@Darrin,
Have they checked your wife's breathing rate? I have an irregular heart beat from time to time that was traced to the fact that my respiration is very slow, half what is normal and I have a lung capacity that is 20% to 30% larger than normal for my body weight (something to do with being athletic when I was young, I ran everywhere). They told me that when carbon-dioxide builds up in my lungs it can trigger an additional heart beat that is out of sync with my normal rhythm and can feel like my heart has skipped a beat. When it happens several times in quick succession it feels like my heart has stopped for several seconds and can be painful. I look down at my chest and ask "are you going to start back up, or what?"
There was no treatment recommended, but it is still troubling and I think I am going to get a second opinion soon, but it does not happen often and sometimes I can go for many months without a single occurance. Hope this is helpful, and if it is not the case for your wife, at least you can rule out one more possible cause.
@mbrantley,
Let us know how the USB networking goes on the Amiga, what was the price for the USB networking adapters?