Imagining a better pacemaker

Multiple surgeries to replace batteries and leads could become a thing of the past for children with pacemakers

leadless pacemakerPacemakers have made a huge difference for children with congenital heart defects.  Here at the Congenital Heart Center we generally implant pacemaker devices in children each week, for conditions ranging from slow heart rates they were born with to abnormal rhythms arising after complicated heart operations.

Pacemakers are often needed for children with a type of arrhythmia in which heart rhythms are too slow. The device follows the child’s heart beat and keeps it from falling below a certain rate.

While these life saving devices have made a positive difference for countless children since initially developed in 1958, they are not without disadvantages.  One major weakness in our current pacemaker models is the need for battery replacement.  Although a pacemaker uses only microwatts of power, the batteries currently have a lifespan of 6-12 years.  This means that a person with a pacemaker implanted during childhood could require as many as 10 surgeries in their lifetime just because of depleted batteries.

Another limitation of current pacemaker models has to do with the leads, the wires that pass from the device through the veins and into the heart.  Leads may need to be replaced for a number of reasons, either because they fracture and stop working, because the child outgrows them during normal childhood growth, or because the veins through which they are placed can become obstructed and limit circulation as well as making replacement of the leads difficult.

Our team implants these devices in 5-10 children every month, so these limitations are a very real concern for us.  We are always looking for longer-lasting technologies for our kids, who we hope have long lives ahead of them.

One of the perks to working at a children’s hospital that is part of the one of the world’s finest universities is the ability to harness incredible minds from across multiple fields to tackle problems in creative ways.

A few years ago, I started working with Dr. Daniel Inman from the University of Michigan Department of Aerospace Engineering to develop a device we think has the potential to address both these problems.  Together with our colleagues, we have developed a prototype for a leadless cardiac pacemaker equipped with an energy harvester designed to derive its energy from the motion of the beating heart.  The harvesting device will convert heart beat vibrations to electrical energy that can be used to power the pacemaker.

Already, we have finished preliminary studies that show that the energy harvester is functional across a wide range of heart rates (20-600 bpm). This aspect is extremely important to ensure that energy is harvested during periods of lower or higher heart rates, such as during sleep or physical activity. Our preliminary work has shown that the energy harvester could produce up to 25 times the power required for a pacemaker, is small enough in size, and can store extra energy from the regular heart beat to be used in the future, if needed.

We are very excited about the potential of this technology.  While it could still be years before we are able to see a device like this commercially available for physicians to use with their patients, we know that thanks to the research underway here, each day we are closer to that reality.

Take the next step:

David Bradley, MDDavid J. Bradley, MD, is a pediatric cardiologist at University of Michigan C.S. Mott Children’s Hospital.  Dr. Bradley’s research interests include interventional heart rhythm ablation techniques, pediatric device implantation, new pacing devices, postoperative arrhythmias, channelopathies, and sudden death prevention.



best children's hospitalUniversity of Michigan C.S. Mott Children’s Hospital is consistently ranked one of the best hospitals in the country. It was nationally ranked in all ten pediatric specialties in U.S. News Media Group’s “America’s Best Children’s Hospitals,” and among the 10 best children’s hospitals in the nation by Parents Magazine. In December 2011, the hospital opened our new 12-story, state-of-the-art facility offering cutting-edge specialty services for newborns, children and women.