Thank you for posting your question. Awareness of ones own heart beats is known as palpitations. There are certain cardiac and non cardiac causes of this which also includes ingestion of certain things like excessive tea/coffee or certain drugs. However it is quite unlikely that an 8 yr old would appreciate his own heart rate, let alone attributing chest pain to his heart. Hence, the way the symptoms are being described by your son, it is likely that he is enacting something that he has seen or heard somewhere. However, not to take his symptoms lightly, I would suggest you keep a watch on his symptoms and look for associated changes like sudden loss of colour from his face, vomiting, radiation of pain to any other site,lethargy or irritability, decreased urine output etc. Apart from this acitdity or heart burn could also cause symptoms similar to chest pain. In this case decreasing intake of spicy food , having cold milk or ice cream, or drugs like omeprazole or ranitidine may be found to be useful. Having said so, if the symptoms continue and if you wish to rule out heart disease, an ECG may be done. If found necessary this may be followed by chest Xray or echocardiography. If you have any more doubt regarding the case, do write back.