A malfunctioning temporary pacemaker is a true “code blue” waiting to happen. Troubleshooting requires a systematic approach, moving from the patient back to the generator. Here is a guide to identifying and fixing the most common pacing pitfalls.
1. The Troubleshooting Algorithm: “Patient to Pulse Generator”
When the monitor shows a problem, check these components in order:
- The Patient: Hemodynamically stable? If not, initiate ACLS/CPR while troubleshooting.
- Connections: Ensure the pacing lead is securely locked into the extension cable and the extension cable is snug in the pulse generator.
- The Generator: Is it turned on? Is the “Low Battery” light flashing?
- The Lead: Has the transvenous lead migrated? (Check the centimeter markings at the insertion site).
2. Common Pacing Malfunctions
A. Failure to Capture
The Look: Pacing spikes are present, but no QRS complex follows.
- The Pitfall: The “Exit Block.” The current isn’t strong enough to depolarize the myocardium.
- The Fix: * Increase the Output (mA) to the maximum to see if capture returns.
- Reposition the patient (turning to the left lateral decubitus position can sometimes improve lead-to-wall contact).
- Check for electrolyte imbalances (hyperkalemia) or drug toxicities that raise the threshold.
B. Failure to Sense (Oversensing)
The Look: The pacer is not firing despite a slow intrinsic rate. It thinks it sees “cardiac activity” that isn’t there.
- The Pitfall: “Seeing” large T-waves, P-waves, or even skeletal muscle twitching (shivering).
- The Fix: * Decrease Sensitivity (increase the mV number). This makes the “fence” higher so the pacer ignores the background noise.
- Check for nearby electromagnetic interference (e.g., cell phones or ungrounded equipment).
C. Failure to Sense (Undersensing)
The Look: Pacing spikes appear randomly, often falling on T-waves (can cause R-on-T phenomenon), because the pacer doesn’t see the patient’s own beats.
- The Pitfall: The “fence” is too high.
- The Fix: * Increase Sensitivity (decrease the mV number). This makes the pacer more “alert” to small intrinsic signals.
3. The “Last Resort” Settings
If you are losing capture and the patient is deteriorating, use the Emergency/Safety Settings:
- Rate: 80–100 bpm.
- Output (mA): Set to maximum (usually 20 mA).
- Sensitivity: Set to “Asynchronous” (or the lowest mV value) to ensure the pacer fires regardless of what it “sees.”
4. Technical Pitfalls to Avoid
| Pitfall | Prevention/Correction |
| Battery Depletion | Always tape a spare 9V battery to the back of the generator. |
| Lead Migration | Secure the lead at the skin with a “wing” suture and transparent dressing. |
| Accidental Turn-off | Use the protective plastic cover over the dials/buttons. |
| Microshock | Always wear gloves when handling the pacing terminals to prevent stray static from causing arrhythmias. |
Daily “Threshold” Check
Daily checks are vital. Always document the Capture Threshold (the minimum mA required to consistently pace). If the threshold has jumped from 2 mA to 10 mA overnight, your lead has likely migrated or there is increasing edema at the tip—predicting a failure before it happens.