Pacemaker Safety and ICD's are a concern with some of our customers. We wanted to take some time and address any concerns with our product and the safety of pacemakers.
The overarching concern with any pacemaker or ICD is magnetic fields. Magnetic fields can stop these devices or reprogram these devices. We want to be detailed in our response to safety so you can make the most informed decision.
We have always been cautious about making broad statements about how pacemakers might behave around our product. Our FAQ has deferred to medical professionals:
Is the ChairSpeaker safe with pacemakers? We are not medical professionals, so we cannot offer guidance on pacemaker safety. Please consult a physician for this information.
While this is a safe statement that keeps our lawyers happy, it does little to help someone buying a ChairSpeaker or help doctors understand the concern. We have put together our findings and our test on the risk of using a ChairSpeaker with a pacemaker.
We understand how strong our magnets are in our speakers, but understanding the magnetic susceptibility of every pacemaker and ICD (implantable cardioverter-defibrillator) ever implanted seemed too daunting a task. Lately, we've been wondering if there's some answers that might help customers and doctors looking at a ChairSpeaker.
What Magnetic field strength is OK for use?
We've found a few sources that cite 10 gausses as the maximum magnetic field in which a pacemaker will operate properly. Sources include this report on pacemakers and music players from Boston Scientific, one of the major manufacturers of pacemakers. They say, "As described in the pacemaker and defibrillator instructions for use, exposure to strong magnetic fields >10 gausses (1 mTesla) may alter implanted device function."
Research presented at the American Heart Association's Scientific Sessions 2008, as summarized in this article, also indicates that a "Field strength of 10 gausses at the site of the pacemaker or defibrillator has the potential to interact with the implantable device."
Another good paper also described a 1 mT (1 milliTesla = 10 gauss) limit: Interference of neodymium magnets with cardiac pacemakers and implantable cardioverter-defibrillators: an in vitro study, from the Institute for Biomedical Engineering University in Switzerland. A Swiss public health site also references that paper and describes safe distances to some neodymium magnet sizes.
Medtronic, another major manufacturer of pacemakers and ICDs indicated a 5 gauss limit for DC magnetic fields. Since this topic is a critical medical issue, we suggest deferring to the lowest, most conservative value of 5 gausses.
How far from my magnet is that?
For a given size magnet, you can use a magnet calculator to find the magnetic field strength at a distance from the magnet. Using these calculators you can find the distance where the field strength drops below 5 gausses.
We've worked out some of the math and summarized it in the table below. It shows the minimum distance to get below 5 gausses for many cylinder magnet sizes.
Note that these numbers are only true along the magnetization axis of the magnet, and for a magnet in free space. Other magnets or steel objects nearby can alter results. That said, it's a great guideline. After we had this guideline we used an EMF -Tester ( Meterk MK08) to confirm our calculator's results.
As you can see in the picture above the result is below the calculated perfect magnet in a perfect environment. Our measurements were lower as expected 3.4 gausses at around 2 inches.
In short our research showing that 5 gausses threshold should not be reached in typical use. However, if the ChairSpeaker was to be placed within 6.6" of the pacemaker a theoretical limit could be reached. Our actual test shows the actual 5 gausses limit under 3 inches.
In typical use, the ChairSpeaker is about 10 to 24 inches away from any typically placed Pacemaker or ICD. Never place a speaker on or near any pacemaker or ICD.
As a point of reference, I tested my iPhone X I received a reading of 35.4 gausses.
KARE, LLC makes no warranty concerning the validity of the 5 gausses threshold described here for deactivating implanted medical devices. It's impossible for us to know, or make blanket statements about every medical device ever implanted. This article is intended as more of a guideline to help you and your doctors assess risks associated with ChairSpeaker. Please consult your physician if you're going to get a strong magnet anywhere near your pacemaker or another medical device.