Direct Current (DC) Cardioversion
Scope
This section summarises synchronised DC cardioversion for organised tachyarrhythmias in the emergency setting: indications, energy selection, practical technique, rescue actions when shocks fail, and special considerations. Recommendations reflect Resuscitation Council UK (RCUK ALS) and NICE NG196 where relevant.
What it is and why it is used
DC cardioversion delivers a synchronised electrical shock timed with the R wave to terminate organised supraventricular or ventricular tachyarrhythmias and restore a stable rhythm. It is the treatment of choice for unstable tachyarrhythmias with life‑threatening features and is a reasonable first‑line rhythm control for stable sustained monomorphic ventricular tachycardia when rapid restoration is required or drugs are unsuitable (RCUK ALS).
Indications (practical)
- Immediate synchronised cardioversion for unstable tachyarrhythmia with life‑threatening features (hypotension, shock, syncope, severe ischaemia, pulmonary oedema).
- Stable monomorphic ventricular tachycardia with a pulse: consider DC cardioversion as first‑line rhythm control.
- Symptomatic or drug‑resistant supraventricular tachycardia (SVT) or atrial flutter when rapid termination is required.
- Atrial fibrillation (AF): emergency DC cardioversion if unstable.
- Elective cardioversion for AF >48 hours (or unknown duration): follow anticoagulation pathways per NICE NG196 (≥3 weeks therapeutic anticoagulation before elective DC cardioversion, or TEE‑guided cardioversion with appropriate periprocedural anticoagulation).