The heart is becoming my favorite nursing preoccupation. I could write pages about the pathophysiology of a heart attack (myocardial infarction/MI), or you could just watch this really good video. In a heart attack, the heart essentially essentially chokes itself to death.
To correct for the "choking", the coronary arteries must be widened, which can be done by placing a Stent, or artificial tube, in the coronary arteries to widen it. An excellent explanation:
Here is the actual video of someone's angiogram where they are injecting the dye in order to see various parts of this guy's vasculature.