Hi there Kim
Yeup, palpitations is just one scary symptom of a panic attack, or anxiety in general. I get them too from time to time. If you drink coffee or smoke, this could induce the palpitations too. (I smoke and can get them after a cigarette) I've had quite a few palpitations this week, if it eases your anxiety a little. :) So you're not alone. I've had my heart checked out too, and got the all clear. It's all part of the fight or flight response. Your body gets anxious and is building itself up for a quick get away or attack. So your heart beats fast for seemingly no reason, to get the blood flowing to your limbs for speedy reflexes. Even though you may not be in any danger, it's the body's natural reaction to anxiety.
It's always good to get these things checked out.
Hope this helps. :)