What is the management of ventricular fibrillation?

Management of Ventricular Fibrillation

Ventricular fibrillation (VF) should be treated immediately with an unsynchronized electric shock with an initial energy of 200J, followed by escalating energies of 200-300J and 360J if needed, along with high-quality CPR. 1, 2

Immediate Management

• Recognize VF on cardiac monitor as disorganized electrical activity without discernible QRS complexes 2
• Begin high-quality CPR immediately with minimal interruptions at a rate of at least 100 compressions per minute and a depth of 2/3 of the anteroposterior chest diameter 1, 2
• Connect a monitor/defibrillator as soon as possible 1
• Deliver an immediate unsynchronized shock for VF with an initial energy of 200J (monophasic) or according to manufacturer's recommendations for biphasic defibrillators 1, 2
• If the first shock is unsuccessful, administer a second shock at 200-300J, then a third shock at 360J if necessary 1, 3
• Resume CPR immediately after each shock, beginning with chest compressions 2

Medication Administration

• Establish IV/IO access while continuing CPR 2
• Administer epinephrine 1mg IV/IO every 3-5 minutes 2
• Consider amiodarone for refractory VF:
  • Initial dose: 150mg IV infused over 10 minutes 3, 4
  • Follow with constant infusion of 1.0mg/min for 6 hours 3
  • Then maintenance infusion of 0.5mg/min 3, 4
• For breakthrough episodes of VF, use 150mg supplemental infusions of amiodarone (mixed in 100mL of D5W and infused over 10 minutes) 4
• Lidocaine (1.5mg/kg IV/IO) may be considered if amiodarone is unavailable 2

Post-Resuscitation Care

• Correct electrolyte abnormalities, particularly potassium and magnesium, to prevent recurrent episodes of VF 3, 2
• Search for and treat reversible causes: hypovolemia, hypoxia, acidosis, hypo/hyperkalemia, hypothermia, pneumothorax, tamponade, toxins, thrombosis (pulmonary and coronary) 1, 2
• Maintain adequate ventilation and oxygenation after return of spontaneous circulation 1, 2
• Consider beta-blockers if VF occurred in the context of acute myocardial infarction 1, 2
• Infusions of antiarrhythmic drugs may be continued for 6-24 hours after an episode of VF, then reassess the need for further arrhythmia management 3

Special Considerations

Prolonged VF (>5 minutes)

• For unwitnessed arrest or prolonged VF, consider 2 minutes of CPR before the first shock 2, 5
• Research suggests that patients with VF and ambulance response times longer than 5 minutes had better outcomes with CPR first before defibrillation 5
• High-dose epinephrine and CPR preceding countershock may improve cardiac resuscitation outcome from prolonged VF 6

Wolff-Parkinson-White Syndrome

• Immediate electrical cardioversion is recommended for patients with Wolff-Parkinson-White syndrome and atrial fibrillation with rapid ventricular response associated with hemodynamic instability 1
• Avoid administering IV beta-blockers, digitalis, diltiazem, or verapamil in patients with pre-excitation syndromes, as these can facilitate conduction through accessory pathways and precipitate VF 1

Myocardial Infarction

• Primary VF is most common (3-5%) in the first 4 hours after myocardial infarction 3
• After successful defibrillation, aggressive attempts to reduce myocardial ischemia should be undertaken, including beta-blockade, intra-aortic balloon pumping, and emergency revascularization 3
• Drug-refractory polymorphic VT in the setting of MI should be managed by aggressive attempts to reduce myocardial ischemia 3

Common Pitfalls to Avoid

• Do not delay defibrillation for witnessed VF arrest 2
• Avoid excessive interruptions in chest compressions, including for rhythm checks 2
• Do not use synchronized cardioversion for VF (always use unsynchronized shocks) 2
• Avoid excessive ventilation, which can decrease cardiac output during CPR 2
• Do not treat isolated ventricular premature beats, couplets, runs of accelerated idioventricular rhythm, and nonsustained VT 3

Clinical Evidence on Amiodarone Efficacy

• Randomized studies have shown that higher doses of IV amiodarone (approximately 1000mg over 24 hours) were more effective than lower doses (approximately 125mg) in suppressing recurrent VF or hemodynamically unstable VT 4
• The median rate of VT/VF episodes was 0.02 episodes per hour in patients receiving high-dose amiodarone versus 0.07 episodes per hour in those receiving low-dose treatment (approximately 0.5 versus 1.7 episodes per day) 4
• Time to first recurrent episode of VT/VF was significantly prolonged with high-dose amiodarone treatment 4