They have done something like that. The two devices on offer are:

1) A unit that has multiple (~ 8 IIRC) electrodes placed (by hospital
staff) at various points on the patient. It has a button to record an
event marker. I'm unsure of the upload method but it may be USB. This
unit would do the job perfectly, but the problem is you only get the use
of it for 24 hours and there is a long waiting list to even get one.
Murphy's Law has so far meant an episode never occurs when the unit is
in place.

2) A box with 4 electrodes (studs) built onto the unit. It records 60
seconds of heart beat when activated. You can only record 2 events
before having to download over the phone to the hospital. The problem
with this unit is that by the time the patient gets the unit positioned
correctly (remember they may have been asleep), the episode is half
over. I checked the unit for the manufacturers details, but it appears
they have gone bust! I'd say this unit is old technology and next to
useless for a lot of applications.

I've found some EKG circuits on the 'net (one here:
http://home.att.net/~jnozum/EKGHappy.htm), so that may be a good way to
go. It would be interesting to build anyway. Maybe that feeding into an
EEPC via some opto isolation (after the A2D) could be the best overall
solution.
David...

David Euans wrote:
> David-
> Your friend should ask his/her doctor about ordering a cardiac event  
> recorder.  Basically what happens is that the patient wears a device  
> which is constantly capturing and saving the last few minutes of an  
> EKG tracing.  He/she pushes a button whenever the abnormal heartbeat  
> or whatever occurs.    After pushing the button the patient is  
> instructed to call a monitoring service and downloads over the phone  
> the last 15 or so minutes of heart beats prior to the button push.   
> Typically, the patient wears the device for 2-4 weeks which is usually  
> enough to get the needed information.  It is usually a very helpful  
> test.
>
> For true diagnostic purposes you really need to capture an EKG signal  
> and save that.  An R-R interval recording device may confirm the  
> presence of an arrhythmia but still leave the exact diagnosis in  
> question.  The absence of any abnormal rhythm during or preceding the  
> symptoms would lead one away from a cardiac diagnosis.
>   
-- 

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David Duffy        Audio Visual Devices P/L
Unit 8, 10 Hook St, Capalaba 4157 Australia
Ph: +61 7 38235717      Fax: +61 7 38234717
Our Web Site: www.audiovisualdevices.com.au
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