Have you ever tried to get water out of a soaking wet towel?

If so, you’ve probably found the most effective technique is grabbing the towel by both ends and twisting in opposite directions while you squeeze.

It turns out the heart uses a similar twisting and squeezing motion to pump blood through your body. It’s a complex set of motions powered by a sheet of cardiac muscle covering the ventricles.

Researchers at the Massachusetts Institute of Technology (MIT), Massachusetts General Hospital and collaborating institutions recently used this insight to create a new biorobotic hybrid heart—a real pig heart with a layer of soft, robotic, remotely inflatable bubbles in place of muscle tissue.

The robotic bubble matrix was designed by researchers at MIT, but its placement on the heart (which had its original muscle tissue removed) was informed by cardiac imaging data provided by the lab of Christopher Nguyen, PhD.

Dr. Nguyen is Principal Investigator of the Cardiovascular Bioengineering and Imaging Lab in the Cardiovascular Research Center at Mass General and Assistant Professor of Medicine at Harvard Medical School.

The breakthrough design of the biorobotic heart could help to accelerate the development of new prosthetic valves and cardiac devices for patients with heart disease—the leading cause of death for men and women in the United States.

Translating Structure Into Function

The project originated in the lab of Ellen Roche, PhD, a professor of biomedical imaging at MIT whose research is focused on identifying new approaches to cardiac device design.

Roche and Clara Park, a graduate student, first attempted to replicate this beating motion by studying the 3D anatomy of the heart. When this proved unsuccessful, Roche contacted Nguyen, who is known for his detailed images of heart tissue.

Nguyen and his team then used a technique called diffusion tensor imaging built 3D and 2D maps of the muscle fibers surrounding the left ventricle of the heart.

Roche’s team then aligned the robotic bubble matrix to mimic the orientation of the muscle fibers they observed.

“It’s well accepted in engineering that structure informs function,” Nguyen explains. “The thought was if we built it structurally in the proper way, we should be able to replicate the same function.”

The result? A pumping biorobotic heart that allows researchers to replicate heart rate, contraction and blood flow in a controlled laboratory setting.

The heart model could accelerate the development of replacement cardiac valves and devices, which must be tested extensively in fully artificial heart models and in animals before going into clinical trials in humans.

The team, which includes collaborators from Boston Children’s Hospital, Harvard Medical School, the Royal College of Surgeons in Dublin and Nanyang Technology University in Singapore, published their results in Science Robotics last year.

Could Custom Devices and Replacement Hearts Be Next?

Nguyen says the long-term vision of the team’s work is to use scanning data to replicate patient-specific heart structure, size, and function in this biorobotic hybrid form. They can then use the lab model to custom build cardiac devices to fit individual hearts.

“The biggest problem with cardiac devices is that they are one size fits all,” he explains. “That doesn’t always work out so well.”

With further advances in tissue engineering, Nguyen believes it may one day be possible to use the hybrid hearts as “replacement” hearts for patients with heart failure.

In this futuristic scenario, the patient’s heart would be surgically removed and refitted with the robotic bubble matrix, then placed back inside the patient—all in one operation.

“I can see this having a much bigger impact in the future, because we have millions of people with heart failure around the world,” he says.

“Current treatments only improve symptoms and may help you live longer. However, many cases of heart failure cannot be reversed and it’s only a matter of time before those patients need a new heart.”

About the Mass General Research Institute
Research at Massachusetts General Hospital is interwoven through more than 30 different departments, centers and institutes. Our research includes fundamental, lab-based science; clinical trials to test new drugs, devices and diagnostic tools; and community and population-based research to improve health outcomes across populations and eliminate disparities in care.
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