Ventricular Fibrillation

Question 1

Definition

Answer 1

An irregular broad-complex tachycardia that can cause cardiac arrest and sudden cardiac death.

Question 2

Aetiology

Answer 2

· The ventricular fibres contract randomly causing complete failure of ventricular function

· Most cases occur in patients with underlying heart disease

Question 3

Risk factors

Answer 3

o Coronary artery disease
o AF
o Hypoxia
o Ischaemia
o Pre-excitation syndrome

Question 4

Epidemiology

Answer 4

· The MOST COMMON arrhythmia identified in cardiac arrest patients

· Incidence of VF parallels the incidence of ischaemic heart disease

Question 5

Presenting symptoms (history)

Answer 5

o Chest pain
o Fatigue
o Palpitations

Question 6

Presenting symptoms (pre-existing conditions)

Answer 6

o Coronary artery disease
o Cardiomyopathy
o Valvular heart disease
o Long QT syndrome
o Wolff-Parkinson-W
o Brugada syndrome

Question 7

Investigations

Answer 7

· ECG

· Cardiac enzymes (e.g. troponins) - check for recent ischaemic event

· Electrolytes - derangement can cause arrhythmias, including VF

· Drug levels and toxicology screen - anti-arrhythmics can (ironically) cause arrhythmia, as can various recreational drugs (e.g. cocaine)

· TFTs - hyperthyroidism can cause tachyarrhythmias

· Coronary angiography - if patient survives VF, to check the integrity of coronary arteries

Question 8

Management plan

Answer 8

· VF requires urgent defibrillation and cardioversion

· Patients who survive need full assessment of left ventricular function, myocardial perfusion and electrophysiological stability

· Most survivors will need an implantable cardioverter defibrillator (ICD)

· Empirical beta-blockers

· Some patients may be treated with radiofrequency ablation (RFA)

Question 9

Possible complications

Answer 9

· Ischaemic brain injury due to loss of cardiac output
· Myocardial injury
· Post-defibrillation arrhythmias
· Aspiration pneumonia
· Skin burns
· Death

Question 10

Prognosis

Answer 10

· Depends on the time between onset of VF and medical intervention

· Early defibrillation is essential (ideally within 4-6 mins)

· Anoxic encephalopathy is a major outcome of VF