A wireless pacemaker that can dissolve in the body has been created for patients who need only temporary help to regulate their heartbeat.
Since the first pacemaker was implanted in 1958, millions of people have benefited from the devices. According to the national audit for cardiac rhythm management, 32,902 pacemakers were implanted for the first time in the UK in the year 2018-19 alone.
But while some people require permanent pacemakers, others need them for days or weeks – for example after open-heart surgery.
“After a critical risk period, the pacing functionality is no longer needed,” said Prof John A Rogers of Northwestern University in Illinois, US, a co-author of the study revealing the new model.
While pacemakers can already be used for temporary periods, experts say there are problems, including that leads placed through the skin can pose an infection risk. The external power supply and control system can become accidentally dislodged, and heart tissue can be damaged when the device is removed.
Now researchers say they have developed a battery-free pacemaker that can be implanted directly on to the surface of the heart and absorbed by the body when no longer needed. The device – which Rogers said would cost about $100 (£70) – is free of leads and can be controlled and programmed from outside the body.
Writing in the journal Nature Biotechnology, Rogers and colleagues report how they made the device – which is thin, flexible and weighs less than half a gram – from materials including magnesium, tungsten, silicon and a polymer known as PLGA, all of which are compatible with the body but which undergo chemical reactions that allow them to dissolve and be absorbed over time.
The device, which resembles a tiny tennis racket in shape, is powered by wireless technology in which radio frequency power from an external device is sent to a receiver within the pacemaker where it is converted into an electrical current that is used to regulate the heart. Rogers said similar technology was used in applications such as wireless charging of smartphones and electric toothbrushes.
The team trialled the device in hearts from mice and rabbits, as well as slices of human heart and within live dogs and rats. The work in dogs, the team said, showed the system could generate the power transfer necessary for the device to be used in adult humans.
Within rats, the device was able to operate for four days with scans at two weeks revealing it had begun to dissolve. At seven weeks it was no longer visible on scans.
The team said they could tweak the thickness of the substance that encompasses the electronic materials to tailor the timescale over which the device operates and breaks down to suit different needs.
But there is plenty still to do.
“We have tested the devices on small and large animal models and on human hearts from organ donors – but not yet on human patients,” Rogers said, adding it can take years for a new implantable device to pass through the relevant regulatory processes.
Prof Sir Nilesh Samani, the medical director at the British Heart Foundation, which was not involved in the work, welcomed the study.
“This is an exciting and innovative development which could be useful for some patients after cardiac surgery who develop a temporary problem with the electrical conduction of their heartbeat,” he said. “This will need further testing to establish that it is safe and effective but, if this proves to be case, then it could prevent patients ending up with permanent pacemakers unnecessarily.”