Pacing Pitfalls: Troubleshooting a Failing Temporary Pacemaker

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:

1. The Patient: Hemodynamically stable? If not, initiate ACLS/CPR while troubleshooting.
2. Connections: Ensure the pacing lead is securely locked into the extension cable and the extension cable is snug in the pulse generator.
3. The Generator: Is it turned on? Is the “Low Battery” light flashing?
4. 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.