Representative illustration. A traditional temporary pacemaker requires invasive open heart or endovascular surgical methods to both implant and remove.
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Scientists at Northwestern University in the US have engineered a pacemaker smaller than a grain of rice. The makers of the device say it can be implanted in a non-invasive procedure and that it doesn’t need an external power source to operate.
The device opens the possibility of replacing other, more cumbersome medical procedures, especially for infants born with congenital heart disease and people recovering from cardiac surgery.
The team published its paper in Nature on April 2.
People who have just undergone heart surgery need temporary pacemakers — as do infants born with congenital heart disorders. Both groups are prone to declining cardiac health and slow heart rates for some time.
The biggest highlight of the new device is its small size — so small that its developers have said it can simply be injected into the heart. While scientists at Oklahoma University had previously built a small pacemaker, the new one from Northwestern University is reportedly smaller by 2.5-times.
A traditional temporary pacemaker requires invasive open heart or endovascular surgical methods to both implant and remove.
In the four to seven days when the pacemaker is required, electrodes in larger devices also have to be integrated with the tissue, rendering their removal a non-trivial procedure for the patient. In fact, this procedure has been known to increase the risk of infections, internal bleeding or sometimes even death.
The new device has been made with bioresorbable materials, meaning that after the required duration, the pacemaker simply dissolves into the tissue, causing no harm to the person.
It has two electrodes on the bottom-most of its multiple functional layers. They interact with the body’s fluids to convert chemical energy into electrical energy, like how a car battery does but at a much smaller scale. This is its power source.
Once the pacemaker is injected into the body, the patient wears a patch on the outside of the chest that relays signals to the device. If the patch detects any irregularities in the heart rate, an LED attached to it flashes infrared light at the rate at which the heart ought to beat. The pacemaker receives these light signals and adjusts its signals.
Infrared light passes through the body pretty easily — it’s the same wavelength of light pulse oximeters use to elucidate blood oxygen levels, for example.
The researchers measured the delay between the flashes and the readjustment to be 25 microseconds, “far beyond the requirements for cardiac pacing,” per their paper.
The researchers said many of these little pacemakers could be placed along the heart’s walls to help pace the organ at multiple points.
They were able to test and confirm the usefulness of the device in adult hound dogs, rats, and pigs as well as in donated human hearts.
Navaneeth Krishna V. is an undergraduate research student at IISER Pune.
Published – April 22, 2025 06:00 am IST