Has anyone experience heart palpitations while on lamotrigine?

Hi, MissEK!
"Uncommon (0.1% to 1% of users): Flushing, hypertension, palpitations, postural hypotension, tachycardia"
I myself haven't experienced any side effects with my lamotrigine but it has been reported in some users. Have you just started taking the lamotrigine? Some initial side effects resolve over a few days to several weeks.
They may be benign but you should report them to your doctor for professional advice.