Which term describes the normal heart rhythm with the sinus node initiating impulses?

• A. Murmur
• B. T-wave
• C. NSR
• D. QRS complex

Answer: (C)

Normal Sinus Rhythm describes the normal heart rhythm in which the sinus node initiates impulses. This means the heart’s natural pacemaker is driving the rhythm, producing a regular, steady rate (typically 60–100 bpm in adults) with each impulse generating a P wave before every QRS complex and a normal PR interval. In other words, the SA node sets the pace and the conduction pathway to the ventricles functions properly, so the ECG shows orderly atrial depolarization followed by ventricular depolarization. The other terms refer to different ECG or heart findings: a murmur is an abnormal sound from turbulent blood flow, the T wave reflects ventricular repolarization, and the QRS complex reflects ventricular depolarization.