Axiom Home Page Forums General Discussion Advice from Axiom Owners Speaker Magnet Fields and ICD's

Hi Guys,

I wonder if anyone has had any experience with and Internal Cardiac Difibulator (ICD). My g/f may have to get one, and one of the comments from the doctors was that strong speaker magnets may have in impact on these units (ICD), and cause them to go off! An ICD is a unit that is a built-in difibulator that fires if the patients heart has an irregular beat, or stops.

My set-up is M60, Q8s, VP150, and an SVS20-39Pci in the living room. I have the room set up in 5.1, so the speakers are all around the room. The sub is in the corner by the TV though, so its magnet is probably 10 feet from the sitting area. The M60's are probably 7 feet from sitting area as well. The VP150's are on either side of the couch, probably 6 feet away from listening position.

If anyone has had any experience with these units (or maybe even has one) I would really appreciate any comments. I sure hope I don't have to get rid of my stereo

From reading the Axiom site, the M60's and VP150 are magnetically shielded ("Video Shielded"). So the SVS and the QS8's are the only ones of concern. However, I would guess that the SVS is shielded as well. BTW, sorry about the bad news and I hope all is well. Best wishes.

I'd check with SVS to see if that sub is sheilded; it would be my biggest concern, although the M60s and QS8s may also be a problem. The VP150 is shielded, so you shouldn't have to worry about that one. Other than just thinking off the top of my head, I don't have any experience with such devices.

hey there Din, I happen to be a Medtronic Rep in the field, in the cath lab and OR implanting ICD's almost every day. As a matter of fact I've got a case first thing in the am tomorrow, implanting a BI V ICD. Your ? about ICD's is common, and a good one, but trust me these devices are solid, and totally misunderstood. With reguard to strong magnetic fields, Yes they ( strong mag fields) can temporarily! suspend detection to the ICD which is supposed to detect tachyarrythmias, ( Fast lethal heart rates) but you need to be very close for this to happen, and its only temporary, thats what I educate my Pt's who receive them. Listen if your G/F is getting one I'd be glad to share some insight to the available technology out there, believe me when I say Pattern and rate discrimination and a fast charge time with a battery voltage that wont EVER drop below 2.6 volts, with ATP therapy down to 240ms is HUGE, (of course im showing off here but it's not for my sake..... if you get my meaning).BTW, I had a wonderful experince last week when a father, at his daughters wedding went into VF and was Defibrillated out of VF into a Normal Sinus Rthym, in under 8 sec,(he forgot to take his meds, tisk, tisk)and was able to tell me how proud he was of her, bla bla bla you get the pic, you can E Mail me privately if you wish to talk.........Sorry to babble on

WOW Steve! This was one question I'd have bet money couldn't be answered here. I was going to suggest that Din contact a medical expert. I figured a medical expert in this field (such as you) would be more likely to know about the danger a speaker's magnet might pose to an ICD, than a speaker expert would know about the subject. What I didn't figure on, was that a medical expert on the subject would show up here. One hell of a first post. Well done.

Thanks, I truely hope his g/f gets the right device for the right reason.(and programmed correctly) It really comes down to how strong his EP or Cardiologist is actually. They ultimately decide. In my experience the good Doc's are up to date with the latest indications etc, and believe me there's some Docs out there I bash my head against, often with no success, I could tell you some funny stories as to how they decide what Pt"s get what, it would Blow your Mind

Thanks for the info Steve,

I do have another question though, how close is "too close"?

She has been seeing doctors in Alberta. I talked to my family doctor, and he confirmed the Dr. she is seeing is a very respected cardiologist, in Alberta anyway. She is going in next week for a boat load of tests in order to make a final decision.

Din, I spoke to my tech guys in Minneapolis, you need 10 gauss to close the reid switch inside the ICD to suspend detection. In order for that to happen the speaker would have to be in contact with the person ie, moving the speaker. Also, my tech told me they have tested in the field for exactly this issue, without ever having a problem. So hopefully as long as your playing sweet music thru your axioms that your g/f can enjoy, your golden, and good luck with everything. SteveR

Hi Din,

Fascinating answers from Steve, and there is also the inverse square ratio law is at work here. Without looking it up (anyone well versed in this?), the farther you move away from the magnetic source, the magnetism drops off rapidly (it isn't a linear drop). At a distance of two feet, unshielded speaker magnets would have no effect.

The same law comes into play with Sound Pressure Levels vs. power requirements for speakers as you increase the distance from the loudspeaker.

Regards,

Interestingly, though I have no experience with this at all, I intuitively assumed whta Alan said. Upon reflection, I think that's because I can remember playing with magnets as a boy. You could set them on a table (arbitrary numbers here, just for example's sake) say an inch apart and they'd just sit there. Move them a fraction of an inch closer, and "SNAP" they're joined at the hip. It was like going from no magnetism, to intense magnetism, with only a slight change in distance.

Moving them apart was the same. Lots of attraction as you moved them apart to, suddenly, no attraction. The magnetism fell off rapidly, not in a linear manner.

You can learn a lot about physics by experimentation as a boy. Such as how fast a body (your own) call fall from the rafters of the unfinished new house you're playing in, all the way to the basement. Trust me! It's VERY fast!