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# Ventricular tachycardia

Ventricular tachycardia is a fast rhythm that starts in the lower chambers of the heart. It can cause fainting, cardiac arrest and sudden death.

Updated 2026-11-01

## Structures involved

Tap one to see what it is and open it in 3D.

- [Left ventricle](https://durgical.com/en/anatomy/left-ventricle/)
- [Right ventricle](https://durgical.com/en/anatomy/right-ventricle/)
- [Bundle branches](https://durgical.com/en/anatomy/right-bundle-branch/)
- [Interventricular septum](https://durgical.com/en/anatomy/interventricular-septum/)
- [LAD (anterior descending artery)](https://durgical.com/en/anatomy/anterior-interventricular-artery/)
- [Bundle of His](https://durgical.com/en/anatomy/atrioventricular-bundle/)

## Why it happens

- [The myocardial infarct over time: what the pathologist sees from hours to months](https://durgical.com/en/general-pathology/the-myocardial-infarct-over-time-what-the-pathologist-sees-from-hours-to-months/)
- [How arrhythmias arise](https://durgical.com/en/physiology/how-arrhythmias-arise/)
- [The cardiac conduction system](https://durgical.com/en/physiology/the-cardiac-conduction-system/)
- [The ventricular action potential](https://durgical.com/en/physiology/the-ventricular-action-potential/)
- [Cardiac muscle: intercalated discs](https://durgical.com/en/histology/cardiac-muscle-intercalated-discs/)

## What it is

A tachycardia of three or more consecutive beats arising below the [bundle of His](https://durgical.com/en/anatomy/atrioventricular-bundle/), usually above 100 beats per minute, with wide QRS complexes on the ECG. It may be stable, unstable or pulseless.

## Who gets it

Most cases occur in people with structural heart disease, especially scar from a previous infarction. In Colombia and Latin America, chronic Chagas cardiomyopathy is an important and characteristic cause of sustained VT and sudden death.

## Causes

- Scar from a previous myocardial infarction (re-entry around the scar), the most common cause of monomorphic VT
- Acute ischaemia, which typically causes polymorphic VT
- Cardiomyopathies: Chagas, dilated, hypertrophic, arrhythmogenic right ventricular
- Long QT (congenital or drug-induced) causing torsades de pointes; hypokalaemia and hypomagnesaemia
- Idiopathic VT in structurally normal hearts (outflow tract, fascicular)

## Risk factors

- Previous myocardial infarction and low ejection fraction
- Heart failure
- Electrolyte disorders and QT-prolonging drugs
- Family history of sudden death or inherited channelopathy

## Pathophysiology

Most sustained VT is re-entry: an electrical circuit loops through slow-conducting tissue at the edge of a scar. Activation spreads from muscle cell to muscle cell instead of through the His-Purkinje system, so the QRS is wide. The fast rate shortens filling and lowers output, and VT can degenerate into ventricular fibrillation.

## Classification

- Non-sustained (under 30 seconds, no compromise) or sustained (30 seconds or more, or needing termination)
- Monomorphic or polymorphic; torsades de pointes is polymorphic VT with a long QT
- Stable with a pulse, unstable with a pulse, or pulseless

## Symptoms and signs

- Palpitations
- Dizziness, presyncope or syncope
- [Chest](https://durgical.com/en/anatomy/region/chest/) pain and dyspnoea
- Hypotension and signs of shock
- Sudden collapse when there is no pulse

## Red flags

- Syncope or hypotension with a wide-complex tachycardia
- Altered consciousness or no pulse
- Polymorphic VT or torsades de pointes
- VT in a patient with known heart failure or a previous infarction

## Diagnosis

**Clinical**
Check pulse, blood pressure and consciousness first, since stability decides treatment. A wide-complex tachycardia in someone with structural heart disease is treated as VT until proven otherwise; cannon a waves and a variable first heart sound suggest AV dissociation.

**Tests**
12-lead ECG: wide regular QRS, AV dissociation, capture and fusion beats, concordance in the precordial leads. Potassium, magnesium, troponin; QT interval after conversion; Holter monitoring; Chagas serology in people from endemic areas; electrophysiological study in selected cases.

