I have Breville espresso maker and will usually have 3-4 doubles (6-8 shots) before I go to work. Admittedly caffeine does very little for me and that's what it takes to start my morning. I would agree this kid had an underlying medical condition, maybe not heart specifically, but something. My little brother does not tolerate caffeine very well, he in fact ended up in the ER with an erratic heartbeat after drinking a few energy drinks in a short period of time.