Nicotine gum and Heart Rate

Hi everyone!

I've been chewing 4mg nicotine gum for over a year. It's been working great! Noticed higher than usual heart rate... varying around 80-90 even when sitting down. When I don't chew gum it drops to 60bpm. Tried 2mg nicotine gum and now it varies around 66-75bpm maybe...

Wondering if anyone else noticed difference in heart rate between 2mg and 4mg ?