A nurse is monitoring a client who is on telemetry. Which of the following findings on the ECG strip should the nurse recognize as normal sinus rhythm?

Choice A reason: In normal sinus rhythm, the P wave precedes the QRS complex, indicating atrial depolarization followed by ventricular depolarization. This reflects proper electrical conduction from the sinoatrial node through the atria to the ventricles, with a P-R interval of 0.12–0.20 seconds, a hallmark of normal heart rhythm. Choice B reason: A QRS duration of 0.35 seconds is abnormal, indicating delayed ventricular depolarization (normal is 0.06–0.12 seconds). This could suggest bundle branch block or other conduction abnormalities, not consistent with normal sinus rhythm, which requires a narrow QRS and proper P wave-QRS sequence. Choice C reason: A P wave appearing after the QRS complex is not normal sinus rhythm. This may indicate retrograde conduction, as in junctional rhythms, where ventricular depolarization precedes atrial activity. Normal sinus rhythm requires the P wave to precede the QRS, reflecting proper atrial-to-ventricular conduction. Choice D reason: A P-R interval of 0.40 seconds is prolonged (normal is 0.12–0.20 seconds), suggesting first-degree heart block, not normal sinus rhythm. This delay in conduction from atria to ventricles disrupts the normal timing of electrical impulses, disqualifying it as a characteristic of normal sinus rhythm.