Educational draft · awaiting clinical reviewThe full textbook explains uncertainty but does not replace live national or local guidance, specialist advice, or current prescribing information.
Deliver synchronised cardioversion safely, choose rhythm-specific energy and use emergency antiarrhythmics in their correct licensed or resuscitation context.
Electrical cardioversion is the fastest reliable rhythm treatment for a perfusing tachyarrhythmia causing life-threatening adverse features. Pad position, synchronisation, adequate energy and safe sedation all matter, but the underlying rhythm still determines the initial energy.
Antiarrhythmic drugs can terminate arrhythmia, slow conduction or facilitate a repeat shock, but every drug can also worsen another rhythm. Regularity, QRS width, pre-excitation, QT interval and ventricular function must be checked before selecting one.
Dose context is essential. Resuscitation Council regimens are designed for peri-arrest algorithms and can differ from the general eMC Summary of Product Characteristics; both should be named rather than blended into an invented compromise.
Shock, syncope with severe or ongoing hypotension, myocardial ischaemia, severe pulmonary oedema or immediately post-ROSC favours immediate electricity.
The defibrillator should place a marker on each R wave; erratic or T-wave markers require lead/gain adjustment before charging when a pulse is present.
AF is irregular without organised atrial activity; flutter may be regular at about 150/min with 2:1 block, and the recommended initial energies differ.
Vagal manoeuvres then rapid-bolus adenosine are appropriate only in stable regular narrow tachycardia when flutter and pre-excitation concerns have been considered.
Regular broad tachycardia is VT until proven otherwise; irregular broad tachycardia may be pre-excited AF or polymorphic VT and should not receive routine AV-nodal blockade.
Sinus-node disease, AV block and drug effects can produce significant pauses after cardioversion, so pacing capability and continued monitoring are required.
Do not use for irregular broad tachycardia or pre-excited AF. Give with continuous ECG and immediate resuscitation capability. The cited UK SmPC contraindicates bronchospastic chronic lung disease including asthma, long-QT syndrome, severe hypotension, decompensated heart failure, and sick-sinus or second-/third-degree AV block without a functioning pacemaker; avoid concurrent dipyridamole unless an expert-adjusted strategy is essential.
Continuous ECG and BP monitoring; stop or slow for hypotension, QRS widening or QT prolongation.
Avoid in torsades and pre-excited AF. IV administration requires ECG/BP monitoring; chronic therapy can injure lung, liver, thyroid, eye, skin and nerves and has many interactions.
Many defibrillators revert to an unsynchronised mode after a shock. Check the R-wave markers again before pressing for the next shock.
RCUK 2025 considers maximum defibrillator output a reasonable initial synchronised strategy for AF rather than an escalating low-energy sequence.
Its extremely short half-life means a rapid proximal bolus and immediate flush are essential; a slow infusion is ineffective.
A successful shock restores rhythm but can mobilise pre-existing atrial thrombus; anticoagulation timing remains a separate safety step.
The amiodarone SmPC provides a weight-based general infusion, while RCUK specifies fixed peri-arrest doses. State which authority and scenario is being used.
A conscious unstable patient needs anaesthetic expertise because induction can worsen hypotension; this reinforces preparation but should not create a dangerous delay.
Delivering an unsynchronised shock to a patient with a pulse and organised QRS complexes.
Failing to re-enable synchronisation after the first shock.
Using the same initial energy for AF, flutter and VT despite current rhythm-specific RCUK guidance.
Mixing the RCUK amiodarone regimen with the SmPC regimen without naming the clinical context.
Stopping anticoagulation immediately after successful AF/flutter cardioversion.
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A patient with a pulse has unstable atrial flutter. Which initial synchronised biphasic energy matches current RCUK guidance?
National guidance is shown before implementation-dependent detail. Typical adult dose examples remain subject to patient factors, contraindications and the live BNF or specialist protocol. Source check completed 27 Aug 2026; clinical approval remains outstanding.
Editorial contact: Doctor’s Passport editorial team. Source-check date is separate from clinical approval. Report a content problem ·
Not for mechanical valves or moderate-to-severe rheumatic mitral stenosis; assess Cockcroft-Gault renal function, bleeding and adherence. The cited SmPC does not recommend apixaban when creatinine clearance is below 15 mL/min or during dialysis.