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Discussion Starter #1
A week and a half ago I had a pacemaker put in. I'm doing quite well and am quite happy to have this little device insuring a regular heartbeat. I have a little booklet advising me of things to avoid. There are three things on the list that must be avoided at all cost.

1)Stun Guns
2)Jackhammers
3)Leaning over the open hood of a running car engine.

It seems that alternators put out a magnetic field very bad for pacemakers. It dawned on me while driving to work this morning
that this might end my Elise dreams as the engine is close to your back, not front mounted a distance beyond your feet, enclosed in a metal compartment. The Elise being glass also might throw a wrench into the works as hood open or closed wouldn't make much difference shielding wise. I know there is a sheet metal called mu-metal that is very effective at shielding from magnetism, which I will investigate.

If you would please take a look at how high the aluminum chasis
comes in relation to your back/neck. How much metal is between the engine and your back ? Also which side is the alternator mounted on, drivers or passengers ? Approx what is the distance between the alternator and the drivers spine ?

Thanks for your time

Steve
 

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First, glad to hear the pacemaker is working well for you, and you are recovering nicely.


I don't have my car yet, but I took a lot of pictures. I seem to remember that the firewall is aluminum. I am not sure it will act as any sort of shield for magnetism. But it may shield against electromagnetic radiation. It's been a long time since I had physics, but I think they are different, and shielding against them is different.

It's not something I would want to test in an uncontrolled enviroment. I would guess the real problem would be unshield igition system voltages (i.e. non-resistor plugs or spark plug wires).

I hope thing work out. However, apparently AM reception is a problem on one guys car, so electromagnetic interference could be a problem.

Greg
 

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That's an interesting list of stuff to avoid! Fortunately, no jackhammers in this car, AFAIK. :D

Glad to hear you're doing well.
 

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In my experience with pacemakers in the cath lab and ICU, it'd take a pretty significant magnetic force right over the site of the pulse generator for it to have any affect. The magnet you use to adjust pacers is very powerful but must be held directly on the spot. Seems highly unlikely that it'd be an issue, I looked, the alternator is a good 2 feet away from driver's side it's on the right and the headers are in the way as well.

Just to ease your mind tho, should have gotten a pacemaker id card from the manuf. Call the toll free number, I'm sure it's not an issue.
Chris
 

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Discussion Starter #5 (Edited)
zvezdah1 said:
In my experience with pacemakers in the cath lab and ICU, it'd take a pretty significant magnetic force right over the site of the pulse generator for it to have any affect. The magnet you use to adjust pacers is very powerful but must be held directly on the spot. Seems highly unlikely that it'd be an issue, I looked, the alternator is a good 2 feet away from driver's side it's on the right and the headers are in the way as well.

Just to ease your mind tho, should have gotten a pacemaker id card from the manuf. Call the toll free number, I'm sure it's not an issue.
Chris
I have called them, after making the post, and the magic number is 10 gauss. Above that at the pacemaker position will affect the device. Below it is safe. The Elise is supposed to get your heart pumping, just not that way :) The manufacturer doubted it would be an issue, but since it is a potential life threatening one I better check.

I suppose I'll have to find a measuring device and set it in the drivers seat with the engine reved once a demo car comes into my area. Thats good news that the headers are between the driver and the alternator and that it is on the passenger side.

Regards

Steve
 

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I do solid state Nuclear Magnetic Resonance (NMR) spectroscopy. We have big magnets. I'll attach a picture of one of our magnets and give you an idea of where the ten gauss line is. I'm sure that the ten gause line for your alternator is not very far out (if it makes 10 gauss at all). Ten gauss is about what you get from a strong refrigerator magnet right at the surface.

This magnet makes 14.09 Tesla. That's 140,900 Gauss. The 5 Gauss line is about 10 feet from the center of the magnet. The 10 Gauss line is just a bit outside of the surface of the magnet casing.



In short, you probably don't have anything to worry about unless you press the pacemaker up against an alternator at high RPM. And even then I don't think stray fields are your biggest concern.
 

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Discussion Starter #8
NMRJock said:

This magnet makes 14.09 Tesla. That's 140,900 Gauss. The 5 Gauss line is about 10 feet from the center of the magnet. The 10 Gauss line is just a bit outside of the surface of the magnet casing.

