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Ventricular Fibrillation ECG Guide

May 6, 2025

Lecture: ECG Interpretation Made Easy - Ventricular Fibrillation

Introduction

  • Part of a video series on ECG interpretation.
  • Focus on ventricular fibrillation (VF), a high-yield ventricular rhythm.
  • Other videos cover premature ventricular complexes and ventricular tachycardia.

What is Ventricular Fibrillation?

  • Chaotic firing of multiple ectopic foci in the ventricles.
  • Normally, SA node initiates electrical currents causing atrial contraction.
  • In VF, ectopic foci generate abnormal electrical activity overpowering SA node.
  • Ventricles experience seizure-like activity, hindering proper contraction.

ECG Characteristics

  • No P waves, QRS complexes disappear.
  • Rhythm is haphazard and irregular.
  • Cardiac output drops to zero as ventricles do not contract properly.

Clinical Manifestation

  • Rapid onset of symptoms: chest pain, shortness of breath, palpitations, dizziness.
  • Patient becomes pulseless and unconscious within seconds.
  • Immediate intervention required; otherwise, the condition is fatal.

Common Causes of Ventricular Fibrillation

  • Coronary artery disease.
  • Previous myocardial infarction (MI).
  • Electrolyte imbalances (hypokalemia, hyperkalemia).
  • Electrophysiologic disorders such as long QT interval syndromes.

Types of Ventricular Fibrillation

  • Coarse VF: prominent ECG waves.
  • Fine VF: appears more like a straight line with small bumps, distinguishable from asystole.

Management

  • Immediate Action: Start CPR immediately.
  • Use defibrillation; shock the patient as soon as possible.
  • Follow Advanced Cardiovascular Life Support (ACLS) protocols.

ACLS Protocol

  • Shockable rhythms: VF and pulseless ventricular tachycardia (VT).
    • Shock, CPR, reassess, administer epinephrine, and consider amiodarone.
  • Non-shockable rhythms: Asystole and pulseless electrical activity.
    • Do not shock; continue CPR and administer epinephrine.

Drug Therapy

  • Epinephrine: 1 mg every 3-5 minutes.
  • Amiodarone: First dose 300 mg, second dose 150 mg.
  • Consider lidocaine if amiodarone is not available.

Reversible Causes (The H's and T's)

  • Hypovolemia, hypoxia, hydrogen ion (acidosis), hypo-/hyperkalemia, hypothermia.
  • Tension pneumothorax, cardiac tamponade, toxins, thrombosis (pulmonary and coronary).

Conclusion

  • Summary of ventricular fibrillation: appearance on ECG, causes, characteristics, and management.
  • Emphasis on the need to follow ACLS protocols for management.

If you found this helpful, check out related videos on ECG interpretation for further learning.

Full transcript