magnetic interference from Riding mower

I have experienced several incidents of false pacing of my AbbottLAB three-wire ICD.This has happened on my 21 HP. riding mower. I had a three-wire ICD implanted about 5 months ago .The head of electrophysiology at Emory University did my surgery .He's the best of the best . I don't know if the bumps are causing this or the magnetic field. I have read several responses from the group concerning this problem .Has anyone use Shirts using silver-infused fabrics to block the waves? All the research have read say experiments by college professors have researched this concept proving that reflective clothing works. Has anyone used this clothing.Geo


Bumps & Vibration

by Good Dog - 2023-08-25 20:18:47

I am not qualified to answer this, but I'll hazard a guess anyway. My guess is that your problem is NOT the magnetic field. It would seem to make sense that it is the vibration coming from the mower engine and the wheels. I believe that, because I've worked with and on a lot of equipment ranging from chain saws to 4,000 h.p. 11,000 volt synchronous motors over the course of many, many years. I've never experienced a problem such as you describe. Although I have never had the rate response turned-on except for a short few weeks. It seems very hard to believe that a magnetic field from a 21 h.p. internal combustion engine could cause this problem.

Magnetic interference

by AgentX86 - 2023-08-25 20:42:16

Well, I've been on this subject for five years now.  My EP, also at Emory, said that I am not to use a lawn tractor.  Also, I'm not to work under the hood of a car when it's running, for the same reason.  The problem is the alternator.  An operating alternator has a stron rotationg magnetic field that can induce a current in the pacemaker leads.  This can cause an over or under-sensing condition. Since I am dependent, there was not ifs about this proscription.  My wife was in the room so I had to hire someone to mow he lawn.  Darn!

And no.  There is no reasonable (that you could possibly carry) shield against magnetic fields in this frequency range.  You'd need a ferrous (iron) material inches thick.

Edit: Handheld tools aren't a problem because they don't have an automotive type of ignition. There is no alternator.

Bumps and vibrations part 2

by Beni - 2023-08-25 20:57:29

I can only speak from personal experience but  I use a John Deere X380 riding mower (23 h.p.) every 4 days to cut about 1.5 acres of  grass.  The terrain is very uneven and although this mower has a much better ride than the previous one, it still is pretty rough.  It has a gas engine.

In addition, I also use a Case Farmall 30 (32 h.p.) tractor with a 6 foot finishing mower to cut an additional 1.5 acres of meadow once a week.  The tractor has diesel engine and runs a bit rougher than the rider.

Both pieces of equipment are fairly new.

I have an Abbott CRT-D, which like your unit, is a 3 wire device.  While I may need chiropractic treatment after finishing my grass cutting duties, I have never experienced any episodes of false pacing or any issue, really, with my cardiac device while using the equipment. 

I would also add that before I started using the riding mower or the tractor, I checked with Abbott's customer service department and the technician assured me that as long as I maintained a distance of 12 inches between my cardiac device and the engine while it was running, I would be fine.

My advice, if I may offer it to you, would be to contact Abbott directly, telling them the model number of your device and date of implant along with the year, make and model of your mower.  Like everything else, newer models of both the cardiac devices we have as well as the lawn equipment have improved dramatically over time and, perhaps, Abbott can offer you some insights into what maybe causing your pacing issues.  Perhaps they have encountered this issue before.  It has been my experience that the manufacturer - in this case, Abbott - understand the possible limitations of their devices the best.

All the best.

Magentic field

by AgentX86 - 2023-08-26 00:09:50

The size of the engine doesn't matter much.  The problem with riding mowers (lawn tractors, really) is that you're sitting directly on top on the alternator. That's why the issue is working under the hood of the car.  The driver is a long way from the alternator but working under the hood, you could come very close to it.

The other issue may be the lead polarity.  Unipolar leads would much more sensitive than bipolar.  My CRT-P has one bipolar and the LV is unipolar. A bipolar lead will tend to cancel any induced current (induced into both leads).

The manufacturer isn't going to tell you anything.  They certainly don't care about the model of the tractor.  They didn't test it so would have nothing to say, even if they made such statements (other than "no").

Lawn tractors

by Lavender - 2023-08-26 09:22:46

I don't know about the clothing. I do know that my pacemaker tech said it was fine for me to use my cub cadet lawn tractor. I have a Boston Scientific CRT-P. I mow at least weekly. Never any issues. 

Agent X86

by Beni - 2023-08-26 12:03:06

I want to thank you, AgentX86, for your thorough, if somewhat dismissive critique, of my response to GEORGEAZARMITCHELL’s earlier post.  A response, I might point out, that was not directed at you.

Forgive me for failing to realize – not to mention appreciate - your standing as the in-house expert on all things lawnmower related.  After all, as you state, you have “been on this subject for five years now”.  My bad.

Your attempt to undermine the validity of my response by correcting my terminology from lawn mowers to “lawn tractors, really” is interesting.  Petty but interesting.  Actually, a lot of your comments are interesting.  Frequently factually incorrect but interesting.  (Not to put too fine a point on it but blame my fascination with human responses and behaviour on that cursed post graduate advanced degree I have in Psychology.  Human behaviour is my “thing” and I pay close attention to not only what one does or says but how they respond in certain situations. One might say the “nuances” of human behaviour.  But I digress and I certainly would not want you to think I am bragging.  Heavens!  I’m not.  I’m just saying.)  But in the end, your opinions are your opinions and although I disagree with many of them, it would never occur to me to try to belittle you by nitpicking my way through them.  That is a bit of a bully tactic.  A way to silence people.  If there is one thing this forum is, it is civil.  And, for the most part, respectful.  That makes it rare find in this day and age.

