Definition of Ventricular fibrillation

Ventricular fibrillation (VF) is a type of ventricular arrhythmia characterised by rapid, irregular,
ineffective and uncoordinated ventricular activation with no mechanical effect.
There is chaotic electrical disturbance of ventricles, with impulse occuring irregularly at rate
of 300–500/min. Cardiac output falls to zero.
It is the most common cause of sudden death. It may occur as a primary arrhythmia or as a
complication in acute myocardial


• Acute myocardial infarction.
• Electrolyte imbalance (hypokalemia, hypomagnesemia).
• Electrocution.
• Others—drowning, drug overdose (digitalis, adrenaline, isoprenaline).

ECG Findings

QRS—Chaotic, wide, bizarre, irregular.
• Patient—unconscious.
• Pulse—absent.
• BP—not recordable.
• Respiration—ceases or absent.
• Pupil—dilated, less or no reaction to light.
• Heart sounds-absent.

Treatment of Ventricular fibrillation

• Immediate defibrillation—200 Joules. If no response, another shock with 200 Joules. If still
no response, another shock with 360 Joules is given.
• If three shocks unsuccessful—adrenaline IV, followed by cardiopulmonary resuscitation.
• If defibrillator is not available—cardiopulmonary resuscitation should be given.
• The patient who survives from VF in the absence of identifiable cause is at high risk of sudden
death. It is treated with ICD.