5.3 Synchronized Cardioversion and Transcutaneous Pacing
Key Takeaways
- Synchronized cardioversion is used for unstable tachycardia with a pulse.
- Defibrillation is unsynchronized and used for pulseless VF/pVT or unstable polymorphic rhythms when synchronization is not possible.
- Transcutaneous pacing is a key bridge for unstable bradycardia.
- Sedation is desirable for conscious patients when time and perfusion allow, but do not delay lifesaving electricity for severe instability.
5.3 Synchronized Cardioversion and Transcutaneous Pacing
Electrical therapy questions test whether the candidate can choose the correct type of shock or pacing. Synchronization matters when a pulse is present and the rhythm allows it.
Current official baseline
The adult advanced life support guidance covers cardiac arrest rhythms, defibrillation, airway decisions, drugs, peri-arrest tachycardia and bradycardia, and termination decisions. Use the official AHA 2025 Adult Advanced Life Support Guidelines page when your course materials or training-center instructions differ from third-party summaries: AHA 2025 Adult Advanced Life Support Guidelines.
What you need to know
| Decision point | What to do |
|---|---|
| Cardioversion | Use synchronized cardioversion for unstable tachycardia with a pulse, including many unstable narrow and regular wide-complex tachycardias. |
| Defibrillation | Use unsynchronized shock for pulseless VF/pVT and for rhythms where synchronization is not possible in a crashing patient. |
| Pacing | Use transcutaneous pacing for unstable bradycardia when atropine is ineffective or unlikely to work quickly enough. |
| Comfort | If the patient is conscious and time permits, provide sedation or analgesia, but perfusion takes priority. |
How this shows up on BLS/ACLS questions
BLS and ACLS items usually test priority. Read the patient state first: age, pulse status, breathing status, rhythm, stability, and number of rescuers. Then choose the action that protects perfusion, oxygenation, defibrillation timing, or the correct algorithm branch. If an answer sounds advanced but delays CPR, shock delivery, ventilation, or an urgent stability intervention, it is usually a distractor.
Scenario anchor
A conscious patient with monomorphic wide-complex tachycardia is hypotensive. The correct electrical treatment is synchronized cardioversion with sedation if feasible, not defibrillation by default.
Common traps
- Forgetting to press synchronize before cardioversion.
- Delaying cardioversion for IV placement in a severely unstable patient.
- Pacing a patient who actually has pulseless arrest instead of starting CPR.
Study action
Write this section as a one-line rule in your own words, then test it with mixed questions from the BLS/ACLS practice bank. Do not review only the matching topic. Mix it with nearby branches so you can tell when the rule applies and when it does not. For example, compare respiratory arrest with a pulse against pulseless arrest, or compare unstable tachycardia against VF/pVT arrest. The exam rewards that discrimination more than memorizing isolated facts.
A patient with symptomatic bradycardia is given atropine without improvement. While preparing for transcutaneous pacing, which IV infusion can be used as a bridge treatment?
A patient with a high-degree AV block is on a dopamine infusion at 8 mcg/kg/min and a transcutaneous pacemaker. What is the DEFINITIVE treatment?