Sinus Tachycardia is best described as which rhythm?

• A. Atrial Fibrillation with Rapid Ventricular Response
• B. Ventricular Tachycardia
• C. Sinus Tachycardia
• D. Torsades de Pointe

Answer: (C)

Sinus tachycardia is a fast but regular rhythm that keeps the normal electrical pathway starting from the sinus node. On the ECG you’ll see a P wave before every QRS complex, a normal PR interval, and a narrow QRS, but the rate is above 100 beats per minute. This means it’s the same sinus rhythm as normal heartbeats, just faster, rather than a rhythm arising from another part of the heart or with abnormal conduction.

This distinguishes it from atrial fibrillation with rapid ventricular response, which would show no discrete P waves and an irregular rhythm; from ventricular tachycardia, which usually has wide, abnormal QRS complexes; and from torsades de pointes, which is a polymorphic VT with twisting QRS morphology.