**Imaging**
Echocardiography to assess ejection fraction and structural disease; cardiac MRI to detect scar or infiltration; coronary angiography when ischaemia is suspected.

## Differential diagnosis

- Supraventricular tachycardia with aberrant conduction (bundle branch block)
- Pre-excited tachycardia (Wolff-Parkinson-White)
- Sinus tachycardia with a pre-existing bundle branch block
- Hyperkalaemia or sodium-channel-blocker toxicity with wide QRS
- Pacemaker-mediated tachycardia

## Goal of treatment

Terminate the arrhythmia safely according to haemodynamic stability, correct triggers such as ischaemia and electrolytes, and prevent recurrence and sudden death.

## Treatment

**Acute**
Pulseless VT: managed as cardiac arrest with CPR and immediate defibrillation.

**Acute**
Unstable VT with a pulse (hypotension, shock, altered mental status, ischaemic pain, heart failure): urgent synchronised cardioversion with sedation when possible.

**Medical**
Stable monomorphic VT: intravenous antiarrhythmics (amiodarone, procainamide or lidocaine) or elective synchronised cardioversion; correction of potassium and magnesium.

**Medical**
Torsades de pointes: intravenous magnesium sulfate, stopping QT-prolonging drugs, and increasing heart rate (pacing or isoproterenol) when it recurs.

**Procedure**
Prevention of sudden death: implantable cardioverter-defibrillator in selected patients; catheter ablation for recurrent VT; long-term beta-blockers or amiodarone.

## Complications

- Degeneration into ventricular fibrillation and sudden cardiac death
- Cardiogenic shock
- Syncope with injury
- Worsening heart failure
- Tachycardia-induced cardiomyopathy when incessant

## Prognosis

Depends on the underlying heart. Idiopathic VT in a normal heart has a good outlook and often responds to ablation; VT with scar or low ejection fraction carries a high risk of sudden death, which an implantable defibrillator lowers.

## Prevention

- Early reperfusion of infarction and optimal heart failure treatment
- Avoiding QT-prolonging drug combinations and correcting electrolytes
- Chagas control and screening in endemic areas

## Test yourself

Think of the answer, then tap the question to see it.

## How is a wide-complex tachycardia in a patient with a previous infarction managed until proven otherwise?

As ventricular tachycardia.

## What is the treatment of unstable VT with a pulse?

Synchronised electrical cardioversion.

## Which ECG findings strongly favour VT over SVT with aberrancy?

AV dissociation, capture beats and fusion beats, and precordial concordance.

## What is the first-line drug for torsades de pointes?

Intravenous magnesium sulfate, along with stopping QT-prolonging drugs and correcting potassium.

## Which parasitic heart disease is a classic cause of VT in Latin America?

Chronic Chagas cardiomyopathy, caused by Trypanosoma cruzi.

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## Related conditions

- [Cardiac arrest (VF, pulseless VT, asystole, PEA)](https://durgical.com/en/conditions/cardiac-arrest/)
- [Myocardial Infarction (Heart Attack)](https://durgical.com/en/conditions/myocardial-infarction/)
- [Chagas cardiomyopathy](https://durgical.com/en/conditions/chagas-cardiomyopathy/)
- [Dilated cardiomyopathy](https://durgical.com/en/conditions/dilated-cardiomyopathy/)
- [Hypertrophic cardiomyopathy](https://durgical.com/en/conditions/hypertrophic-cardiomyopathy/)
- [Heart failure](https://durgical.com/en/conditions/heart-failure/)
- [Supraventricular tachycardia (AVNRT, AVRT)](https://durgical.com/en/conditions/supraventricular-tachycardia/)

Educational information, not medical advice. For any symptom, see a health professional.

Sources: [Ventricular tachycardia: MedlinePlus Medical Encyclopedia](https://medlineplus.gov/ency/article/000187.htm) (MedlinePlus, US National Library of Medicine, 2026); [Chagas disease (also known as American trypanosomiasis)](https://www.who.int/news-room/fact-sheets/detail/chagas-disease-(american-trypanosomiasis)) (World Health Organization, 2026).

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Source: https://durgical.com/en/conditions/ventricular-tachycardia/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/conditions/ventricular-tachycardia/