Hi, Of course, you must be having some odd feeling in the chest and that might be mimic heart rate changes. But in fact that may not be the pure heart rate changes due to some heart disease, exercise, playing game increases the heart rate, and if this is associated with breathing difficulty, fainting, blackout then it has to be ruled out for cardiac disease. The condition cannot be left like that only without the testing like EKG and ECHO, else it is the physiological phenomenon. Hope I have answered your query. Let me know if I can assist you further.