Cardiovascular · Topic 19 of 48

Ventricular Tachycardia

Cardiovascular · wide-complex tachycardia

Ventricular Tachycardia

Wide-QRS tachycardia is VT until proven otherwise: synchronized cardioversion if unstable, amiodarone or procainamide if stable — never a calcium channel blocker.

Key numbers

Wide-complex tachycardia: VT until proven otherwiseQRS ≥ 0.12 s

Unstable VT: synchronized cardioversion100 J synchronized

Stable VT: amiodarone or procainamideamiodarone 150 mg / 10 min

Sustained VT lasts 30 seconds or longersustained ≥ 30 s

01 · The ruleWide-complex tachycardia: VT until proven otherwise

Treat any wide-QRS (≥ 0.12 s) tachycardia as ventricular tachycardia until proven otherwise — a patient who tolerates it well can still be in VT.

02 · DoUnstable VT: synchronized cardioversion

VT with a pulse plus hypotension, altered mentation, shock, ischemic chest pain or acute heart failure: immediate synchronized cardioversion — 2025 AHA initial energy 100 J for monomorphic VT, sedating when feasible.

03 · GiveStable VT: amiodarone or procainamide

Stable monomorphic VT: amiodarone 150 mg IV over 10 minutes (repeat if VT recurs, then 1 mg/min for 6 hours) or IV procainamide; synchronized cardioversion if drugs fail.

What it is

Core idea

Sustained VT lasts 30 seconds or longerVT is 3 or more consecutive ventricular beats at ≥ 120 bpm (some use ≥ 100); nonsustained VT lasts < 30 s, sustained VT ≥ 30 s or needs earlier termination for collapse.

Causes & risk factors

Why it happens

Check potassium, magnesium and ischemiaMost VT occurs with structural heart disease (prior MI, cardiomyopathy); correct hypokalemia, hypomagnesemia, acidemia and hypoxemia, and look for proarrhythmic drugs.

Presentation

What you'll see

AV dissociation, fusion or capture beats favor VTECG findings favoring VT: AV dissociation (independent P waves), fusion beats, capture beats, precordial QRS concordance and a northwest (extreme) frontal axis.

Do right now

In this order

First moves

Wide-complex tachycardia: VT until proven otherwiseQRS ≥ 0.12 s

→

Unstable VT: synchronized cardioversion100 J synchronized

→

Stable VT: amiodarone or procainamideamiodarone 150 mg / 10 min

→

Check potassium, magnesium and ischemia

Why each step

Wide-complex tachycardia: VT until proven otherwiseTreat any wide-QRS (≥ 0.12 s) tachycardia as ventricular tachycardia until proven otherwise — a patient who tolerates it well can still be in VT.

Unstable VT: synchronized cardioversionVT with a pulse plus hypotension, altered mentation, shock, ischemic chest pain or acute heart failure: immediate synchronized cardioversion — 2025 AHA initial energy 100 J for monomorphic VT, sedating when feasible.

Stable VT: amiodarone or procainamideStable monomorphic VT: amiodarone 150 mg IV over 10 minutes (repeat if VT recurs, then 1 mg/min for 6 hours) or IV procainamide; synchronized cardioversion if drugs fail.

Management

Orders

Pulseless VT: CPR and defibrillationPulseless VT is cardiac arrest: start CPR and defibrillate — biphasic at the manufacturer dose (typically 120–200 J; device maximum if unknown) or monophasic 360 J — following the ACLS shockable-rhythm algorithm.

Procainamide 20–50 mg/min to an endpointProcainamide 20–50 mg/min IV until the arrhythmia stops, hypotension develops, the QRS widens > 50% or 17 mg/kg is given (then 1–4 mg/min); avoid with prolonged QT or heart failure.

Adenosine only if regular and monomorphicIV adenosine may be tried for diagnosis or treatment only in stable, regular, monomorphic wide-complex tachycardia — it terminates rhythms using the AV node, not VT; never give it if unstable, irregular or polymorphic.

Polymorphic VT: unsynchronized shockSustained polymorphic VT cannot be reliably synchronized: give an immediate unsynchronized, defibrillation-dose shock.

ICD after sustained VT without reversible causeAfter sustained VT without a transient or reversible cause, implant an ICD; add a beta-blocker when structural heart disease is present, and amiodarone if an ICD cannot be used.

Red flags & don'ts

Avoid harm

No verapamil or diltiazem for wide-complex tachycardia avoidVerapamil and diltiazem are harmful in wide-complex tachycardia (Class 3: Harm): they do not terminate VT and can cause profound hypotension, shock and cardiac arrest.

The rules

Know these

Reversible-cause VT needs no long-term therapyVT within 48 hours of an MI or from a corrected reversible cause (electrolyte or acid–base disorder, proarrhythmic drug) does not require long-term antiarrhythmic or ICD therapy.

One antiarrhythmic at a time; defibrillator readyAvoid combining amiodarone, procainamide and sotalol (additive proarrhythmia) and keep a defibrillator ready — any of them can convert VT to a faster, unstable rhythm.

VT or SVT with aberrancy?

Commonly confused

Usual substrate	Prior MI or cardiomyopathy
ECG clues	AV dissociation, fusion and capture beats, concordance
Adenosine (stable, regular, monomorphic)	Does not terminate it
When uncertain	Treat as VT

Commonly confused

Tell apart

Normal-QT polymorphic VT: treat the ischemiaPolymorphic VT with a normal QT is usually acute ischemia: treat the ischemia (beta-blocker, emergent coronary intervention) and consider lidocaine or amiodarone; routine magnesium is not useful.

More detail

Reference

Show 7 reference facts

IV amiodarone, procainamide or sotalol may be considered for wide-complex tachycardia (Class 2b); lidocaine acts quickly but is less effective for hemodynamically tolerated VT, and amiodarone was not better than procainamide.

Idiopathic outflow-tract VT (LBBB-like, inferior axis, no structural disease) responds to IV adenosine; verapamil-sensitive fascicular VT (RBBB-like with left axis deviation) responds to IV verapamil.

For recurrent VT in a patient with an ICD, a beta-blocker is first choice, then sotalol, then amiodarone; catheter ablation of the substrate is the alternative.

Accelerated idioventricular rhythm ("slow VT", below the VT rate cutoff) is usually benign and is treated only if it causes hemodynamic symptoms.

Nonsustained VT in a patient with structural heart disease, particularly with an ejection fraction below 35%, is a sudden-death marker that warrants further evaluation for an ICD.

Untreated VT frequently degenerates into ventricular fibrillation and cardiac arrest.

A wide-complex tachycardia can be called SVT with aberrancy when prior ECGs show the same bundle branch block or pre-excitation; otherwise it is managed as VT.

Pearl

Wide and fast? Assume VT — shock it if unstable, amiodarone or procainamide if stable, and never a calcium channel blocker.

Sources · Merck Manual Professional — Ventricular Tachycardia (VT) · 2025 AHA Guidelines for CPR and ECC — Part 9: Adult Advanced Life Support (Circulation 2025; doi 10.1161/CIR.0000000000001376), cpr.heart.org text · AHA 2025 Interim Training Materials — ACLS Provider Manual changes (synchronized cardioversion energies) · AHA 2025 ACLS algorithms poster set (Adult Tachyarrhythmia With a Pulse and Adult Bradycardia With a Pulse — doses/details), international edition · Merck Manual Professional — Reentrant (Paroxysmal) Supraventricular Tachycardias (PSVT) · Starter sheet built from the verified AGACNP fact map (facts reviewed 2026-10-15).