What is sinus tachycardia?

Sinus tachycardia is defined as a heart rate that is faster than normal, or greater than 100 beats per minute in an adult, according to the American Heart Association. During sinus tachycardia, the sinoatrial node, or natural pacemaker, of the heart is sending out electrical signals more quickly than usual.

Sinus tachycardia is a common response to conditions such as fever, strenuous exercise, fear, anxiety and certain medications or street drugs, states the American Heart Association. It is occasionally associated with low blood count, overactive thyroid, heart damage and severe bleeding. Treatment for sinus tachycardia involves determining and correcting the underlying cause.