I apologize for delay in replying. There are two major causes of Palpitation
. Firstly, because any structure disease of heart thereby any valve connecting two chamber is not efficient in function, say it does not close when it needed to. Thereby leading to leakage of blood into any chamber when it is not supposed to occur that produces more volume of blood the heart chamber
has to pump. This causes overloaded heart which gives pounding sensation while beating specially after exertion. This does not appear to be in your case. Auscultation of heart by a doctor can give final no to this diagnosis. The second cause is rapid heart rate; regular or irregular; episodic or continuous for long time precipitated by intake of caffeine is one example it can be without any apparent structural cause or etiological or precipitating factor. Once cardiac auscultation is normal your doctor will ask for 24 holter recording with advise to you to keep a diary so that event and its nature is noted and what relation it bears to symptoms. Do you feel tightness of chest on left side when you have palpitation (Incidentally, heart as an organ is located in the central organ of chest!). The amount of caffeine is not of material importance some may get with a little amount. Your concern should take you to a doctor who can determine the nature of palpitation and its cause. It is also to be decided whether you need a prescription drug or not. Some people do grow out of episodes of palpitation.
Dr Anil Grover