, 2025-05-08 13:25:00
The future of cardiac pacing may boil down to a single grain of rice.
Engineers at Northwestern University in Chicago have developed a biodegradable pacing device so small it can be injected by needle into the heart muscle of newborn babies. The design of the tiny gadget, designed for temporary use and still in the experimental stage, leans heavily on techniques from the semiconductor industry, whose prime directive is to shrink an ever larger number of transistors into an ever smaller package.
The new technology is wirelessly connected to a small, wearable patch worn on the chest. When the patch detects an irregular heartbeat it transmits a signal via infrared light pulses that penetrate the skin. The light flashes on and off at a rate that corresponds to the desired rhythm, thereby correcting the pace of the heart.
“The electrodes of the pacemaker serve not only as the electrical interface to the heart, but they also establish — through the naturally occurring biofluids — a galvanic cell that acts as a battery to power the device,” said John Rogers, PhD, professor of materials science and engineering, biomedical engineering, and neurological surgery at Northwestern, who led the development of the pacemaker.
In addition to its miniscule size the pacemaker is also made of resorbable biomaterials .
“The polymers and biomaterials that are well established for resorbable sutures can be used,” Rogers said. “The metals — magnesium and molybdenum — are also bioresorbable. They are essential elements for a healthy diet, in fact. The semiconductor material for the phototransistor is ultrathin silicon, something that’s also required for natural body processes.”
“The bioabsorbable nature of the design is a distinguishing feature,” said Nazem Akoum, MD, head of cardiac electrophysiology and a clinical professor of medicine at the University of Washington School of Medicine, Seattle. “It allows for multiple deployments throughout the patient’s phases of care and minimal residual hardware which reduces the risk of infections and other complications.”
Much of the motivation for creating something so small, impermanent, and life-saving was to aid pediatric heart surgeries, according to Northwestern University’s paper published in Nature. Approximately 40,000 infants born in the United States each year enter the world with a heart defect. Many of those who undergo surgery to correct the problem require temporary pacing for a week or so.
Temporary pacemakers also can be indicated in adults who have undergone heart surgery — either to keep the heart in rhythm during recovery or as a bridge until a permanent device can be implanted.
The lack of physical leads in the new device avoids a drawback of conventional temporary pacemakers, whose wires penetrate the skin. These devices are associated with the risk for infection, torn or damaged tissue, and bleeding — none of which has occurred so far in tests of the miniaturized implant, Rogers said.
“The work of the researchers at Northwestern is groundbreaking,” Akoum said. “This can replace the conventional approach which utilizes wire electrodes sewn by the surgeon onto the heart muscle and connected to an externalized power source.”
Despite successful evaluations based on animal model tests and hearts from organ donors, Rogers estimated it will complete its approval for humans in about 5 years. Rogers said teaching surgeons how to implant the tiny devices will be relatively easy.
And the technology has room to shrink. “It would come with a sacrifice in operating lifetime,” he said, “but we could go even smaller.”
Rogers and Akoum reported having no relevant financial relationships.
