Fully Implantable, Wireless Pacemaker Talks to Patient and Dissolves After Use

For nearly two decades, a team of researchers has been developing soft, flexible, wireless wearable devices and bioresorbable electronic technologies. Now, in a new study, the team has combined and coordinated their bioresorbable, leadless pacemaker with four different skin-interfaced devices to work together. The skin-mounted devices are soft, flexible and can be gently peeled off after use, eliminating the need for surgical removal. The pacemaker naturally dissolves in the body after a period of need.

Last summer, scientists at Northwestern University (Chicago, IL, USA) had introduced the first-ever transient pacemaker - a fully implantable, wireless device that harmlessly dissolves in the body after it’s no longer needed. Now, in their latest study, the team unveiled a new, smart version that is integrated into a coordinated network of four soft, flexible, wireless, wearable sensors and control units placed around the upper body. The new transient pacemaker and sensor/control network can be used in patients who need temporary pacing after cardiac surgery or are waiting for a permanent pacemaker.

The pacemaker wirelessly harvests energy from a node within the network - a small wireless device that softly adheres to the patient’s chest. This technology eliminates the need for external hardware, including wires (or leads). To enable the system to communicate with the patient, the investigators incorporated a small, wearable haptic-feedback device that can be worn anywhere on the body. When the sensors detect an issue (such as low battery power, incorrect device placement or pacemaker malfunction), the haptic device vibrates in specific patterns that alert wearers and inform them of the problem.

Since Northwestern’s transient pacemaker was first introduced a year ago, the scientists have made multiple improvements to advance the technology. While the previous device was flexible, the new device is flexible and stretchy, enabling it to better accommodate the changing nature of a beating heart. The new iteration also uses a biocompatible adhesive that allows the lightweight, thin device to softly laminate onto the heart’s surface without needing sutures. Another new benefit: As the transient pacemaker slowly and harmlessly dissolves, it now releases an anti-inflammatory drug to prevent foreign-body reactions.

Perhaps the most impactful advance is the device’s ability to provide pacing on-demand, based on when the patient needs it. Synced with the pacemaker, the chest-mounted cardiac module records an electrocardiogram in real time to monitor heart activity. In the study, investigators compared this wireless technology to gold-standard electrocardiograms and found it was as accurate and precise as clinical-grade systems. The team believes their system would be most beneficial for the most vulnerable patients. Every year, approximately 40,000 babies are born with a hole in the wall that separates their heart’s upper chambers. About 10,000 of these cases are life threatening, requiring immediate surgery. After surgery, 100% of babies receive a temporary pacemaker.

“In current settings, temporary pacemakers require a wire that is connected to an external generator that stimulates the heart,” said Igor R. Efimov, PhD, professor at the McCormick School of Engineering. “When the heart regains its ability to stimulate itself appropriately, the wire has to be pulled out. As you might imagine, this is a pretty dramatic procedure to pull out a wire connected to the heart. We decided to approach this problem from a different angle. We created a pacemaker that simply dissolves and does not need to be removed. This avoids the dangerous step of pulling out the wire.”

“This marks the first time we have paired soft, wearable electronics with transient electronic platforms,” said Northwestern’s John Rogers, PhD, the Louis Simpson and Kimberly Querrey Professor of Materials Science and Engineering, Biomedical Engineering. “This approach could change the way patients receive care providing multinodal, closed-loop control over essential physiological processes — through a wireless network of sensors and stimulators that operates in a manner inspired by the complex, biological feedback loops that control behaviors in living organisms.”

“Current pacemakers are quite intelligent and respond well to the changing needs of the patients,” said Rishi Arora, MD, professor of Medicine in the Division of Cardiology. “But the wearable modules do everything traditional pacemakers do and more. A patient basically wears a little patch on their chest and gets real-time feedback to control the pacemaker. Not only is the pacemaker itself bioresorbable, it is controlled by a soft, wearable patch that allows the pacemaker to respond to the usual activities of life without needing implantable sensors.”

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