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Researchers use revived hearts to study atrial fibrillation

A portion of a donated human heart is kept alive and beating in a laboratory at The Ohio State University Wexner Medical Center. Researchers reanimate the heart to look for hidden sources of irregular heartbeats. Credit: Courtesy of Ohio State

Ohio State researchers are seeking to find the cause of heart-rate irregularities with the help of hearts that have already stopped beating.

Vadim Fedorov, an associate professor in OSU’s Department of Physiology and Cell Biology, developed a system to make a donated heart beat without the human body. Fedorov is able to then observe the heart and its beating using a high-resolution technique to better examine the upper sections of the heart, known as the atria, by forming a 3-D structural image to help understand the cause of a common irregular heartbeat problem called atrial fibrillation.

“What we created here — this high-resolution, optical-mapping system with four cameras — is only available at the Ohio State University,” Fedorov said. “No other group yet can do this atrial experiment and recover the heart and make it beat again to study it for another 12 hours.”

Fedorov explained that atrial fibrillation is a specific heart-rate irregularity experienced by millions of people in the United States. It’s a leading cause of strokes and causes dysfunction of the heart and brain.

Four years ago, Fedorov and his team developed a program where they collected living hearts with a history of atrial fibrillation from the hospital.

“We put this living heart in the ice and bring it to the lab,” Fedorov said. “Then we do a special surgical procedure while we put a tube in the artery of the main core atria and infuse a special solution inside of the atria to put the heart at the normal 37 degrees Celsius, after which the heart will beat again.”

However, this process only enables researchers to see the physical and chemical activities. To see electric activities of the whole heart, a special fluorescent dye is injected to reveal the electric waves, Fedorov said.

“We cannot see by our own eyes, but the electric activity can be seen by our high-resolution cameras,” Fedorov said. “We have four cameras focusing on the heart from different angles, each of them have 100-by-100 pixels, which means each of them can record, simultaneously, 10,000 recordings. We have 40,000 simultaneous optical recordings.”

Brian Josef Hansen said those recordings and observations made using the dye can take researchers past what can be seen with the human eye.

“Heart cells are connected to each other and an electric current moves through the cells to make them contract,” said Brian Josef Hansen, a graduate student in the OSU Medical Scientist Training Program, “Usually this starts in one place then spreads and stops. However, in re-entry circuits, the electric wave gets stuck in a circle that never stops which causes the fibrillation.”

Fedorov said he believed the team’s techniques could help other doctors more precisely define the source of atrial fibrillation in their patients.

“Right now, the doctors are trying to find these re-entries within patients, but their techniques are very limited because they have to access the heart through the patient’s veins which leads to a limited view,” Hansen said. “In our system, they can see the electrical waves as they move through the heart and, combined with the use of (MRI), we can help the doctors to determine the structural characteristics of the re-entry circuits.”

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