what is sinus arrhythmia in ecg
Sinus arrhythmia refers to the normal increase in heart rate that occurs during inspiration (when you breathe in). This is a normal response and is more accentuated in children than adults. Sinus tachycardia refers to a fast heartbeat (tachycardia) because of rapid firing of the sinoatrial (sinus) node. This occurs in response to exercise, exertion, excitement, pain, fever, excessive thyroid hormone, low blood oxygen (hypoxia), stimulant drugs (such as caffeine), etc.