Involves very rapid and irregular ventricular activation with no mechanical effect

Aetiology

• In the vast majority of cases is a manifestation of underlying ischaemic heart disease
• Other causes include cardiomyopathy, electrolyte imbalance and overdoses of cardiotoxic drugs

Pathophysiology

• Usually provoked by a ventricular ectopic beat

Clinical features

• Patient is pulseless and becomes rapidly unconscious; respiration ceases (cardiac arrest)

Investigations

ECG

• An irregular broad complex tachycardia on the electrocardiogram is assumed to be ventricular fibrillation
• Bizarre irregular, polymorphic waveform
  • No recognisable QRS complexes
  • Random frequency and amplitude
  • Uncoordinated electrical activity

Management

Initial management

Management is according to the Advanced Life Support guidelines:

• The initial priorities will be as for the Basic Life Support: ensure the airway is patent, check for signs of life (pulse and breathing), and commence CPR
• Ventricular fibrillation is a shockable rhythm: the next step is to administer defibrillation (unsynchronised cardioversion using a 200 J biphasic shock)
• Chest compressions should then be resumed
• 1 mg adrenaline (10 ml 1:10 000) plus 300 mg amiodarone should be administered after the 3rd shock