Educational Content: This article is for informational purposes only and does not constitute medical advice. Always consult a healthcare provider for diagnosis and treatment.

Definition of Tachycardia, sinus

Medically reviewed by Dr. Otari Nergadze, Neurosurgeon | Updated: January 2026

Tachycardia, sinus: A fast heartbeat (tachycardia) because of rapid firing of the sinoatrial (sinus) node.

The sinoatrial (or sinus) node is the natural pacemaker of the heart. It is located in the wall of the right atrium (the right upper chamber of the heart). Normal cardiac impulses start there and are transmitted to the atria and down to the ventricles (the lower chambers of the heart).

Sinus tachycardia occurs in response to exercise, exertion, excitement, pain, fever, excessive thyroid hormone, low blood oxygen (hypoxia), stimulant drugs (such as caffeine and amphetamines), etc.

Although sinus tachycardia is usually a response to one or another fleeting stimulus, it can upon occasion be a sign of heart failure, heart valve disease, or another significant illness.