WiFi router and possible interference with PM

My 3rd Generator replacement 2/23/2020

by Pjmage@att.net - 2020-04-24 09:19:08

Hi

Had my surgery to replace PM and lead revision. Dr unable to do lead revision because my Subclavian vein is totally blocked. It appears my body responded to this blockage over the years by developing collaterals.  Has anyone experienced this? There are options Dr will discuss with me later.

Thanks for the feedback.

by crustyg - 2020-04-24 12:19:23

I fully understand your reluctance.  I think I was encouraging you to do the test (fairly confident that nothing would happen) precisely so that you wouldn't carry on worrying about it (it's the old get-back-on-the-horse-after-a-fall approach!).

In general our PMs are very robust devices and there are *very* few things we interact very closely with in a domestic environment that might affect normal PM operation.  For the DIY enthusiasts and at industrial premises there are a *few* things that are quite likely to have some impact - arc-welding, industrial-scale generators etc.  The magnetic fields around loudspeakers (and electron microscope and magnetic sector mass-specs) are very carefully shaped and concentrated, so although powerful they are unlikely to cause a problem.   Induced voltages in our leads are the most likely cause of issues (hence the side-discussion about MV interference).  The WiFi router always looked like the most possible culprit - but still unlikely at that.

Best wishes, and thanks for the update.

Just an idea . . .

by Gemita - 2020-04-24 14:28:11

Hello Tac,

if not too impractical ! why dont you take all your equipment (router etc.) with you to your next appointment and re-enact the crime scene at your clinic, to see if you can reproduce those scary sensations.  At least you will be with the doctors and they can place their magic wand over your pacemaker immediately and confirm/see first hand what is going on.  You on the other hand will be in safe hands if something untoward does happen and at least you might be able to get some answers.  I wouldnt just interrogate your data for April 20th - highly unlikely that definitive evidence will be presented to you in this way.  Yes it might see an increase in heart rate and other irregularities during the period, but we can all get sudden increases in heart rate due to a number of factors. If you test the equipment in their presence and the same thing happens, surely you will have your answer ?

Hello Pjmage,

I have developed large collateral veins around my pacemaker site and I have informed my EP because I believe I have developed a blockage somewhere too.  It could have been worse in that we could have experienced a total blockage but nature has intervened and found a way to keep our blood flowing.  I do hope for the best for you.

Interrogation?

by Gotrhythm - 2020-04-24 15:33:24

Don't place any dependence on the event showing up in your interrogation.

The pacemaker only records what it's programmed to record, and only if it happens above a certain percentage.

My pacemaker indicated "no" PVCs while the tech and I watched my heart do 3 PVCs in a row.

Pulsing

by Chiefsub68 - 2020-04-24 16:01:58

Hi Tac. Did it feel like a pulsing of the area around your pacemaker? I had mine fitted about six years ago and very occasionally, when I am at a certain angle sitting down, either in front of the computer or watching the telly, the PM pulses a muscle next to my heart as well as the ticker itself. It is rather bizarre, but this could account for your issue. 

Collateral veins

by AgentX86 - 2020-04-24 17:28:49

I had them form around blockages in my coronary arteries. I had two 100% blocked and another 90%. Evidently the progression was slow enough that the collaterals had time to grow large enough to keep me alive. This process is well known.

I cant see how this is possible

by dwelch - 2020-04-25 00:00:59

I cant see how this is possible, doesnt put out enough power, etc, etc.  TV, radio, etc are passing through your house/body as well.  Your cell phone, etc...

Just a coincidence...

To affect your device it either needs to be a pretty strong field (clime a phone and hug a transformer and that might not even be close enough to the the transformer itself.  Or a signal that speaks the right protocol at the right frequency, which is the box you get an interrogation on (but only through the thing they place over it) or the take home box if you have which is or can be wireless. (or some of the ones with a phone app but you have to have the phone app).   the take home ones should just collect data.

I can't believe this is possible

by LondonAndy - 2020-04-25 18:33:16

Just read your previous post, and IF ANYTHING it would be more likely to be interference from the magnets in the Sonos speaker, not the WiFi router, but even then the speaker would have to be really close to your body.  I have stood next to (and sat on) big, floor standing speakers in nightclubs and they have not affected my pacemaker.

Almost anything is *possible*, but usually unlikely

by crustyg - 2020-04-29 13:27:26

At the risk of starting a flame war, I can see how interference with a PM is *possible* - just not very likely.

Consider someone whose PM leads are not sensing well (check posts from end of March '20), right at the bottom of the usable range, 2mV.  So the PM is only *just* receiving a signal that tells it that there has been an electrical activation in that part of your heart.  Now put a moderate power RF signal right next to (2inches - 25mm) the pacing lead - and imagine that this source induces 50mV of signal in the lead.  Probably the induced voltage will appear in both sides of a lead and the analogue amps in a PM are designed to have a very high common-mode rejection ratio, so normally this induced voltage wouldn't have any effect.  But with the PM's amplifier gain turned right up (to cope with the poor signal from the fibrosis at the lead tip, it does this automatically itself) the amp is now swamped with input, so it doesn't detect anything for several seconds, and the normal heart electrical signal can't be detected.  Depending on how the PM is programmed it might drop into an async pacing mode just to keep you going, and this could easily feel very odd to the PM-user.

Most of the interferences that our PMs can suffer from aren't direct disruption at the PM box end (except a powerful enough magnet to activate Magnet Mode), but are interference with the quite small voltages that our leads pick up from the heart muscle.  That's why hand-held security wands are still a significant problem for PMs - the wand induces quite large voltages in the leads which affect the sense=>pace operation of the PM - only temporarily.  The PM carries on as normal as soon as the wand is removed, which is why they train the operators not to hold the wand over the chest of folk where a positive signal is found in the common PM locations.

There is a world of difference between 'not possible' and 'possible but very unlikely'.  I said before I don't think this is likely to have been cause => effect.  But 'not possible' or impossible - no.  Definitely possible IMHO.  As an aside, the signals and voltages used by the BostonSci Minute Ventilation (measures chest impedance) are an order of magnitude smaller, but there is zero doubt that the measurements (upon which the MV feed into rate-response depends) can be disrupted by varying magnetics fields - mag resistance on a bike turbo trainer is a common one.

It is also possible ....

by LondonAndy - 2020-04-29 17:59:03

... that Tac will be hit by a meteorite and no longer have this worry ... ;)