A prototype for a leadless pacemaker that converts the heart's oscillations into voltage generated 10.9% of the energy needed to stimulate one heartbeat in a laboratory benchtop experiment.
If the amount of "harvested" energy could be increased to better power the pacemaker's battery and the device is shown to be safe and effective in humans, a future version of this device could offer the advantages of a leadless pacemaker without potential difficulties when replacing the battery.
Babak Nazer, MD, an associate professor of medicine at the University of Washington in Seattle will present findings from this experimental device at the upcoming American Heart Association (AHA) 2023 Scientific Sessions in Philadelphia.
"We have a generation one prototype to harvest 10% of the energy needed to power the next heartbeat and we are continuing to improve upon multiple elements of our device — material, shape, and assembly — to at least get that harvesting efficiency to 20% before we start to seriously engage in any relationships with any existing medical device companies," Nazer summarized in an interview with theheart.org | Medscape Cardiology.
The team is eager for feedback from physicians, researchers, and potential medical device company partners, he said, regarding the amount of energy harvesting/battery-life saving they would want to see.
"It's a clever, interesting idea, because when the heart contracts it makes mechanical energy that can be somehow turned into electrical energy to power the pacemaker," Kenneth A. Ellenbogen, MD, who was not involved with this research, told theheart.org | Medscape Cardiology.
Ellenbogen, Kimmerling Professor of Cardiology at the VCU School of Medicine in Richmond, Virginia, was a co-author of the 2018 ACC/AHA/HRS Guideline on the Evaluation and Management of Patients With Bradycardia and Cardiac Conduction Delay.
"It's an incredibly interesting proof-of-concept," he said, "but by no means is it going to replace the current battery powered pacemaker," just yet.
The current lithium batteries in the two approved leadless pacemakers "are actually very efficient and can last 15 years in some patients," he noted. And the prototype in the current study only generates about 10% of the electric energy needed by a pacemaker.
Nevertheless, this line of research "has the potential, in the future, maybe to markedly decrease the size of the leadless pacemaker, or maybe markedly prolong battery longevity," he speculated.
"We have a long way to go," Nazer conceded. The study did not consider the energy that a pacemaker requires to monitor the heartbeat and communicate findings back to the pacemaker. In addition, it is not clear whether the device would be safe and effective in people.
"I don't think we will ever become a 'perpetual motion machine,'" he said. The left ventricle is just not that efficient and the right ventricle doesn't squeeze that hard, generally. "How much [energy] we have to harvest is really a question for the ultimate strategic partner and an economic analysis," he said.
"We do have generation 2 device ideas for how we could get there," Nazer added. Future work will focus on increasing energy harvesting through material selection, device structure, and circuit design.
"We hope to prolong battery life further and expand access of this product to younger patients, who would hopefully require fewer implants over their lifetime," he said in a press release from the AHA.
Energy-Harvesting Leadless Pacemaker
As previously reported, in July 2023, the US Food and Drug Administration (FDA) approved the first leadless dual-chamber pacing system, Abbott's AVEIR DR, and in 2020, approved Medtronic's Micra AV leadless pacemaker.
There are several benefits to a leadless pacemaker over a conventional transvenous pacemaker, Nazer said, such as a virtually zero percent infection rate. The device doesn't block any of blood vessels, and there is no lead to fracture.
Disadvantages are that the battery cannot be replaced as easily as that of a transvenous pacemaker. Removing a leadless pacemaker, which is inside the heart, may be difficult, so it may be necessary to implant new pacemakers alongside the previous ones that have lost their battery charge.
A limited battery life and challenges in retrieval of the device from inside the heart, after a long time, restrict the use of leadless pacemakers in younger patients, such as those in their 40s, said Nazer. Current batteries can't be recharged and have an estimated life of 7-12 years, he noted.
The research team aimed to extend the battery life of a leadless pacemaker by harvesting energy from right ventricular pressure fluctuations using a housing made of biocompatible piezoelectric materials, "which can transduce pressure into voltage, and thus recharge the battery," the authors write.
They engineered three prototypes that had a similar size as current commercially available leadless pacemakers, which are about one third the size of a AAA battery.
They placed the devices in a cardiac pressure simulator to test their voltage output in response to oscillating pressures simulating those of the right ventricle at a heart rate of 60 beats/min. The best prototype harvested approximately 10% of the energy necessary to pace a heartbeat.
Nazer's laboratory is funded by the National Heart, Lung, and Blood Institute, of the National Institutes of Health. The study was supported by the University of Washington's Department of Bioengineering via the Masters in Applied Bioengineering program and performed in collaboration with Mohammad H. Malakooti, PhD, from the University of Washington's Department of Mechanical Engineering. A provisional patent on this technology is licensed to the University of Washington. Nazer is a consultant for Edwards Life Sciences and is a consultant for and has received research funding from Biosense Webster.
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Cite this: Novel Leadless Pacemaker Prototype Partly Recharges Itself - Medscape - Nov 06, 2023.
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