yes caffeine can cause your heart to do this, my son was drinking the red bull drinks, 3-4 a day had to end up going to the cardio dr told him to get off he did it went away. i have not had caffeine in 15 years but its not only in drinks , its in peanut butter , choclate, peanuts, lots other things need to read labels and the msn in foods can cause your heart to skip/beat hard /fast . you have to eat the foods and see what affects your beat .
Most likely the caffeine. Caffeine has this affect on the heart. Also, all the sugar in mt dew can cause kidney stones. I am a heavy Pepsi drinker drinking about 4 to 8 cans a day and I know it does make my heart pound differently.