Ventricular tachycardia

Question 1

What is ventricular tachycardia?

Answer 1

A type of broad complex tachycardia characterised by a heart rate of more than 100bpm and a QRS width of more than 120ms.

Question 2

Aetiology of ventricular tachycardia?

Answer 2

Patients usually have structural heart disease e.g. previous MI, cardiomyopathy

Other causes:
- Electrolyte abnormalities such as hypokalaemia and hypomagnesaemia.
- Drugs that cause QT prolongation e.g. clarithromycin, erythromycin.
- Inherited channelopathies e.g. brugada syndrome

Question 3

Pathophysiology of monomorphic VT?

Answer 3

Can be caused by increased automaticity, or due to re-entry circuit within ventricle.

Question 4

Pathophysiology of polymorphic VT?

Answer 4

Caused by abnormal ventricular repolarisation e.g. long QT syndrome, drug toxicity and electrolyte imbalances.

Question 5

Symptoms of ventricular tachycardia?

Answer 5

Often results in pre-syncope (dizziness), syncope, hypotension and cardiac arrest.

May be remarkably well tolerated in some patients.

Question 6

Signs of ventricular tachycardia?

Answer 6

Pulse rate typically between 120-220 bpm

Question 7

ECG appearance for monomorphic VT?

Answer 7

Constant QRS morphology

Broad complex rhythm

Rapid rate

Question 8

ECG appearance for polymorphic VT?

Answer 8

QRS complex varies in amplitude

Question 9

ECG appearance for torsades de pointes?

Answer 9

Specific polymorphic VT associated with a long QT interval

QRS complexes appear to twist around isoelectric line