Pacemaker and ICD Emergencies
Objective: Spot pacemaker failure to capture and repeated ICD shocks. Place defibrillator pads off the generator. Use a magnet only when protocol and the device card say what it will do.
Why this matters
A pacemaker spike without a heartbeat is not a working pacemaker. An ICD is an implanted defibrillator. If it shocks a conscious patient, it saw something it was programmed to treat, or it was wrong. An ICD that keeps firing during VF has not replaced your pads. VF means ventricular fibrillation.
A pad on the generator can hurt the device and the patient. The generator is the box under the skin. Do not delay care to hunt for a magnet your protocol does not use.
- Spikes without a QRS, or a QRS without a pulse, mean failure to capture or failure of perfusion. Treat the patient.
- Place external pads so the shock crosses the heart, and keep them off the generator. Anterior-posterior is often easier if the generator is in the way.
- A magnet changes some devices and not others. Use one only if you were trained and the protocol or device card tells you the expected effect.
- There are spikes and no pulse. This is failure to capture. I am pacing or running the arrest path per protocol.
- The pads are off the generator.
- I am not putting a magnet on unless our card says what it will do.
Clinical sequence
- Check the pulse, the blood pressure, and mental status first. A single ICD shock in a stable patient needs an evaluation and a 12-lead, not roadside reprogramming.
- If there are pacemaker spikes and no capture, or the rate is too slow and the patient is unstable, use the symptomatic bradycardia and transcutaneous pacing pathway. Do not wait for the clinic.
- If the patient is pulseless, start CPR and read the rhythm. VF and pulseless VT are still shocked with your defibrillator. VT means ventricular tachycardia. The ICD does not own the resuscitation.
- Keep defibrillator pads off the generator. Do not park a pad on the box.
- Bring the device card if the family can find it. A magnet, if your system uses one, is for specific problems such as inappropriate shocks in a patient who is perfusing. Use it only for the effect you were taught.
Teaching points
- A failing permanent pacemaker can cause unstable bradycardia. AHA 2025 includes that in bradycardia care. Transcutaneous pacing is the bridge. Capture still means a pulse, not only a wide QRS after a spike.
- Oversensing and undersensing are device words. On scene you only need the result. There are too many shocks, or there are not enough heartbeats.
- Recent surgery and a twitching chest muscle can be a lead that perforated, or the pacemaker stimulating the diaphragm. That patient needs a device-capable hospital, not a field adjustment.
Common errors
- Calling spikes without a pulse “a paced rhythm, so they are fine.”
- Withholding external defibrillation because an ICD is implanted.
- Applying a household magnet without knowing whether it will suspend detection.
Practice
One-minute check
Three calls: spikes and no pulse; one shock and the patient is awake; VF and the ICD is clicking. Say the action for each, and where the pads go.
Sources & Further Study
Named guidelines for further study. They are not clinical orders and do not replace your protocol or medical direction.
- AHA 2025 Adult Advanced Life Support — unstable bradycardia and pacing; defibrillation of pulseless VF and VT
- AHA 2025 Special Circumstances — implanted devices do not replace external defibrillation in arrest
Education only. Apply learning within your protocols and medical direction. This is not clinical care guidance.
Check Your Understanding
Questions drawn only from this lesson. After you check, the key is highlighted. Education practice — not a certification exam.