Electrical phase: Initial 4 minutes of VF.
Hemodynamic phase: 4 minutes to 10 minutes after the onset of VF.
Metabolic phase: Beyond 10 minutes after the onset of VF.
If EMS (Emergency medical service) arrives within 4 min (electrical phase) – defibrillation first – It is likely to be coarse VF and responds better to defibrillation.
If after 4 min, but before 10 min, cardiopulmonary resuscitation (CPR) followed by defibrillation.
If beyond 10 min, limited success – induction of hypothermia is recommended.