My heart suddenly beat REAL HARD twice and went back to normal?

I would say it's normal, because it seems like you were probably asleep, went out to the cold, and climbed those stairs, which would make your heart or ciculatory system adjust to the new day. Look into Tachtycardia, if I spelled it correctly. It's an irregular heartbeat disease which can worsen. Good job for going to see your doctor again.

sounds like paroxysmal atrial tachycardia (PAT). It is very common and almost always harmless. It is simply when your atria get overexcited and start beating from multiple different cells. It can be triggered by simulants (like coffee or drugs) or stress. When it happens again, try coughing or bearing down like you need to have a bowel movement. That is usually enough to take care of it.

I used to get those all of the time between the ages of 17 and 24. I still get them but less frquently. The doctor was never able to find anything, even after I did this 3 day thing with a harness heart monitor. Of course it never happens when they have a machine hooked up. I finally came to the conclusion that these were minature panic attacks or something. They never happenned when I was stressed out, but usually after all the stress was done with.

The way it was explained to me, the heart is not a mechanical pump and it does not operate correctly every time. It beats millions of times and it lays an egg once and a while. I got this explanation when I was told that my defibrillator recorded something like 2000 premature ventricular contractions(PVC) in a month. I know the feeling you describe. My guess is it is PVC's but you should go back to your doctor. A couple of links on PVC info are attached.

It sounds like an arrythmia(i know i spelled that wrong). Its when your eheart beats irregularly for a moment. Sometimes it causes your heart to beat to hard to. it's a really good idea to see your doctor. tell him this has happened before. if he says its nothing, push it. chances are, it is something.