Ventricular fibrillation

• Disease Description (Causes and Symptoms)

  • Definition·Pathophysiology: Ventricular fibrillation (VF) is a condition in which the ventricular muscles exhibit disorganized electrical activity at an extremely high frequency (approximately 350–600 times/minute) and are unable to contract effectively. The electrical chaos causes effective cardiac output to be lost, resulting in immediate circulatory failure and pulseless systemic ischemia.
  • Main causes:
    • Ischemic heart disease/acute myocardial infarction (particularly frequent within the first several hours)
    • Cardiomyopathy, heart failure, after cardiac surgery
    • Electrolyte abnormalities (low/high potassium, low magnesium)
    • Hypoxia, hypothermia
    • Pericarditis, rheumatic heart disease, hypertensive heart disease
    • Excessive alcohol consumption, medications (antiarrhythmic drugs·QT-prolonging drugs·toxic drugs)
    • Rarely, electrophysiological abnormalities without structural abnormalities (primary VF)
  • Main symptoms:
    • Sudden loss of consciousness (syncope), inability to palpate a pulse, cessation of breathing or extremely weak breathing
    • Immediately before VF, tachycardia, palpitations, shortness of breath, dizziness, and similar symptoms may occur
  • Diagnosis:
    • Electrocardiogram (ECG): P waves, QRS complexes, and T waves are not visible because of disorganized waves that are coarse or fine
    • Clinically, when unresponsiveness, apnea, and pulselessness (cardiac arrest) are present, immediately consider it VF and begin treatment

• Treatment

  • Emergency treatment (key principles for saving life)
    • Immediate defibrillation using a high-energy defibrillator: perform immediately if possible (survival rates drop sharply with delays). Defibrillation energy and method should follow the equipment and guidelines (generally, the manufacturer-recommended energy is used with biphasic equipment).
    • Continue high-quality cardiopulmonary resuscitation (CPR) until the defibrillator is prepared or becomes available for use (following the recommended depth and rate of chest compressions).
    • Examples of the ACLS protocol:
      • Repeated attempts at defibrillation (immediately perform 2 minutes of CPR after defibrillation)
      • Administer epinephrine 1 mg IV/IO every 3–5 minutes (in cases of persistent VF/coronary cardiac arrest)
      • Antiarrhythmic drugs: first-line amiodarone 300 mg IV bolus, with an additional 150 mg if necessary; lidocaine is an alternative option (weight-based dosing)
    • Assess and correct potentially accompanying reversible causes (“Hs and Ts”): hypoxia, hypovolemia, hydrogen ions (acidosis), low/high potassium·low magnesium, hypothermia, drug poisoning, cardiac tamponade, tension pneumothorax, pulmonary embolism, coronary artery thrombosis, and others
  • Management after defibrillation (ROSC, return of spontaneous circulation)
    • Provide oxygen·secure the airway, monitor hemodynamics, and continuously observe the ECG
    • Tests to determine the cause: blood tests (electrolytes·cardiac enzymes), chest imaging, echocardiography, coronary angiography (when acute coronary occlusion is suspected), and consideration of an electrophysiological study
    • If myocardial ischemia is suspected as the cause, immediately evaluate for percutaneous coronary intervention (PCI)
    • Consider temperature management (targeted temperature management, TTM) according to guidelines
    • Prevention of recurrence: if indicated for survivors, implantable cardioverter-defibrillator (ICD) implantation (secondary prevention); antiarrhythmic drugs or catheter ablation may be used if necessary (when an electrophysiologically inducible focus is present)
  • Lifestyle management·Precautions
    • Immediate emergency treatment is essential (delays can be fatal)
    • Actively treat underlying conditions (coronary artery disease, electrolyte imbalance, endocrine abnormalities, etc.)
    • Avoid excessive alcohol consumption and be cautious with drugs that can cause QT prolongation
    • If an ICD is implanted, follow instructions regarding device management and activity restrictions

• Outpatient Visit Checkpoints (Examples of What to Bring and Questions)

  • What to bring:
    • A list of all medications currently being taken (including prescriptions·OTC drugs·herbal medicines·supplements)
    • A summary of past medical history (particularly cardiovascular history and recent myocardial infarction·surgery·hospitalization records)
    • Previous test results (ECG, echocardiography, coronary artery tests, and recent blood test results)
    • The time·circumstances·duration·symptoms when seizures or syncope occurred (symptom diary), along with witness observations
    • Family history (sudden death·inherited heart disease)
    • Information about implanted devices such as an ICD·pacemaker (if present)
  • Examples of questions to record in advance for the outpatient visit:
    • Detailed circumstances surrounding any recent syncope or sudden cardiac arrest (during exercise, at rest, after taking medication, etc.)
    • Frequency and triggers of recurrent arrhythmia symptoms (tachycardia·syncope)

• Examples of General Questions to Ask the Doctor

  • What do you think is the cause of this condition? What additional tests are needed?
  • Is an ICD necessary in my condition? What are the indications and risks?
  • What are the main side effects and interactions of the medication you plan to prescribe?
  • What is the prognosis, and what should I do to reduce the risk of recurrence?

• Examples of Disease-Specific Questions

  • If my ventricular fibrillation was caused by coronary artery disease (acute myocardial infarction), is immediate coronary angiography (PCI) recommended?
  • An electrolyte abnormality or medication-induced cause is suspected; what blood tests, medication discontinuation, or treatment can prevent this?

Additional Key Points

• VF is an emergency, life-threatening condition, and immediate defibrillation and high-quality CPR are the top priorities. If not treated promptly, the fatality rate is extremely high.
• After survival, systematic evaluation to determine the cause and prevent recurrence (coronary artery testing, electrolyte·endocrine testing, echocardiography, electrophysiological study, etc.) and appropriate secondary prevention (PCI, medication therapy, ICD, etc.) are important.