I think this song is about a guy she's so in love with, he makes her heart stop. I could relate to the song in this way, because I have met a guy who could make my heart skip a beat everytime he says my name. I never could get over that feeling. Even after many years, he still has that effect on me. But maybe it's just too much caffeine causing her arrythmia. Which I could still relate to. During my medical internship, I drink about 3 cups of coffee when I'm on duty so I could stay awake. One morning I was from duty, I felt chest pains. I had an ecg done it turned out to be pvcs in bigeminy. So now I drink coffee sparingly.