Ventricular tachycardia Flashcards
What is ventricular tachycardia?
A type of broad complex tachycardia characterised by a heart rate of more than 100bpm and a QRS width of more than 120ms.
Aetiology of ventricular tachycardia?
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
Pathophysiology of monomorphic VT?
Can be caused by increased automaticity, or due to re-entry circuit within ventricle.
Pathophysiology of polymorphic VT?
Caused by abnormal ventricular repolarisation e.g. long QT syndrome, drug toxicity and electrolyte imbalances.
Symptoms of ventricular tachycardia?
Often results in pre-syncope (dizziness), syncope, hypotension and cardiac arrest.
May be remarkably well tolerated in some patients.
Signs of ventricular tachycardia?
Pulse rate typically between 120-220 bpm
ECG appearance for monomorphic VT?
Constant QRS morphology
Broad complex rhythm
Rapid rate
ECG appearance for polymorphic VT?
QRS complex varies in amplitude
ECG appearance for torsades de pointes?
Specific polymorphic VT associated with a long QT interval
QRS complexes appear to twist around isoelectric line