Question: What is sinus tachycardia, and is it something that should be treated?
Answer :Sinus tachycardia is the heart rate's normal response to any type of stress -- whether that stress be exertion or caffeine, a cold, fever -- but it's the heart responding normally with an increased heart rate. Anytime the heart rate goes above 100, we call that a tachycardia. The sinus is the group of cells in the upper part of the right atrium that controls the heart rhythm, and it in itself is controlled then by the nervous system, specifically adrenaline. So anything that increases adrenaline will increase your heart rate, the sinus drives that heart rate in its normal function.