PassFinals
Cardiovascular

Ventricular Tachycardia (VT)

Ventricular tachycardia (VT) arises in ventricular myocardium below the His bundle, so activation spreads slowly cell to cell, widening the QRS complex and desynchronising ventricular contraction.

In a nutshell

Ventricular tachycardia (VT) is a broad-complex tachycardia arising in ventricular muscle. Check the pulse first: pulseless VT is defibrillated as a cardiac arrest, while VT with a pulse and any life-threatening feature gets synchronised cardioversion at 120 to 150 J.

Classic presentation

A patient with a previous myocardial infarction has palpitations and presyncope, and the monitor shows a regular broad-complex tachycardia with atrioventricular (AV) dissociation and occasional capture beats.

Key points

  • Treat every broad-complex tachycardia as VT unless supraventricular tachycardia (SVT) with bundle-branch block has already been specifically diagnosed. That is Resuscitation Council UK's stated rule.
  • VT is three or more consecutive ventricular beats above 100 per minute. Sustained means 30 seconds or longer, or needing earlier termination.
  • Never give verapamil, diltiazem or an intravenous beta-blocker to a broad-complex tachycardia that has not been proved supraventricular.
  • Torsades is the polymorphic VT that occurs with a long QT interval. Polymorphic VT without QT prolongation is a different problem, usually acute ischaemia.
  • Intravenous magnesium works in torsades even when the serum magnesium is normal.
  • The algorithm's 8 mmol and the BNF's 2 g are the same magnesium dose: the BNF equates 200 mg of magnesium sulfate heptahydrate with 0.8 mmol of magnesium.
  • Any sustained VT needs monitored admission and a hunt for ischaemia, ventricular dysfunction, scar, culprit medicines and inherited disease.
  • An arrhythmia occurring immediately after return of spontaneous circulation (ROSC) is itself a life-threatening feature, added in the 2025 guidelines.

First-line investigation

Feel for a pulse while attaching continuous ECG, blood-pressure and oxygen-saturation monitoring. Record a 12-lead ECG only if it does not delay an indicated shock.

Management

Decide by pulse, then by stability

  • No pulse: unsynchronised shock, at least 150 J biphasic or 130 to 150 J pulsed biphasic, then CPR. Manage exactly as ventricular fibrillation (VF).2
  • After three shocks give adrenaline 1 mg IV, repeated every 3 to 5 minutes, plus amiodarone 300 mg IV; a further amiodarone 150 mg IV after five shocks.2,3
  • Pulse present: ABCDE (airway, breathing, circulation, disability, exposure), monitoring, IV access, oxygen only if saturations are below 94%, 12-lead ECG, and treat reversible causes.1
  • Unstable if any of: shock, syncope with severe or ongoing hypotension, myocardial ischaemia, severe heart failure with pulmonary oedema, or immediately after ROSC.1

Unstable VT with a pulse

  • Synchronise the shock to the R wave. Give 120 to 150 J initially, step the energy up if it fails, up to three attempts. Sedate or anaesthetise a conscious patient.2,1
  • Still unstable after shocks: procainamide 10 to 15 mg/kg IV, maximum 1 g, over 20 minutes, or amiodarone 300 mg IV over 10 to 20 minutes. Then shock again.2,1
  • An amiodarone load may be followed by 900 mg IV over 24 hours. Choose between the two drugs by local availability and protocols.2
  • Keep oxygen 1 m from the chest and pads over 8 cm from an implanted device. If the pulse is lost, stop synchronising and defibrillate.2

Stable monomorphic VT

  • Synchronised cardioversion is still recommended when there is structural heart disease or uncertain myocardial damage, even though the patient is stable. Seek expert help.2,1
  • Drugs only if the sedation or anaesthesia risk is too high: procainamide 10 to 15 mg/kg IV over 20 minutes first. If drugs fail, cardiovert with expert advice.1
  • If procainamide is unavailable or contraindicated, give amiodarone 300 mg IV over 10 to 60 minutes, then 900 mg IV over 24 hours.1,3
  • IV adenosine is allowed only for a regular broad-complex rhythm confidently suspected to be SVT with aberrant conduction. If it fails, treat as VT.1,3

Polymorphic VT, torsades and electrical storm

  • Stable torsades: magnesium sulfate 8 mmol IV over 10 minutes on the algorithm. The BNF gives 2 g by IV injection over 10 to 15 minutes, repeated once if necessary.1,7
  • Stop QT-prolonging medicines, correct potassium and magnesium, consider isoprenaline or temporary pacing to raise the heart rate with expert help, and avoid amiodarone.1,4
  • Unstable or pulseless polymorphic VT: shock. Give an unsynchronised shock if the defibrillator cannot lock on to the continually changing complexes.1,2
  • Electrical storm or repeated ICD shocks: critical care, immediate electrophysiology input, and treat ischaemia, heart failure, hypoxia, electrolytes and proarrhythmic medicines.6,4

