ah....can you tell us what it is???
The hitch in my EKG's gitalong or the chemical they put into your IV to make your heart race like you just finished the original Marathon?
They never told me what the hitch was, apparently nothing important, since they let me have the surgery. I'm just "different" I guess.
As to the chemical, I'll have to look that up, although there are several that they use for that, as there are several radioactive cocktails that that they also put into your veins. (That part was kind of cool, and they did it both before and after the stress test. You can read about it at Centenary Cardiology
The common chemicals used to speed up the heart without the exercise are Dobutamine, which is similar to adrenaline, and Atropine, which may be given with the dobutamine to increase your heart rate. There are others as well, and to tell the truth, I don't remember which one or ones, they used on me. I just remember it being unpleasant in the extreme, but thankfully short.