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Ventricular Fibrillation, Emergency Medicine

Basics

Description

- 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

  • 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 abnormalitiesCongenital and acquired prolonged QT syndromes.Short QT syndromeBrugada syndrome
  • Premature ventricular complexes (PVCs) with R-on-T phenomenon
  • Other less common causes of VF:ElectrocutionHypoxiaHypothermiaBlunt chest traumaIatrogenic 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:EKGCardiac USCXR, 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 biphasicBiphasic 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 shockBiphasic energy level:Follow manufacturers recommendations (e.g. 120 " 200 J) for 1st shock; if unknown, use maximum availableSame or higher energy for subsequent shocks360 J monophasic for 1st and subsequent shocksMay repeat q2min until rhythm changes
  • CPR:Immediately resume CPR after each shock for 2 min starting with chest compressions30:2 compression " ventilation ratio if no advanced airway in place ≥100 compressions per minuteMinimize 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 shockMay repeat q3 " 5minVasopressin may replace 1st or 2nd dose of epinephrine
  • Antiarrhythmic medications if refractory VF:Start after 3rd shockAmiodaroneLidocaine if amiodarone is not availableMagnesium for torsade de pointesMay consider a continuous infusion of the antiarrhythmic agent associated with ROSC
  • Advanced airway management:Should not delay initial CPR and defibrillationResume CPR with continuous chest compressions ≥100/min and 1 ventilation every 6 " 8 secUse 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.

See Also (Topic, Algorithm, Electronic Media Element)

2010 ACLS Guidelines

Codes

ICD9

427.41 Ventricular fibrillation

ICD10

I49.01 Ventricular fibrillation

SNOMED

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