Ventricular Tachycardia

Question 1

DEFINITION: VT

Answer 1

Broad complex tachycardia originating from ectopic foci in the ventricles

MEDICAL EMERGENCY (complication VF)

Sustained VT =

• VT lasting > 30 s OR
• VT + haemodynamic compromise

Question 2

What are the two main types of VT?

Answer 2

1. Monomorphic - caused by MI
2. Polymorphic e.g. Torsade de Pointes (caused by prolongation QT interval)

Question 3

CAUSES: prolongation of QT interval

Answer 3

• 1. Congenital*
• 2. Electrolyte imbalance*
• Hypocalcaemia
• Hypokalaemia
• Hypomagnesaemia

3. Cardiac

• MI
• Myocarditis

4. Other

• Hypothermia
• Subarachnoid haemorrhage

5. Drugs

• Antiarrhythmics: Amiodarone, sotalol
• AntiDep: TCAs, fluoxetine
• Chloroquine
• Erythromycin

Question 4

CLINICAL FEATURES: VT

Answer 4

Symptoms

• Palpitations
• Chest Pain
• Syncope

Signs

• Tachycardia + hypotension
• Varying S1
• Occasional JVP cannon waves (giant ‘a’ waves)

Question 5

INVESTIGATIONS: VT

Answer 5

ECG

• Wide complex tachycardia (>100ms, bigger than 3 small squares)
• Organised pattern

Question 6

MANAGEMENT: VT

Answer 6

IF haemodynamically unstable = DC CARDIOVERSION

IF haemodynamically stable = ANTIARRHYTHMICS

• AMIODARONE OR
• LIDOCAINE OR
• PROCAINAMIDE

IF drug therapy fails

• electrophysiological study
• implantable cardioverter-defibrillator (esp: sig. impaired LV function)

Question 7

What is found on Torsades de Pointes ECG?

Answer 7

• Spindle-shaped QRS

Question 8

How is Torsades De Pointes managed?

Answer 8

IF congenital

• Beta-blockers
• Acute pacing

IF not congenital

• IV magnesium sulphate