Broad complex tachycardia

Broad complex tachycardia
ECG shows rate of >100bpm and QRS complexes >120ms (>3 small squares on ECGs done at the standard UK rate of 25mm/s).

Principles of management
If in doubt, treat as ventricular tachycardia (the commonest cause).
Identify the underlying rhythm and treat accordingly.

Differential
Ventricular tachycardia (VT) including torsade de pointes
SVT with aberrant conduction, eg AF, atrial flutter
Pre-excited tachycardias, eg AF, atrial flutter,
or AV re-entry tachycardia with underlying WPW.
(NB: Ventricular ectopics should not cause confusion when occurring singly; but if >3 together at a rate of >120, this constitutes VT.)

Identification of the underlying rhythm
may be difficult, seek expert help.

Diagnosis is based on the history: if IHD/MI the likelihood of a ventricular arrhythmia is >95%, a 12-lead ECG, and the lack of response to IV adenosine.

ECG findings in favour of VT:
Fusion beats or capture beats (ECG).
Positive QRS concordance in chest leads.
Marked left axis deviation or rightwards axis.
AV dissociation (occurs in 25%) or 2 : 1 or 3 : 1 AV block.
QRS complex >160ms.
Any atypical bundle-branch-block pattern.