Wi Fi Router and pacemaker

It's possible

by crustyg - 2020-04-21 03:26:58

External devices that actually directly affect a PM are uncommon in a domestic setting - the PM electronics are well designed and well shielded.  The leads are inherently unlikely to act as simple aerials as these days each lead is effectively a co-axial cable where the inner cable is shielded by the external lead.

However, unless you have had the magnet response on your PM disabled (very unusual) a strong enough magnetic field near the PM could have switched your PM to a fixed pacing mode which might be quite a lot faster than your normal resting rate and which could make you feel odd.  The Sonos speakers some powerful magnetic fields around them - one of the reasons why they sound so good.

The PM detects quite small signals and it's possible that one or both of your leads could pick up enough of a signal for your PM to see an induced signal that masquerades as a normal electrical activity from your heart so the PM doesn't deliver a pace at that moment, or worse, your PM tries to outpace the signals that it sees (depends a lot on your pacing mode and the specific features enabled in your PM).

All the above is theoretical, but assuming that it's what happened, as you saw, moving away fixed the issue.  Magnetic fields reduce by an inverse square function of distance so even a small increase in distance reduces the magnetic coupling really quickly (and pax engineering experts, it's not a static monopole).  And of course, it's possible that it was all just coincidence.  Post hoc, ergo propter hoc is the old Latin warning that just because something happens after something else, doesn't necessarily mean that the events are causally related.  Smart folk the ancient Romans.

Please don't read the above as a warning to not go near your smart speaker or WiFI hub: just recognise that it's *possible* that there was a cause and effect interference *AND* that simply moving a little further away fixed the problem.

HTH.

I agree it's unlikely

by crustyg - 2020-04-21 09:59:01

But not impossible.  It's an easy enough experiment for Tac to conduct, but would require a certain amount of determination.  I used to work a lot with moderately high voltage DC circuits (200-1500V) and it surprised me how inadvertently touching a small solder spike can feel just like a DC shock: once experienced there's an obvious reluctance to put fingers in there again, even after a properly working (and tested) volt-meter has just shown that all is safe.  Back in the day, working on colour CRT TVs (25kV capacitors) with metal chassis that were often live produced a healthy respect for the energies involved.  Lots of fun safely discharging that kit (and using a safety isolation transformer).

Perhaps because I'm old and stupid, if it were me, I *would* redo the test / experiment just so that I know.  On a slight tangent it's now been proved beyond any doubt (in my tiny mind) that the MV feature of my PM is affected by magnetic fields from static bikes with non-friction resistance units, and we know from BostonSci's recall/firmware update back in 2018 that it's possible to create incorrect signals in the leads that can affect a PM's operation (although I accept that MV is a special case - really tiny AC voltages compared to normal heart activation signal sizes).

HIGHLY UNLIKELY

by AgentX86 - 2020-04-21 10:00:59

There is VERY little chance that the router had any affect on your PM, nor your speakers. If the magnetic switch were activated the PM would go into a "safe mode", which is a constant rate (something like 60bpm) with all features turned off. It would not race. Unless you were laying right on the speakers this isn't possible anyway.

Almost assuredly this is a coincidence and is something that needs to be checked out. If you can catch it in the act and transmit the PM data to the mothership immediately, your doctors will get a better picture of what's happening than relying on the data stored in the PM's memory.

I agree

by Graham M - 2020-04-21 14:51:18

with AgentX86. I work with electron microscopes that have electromagnets as lenses and haven't had any problems. My Medtronic PM has a safe mode of 85bpm, which I can recognise because the EP turned it up for a few seconds so that I would know how it felt.

You make my point very well

by crustyg - 2020-04-21 17:04:18

I think you are correct, that there was no causal relationship between what Tac felt and being so close to the electronics kit.  Which is exactly why I said that *I* would repeat the activity as an experiment to put my mind to rest that it's a safe activity that I wouldn't need to worry about ever again.

For what it's worth my Magnet rate is currently set to 100bpm, which seems odd given that my lower rate limit is 50bpm and would certainly feel very uncomfortable to me if activated.  It's not just that no-one has ever looked at it - it was enabled for the first six weeks post implant.  Perhaps it's just as well that my magnet response has been disabled.  I expect that the EP techs and I will discuss the magnet rate at my next clinic visit.