Educational draft · awaiting clinical reviewUse Rapid for revision, not patient-care decisions. Check current national and local guidance and the BNF or BNFC before acting.
2 min synopsisUK scopeSources checked 27 Aug 2026Clinical review pending
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Escalate
Call 999 after more than one ICD shock, any shock with collapse or ongoing chest pain, breathlessness, palpitations or presyncope, or suspected electrical storm. If a shockable cardiac arrest persists, deliver external defibrillation with pads more than 8 cm from the generator; a magnet can suspend inappropriate ICD shocks but does not disable pacing.
Synopsis
Select ICD or cardiac resynchronisation therapy for appropriate arrhythmic and heart-failure indications, and respond safely to shocks and device complications.
An ICD detects ventricular tachyarrhythmia and can deliver anti-tachycardia pacing or a shock; it does not prevent the arrhythmia from starting.
Secondary prevention considers survivors of VT/VF arrest or haemodynamically important sustained VT after reversible causes are excluded.
Primary prevention balances LVEF, heart-failure status, substrate, life expectancy and competing non-arrhythmic mortality after optimised treatment.
Key red flags
Electrical storm
Three or more episodes of sustained ventricular arrhythmia or appropriate ICD therapies within 24 hours is a critical syndrome requiring specialist intensive management.
Investigation priorities
01
Device interrogation with stored electrogramsFirst step
Determine rhythm, therapy sequence, appropriateness, battery and lead integrity.
Management branches
secondarySecondary-prevention ICD assessment
The patient survives VT/VF arrest or sustained haemodynamically important VT.
Stabilise, document the rhythm and identify reversible causes such as acute ischaemia, electrolyte disturbance, drug toxicity or a transient acute illness.
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.