Hello. Welcome to HCM and thank you for your question. I understand your concern. Sinus node is the part of the heart tissue which generates every electrical impulse, which is conducted through other specialized tissues, to depolarize every part of the heart. Sometimes, another area of the heart tissue fires one beat (premature atrial or ventricular beat), which causes the skipped heart beat . The sinus node, immediately takes over after a short pause, by producing a normal, but more forceful heart beat. This is accompanied with difficulty in breathing and the sensation of heart jumping out from the throat . This is called a palpitation. The premature heart beats are found in almost all healthy individuals with are physically active, under psychological stress and, even, by changes in hormonal levels which happen normally during a day. Therefore, I recommend you that there is nothing to worry about, as this is a phenomenon that anyone can experience, because of the above mentioned reasons. If these phenomena are judged as worrisome and often by you, you can be put on a 24-hour rhythm monitor, to evaluate the number of cases that they happen in a day. I hope I was helpful with the answer. Take care. Best regards, Dr. Meriton