On Tue, 6 Jan 2009 23:21:22 -0800, "Michael Koblic"
wrote:


"Ignoramus6829" wrote in message
m...
Here's a very good article on this subject.

Cardiac pacemakers are electronic devices with sensing circuits which
detect small electrical signals from inside the heart. Pacemakers may
detect extraneous electrical signals from other sources. The pacemaker
can incorrectly interpret these signals as heart activity, which may
inhibit the pacemaker. The result could be no output pulse or
asynchronous pacing. Asynchronous pacing means that there is no
coordination between the heart and the pacemaker.

If you have a St. Jude Medical pacemaker and use or are in close
proximity to an electric welder, you shouldn?Tt have any
problems. However, this doesn?Tt mean that there is a total absence
of the effects of welding interference on pacemakers. Any problems
caused by radiated interference will end when the arcing ends.

http://www.sjm.com/_MediaAssets/docu...arcwelding.pdf


Similar precautions apply to working on car engines and possibly other
activities generating electromagnetic fields. I have always been interested
in the effect of amateur radio on pacemakers. The research I did, some with
help of pacemaker company representatives, was rather inconclusive.
Personally I would avoid a ham shack in operation having seen RF sparks on
metal objects otherwise not connected to anything, light bulbs connected to
a piece of wire lit up by a KW with a key down, neighbours' lamps turned on
and off and many other amusing phenomena.

The message I think is that you *can* have problems while arc welding, be it
a St. Jude, Medtronics or any of the others. One problem not mentioned is
re-programming the pacemaker which may enter the back up mode and not revert
when the EM field is gone. Some may not notice it, some may become
symptomatic.

A similar situation arises during surgery when the surgeon uses
electro-cautery to stop bleeding. The usual procedure in this region is to
convert the pacemaker pre-operatively to a fixed output that cannot be
inhibited and crank up the voltage. The pacemaker is checked and
reprogrammed carefully back to the original settings after the surgery. This
is clearly not an option while welding :-)

Oh, and I would not expect a discussion with your MD to provide any more
information than what is in the article. Unless he works in a major centre
and does nothing but pacemakers. Even then I have my doubts...

He does work in a major cardiac center, he does specialize in ICD's
and there are at least two major mfrs of ICD's here in town ... so he
just might know more than one might expect.

Don Foreman wrote:
Oh, and I would not expect a discussion with your MD to provide any
more information than what is in the article. Unless he works in a
major centre and does nothing but pacemakers. Even then I have my
doubts...

He does work in a major cardiac center, he does specialize in ICD's
and there are at least two major mfrs of ICD's here in town ... so he
just might know more than one might expect.

Witht that description it is his job to know it *all*...