I framed my response to Mr. Mitchell very carefully by declaring in the opening sentence I was speaking from personal experience.  I was not making any claim to inside knowledge or expertise.

You correct my mentioning the horsepower of the machines I use by stating “the size of the engine doesn’t matter much”.  Well, it may or may not matter but I was simply replying to Mr. Mitchell using the same metrics he had used in his post.  Now, you may or may not know this about Mr. Mitchell but he listed in his bio having an associate degree in automotive technology.  (I read bios, obviously.)  Because of his educational background, I am going to go out on a limb here, and assume he may or may not know a thing or two about engines.  So, I felt, besides offering an “apples to apples”, as it were, response to his query that there may be some importance in mentioning the horsepower of the machines I use. (He also indicated he is a woodworker and I would imagine he is familiar with table saws, miter saws and drill presses not to mention planers and joiners.  Mind you, that is just an assumption on my part.)

You also go on to speak of “lead polarity”.  In his post, Mr. Mitchell mentions having an “Abbott LAB three-wire ICD” which was implanted about 5 months ago.  He did not mention the model’s name or number.  You immediately make the assumption that the unit may have a unipolar lead.  Wouldn’t the manufacturer be the best source of information for Mr. Mitchell regarding the leads if he should have questions? The leads all have a serial number.  Most, if not all of us, have one of those identity cards and, in many cases, it is easier and timelier to contact the manufacturer for information about the leads than it is our respective specialists.  I mean, just because your unit, which according to your BIO was implanted some years ago, has a unipolar lead does not mean that Mr. Mitchell’s does.  His is much newer.  (And for your information, my CRT-D has a quadripolar lead and two bipolar ones.  Just in case you might wonder.)

Finally, you talk about your EP telling you not to use the riding “lawnmower” because the alternator is located under the seat.  MY EP told me to contact Abbott with these type of questions regarding the safe use of equipment with cardiac devices because “I didn’t design them (the cardiac devices) and these units have become incredibly sophisticated”.  He went on to say that the manufacturers have massive data bases about their respective devices for this very reason.  That is why I suggested it to Mr. Mitchell.

In closing, I would like to add to your not-so-extensive knowledge base in the field of riding lawnmowers, by telling you that the current machine we have, the JD X380 (23 h.p.) has an alternator that is not located under the seat but instead under the hood.  A fly wheel design, regulated, 12 amps.  And to further complicate matters for you, my old JD rider (17 h.p.) did not have an alternator at all!  I mean, who knew?!

The truly sad aspect of your response to my lawnmower comment (which is not the first time you took the time to mock my response.  The last time was about CPAP masks and magnetics.  Magnetics.  Another area of expertise.  BTW, do you use a CPAP machine?  Are you aware of the multitude of mask and frame styles.  I do use one and I am aware of the types, some of which use magnets, out there.) occurs to me when I recall your note to me when I first joined the forum.  I had expressed my apprehension about my upcoming surgery and recovery period and your response was the vey epitome of kindness and support.  I felt very comforted by it and I appreciated you taking the time to ease my concerns and anxiety.

My apologies to the members of the Forum for such a lengthy response.




by docklock - 2023-08-26 15:33:17

I now know why there are so many "views" and so few "comments".  

cant imagine

by dwelch - 2023-08-27 02:10:54

I cant remotely see how an alternator even if you were hugging it was emitting that much emf. You need something on the order of a dam power generator or a substration transformer to generate a field that would affect the device within 6 inches.   Sitting on it means you are far more than the one to half an inch you would need to be from that alternator to be in its field.

Find a metrologist, rent a good gauss meter and you will see what I am talking about.  

The problem is elsewhere.

If we want to continue to persue this (fill in the blank) notion then lay some tin foil on the seat, or a sheet of thin metal of some sort, then you would need a truck sized coil to generate a field that would go around that barrier and be strong enough at a couple of feet away.  Wearing a shirt will either do nothing or keep you within the field instead of out.

If you have a rate response device, then that is likely the answer.  Can have them disable it, can wear a halter or perhaps the device logs this and a simple dump of the events will show time of day of these events.  


Dam Power generator

by Good Dog - 2023-08-27 07:52:22

Call me stupid, because I guess that would be fair. In the 36+ years I've had my pacemaker I've thoroughly tested it for magnetic field interference. That is why I made the previous comment that I did. I find the comment from dwelch regarding sitting on a dam power generator interesting, because I came pretty close to doing exactly that. While attending a multi-day seminar at the New York, Niagara Falls power generating facility, I actually leaned up against an operating turbine. I have to say that in addition to working around large motors and generators my entire career, this arguably may have been the dumbest thing I ever did. Regardless, my point is that it had zero effect on my PM. I always believed that strong magnetic fields would likely just trigger the magnet rate of 85 bpm. If so, and/or if I suddenly felt bad I would simply move away as recommended by Medtronic.

I think that we also must keep in mind that the lawyers likely play the biggest role in preventing the PM manufacturer from giving safety assurances for things beyong their control.

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