Ventricular fibrillation

Question 1

Define ventricular fibrillation

Answer 1

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

Question 2

Explain the aetiology/risk factors of ventricular fibrillation

Answer 2

The ventricular fibres contract randomly causing complete failure of ventricular function. Most cases occur in patients with underlying heart disease.

Risk Factors:
Coronary artery disease
AF
Hypoxia
Ischaemia
Pre-excitation syndrome

Question 3

Summarise the epidemiology of ventricular fibrillation

Answer 3

The MOST COMMON arrhythmia identified in cardiac arrest patients

Incidence of VF parallels the incidence of ischaemic heart disease

Question 4

Recognise the presenting symptoms and signs of ventricular fibrillation

Answer 4

History of:
Chest pain
Fatigue
Palpitations

There may be known pre-existing conditions:
Coronary artery disease

Cardiomyopathy

Valvular heart disease

Long QT syndrome

Wolff-Parkinson-White syndrome

Brugada syndrome (mutated Na+ channels)

Question 5

Identify appropriate investigations for ventricular fibrillation

Answer 5

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 6

Generate a management plan for ventricular fibrillation

Answer 6

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 7

Identify possible complications of ventricular fibrillation

Answer 7

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

Question 8

Summarise the prognosis for patients with ventricular fibrillation

Answer 8

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