NdFeB magnets vs. pacemakers

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NdFeB magnets, being the strongest known permanent magnets, are warned to be
a hazard to people with pacemakers. I would expect a magnet could disrupt a
device that uses magnetic or certain static fields for operation, such as
computer hard drives, magnetic recording media, CRT screens, etc. It can
also mechanically damage some things, like bending the fragile mask inside
a CRT tube.

But I have found no effect of such a magnet on an electric circuit.

So my question, what is in a pacemaker that would make it susceptible to a
strong magnetic field like this?

Yeah, this is probably more of a biomedical engineering question than just
an electrical engineering question. But sci.engr.biomed seems to be dead
(not counting spam).

 

[Andrew Gabriel]

NdFeB magnets, being the strongest known permanent magnets, are warned to be
a hazard to people with pacemakers. I would expect a magnet could disrupt a
device that uses magnetic or certain static fields for operation, such as
computer hard drives, magnetic recording media, CRT screens, etc. It can
also mechanically damage some things, like bending the fragile mask inside
a CRT tube.

But I have found no effect of such a magnet on an electric circuit.

So my question, what is in a pacemaker that would make it susceptible to a
strong magnetic field like this?

Yeah, this is probably more of a biomedical engineering question than just
an electrical engineering question. But sci.engr.biomed seems to be dead
(not counting spam).

A couple of things I might guess at...

The obvious risk of something metalic/magnetic being displaced.
I don't know if there are any such susceptable parts in a pacemaker.

The other thing is that a magnetic field will exert a force on a
moving electron, i.e. signals travelling along nerves. At some point,
this will disrupt the nerve signalling. A pacemaker is interfacing
with nerve signals, both reading and generating them.