Ventricular Fibrillation, Emergency Medicine

Basics

Description

Ventricular fibrillation (VF) is completely disorganized depolarization and contraction of small areas of the ventricle without effective cardiac output.
Cardiac monitor displays absence of QRS complexes and T-waves with the presence of high-frequency, irregular undulations that are variable in both amplitude and periodicity.

Etiology

Damaged myocardium creates sites for re-entrant circuits:
- Myocardial damage may be caused by multiple factors including ischemia, necrosis, reperfusion, healing, and scar formation
Most often a result of severe myocardial ischemia:
- 7% of patients with STEMI develop sustained VF, 80 " 85% occurring in the 1st 24 hr
Complication of cardiomyopathy:
- Up to 50% of patients with dilated cardiomyopathy suffer an episode of VF.
- In hypertrophic cardiomyopathy, unexpected sudden death occurs with reported frequency of up to 3%/yr.
Nonischemic causes of ventricular tachycardia may evolve into VF:
- Drug toxicities (cyclic antidepressants, digitalis)
- Electrolyte or acid " base abnormalities
- Congenital and acquired prolonged QT syndromes.
- Short QT syndrome
- Brugada syndrome
Premature ventricular complexes (PVCs) with R-on-T phenomenon
Other less common causes of VF:
- Electrocution
- Hypoxia
- Hypothermia
- Blunt chest trauma
- Iatrogenic myocardial irritation from pacemaker placement or pulmonary artery catheter
Idiopathic VF (5 " 10%)

Primary ventricular dysrhythmias are extremely rare in children.
VF usually results from a respiratory arrest, hypothermia, or near drowning.

Diagnosis

Signs and Symptoms

Loss of consciousness
Seizure
Transient gasping followed by apnea
Absent pulse and heart sounds
Death if the rhythm remains untreated:
- VF is the initial rhythm in ’ Ό5 " 70% of patients sustaining sudden cardiac death in the pre-hospital setting

Essential Workup

AED or manual defibrillator to confirm and treat a shockable rhythm
Cardiac monitor

Diagnosis Tests & Interpretation

Lab

Lab tests are not useful during resuscitation
After return of spontaneous circulation (ROSC): Electrolytes including calcium and magnesium, BUN, creatinine, troponin, ABG, lactic acid level, and toxicology screen

Imaging

After ROSC
To identify cause of VF:
- EKG
- Cardiac US
- CXR, also to monitor placement of an endotracheal tube (ETT)

Differential Diagnosis

Asystole:
- Fine VF may mimic asystole in a single lead.
- Check rhythm in another lead for fine fibrillations

Treatment

Early defibrillation of VF is the most important determinant of survival, and each minute without defibrillation reduces survival by 7 " 10%.
Single shock defibrillation strategy is the current standard
Supraventricular tachycardia or VT with a pulse may degenerate into VF if cardioverted without synchronization.
In a hypothermic cardiac arrest with VF, follow standard defibrillation strategy while rewarming the patient
Do not defibrillate any conscious patient.

Controversies

Escalating biphasic energy levels have been shown to improve conversion of VF:
- Almost all automated external defibrillators (AED) and manual defibrillators commercially available are biphasic
- Biphasic defibrillators are recommended because less energy is required
Some study raised questions on the benefit of epinephrine in cardiac arrest
The benefit of amiodarone or lidocaine in post cardiac arrest after ROSC is uncertain
The benefit of procainamide as a 2nd-line antiarrhythmic remains controversial and is no longer included in the AHA guidelines

Pre-Hospital

Promptly recognize cardiac arrest
Follow initial stabilization/therapy
Ideally, transport to the closest facility delivering comprehensive post cardiac arrest treatment

Initial Stabilization/Therapy

Use AED or manual defibrillator as soon as available
Perform early CPR starting with chest compressions until defibrillator is ready
Defibrillator confirms shockable rhythm
Initiate SCREAM acronym
Shock:
- Immediate defibrillation with 1 shock
- Biphasic energy level:
  - Follow manufacturers recommendations (e.g. 120 " 200 J) for 1st shock; if unknown, use maximum available
  - Same or higher energy for subsequent shocks
- 360 J monophasic for 1st and subsequent shocks
- May repeat q2min until rhythm changes
CPR:
- Immediately resume CPR after each shock for 2 min starting with chest compressions
- 30:2 compression " ventilation ratio if no advanced airway in place
- ≥100 compressions per minute
- Minimize CPR interruptions
Rhythm check after every 2 min of CPR
Secondary ABCD survey to try and determine underlying cause while resuscitation in progress
Establish IV/IO access
Epinephrine if defibrillation is unsuccessful:
- Start after 2nd shock
- May repeat q3 " 5min
- Vasopressin may replace 1st or 2nd dose of epinephrine
Antiarrhythmic medications if refractory VF:
- Start after 3rd shock
- Amiodarone
- Lidocaine if amiodarone is not available
- Magnesium for torsade de pointes
- May consider a continuous infusion of the antiarrhythmic agent associated with ROSC
Advanced airway management:
- Should not delay initial CPR and defibrillation
- Resume CPR with continuous chest compressions ≥100/min and 1 ventilation every 6 " 8 sec
- Use capnography to monitor ETT position, optimize quality of CPR, and detect ROSC

