Which statement describes a key feature of normal sinus rhythm?

Which statement describes a key feature of normal sinus rhythm?

• A. P waves preceding every QRS complex
• B. Irregular rhythm with varying RR intervals
• C. Wide QRS complexes with no P waves
• D. Prolonged QT interval

Answer: (A)

In normal sinus rhythm, the impulse begins in the Sinoatrial node and the atrial depolarization (P wave) reliably precedes each ventricular depolarization (QRS complex). This orderly sequence reflects intact SA node pacing and proper AV conduction, so you see P waves that consistently come before every QRS and a regular rhythm with a normal PR interval and narrow QRS complexes. The other descriptions point to rhythm disturbances: an irregular rhythm with varying RR intervals suggests an atrial or ventricular irregularity; wide QRS complexes with no P waves indicate a ventricular rhythm or ectopy; a prolonged QT interval reflects repolarization abnormalities, not normal sinus rhythm. Hence, P waves preceding every QRS is the hallmark of a normal sinus rhythm.

In normal sinus rhythm, the impulse begins in the Sinoatrial node and the atrial depolarization (P wave) reliably precedes each ventricular depolarization (QRS complex). This orderly sequence reflects intact SA node pacing and proper AV conduction, so you see P waves that consistently come before every QRS and a regular rhythm with a normal PR interval and narrow QRS complexes. The other descriptions point to rhythm disturbances: an irregular rhythm with varying RR intervals suggests an atrial or ventricular irregularity; wide QRS complexes with no P waves indicate a ventricular rhythm or ectopy; a prolonged QT interval reflects repolarization abnormalities, not normal sinus rhythm. Hence, P waves preceding every QRS is the hallmark of a normal sinus rhythm.