Battery-free Pacemaker Could Treat More Heart Conditions

Atrial fibrillation, a form of irregular heartbeat, leads to more than 454,000 hospitalizations and nearly 160,000 deaths in the United States each year. During atrial fibrillation, the upper and lower chambers of the heart beat asynchronously. A pacemaker fixes this for patients, shocking the heart into a synchronized rhythm again. When it does so, it shocks all the cells inside the heart—including the pain receptors.

That’s because pacemakers work by implanting one or two leads into the heart that provide limited points of contact. As an alternative, researchers at the University of Arizona have developed a flexible mesh pacemaker that encompasses the entire heart. It also targets only cardiomyocytes, the cells of the muscle that trigger contraction and make up the beat of the heart.

"Whereas right now, we have to shock the whole heart, these new devices can do much more precise targeting, making defibrillation both more effective and less painful," said Igor Efimov, professor of biomedical engineering and medicine at Northwestern University, where the devices were lab-tested. "This technology could make life easier for patients all over the world, while also helping scientists and physicians learn more about how to monitor and treat the disease."

The pacemaker, designed in the lab of Philipp Gutruf at the University of Arizona, relies on light to send targeted signals using a digitally manufactured mesh. The mesh model consists of four petal-like structures made of thin, flexible film, which contain light sources and a recording electrode. The petals, specially designed to accommodate the way the heart changes shape as it beats, fold up around the sides of the organ to envelop it.

“This device has a computer on board where you can input different algorithms that allow you to pace in a more sophisticated way. It's made for research,” said Gutruf.

Because the system uses light to affect the heart, rather than electrical signals, the device can continue recording information even when the pacemaker needs to defibrillate. In current pacemakers, the electrical signal from the defibrillation can interfere with recording capabilities, leaving physicians with an incomplete picture of cardiac episodes.

Another huge benefit of the new pacemaker is that it does not require a battery. Currently, patients with traditional pacemakers must replace the battery every 5 to 7 years. And while the surgery to replace a pacemaker battery is less complex than the initial placement of the device, it’s still considered invasive. Additionally, current pacemakers can only be used to treat a few specific types of disease; whereas, the flexibility of the new device would allow it to respond to varied irregularities in more appropriate ways.

As described in the paper published in Science Advances, the new pacemaker showed success in both ex vivo and in vivo mouse models—even though the research team had to miniaturize the device given the amount of space in the small animals.

“This device class enables new heart failure models and offers a platform to test real-time therapeutic paradigms over chronic time scales by providing means to control cardiac function continuously over the lifetime of the subject,” conclude the researchers.