Wide-Complex Tachycardia Algorithm

A clear decision path for the wide, fast rhythm — stability first, then VT-versus-SVT, with the drugs to use and the ones that can be catastrophic.

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The decision path

Step	Action
1. Wide & fast?	QRS ≥ 120 ms, rate > 100 bpm
2. Pulse?	Pulseless VT / VF → defibrillate + CPR
3. Stable?	Unstable (hypotension, shock, chest pain, heart failure, altered mental status) → synchronized cardioversion
4. Stable + regular	Treat as VT until proven otherwise; consider amiodarone or procainamide
5. Stable + irregular	AFib with aberrancy, pre-excited AFib (WPW), or polymorphic VT — see below

Features that favor VT

Favors VT	Why
AV dissociation	Independent P waves marching through
Capture / fusion beats	Occasional normal or hybrid beats
Very wide QRS, extreme axis	Ventricular origin
Concordance across precordium	All QRS same direction V1–V6
Known structural heart disease / prior MI	Most WCT in these patients is VT

What to give — and what to avoid

Rhythm	Treatment
Stable monomorphic VT	Amiodarone or procainamide; cardiovert if unstable
Polymorphic VT with long QT (torsades)	IV magnesium; correct electrolytes; stop offending drugs
Pre-excited AFib (WPW)	Procainamide; avoid AV-nodal blockers (adenosine, verapamil, diltiazem, digoxin, β-blockers)
Pulseless VT / VF	Immediate defibrillation + CPR

Practise these on the ECG bank and read the ventricular tachycardia guide.

Frequently asked questions

How do you tell VT from SVT with aberrancy?

Features favoring VT include AV dissociation, capture/fusion beats, a very wide QRS with extreme axis, precordial concordance, and a history of structural heart disease. When uncertain, treat as VT.

What is the treatment for stable monomorphic VT?

In a stable patient, antiarrhythmics such as amiodarone or procainamide are used; synchronized cardioversion is used if the patient becomes unstable.

Why avoid calcium channel blockers in wide-complex tachycardia?

If the rhythm is actually VT, verapamil or diltiazem can precipitate profound hypotension and cardiac arrest.

What treats torsades de pointes?

Intravenous magnesium is first-line, along with correcting electrolytes and stopping QT-prolonging drugs.