Today’s battery-powered pacemakers have to be removed every 5 to 7 years when their batteries run out, a costly and inconvenient exercise. But new technology presented at a meeting in the US at the weekend suggests this may one day no longer be necessary: aerospace engineers from the University of Michigan (U-M) in Ann Arbor have developed a prototype pacemaker that can be powered by the heartbeat of the very heart it is treating.
Pacemakers are implanted medical devices that use electrical impulses to control the heart muscle to regulate the beating of the heart.
Amin Karami, a research fellow in the U-M Department of Aerospace Engineering, says in a press statement released on a study presented at the American Heart Association’s Scientific Sessions 2012, that many patients fitted with pacemakers are children, who are destined to live with the implanted devices for many years:
“You can imagine how many operations they are spared if this new technology is implemented,” says Karami.
At the meeting in Los Angeles, Karami reported a study where he and his colleagues tested an “energy-harvesting” device that uses piezoelectricity, which converts energy of motion into electricity.
Karami says piezoelectricity could also be used to power other implantable heart devices that don’t need much energy, such as defibrillators.
To develop the technology, Karami and colleagues measured the amount of vibration in the chest that results from heartbeats. They then reproduced the same amount of vibration in the lab using a “shaker”, and connected it to a prototype “cardiac energy harvester” that they had designed using the principle of piezoelectricity.
The researchers say there are currently two types of energy harvester: linear and nonlinear. The linear ones work well only at a specific heart rate. The nonlinear one, the type they used in their study, uses magnets to boost power generation: this made their harvester less sensitive to changes in heart rate.
They tested their nonlinear device using 100 sets of simulated heartbeats at different heartrates and found it performed as they had expected.
Using the energy from heartbeats, their prototype cardiac energy harvester was able to generate 10 times more energy than that consumed by modern pacemakers.
“The harvester generates sufficient power if the heart rate is between 20 and 600 beats per minute”, they say in their abstract, and that this “proves the piezoelectric energy harvesters can continuously power pacemakers”.
The researchers say the next step is to implant the device, which is about half the size of the batteries used in today’s pacemakers. They hope to integrate their new technology into commercial pacemakers.
Karami says cell phones, microwave ovens, and similar devices would not interfere with their nonlinear device.
The British Heart Foundation (BHF) says the device needs to undergo clinical trials first before we can be sure it is safe.
BHF medical director, Professor Peter Weissberg, says in a statement:
“If researchers can refine the technology and it proves robust in clinical trials, it would further reduce the need for battery changes.”
“For now, if you have a pacemaker, it’s important to attend your annual clinic appointments. Regular checks will allow you to plan for a battery replacement when it is needed,” he urges.
The National Institute of Standards and Technology and National Center for Advancing Translational Sciences funded the study.
Written by Catharine Paddock PhD