Cardiac emergencies and arrhythmias

Ventricular tachycardia, wide-complex tachycardia and electrical storm

Reviewed Nov 2026·2 references
New· views rounded down, updated weekly

Treat a regular wide-complex tachycardia as VT until proven otherwise. Unstable: synchronised cardioversion. Stable: cardioversion under sedation or IV amiodarone. Torsades: magnesium and remove QT drugs. Electrical storm: sedate, beta-block, amiodarone, correct electrolytes, treat ischaemia.

At the bedside

Timed steps
  1. 1

    Pulse?

    0 min

    Pulseless: ALS shockable pathway (module 2). Pulse present: assess stability.

  2. 2

    Synchronised cardioversion

    Unstable

    120-200 J biphasic, escalate; sedate if conscious. Polymorphic VT: unsynchronised shock.

  3. 3

    Cardioversion or drug

    Stable monomorphic

    ESC 2022 favours synchronised cardioversion if anaesthesia risk is low; otherwise amiodarone 300 mg IV over 10-60 min (procainamide where available). Adenosine only for regular monomorphic WCT when SVT with aberrancy is likely.

  4. 4

    QT-related

    Torsades

    Magnesium 2 g IV; stop QT-prolonging drugs; K+ to 4.5-5; if bradycardia-dependent, isoprenaline or overdrive pacing.

  5. 5

    ≥ 3 sustained VT/VF in 24 h

    Electrical storm

    Deep sedation (± intubation), beta-blockade (propranolol or esmolol), amiodarone, correct K+/Mg2+, urgent angiography if ischaemia; ICD reprogramming; ablation or MCS in refractory cases.

  6. 6

    Find the cause

    After

    Ischaemia, scar, cardiomyopathy, myocarditis, electrolytes, drugs (QT), channelopathy. Cardiology referral for ICD/ablation.

Stable VT / storm

Amiodarone

IV
Dose
300 mg over 10-60 min, then 900 mg/24 h

Torsades de pointes

Magnesium sulfate

IV
Dose
2 g over 10-15 min; repeat or infuse 3-10 mg/min if recurs

Clues that a wide-complex tachycardia is VT

FeatureSuggests VT
HistoryPrevious MI, cardiomyopathy, structural heart disease
AV dissociationP waves marching through, capture or fusion beats
QRS width> 160 ms (LBBB-like) or > 140 ms (RBBB-like)
ConcordanceAll precordial complexes positive or all negative
AxisExtreme (northwest) axis
Red flag · call your senior now
Do not give verapamil or diltiazem for wide-complex tachycardia.
Red flag
QTc > 500 ms with ectopy: high torsades risk.
Pitfall
Assuming haemodynamic stability means SVT; VT can be well tolerated.
Pearl
Incessant VT with fever and new heart failure in a young Indian patient: consider myocarditis, including scrub typhus, dengue or diphtheria.

Calculators for this topic

Corrected QT (Bazett)

QT ÷ √(RR in seconds). Over-corrects at fast heart rates.

References

  1. 1

    Zeppenfeld K, Tfelt-Hansen J, de Riva M, et al. 2022 ESC Guidelines for the management of patients with ventricular arrhythmias and the prevention of sudden cardiac death. Eur Heart J. 2022;43(40):3997-4126

  2. 2

    Part 9: Adult Advanced Life Support: 2025 American Heart Association Guidelines for CPR and ECC. Circulation. 2025

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