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JHU students develop more comfortable defibrillator vest

For those waiting on surgery to place a defibrillator inside their chest, special vests can deliver lifesaving shocks in the event of a heart arrhythmia. But the downside, some say, is that the vests are so uncomfortable some patients don't wear them all the time.

A team of undergraduate Johns Hopkins University students, led by an alumnus inventor, set out to build a new prototype defibrillator vest that is more comfortable and works more effectively. The result — a vest that has won competitions and might be headed for approved medical use.

"Each aspect of this had to not only function correctly but we had to think of it separately, like, how do we make it convenient and comfortable for the patient?" said Sandya Subramanian, a rising Hopkins senior who led the undergraduate team that built the prototype. "That's kind of where the complexity is. It made it very interesting as a problem to solve."

Those at risk for a heart arrhythmia — or irregular heart rhythm — include heart attack survivors and those who have undergone open-heart surgery. The long-term solution is usually surgery to install a defibrillator to keep the patient's heartbeat regular, and patients often use an external defibrillator vest while waiting for the operation.

Todd J. Cohen, a Johns Hopkins alumnus and director of electrophysiology at Winthrop-University Hospital in New York, said the only model of defibrillator vest currently approved for medical use, called the LifeVest, could use an upgrade. He pitched the prototype idea to the students and helped oversee their work.

"It's complicated, it's archaic, it's heavy, it cuts into the patients," Cohen said of the LifeVest. "So I gave the suggestion of building a better mousetrap to this year's team."

Chad Elder, a spokesman for Zoll, the company that owns the LifeVest, declined to comment. The cost of the LifeVest is typically covered by insurance.

The team of eight students began by interviewing doctors and patients who use the LifeVest about how they think it could be improved. Cohen and Subramanian said that patients found it difficult to clean and assemble, and that some chose not to wear it all the time. A more comfortable defibrillator vest could mean patients would wear it more often, they said.

"When it's something you have to wear 24/7, small things can become big," Subramanian said of the comfort issue.

Where the LifeVest straps around a patient's torso, the prototype vest, which they are calling CardioGuard, is made of breathable fabric and zips up underneath clothing. Instead of a control box that hangs from the waist, the prototype vest uses a smaller control device that's worn on the wrist.

A computer system monitors the patient's heart rhythm through the skin, and if an arrhythmia is detected, an alarm will go off, giving the patient 30 seconds to cut it off. If it is not disabled within that time frame, the patient is jolted with about 160 joules of electricity.

The team refined the prototype several times and had team members try it on.

"We did a lot of testing on ourselves," said Subramanian. "We had a team member who wore it for a couple nights straight."

Subramanian, a 20-year-old biomedical engineering major, said she enjoyed leading the team she picked to work on the project and liked to think of herself as a "proud parent."

"The most fun part of the design team was working in Clark Hall until 2 to 3 a.m.," she said. "It's very fun to play off of everyone's strengths."

Cohen, who worked with Subramanian on another invention last year, said he could have hired a team of engineers to build the prototype, but he enjoyed working with the students more.

"Seeing them turned on by the challenge, seeing what they can come up with, it's a really unique experience," he said.

The team bested groups of graduate students in a competition sponsored by the North American Professionals and Entrepreneurs Council in April, taking home a $10,000 first-place prize. At the annual Johns Hopkins Biomedical Engineering Design Day event in May, the project won Most Innovative Design and placed first in the People's Choice Award contest.

The team tested the prototype at the Johns Hopkins Medicine Simulation Center with special mannequins that simulate heart patients.

Now Cohen and the team of students are exploring their options to commercialize the prototype. The new vest would have to be tested by the U.S. Food and Drug Administration before it is approved for medical use.

cwells@baltsun.com

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Copyright © 2015, The Baltimore Sun
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