney failure. The heart continued to pump until it was unplugged. Their first patient taught them new ways to improve upon their first continuous flow prototype.

Meanwhile, an Australian, Daniel Timms, was also working on a continuous flow heart. Half the size of a soda can, his design used magnetic levitation to suspend a small rotor with dual impellers as it spun 2,000 to 3,000 times per minute. Cohn and Frazier loved the design and teamed with Timms.

Surgeons implanted Timms’ device in many large animals, including the treadmill-walking calf. The device also provides the right amount of blood flow for a sheep, an animal small enough to serve as an analog for a child. Earlier hearts were too large and powerful for children.

Cohn's excitement for this device is palpable— and human clinical trials are expected to begin within 18 months. “This is the quest for the Holy Grail—and we’re closer than we’ve ever been.”

It will take years to fully test and optimize the heart. Meanwhile, Cohn, now BiVACOR's chief medical officer, continues to wear many hats. He is a professor of surgery at Baylor College of Medicine, an adjunct professor of bioengineering at Rice University and the University of Houston, a surgeon at the Texas Heart Institute, and director of Johnson & Johnson Center for Device Innovation. He also serves on the boards of several medical devices companies, including several commercializing the inventions that he created in his garage workshop.

“But it's also satisfying to take the path less traveled and integrate creativity into your daily life. Because deep down, I’m an innovator—I like to create things.”

With so many accomplishments, many people would slow down and take a break. Not Cohn. He has too many ideas running around in his mind, demanding to get out and get made.

“There are a lot of people who train to be heart surgeons, who roll up their sleeves and do heart surgery for the rest of their life. And it's a very satisfying way to live your life. I love surgery, I do,” he said.

“But it's also satisfying to take the path less traveled and integrate creativity into your daily life. Because deep down, I’m an innovator—I like to create things. And building and iterating and testing and engineering and finding a cool way to solve a problem—that's something that will end up helping a whole lot of people, whether they ever come into my operating room or not.

“What could be better?”

Copyright © 2017 by ASME
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