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Hopitus - 03 Jul 2005 18:30 GMT

Got a new wireless phone (changed carriers, different type/model instrument)
and digging through user's manual, found all this "beware" stuff re medical
devices -
mainly pacers, not to get phone close to body @ that location.
That immediately started me wondering if cell phone proximity could damage
either that Holter monitor you wore, or alter its readings to doc's office
interpretation.
Maybe Howard B. knows the answer.....Holters weren't mentioned in my
manual's "bewares".

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Howard C. Berkowitz - 03 Jul 2005 19:45 GMT

> Got a new wireless phone (changed carriers, different type/model
> instrument)
[quoted text clipped - 9 lines]
> Maybe Howard B. knows the answer.....Holters weren't mentioned in my
> manual's "bewares".

I wouldn't worry about it. The Holter measures signals between
electrodes, at frequencies quite different than cell phones. I've worn
them several times and never had problems with low-power electronics.

I do have a pacemaker, and have gone through the literature about
possible interference as well as discussing it with electrophysiologists
(a subspecialty of cardiology). There really aren't hard reports of
damage with low-power devices.

There are reports with high-power things such as large transformers (as
in electric welders), the magnetron microwave generators of OLD
microwave ovens, and MRIs. The biggest danger, even with the MRI, is
less that the magnetic field is going to yank the pacemaker out of the
chest -- although that has happened -- but that a magnetic field, at
right angles to the internal wires, will produce electricity and conduct
into the heart. There's also a danger these wires can heat.

Recently, there are newer MRI techniques that can safely image parts of
a body other than the chest.

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Hopitus - 03 Jul 2005 20:39 GMT

Thanks, Howard..I forgot you do have a pacer. My eyes lighted on "large
transformers" in your explanation: in my usual location of work before I
retired a year ago, the ER xray room (largeish size comparatively) in two
separate corners of the room were the two huge transformers that converted
AC current 110-220 of our normal needs to the kilovoltage necessary to
produce ionizing radiation.
I wonder if you have any statistics on pacer effects from *those*
high-voltage babies....maybe they have some kinda built-in "fail-safe" like
the electricity circuits they use (i.e. - complete shutdown if any probs)
for pacer effects, I dunno. Something we used to ponder over OT
is that it took almost the exact kilovolts to xray a hoomin finger (2KV) as
were necessary to fry Ted Bundy in the Chair, back in '89 (before they all
got kinder, gentler "lethal injection" on their way out.....wierd but odd
fact.

>> Got a new wireless phone (changed carriers, different type/model
>> instrument)
[quoted text clipped - 29 lines]
> Recently, there are newer MRI techniques that can safely image parts of
> a body other than the chest.

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Howard C. Berkowitz - 03 Jul 2005 23:45 GMT

> Thanks, Howard..I forgot you do have a pacer. My eyes lighted on "large
> transformers" in your explanation: in my usual location of work before I
[quoted text clipped - 3 lines]
> AC current 110-220 of our normal needs to the kilovoltage necessary to
> produce ionizing radiation.

That's an excellent observation. I have concluded I should never use my
arc welder. Left behind by a contractor, I've rarely used it anyway, and
I can always get a gas welder if I really need it.

> I wonder if you have any statistics on pacer effects from *those*
> high-voltage babies....maybe they have some kinda built-in "fail-safe"
> like
> the electricity circuits they use (i.e. - complete shutdown if any probs)
> for pacer effects, I dunno.

There's really very little quantitative data. The conceptual model,
which I've never seen formalized, is the heat or electricity that would
be captured by the surface area of the internal leads, given the
magnetic field strength and distance of the transformer. Inductive
pickup of electricity (e.g., cell phone) seems to be less of a concern.

I'm blanking on the current directly applied to the heart that will
cause ventricular fibrillation, but there's a clue in that the energy
level of an internal defibrillator is 10 to 30 times less than that of a
chest defibrillator.

> Something we used to ponder over OT
> is that it took almost the exact kilovolts to xray a hoomin finger (2KV)
[quoted text clipped - 39 lines]
> > Recently, there are newer MRI techniques that can safely image parts of
> > a body other than the chest.

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jmcquown - 03 Jul 2005 23:16 GMT

> Got a new wireless phone (changed carriers, different type/model
> instrument) and digging through user's manual, found all this
[quoted text clipped - 5 lines]
> Maybe Howard B. knows the answer.....Holters weren't mentioned in my
> manual's "bewares".

Thanks for thinking of me! I only use my cell when I'm out of town so it
shouldn't be an issue.

Jill

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