In a remarkable leap forward for medical technology, engineers at Northwestern University have unveiled a groundbreaking pacemaker so minuscule it can be delivered through the tip of a syringe.
This innovation, detailed in a recent study published in Nature, promises to transform cardiac care, particularly for vulnerable newborns suffering from congenital heart defects.
A Lifesaving Device for the Smallest Hearts
Though adaptable to hearts of all sizes, this ultra-small pacemaker has been specifically engineered with the delicate, fragile hearts of newborn infants in mind. These babies, often born with congenital heart abnormalities, sometimes require temporary cardiac pacing following surgery. The new device offers an unobtrusive, non-invasive solution during the critical recovery period.
Traditionally, a pacemaker is an implantable device designed to help maintain a steady, consistent heartbeat. It’s typically required when a person’s natural cardiac pacemaker either fails to regulate heartbeats adequately or when there’s a blockage in the heart’s electrical conduction system.
The new Northwestern design, however, is more than a mere miniaturization — it’s a complete reimagining of how a pacemaker can be introduced, powered, and eventually absorbed by the body.
Smaller Than a Grain of Rice, Powered by Light
This novel pacemaker is astonishingly tiny — smaller than a single grain of rice. It pairs with a small, soft, flexible, and wireless wearable device that adheres to a patient’s chest. This external component actively monitors the patient’s heart rhythm, automatically activating the pacemaker when it detects an irregular heartbeat.
What sets this system apart is its use of light. The wearable emits short pulses of light that penetrate through skin, breastbone, and muscle to reach the internal pacemaker. These light pulses serve as the activation mechanism, triggering the pacemaker to stimulate the heart and restore a normal rhythm.
A Dissolvable Device That Eliminates Second Surgeries
A distinctive feature of this new pacemaker is its temporary, bioresorbable nature. It’s designed for situations where short-term pacing is necessary — for example, during the first days after neonatal heart surgery.
Once its job is done, the device naturally dissolves into the body’s biofluids, eliminating the need for a follow-up surgical procedure to remove it. All of its components are biocompatible, ensuring they break down harmlessly within the patient’s body.
Proof of Efficacy in Multiple Models
The research team validated the pacemaker’s performance in a variety of scenarios. Their study demonstrated successful operation across large and small animal models and even in human hearts obtained from deceased organ donors.
“We have developed what is, to our knowledge, the world’s smallest pacemaker,” said John A. Rogers, PhD, professor of Neurological Surgery, Dermatology, and in the McCormick School of Engineering, who spearheaded the device’s development.
“There’s a crucial need for temporary pacemakers in the context of pediatric heart surgeries, and that’s a use case where size miniaturization is incredibly important. In terms of the device load on the body—the smaller, the better.”
Designed With Children in Mind
The urgency of this innovation is underscored by the prevalence of congenital heart defects in newborns. “Our major motivation was children,” explained Igor Efimov, PhD, professor of Medicine in the Division of Cardiology and in the McCormick School of Engineering, who co-led the study.
“About 1% of children are born with congenital heart defects, regardless of whether they live in a low-resource or high-resource country. The good news is that these children only need temporary pacing after a surgery. In about seven days or so, most patients’ hearts will self-repair. But those seven days are absolutely critical. Now, we can place this tiny pacemaker on a child’s heart and stimulate it with a soft, gentle, wearable device. And no additional surgery is necessary to remove it,” he added.
Building on Earlier Innovations
This latest creation builds on a previous collaboration between Rogers and Efimov. In 2021, they introduced the world’s first dissolvable pacemaker in Nature Biotechnology. That device, like its successor, was thin, flexible, and lightweight, designed to do away with the bulky batteries, rigid wires, and hardware associated with traditional pacemakers.
The standard practice for temporary pacemakers involves surgically sewing electrodes onto the heart muscle during surgery. Wires from these electrodes exit through the chest, connecting to an external pacing device. Once the temporary pacemaker is no longer needed, the wires are extracted — a procedure that carries risks including infection, dislodgement, tissue damage, bleeding, and blood clots.
“That’s actually how Neil Armstrong died,” Dr. Efimov noted. “He had a temporary pacemaker after a bypass surgery. When the wires were removed, he experienced internal bleeding.”
An Innovative New Power Source
To further miniaturize the pacemaker, the Northwestern team reimagined its power source. Instead of relying on near-field communication as in their previous model, the new device operates via a galvanic cell, a type of battery that generates electrical energy from chemical reactions between two dissimilar metals. When exposed to surrounding biofluids, these metal electrodes form a battery capable of delivering electrical pulses to the heart.
“When the pacemaker is implanted into the body, the surrounding biofluids act as the conducting electrolyte that electrically joins those two metal pads to form the battery,” Dr. Rogers explained.
“A very tiny light-activated switch on the opposite side from the battery allows us to turn the device from its ‘off’ state to an ‘on’ state upon delivery of light that passes through the patient’s body from the skin-mounted patch.”
Harnessing Infrared Light for Deep Body Penetration
To activate the pacemaker reliably and safely, the researchers chose an infrared wavelength of light, which can travel deeply into the body without causing harm. The wearable device continuously monitors heart rhythm, and if it detects a dangerously low rate, it triggers a light-emitting diode that flashes at a pace mimicking a normal heart rate.
“Infrared light penetrates very well through the body,” Dr. Efimov said. “If you put a flashlight against your palm, you will see the light glow through the other side of your hand. It turns out that our bodies are great conductors of light.”
Tiny Yet Powerful
Despite its incredibly small dimensions — just 1.8 millimeters wide, 3.5 millimeters long, and 1 millimeter thick — this miniature pacemaker delivers an electrical stimulation output equivalent to that of a conventional, full-sized device.
“The heart requires a tiny amount of electrical stimulation,” Dr. Rogers said. “By minimizing the size, we dramatically simplify the implantation procedures, we reduce trauma and risk to the patient, and, with the dissolvable nature of the device, we eliminate any need for secondary surgical extraction procedures.”
A New Era for Pediatric and Temporary Cardiac Care
As this technology progresses toward clinical use, it offers a promising new option for both pediatric heart patients and adults in need of temporary pacing following cardiac surgery. Its combination of tiny size, bioresorbable materials, wireless activation, and innovative power sourcing could radically reduce complications, hospital stays, and surgical interventions in the years to come.
See more about the world’s tiniest pacemaker in the video below:
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