Ventricular tachycardia Flashcards
What is ventricular tachycardia?
a regular broad-complex tachycardia originating from a ventricular ectopic focus. Rate usually > 120 bpm.
What is the aetiology of ventricular tachycardia?
Electrical impulses arise from a ventricular ectopic focus
Summarise the epidemiology of ventricular tachycardia
Fairly common
A shockable rhythm seen in cardiac arrest patients
VT incidence peaks at middle age
List 4 symptoms of ventricular tachycardia
Chest pain
Palpitations
Dyspnoea
Syncope
What do the symptoms of VT mimic? Why?
Symptoms of IHD or haemodynamic compromise due to poor perfusion
List 8 signs of ventricular tachycardia on physical examination
Respiratory distress Bibasal crackles Raised JVP Hypotension Anxiety Agitation Lethargy Coma
What are 4 investigations for ventricular tachycardia?
ECG: difficult to distinguish between VT + SVT with aberrant conduction. If in doubt, treat as a VT
Electrolytes: derangement can cause arrhythmias
Drug levels: e.g. digoxin toxicity
Cardiac enzymes: e.g. troponins to check for recent ischaemic event
how do you treat a haemodynamically unstable patient with ventricular tachycardia?
With pulse: cardioversion
Without pulse: defibrillation
List 4 Risk Factors for VT
Coronary heart disease
Structural heart disease
Electrolyte deficiencies (e.g. hypokalaemia, hypocalcaemia, hypomagnesaemia)
Use of stimulant drugs (e.g. caffeine, cocaine)
List 3 complications of VT
Congestive cardiac failure
Cardiogenic shock
VT may deteriorate into VF
Summarise the prognosis of ventricular tachycardia
GOOD if treated RAPIDLY
Long-term prognosis depends on the underlying cause
What is the presence of signs dependent on?
Degree of haemodynamic instability
List 3 features of the ECG seen in VT
Rate > 100 bpm
Broad QRS complexes
AV dissociation
What causative factors should you look for in patients with VT? How do you treat these?
Electrolyte abnormalities (e.g. hypokalemia): correct imbalances Medication-induced QT prolongation: remove offending medication, digoxin immune fab (fragment antigen-binding) for digoxin toxicity
How do you treat a haemodynamically stable patient with ventricular tachycardia?
Antiarrhythmics: lidocaine, procainamide, amiodarone
Cardioversion if medical therapy fails
What are 3 long term therapies for VT?
ICD; indicated in case of VT that does not respond to therapy Catheter ablation Antiarrhythmics (usually class I or III)
Which drug is contraindicated in broad complex tachycardia as can precipitate severe hypotension, ventricular fibrillation or cardiac arrest?
Verapamil
Do not know whether SVT or VT
(can only be used in SVT)
What is Torsades de pointes?
A Polymorphic ventricular tachycardia a/w long QT interval
May deteriorate into VF + lead to sudden death
Give 2 congenital causes of long QT
Jervell-Lange-Nielsen syndrome
Romano-Ward syndrome
List 3 anti-arrhythmics that can cause long QT
Amiodarone
Sotalol
Class 1a antiarrhythmics: Lidocaine, Procainamide, Flecainide
What electrolyte abnormalities cause long QT?
Hypocalcaemia
Hypokalaemia
Hypomagnesaemia
What 3 conditions/ states can cause long QT?
Myocarditis
SAH
Hypothermia
List 5 drugs/ classes that can cause long QT
TCAs
Antipsychotics
Chloroquine
Terfenadine
Erythromycin
What is given in management of torsades de pointes?
IV Magnesium Sulphate
