Help! what can be causing symptomatic sinus tachycardia?

Anxiety plays a role: "symptomatic" means that you can feel the heart. The sinus node is the area in everyone's heart where the normal electrical heartbeat is generated. That is "sinus." a rapid heart beat is "tachycardia, " so symptomatic sinus tachycardia is a normal rapid heartbeat that is felt. Common causes include: anxiety, anemia, dehydration, excess thyroid hormone, and stimulants, (caffiene or some medication).