Ckoenig, Crohn's itself isn't the direct cause, Crohn's can cause other problems which can then lead to heart palpitations.
Vitamin and mineral deficiencies can cause an increase in heart palpitations like magnesium, folate, vitamin B12, vitamin B6, iron, vit C and even having too much vit D can cause palpitations (yet many people with Crohn's are deficient in vit D). Anemia can cause heart palpitations as well. Have some blood work done to see if you're low in anything and if you are then you can begin supplementing to see if that helps.
Stress is definitely related to an increase in palpitations. That and drinking alcohol, smoking (both alcohol and smoking are stimulants which means caffeine and certain medications can also be a possible cause) and lack of exercise have caused an increase in palpitations for me. So I've cut out what I can and have tried to increase the amount of exercise I do.
Lack of sleep is also a major one that increases palpitations yet I'm having a hard time with this one (and anxiety so they're likely related). Even viral infections can increase palpitations which many medications can cause us to be susceptible to.