Thanks for the explanation and photo. You made things pretty clear. I wonder why they bother to mention the "threat" at all.
I don;t think I'll worry much more about it.

Regards

Steve
 

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hey, nmr...where'd ya go to school. i did a fair bit of nmr way back when in grad school at UF.
 

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Information

Hey Steve,
I hope you are doing well. Please call me directly at 914 939-7200. I will put you in touch with someone at Lotus UK who could probably answer all your questions with certainty...........Regards, Mark Starr
 

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Looks like a small world, I used to work for a company that makes NMR instruments. I'm sure that Jock can explain the physics of magnetic fields much better than me (I was on the software side of things), but I also remember that the fields drop off very quickly with distance. If you get close to one of these magnets, they can wipe out your ATM card, or make a mechanical watch stand still. If you stay a few feet away, that won't happen. I believe there's normally a "no pacemaker" warning sign at the door of the room hosting the magnet. Keep in mind that these are serious magnets, you get an idea of the dimension from Jock's picture, and there's a superconducting coil in there. A car alternator is peanuts in comparison.

You certainly don't want to take any risks, but also note that the warning you quote says "leaning over" the engine, not standing close. For example on my car, the alternator sits at the top of the engine, close to the front. Your chest could easily get within inches of it if you leaned over the engine to work on something. That's probably what they're thinking of with the warning.
 

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Sownman said:

I suppose I'll have to find a measuring device and set it in the drivers seat with the engine reved once a demo car comes into my area. Thats good news that the headers are between the driver and the alternator and that it is on the passenger side.
Steve,
Why don't you call the local college and borrow a meter from the lab and check it with a demo car?
 

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LotusLust said:
hey, nmr...where'd ya go to school. i did a fair bit of nmr way back when in grad school at UF.
I got my BS at Ohio Northern University and I'm about to finish my PhD at Michigan State. The Elise is my graduation present to me.
 

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ConeFusion said:
Looks like a small world, I used to work for a company that makes NMR instruments. I'm sure that Jock can explain the physics of magnetic fields much better than me (I was on the software side of things), but I also remember that the fields drop off very quickly with distance. If you get close to one of these magnets, they can wipe out your ATM card, or make a mechanical watch stand still. If you stay a few feet away, that won't happen. I believe there's normally a "no pacemaker" warning sign at the door of the room hosting the magnet. Keep in mind that these are serious magnets, you get an idea of the dimension from Jock's picture, and there's a superconducting coil in there. A car alternator is peanuts in comparison.

You certainly don't want to take any risks, but also note that the warning you quote says "leaning over" the engine, not standing close. For example on my car, the alternator sits at the top of the engine, close to the front. Your chest could easily get within inches of it if you leaned over the engine to work on something. That's probably what they're thinking of with the warning.
Did you work for Chemagnetics before Varian bought them? I just spent a week in Denver and a couple of days in Ft. Collins.
I have gotten new credit cards a couple of times over the years. Today's actively shielded magnets (the one above is not) move the five gause line way in. This is important for siting these systems, as you can't have the five gauss line in an uncontrolled area (hallway, sidewalk outside, etc). We do have pacemaker warning signs most of the places we're supposed to...
 

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ConeFusion said:
No, for Bruker.
So TopSpin is your fault? Actually, I don't have any experience with it. I may soon enough. We just ordered a 900 from Bruker, to be delivered in a few months. If it arrives before I leave I'll spend some time playing with it.
 

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Discussion Starter #18
Re: Information

Mark Starr said:
Hey Steve,
I hope you are doing well. Please call me directly at 914 939-7200. I will put you in touch with someone at Lotus UK who could probably answer all your questions with certainty...........Regards, Mark Starr
Mark...

Thanks for your offer. I may call, but as I just met with the Guidant
(pacemaker company) and doctor, I'm certain there is no issue at all. My first information indicated that a sufficient magnetic influnence could turn off or alter programming of the device. Today
I was told the issue is that the device will fail to give it's difibulating shock while in the presence of a magnetic influence. When the magnet is removed operation immediatly resumes normally. From what the Guidant people, NMRjock, Chris and others have said. Alternator magnetic field influence in the drivers seat should not be an issue at all, and even if so is only as issue while in drivers seat.

Thanks to all


Steve

Regards

Steve
 
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