Inside the lab that’s the beating heart of Medtronic’s product pipeline

The pink, white and red blob of tissue quivers in a vat of clear goop about the size of a kitchen sink.

Graduate students whiz around this slimy beating heart and crawl under the tubes connected to the apparatus cradling the organ as a Medtronic scientist prods a snaking tool around its interior.

This disembodied heart, beating on its own in a cinderblock-walled University of Minnesota basement, propels student experimentation and fuels the Minnesota medtech giant’s innovation pipeline.

“There are days' worth of research that comes out of this project on a given day,” said Dr. Paul Iaizzo, the director of the U’s Visible Heart Laboratories.

Medtronic owns an exclusive licensing agreement to use the lab. Since 1997, the Fridley-run manufacturer of pacemakers and stents has funded half of this lab reanimating human and pig hearts. The windowless space contains more than $20 million in equipment and devices, such as a $1 million micro CT scanner, purchased 35% off with an educational discount.

“Don’t pull anything out of the wall,” joked Sarah Ahlberg, director of research and technology for cardiac ablation solutions.

Iaizzo said the lab is in “the birthplace of the ecosystem of medical devices in Minnesota.” The first battery-powered pacemaker was tested nearby. Surgeons performed early open-heart surgeries in the floors above in the U’s Mayo Building.

Here, Medtronic scientists recently poked around with the device at the center of a multibillion dollar innovation race. The company’s pulsed field ablation catheter, Ahlberg said, is one of two recent blockbuster devices, along with the minimally invasive Micra pacemaker, significantly bolstered by research in the lab. Catheters are thin, tube-shaped devices physicians use to advance miniaturized medical devices into the heart through blood vessels.

Scientists can test other kinds of ablation catheters that use heat or cooling energy to treat the common heart problem of atrial fibrillation on a “slab of meat,” Ahlberg said. But pulsed field ablation catheters can only be tested on live tissue, she added.

A thumping heart is crucial for the device’s research. On a recent Tuesday, it came from a pig.

Ahlberg said pigs have cardiac anatomy similar to that of humans, though a pig heart typically has less plaque and yellow, gelatinous fat covering it, she said.

Human hearts make for better research as pig hearts are typically idealized healthy organs compared with the ones doctors work with, Ahlberg said. They are not viable for transplant.

In a nearby room, hundreds of hearts, some that have been there since 2000, sit in containers filled with formalin. Staff had a few in a sink under running water for 24 hours to rinse off the stinky chemical before research. The university allows anyone to study in this heart library.

Inside the lab, cardiac anatomy and physiology experts assemble and disassemble the web of tubes, wires and high-tech equipment surrounding each new organ getting reanimated, Iaizzo said. The staff has reanimated a grand total of 98 human hearts and studied many more. These hearts are gifted from organ donors and their families.

The heart pumps on its own. But to rev up its engine, the staff shocks it with the type of defibrillator paddles used in a surgical emergency. Screens show heart valves opening and closing.

The heart sits in a chamber, called the Visible Heart apparatus, filled with a clear blood substitute called Krebs–Henseleit solution coming from pre-loaded chambers that look like Pedialyte bottles. A massive machine called a double bypass circulatory system rising above the tub mimics the body’s veins and arteries, controlling the pace at which the fake blood pulses through the organ. A heater warms the liquid to around body temperature as the fluid becomes oxygenated.

“You have to emulate what it would be like in the body,” Iaizzo said. Without red bloods cells, though, the heart only lasts roughly four to six hours before its performance greatly decreases.

The staff first takes images of the heart using inserted, lit cameras that make the organ glow like an alien creature. “We’re a lot like Hollywood,” Iaizzo said.

Graduate students then carry out their research and Medtronic brings in devices to test, prototype and demonstrate.

The company’s staff thread devices into the heart through tubes connected to the organ. The company has two pulsed field ablation catheters: Affera, which it acquired in 2022, and PulseSelect, created by the company itself.

Affera is an all-in-one device to treat AFib, as doctors can map the heart’s physiology as well as activate pulsed field ablation and radiofrequency ablation with the single catheter. A tiny ball made out of what looks like a metallic spider web at the end of the catheter delivers the energy to perform these tasks.

Ahlberg inserted the catheter through a sheath squeezed through one of the tubes. She started to bend the device’s tip to the left and right inside the heart by pushing on levers attached to its handle, which she said is intentionally designed to conform to the grips of a diverse array of doctors.

To map the inside of a cardiac chamber, she pushed the tip against the organ’s interior walls.

A magnetic sensor in the catheter interacts with a magnet under the heart to create a electromagnetic field allowing the device to map out a virtual shell of a heart chamber’s anatomy. This mapping function also detects dead tissue in the heart.

Once the catheter’s sphere has pressed against the inside of the organ, a Medtronic employee activates Affera’s pulsed field ablation function. The heart fidgets quicker than at rest, as the machine delivers over 1,000 volts of energy into it. The machine makes chime sounds to signify this energy delivery.

Some of Medtronic’s original pulsed field ablation testing and designing occurred in this basement. Compared with a company-owned lab, this one is more “off the cuff,” Ahlberg said.

The lab has less restrictive protocols than an operating room or catheterization lab in a hospital. At one point, the researcher joked with a reporter, “Do you wanna feel the heart?” The invitation was declined.

Staff and visitors, she said, collaborate to improvise and retrofit equipment and find solutions. “We can do problem-solving on the fly,” Ahlberg said. Students also get the chance to work alongside industry scientists.

Iaizzo was Ahlberg’s adviser as she completed her biomedical engineering Ph.D. at the U in 2007. She studied large animals in the lab as she worked on her dissertation researching heart pacing. Iaizzo, she says, is her “school dad.”

“It’s like coming home,” Ahlberg said, who visits the lab a few times per month. She called Iaizzo a great mentor, as he’s willing to help and serve as an extension of the team.

Iaizzo said the collaboration has allowed the lab’s staff to be “visionary” and build out its heart library and a cardiac course.

He tells his students to leave their marks on apparatuses in the lab by suggesting technical changes. “We’re always modifying the equipment,” he said. ”We’re always improving our system."

Headshots of former lab students, including Ahlberg, line the lab’s walls, with notes about where they went on to work. Many found their way to Medtronic.

“The coolest part of my job is really all the pictures up here,” Iaizzo said.