In an electrocardiogram, what finding indicates pacing?

In an electrocardiogram, what finding indicates pacing?

• A. Paced spikes followed by a P wave or QRS complex
• B. Absence of spikes
• C. Prolonged PR interval without spikes
• D. Normal sinus rhythm

Answer: (A)

Pacing on an ECG shows up as discrete pacing spikes—the small, sharp deflections that precede the heart’s depolarization. These spikes are the artificial impulses from a pacemaker. When a spike is followed by a P wave, it’s atrial capture; when a spike is followed by a QRS complex, it’s ventricular capture; if both occur, it’s dual-chamber pacing. The key point is that the spike marks the delivered stimulus and its association with subsequent atrial or ventricular activity confirms pacing is happening and is capturing. If spikes occur without any subsequent depolarization, that would indicate loss of capture. Absence of spikes means no pacing, a prolonged PR interval without spikes suggests intrinsic conduction delay rather than pacing, and normal sinus rhythm implies the heart’s own rhythm is driving it.

Pacing on an ECG shows up as discrete pacing spikes—the small, sharp deflections that precede the heart’s depolarization. These spikes are the artificial impulses from a pacemaker. When a spike is followed by a P wave, it’s atrial capture; when a spike is followed by a QRS complex, it’s ventricular capture; if both occur, it’s dual-chamber pacing. The key point is that the spike marks the delivered stimulus and its association with subsequent atrial or ventricular activity confirms pacing is happening and is capturing. If spikes occur without any subsequent depolarization, that would indicate loss of capture. Absence of spikes means no pacing, a prolonged PR interval without spikes suggests intrinsic conduction delay rather than pacing, and normal sinus rhythm implies the heart’s own rhythm is driving it.