Defibrillation sequence: Monophasic 2 J/kg, 2 " 4 J/kg, 4 J/kg
May consider 4 " 10 J/kg or adult maximum dose for subsequent shocks

Ed Treatment/Procedures

Post cardiac arrest care
Identify and treat the cause of the VF arrest recognizing that the most likely cause is acute myocardial infarction:
- Provide percutaneous coronary intervention when indicated
Maintain SpO2 ≥94% and PETCO2 at 35 " 40 mm Hg
Treat SBP <90 mm Hg
Maintain body temperature at 32 " 34 ΊC
Treat hyperglycemia >180 mg/dL (>10 mmol/L)

Medication

Epinephrine: 1 mg IV/IO bolus, may repeat dose q3 " 5min
Vasopressin: 40 U IV/IO bolus single dose
Amiodarone: 300 mg in IV/IO bolus, may repeat 150 mg IV/IO bolus once:
- Amiodarone infusion after ROSC: 1 mg/min for 1st 6 hr then 0.5 mg/min for 18 hr. Max. cumulative dose 2.2 g/24 h
Lidocaine: 1 " 1.5 mg/kg IV/IO bolus, may repeat 0.5 " 0.75 mg/kg IV bolus q5 " 10min; 3 doses max. or max. cumulative dose 3 mg/kg:
- Lidocaine infusion after ROSC: 1 " 4 mg/min (30 " 50 Όg/kg/min)
Magnesium sulfate: 1 " 2 g in 10 mL D5W IV/IO bolus
Follow each medication with a 20 mL NS flush.

Epinephrine: 0.01 mg/kg IV/IO, may repeat q3 " 5min; max. cumulative dose 1mg
Amiodarone: 5 mg/kg IV/IO, may repeat 5 mg/kg; max. cumulative dose 15 mg/kg/d
Lidocaine: 1 mg/kg IV/IO:
- Lidocaine infusion 20 " 50 Όg/kg/min
Magnesium sulfate: 25 " 50 mg/kg IV/IO up to 2 g
Follow each medication with a 3 " 5 mL NS flush.

Follow-Up

Disposition

Admission Criteria
All patients who survive need admission to the ICU/CCU.
Discharge Criteria
No patient who suffers a VF arrest may be discharged from the ED.
Issues for Referral
Patients with episodes of VF occurring >48 hr post-MI may need referral to electrophysiology.

Pearls and Pitfalls

ACC/AHA guidelines recommend that patients with an acute myocardial infarction should have their serum potassium maintained above 4 mEq/L to prevent ventricular dysrhythmias

Additional Reading

de Jong JS, Marsman RF, Henriques JP, et al. Prognosis among survivors of primary ventricular fibrillation in the percutaneous coronary intervention era. Am Heart J. 2009;158:467 " 472.
Hagihara A, Hasegawa M, Abe T, et al. Prehospital epinephrine use and survival among patients with out-of-hospital cardiac arrest. JAMA. 2012;307:1161 " 1168.
Hazinski MF, Nolan JP, Billi JE, et al. Part 1: Executive summary: 2010 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations. Circulation. 2010;122(16 suppl 2):S250 " S275.
Morrison LJ, Deakin CD, Morley PT, et al. Part 8: Advanced life support: 2010 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations. Circulation. 2010;122(16 suppl 2):S345 " S421.
Zipes DP, Camm AJ, Borggrefe M, et al. ACC/AHA/ESC 2006 guidelines for management of patients with ventricular arrhythmias and the prevention of sudden cardiac death. Circulation. 2006;114:e385 " e484.

Codes

ICD9

427.41 Ventricular fibrillation

ICD10

I49.01 Ventricular fibrillation

SNOMED

71908006 Ventricular fibrillation (disorder)
429243003 Sustained ventricular fibrillation (disorder)

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