Is there harm in fast heart rate due to medication?

[ainatlanta]

Hi!  I am a 37 year old female in good health.  During both of my pregnancies (7 and 3 years ago) I noticed irregular pauses and surges of my heart and both times I went to a cardiologist and was told I am fine.  I am sensitive to my heart and can hear and feel it beating when I lay in bed at night.  If I drink alcohol, I may awaken in the night with a racing heart, so I don't do that very often.  But, now I am taking bupropion (wellbutrin) since early November. At the lowest therapeutically effective dose, the medicine has really benefitted me.  However, I am waking some nights with a racing heart, and it seems to beat stronger as well, as I feel the pulsations up my neck with each beat.  I have taken my blood pressure during these racing/pounding heart spells, and it thankfully is normal.  My question is: if I take the medication for a year, and my heart races some, is that really a problem.  Am I putting myself in danger or weakening my heart, or anything else?  I'd really like to take the medicine as it helps me, but I don't want to harm my heart either.  Thanks for any input you might have!