the sample you show is not really accurate to how an EKG displays heart beats.
I think that is what you are getting at with your question.
in this spot below, in the first half a second or so, it shows how an EKG measures a heartbeat.
http://hiredweapon.com/tom/index.php?/coreg-ekg/
I did some research into accurate behavior of an EKG unit.
I created the template and animatic for the spot, which was used for the finished spot.
My EKG setup also made a cameo in this spot as well.. why not re-use a good setup!
http://hiredweapon.com/tom/index.php?/tru-tv/
if this is what you are looking for, I'd be happy to explain how I built it.. very basic.