How does pacemaker rhythm appear on telemetry, and how can you tell capture from loss of capture?

How does pacemaker rhythm appear on telemetry, and how can you tell capture from loss of capture?

• A. Pacing spikes before a beat; capture shows appropriate QRS after spike; loss of capture shows spike without QRS
• B. Pacing spikes after a beat; captured rhythm shows QRS after the spike
• C. Pacing spikes before a beat; loss of capture shows spike before QRS
• D. No pacing spikes are visible on telemetry

Answer: (C)

Pacing spikes before the beat are the telltale sign of a pacemaker on telemetry. When a spike reliably triggers depolarization, you’ll see the pacing spike followed by the expected waveform: for ventricular pacing that means a QRS complex after the spike. That sequence—spike then QRS—shows capture, meaning the pacemaker successfully caused the heart to depolarize. If a spike occurs but no corresponding QRS follows, that’s loss of capture. The pacing stimulus is delivered, but the heart doesn’t respond with depolarization, so no QRS appears after the spike. You may still see intrinsic rhythm activity at other times, but the key distinction is whether a QRS follows the pacing spike. Keep in mind that the exact appearance of the QRS after a spike can vary (morphology, width) depending on pacing location and patient conduction, but the essential concept is spike-plus-QRS = capture, spike-without-QRS = loss of capture.

Pacing spikes before the beat are the telltale sign of a pacemaker on telemetry. When a spike reliably triggers depolarization, you’ll see the pacing spike followed by the expected waveform: for ventricular pacing that means a QRS complex after the spike. That sequence—spike then QRS—shows capture, meaning the pacemaker successfully caused the heart to depolarize.

If a spike occurs but no corresponding QRS follows, that’s loss of capture. The pacing stimulus is delivered, but the heart doesn’t respond with depolarization, so no QRS appears after the spike. You may still see intrinsic rhythm activity at other times, but the key distinction is whether a QRS follows the pacing spike.

Keep in mind that the exact appearance of the QRS after a spike can vary (morphology, width) depending on pacing location and patient conduction, but the essential concept is spike-plus-QRS = capture, spike-without-QRS = loss of capture.