Regular broad‑complex tachycardia (BCT)
A regular broad‑complex tachycardia is a regular tachyarrhythmia with QRS duration ≥ 120 ms.
In the emergency department the pragmatic default approach is rapid recognition, immediate resuscitation, treat as ventricular tachycardia (VT) until proven otherwise, look for reversible causes (including toxins) and arrange definitive cardiology follow‑up.
Local protocols and the Resuscitation Council UK Adult ALS tachyarrhythmia algorithm (RCUK ALS) should guide specific practice.
Initial priorities
- Apply ABCDE resuscitation immediately.
- Establish continuous ECG monitoring, oxygen as required and IV access.
- Obtain a 12‑lead ECG as soon as possible and review it while continuing monitoring.
- Identify “unstable” physiology: any of hypotension/shock, severe breathlessness or pulmonary oedema, ongoing ischaemic chest pain, or reduced conscious level.
- Unstable patients with a life‑threatening tachyarrhythmia require immediate synchronized electrical cardioversion (RCUK ALS).
Common causes
- Ventricular tachycardia (monomorphic or polymorphic) - the most important cause to exclude because of associated structural heart disease and risk of rapid deterioration.
- Supraventricular tachycardia with aberrancy (pre‑existing bundle branch block).
- Pre‑excited tachyarrhythmias using an accessory pathway.
- Drug/toxin causes producing wide QRS from sodium‑channel blockade (tricyclic antidepressants, some antiarrhythmics and antipsychotics, cocaine).