Stable vs Unstable Tachycardia
Source: AHA Guidelines for CPR & ECC 2025 · Last reviewed: Jul 2026
1
Initial Action
Assess airway, oxygen if needed, monitor, 12-lead ECG, IV access.
2
Decision
Patient unstable (hypotension, altered mental status, shock, ischaemic chest pain, acute heart failure)?
Yes → immediate synchronised cardioversion. No → follow the stable pathway below.
Synchronised Cardioversion Procedure
- Consider sedation for conscious patients.
- Turn ON Sync mode.
- Verify sync markers on the R waves.
- Select the appropriate energy level.
- Announce "Clear" and deliver the shock.
Narrow, Regular Complex (e.g. SVT)
3a
Vagal manoeuvres first.
4a
Adenosine if vagal manoeuvres fail.
Wide Complex Tachycardia
3b
If regular & monomorphic with uncertain aetiology → adenosine may be considered. Amiodarone, procainamide, or sotalol may also be considered.
4b
Do not give adenosine in unstable, irregular, or polymorphic WCT. Do not give verapamil/diltiazem in WCT.
Educational quick reference only, not a substitute for clinical judgement.