After ROSC

  • Target oxygen saturation 94% to 98%, carbon dioxide 4.7 to 6.0 kPa, and mean arterial pressure above 60 to 65 mmHg or systolic above 100 mmHg.6
  • Prioritise immediate coronary angiography for clear ST elevation or other high suspicion of coronary occlusion.6
  • While the patient remains comatose, actively prevent fever at or below 37.5°C for 36 to 72 hours. Fever prevention, not targeted cooling.6

Prevent recurrence and sudden death

  • Assess coronary disease, ventricular function and scar, review medicines and electrolytes, and investigate unexplained VT with cardiac MRI, provocation testing and device data.6,4
  • Refer for ICD assessment: NICE recommends one after a serious ventricular arrhythmia, and also for inherited high sudden-death risk or repaired congenital heart disease.5
  • After a cardiac arrest, arrange follow-up within three months of discharge, screening for cognitive, physical and emotional problems, and invite the family.6
  • Driving: a ventricular arrhythmia leading to an ICD indication means 6 months off Group 1 (car) driving and permanent Group 2 (lorry and bus) revocation.8
  • A prophylactic ICD means one month off Group 1 driving. VT ablation with impaired ventricular function means at least 4 weeks, without needing to notify the DVLA.8

Exam traps

  • Pulseless VT is not cardioverted. It is an unsynchronised shockable cardiac arrest.
  • VT with a pulse is not shocked in arrest mode: synchronise to the R wave. Switch to unsynchronised only if the defibrillator cannot lock on.
  • Adenosine may unmask an SVT with aberrant conduction, but if it fails the rhythm is VT and you treat it as VT.
  • Stable monomorphic VT with structural heart disease is not a drugs-then-discharge pathway. Cardioversion is recommended; drugs come in only when the sedation risk is too high.
  • The 1 g procainamide maximum is printed in the unstable box of the tachyarrhythmia algorithm, not the stable one. 15 mg/kg in a 90 kg adult would be 1.35 g.
  • The two amiodarone infusion times differ by box: over 10 to 20 minutes when the patient is unstable, over 10 to 60 minutes when stable.
  • Amiodarone is avoided in torsades because it prolongs the QT interval further.
  • Successful cardioversion or ablation does not by itself remove a NICE indication for an implantable cardioverter defibrillator.
  • Post-arrest temperature management is fever prevention at or below 37.5°C. A comatose patient already at 32 to 36°C is not actively warmed, but that is not a cooling target.

Illustrations

Monomorphic ventricular tachycardiaA predominantly regular broad-complex tachycardia with similar QRS morphology from beat to beat. Intermittent narrower or intermediate complexes may represent capture or fusion beats and support ventricular origin, but treatment must be driven first by pulse and haemodynamic state.W.G. de Voogt, MD, PhD, SLAZ, The Netherlands, Wikimedia Commons · CC-BY-SA-3.0
Short-long-short initiation of torsades de pointesA rhythm strip showing a short-long-short ventricular sequence preceding the onset of polymorphic ventricular tachycardia. Torsades is the long-QT subtype; confirm QT prolongation on surrounding sinus-rhythm ECGs and review medicines and electrolytes.CardioNetworks, Wikimedia Commons · CC-BY-SA-3.0

Key sources

  1. Adult tachyarrhythmia algorithm V3, updated March 2026 (Resuscitation Council UK Adult tachyarrhythmia V3)
  2. Adult advanced life support Guidelines (Resuscitation Council UK Guidelines 2025)Published 27 Oct 2025
  3. FAQs: Advanced Life Support (Resuscitation Council UK professional library)
  4. 2022 ESC Guidelines for the management of patients with ventricular arrhythmias and the prevention of sudden cardiac death (European Heart Journal 2022;43(40):3997-4126, doi:10.1093/eurheartj/ehac262)Published 26 Aug 2022
  5. Implantable cardioverter defibrillators and cardiac resynchronisation therapy for arrhythmias and heart failure (NICE TA314)Published 25 Jun 2014 | Updated 30 Aug 2017
  6. Post-resuscitation care Guidelines (Resuscitation Council UK Guidelines 2025)Published 27 Oct 2025
  7. Magnesium sulfate (BNF drug monograph)
  8. Cardiovascular disorders: assessing fitness to drive (DVLA medical guidance)Published 11 Mar 2016 | Updated 7 Nov 2025

This page is exam revision material, not medical advice, and must not be used for patient care. Always check drug doses against the BNF and current guidance. Full disclaimer.