- September 28, 2021
Flexible, dissolvable electronics could soon pave the way for temporary pacemaker wearers to avert the risks associated with surgical procedures from initial implantation to the removal of the device once its job is done. Northwestern and George Washington Universities have developed what they say is the first-ever transient pacemaker that is not only wireless, battery-free and fully implantable — but also disappears when it is no longer needed. Its biocompatible components can naturally absorb into the body over five (5) to seven (7) weeks eliminating the need for surgical removal.
In a study published on 28 JUN 2021 in Nature Biotechnology, researchers demonstrated the device’s efficacy across a series of large and small animal models. They cited several critical needs for an alternative, temporary pacemaker technology that can deliver the needed electrotherapy while addressing the associated physiological complications.
Northwestern Engineering’s John A. Rogers led the device’s development. “Hardware placed in or near the heart creates risks for infection and other complications,” Rogers said in a press release. “Our wireless, transient pacemakers overcome key disadvantages of traditional temporary devices by eliminating the need for percutaneous leads for surgical extraction procedures — thereby offering the potential for reduced costs and improved outcomes in patient care. This unusual type of device could represent the future of temporary pacing technology.”
Health providers presently use temporary pacemaker devices as a bridge to permanent pacing therapy — or implement them temporarily following cardiac surgery. For temporary pacing after open-heart surgery, surgeons sew the temporary pacemaker electrodes onto the heart muscle. Those electrodes have leads that exit the front of the patient’s chest and connect to an external generator that delivers a current to control the heart’s rhythm.
This hardware carries a considerable risk of complications including infection from bacteria that can form biofilms on pacing leads. Since the device is not fully implanted, the externalized power supply and control system can inadvertently be dislodged when caring for or mobilizing a patient. Additional complications can happen upon removal including laceration and perforation of the myocardium which can occur if the pacing leads become enveloped in fibrotic tissue at the electrodes-myocardium interface.
The transient pacemaker sidesteps the risks of infection, dislodgement, torn or damaged tissues, bleeding and blood clots. It is light and thin, weighs less than half a gram, and is 250 microns thick. The soft and flexible device encapsulates electrodes that softly laminate onto the heart’s surface to deliver an electrical pulse instead of using wires. Researchers say this approach could serve as the basis for the next generation of postoperative temporary pacing technology.
Rogers, who has a background in electronics materials science, says the idea was born from a two-way convergence of needs and capabilities — electronics that can dissolve in water for reducing solid waste and temporary implants that provide some sensing and therapeutic function that naturally disappears after. “We’ve been exploring it for a number of years trying to build up a toolbox of materials … from an exponential academic standpoint with an eye toward opportunities in medicine,” Rogers told Medical Design & Outsourcing.
In the last few years, clinicians approached Rogers and his team and asked for assistance. That is how the transient pacemaker came to light. “It wasn’t us cooking up an idea but us responding to a clinical need and leveraging a unique technological capability we developed over time,” Rogers said. “It was the interventional cardiologist downtown reaching out to us.”
The technology used to create the transient pacemaker goes back about two and a half years and is something Rogers said they have been working on for a while. It began with some conversations with folks at the U.S. Defense Advanced Research Projects Agency (DARPA) amid military needs for sensitive proprietary electronics that would dissolve if they got into the wrong hands. “It got us thinking and I think the sort of inflection point for us was identifying a semiconductor material that we can use,” Rogers said.
That is when he said they stumbled across an underappreciated application of materials chemistry — silicone. Silicone is itself water-soluble and has a slow rate of dissolution, and if left in the water for more than two (2) to three (3) weeks it is gone, according to Rogers. “That was kind of an ‘ah ha’ moment for us,” he said. Rogers and his team were able to use very thin silicone — tiny amounts — but still enough to build transistors and diodes and functional electronic components. Lots of inbound interest from clinicians with various use cases followed. Researchers found the devices helped provide effective pacing in various size hearts in mice, rats, rabbits, canines and human cardiac models “with tailored geometries and operation timescales powered by wireless energy transfer.”
George Washington University’s Igor Efimov co-led the study with Rogers and Dr. Rishi Arora, a Cardiologist at Northwestern Medicine. “The transient electronics platform opens an entirely new chapter in medicine and biomedical research,” Efimov said in a press release. “The bioresorbable materials at the foundation of this technology make it possible to create a whole host of diagnostic and therapeutic transient devices for monitoring progression of diseases and therapies, delivering electrical, pharmacological, cell therapies, gene reprogramming and more.”
The transient pacemaker is not the first bioabsorbable medical device from Rogers Lab, which has been studying transient electronics for more than a decade. Three (3) years ago they announced the development of an implantable, biodegradable, wireless device that speeds nerve regeneration and improves healing of damaged nerves.
REFERENCE: Medical Design and Outsourcing; 01 JUL 2021; Liz Hughes