Oh, a reply to MOZ:
Something interesting I learned just a couple of days ago that a resident told me (don't know if this is true, but seems plausible):
They actually use less anesthesia in cardiovascular vs. general cases. The reason being that inhaled anesthetics have such strong depressant effects on the heart and circulatory system, that, in these very sick patients, could be very detrimental. In fact, they use LESS inhaled anesthetic than required to produce unconsciousness! In other words, these patients may be somewhat awake during their surgeries, and the pain they feel from surgical stimulation actually serves to support their circulatory systems by increasing sympathetic outflow and maintaining blood pressure and myocardial contractility. Sounds almost inhumane, huh? But the thing is, the amount of inhaled anesthetic is enough to produce amnesia, so the patients don't remember a thing. Pretty cool.