Ventricular arrhythmias

Ventricular Arrhythmias - The Heart's Rogue Beats

• Premature Ventricular Complexes (PVCs): Ectopic beats with wide, bizarre QRS. Often benign; can be a sign of ischemia or electrolyte imbalance.
• Ventricular Tachycardia (VT): Run of >3 PVCs at >100 bpm. Can be monomorphic or polymorphic.
  • Sustained: >30 seconds or causes hemodynamic collapse.
  • Treatment depends on stability.
• Torsades de Pointes: Polymorphic VT in setting of long QT interval. Treat with IV Magnesium Sulfate.
• Ventricular Fibrillation (VF): Chaotic, disorganized rhythm. No cardiac output. Fatal unless treated with immediate defibrillation.

⭐ Ventricular fibrillation is the most common arrhythmia responsible for sudden cardiac death, frequently initiated by an episode of ventricular tachycardia.

VT & VF - Code Blue Chaos

• Ventricular Tachycardia (VT): Organized rhythm >100 bpm with wide QRS complexes (>0.12s). Can be monomorphic or polymorphic.

  • Stable VT: Treat with IV antiarrhythmics (Amiodarone, Procainamide).
  • Unstable VT (pulse): Immediate synchronized cardioversion.
  • Pulseless VT: Treat like VF with immediate defibrillation (unsynchronized shock).

• Ventricular Fibrillation (VF): Chaotic, disorganized electrical activity. No identifiable waves. Always pulseless and requires immediate defibrillation.

⭐ Torsades de Pointes: A polymorphic VT with twisting QRS complexes. Associated with long QT syndrome. Key treatment is IV Magnesium Sulfate, not standard antiarrhythmics.

📌 Reversible Causes (H's & T's): Hypovolemia, Hypoxia, Hydrogen ion (acidosis), Hypo/Hyperkalemia, Hypothermia; Tension pneumothorax, Tamponade, Toxins, Thrombosis (pulmonary/coronary).

Torsades de Pointes - The Twisting Threat

• A specific polymorphic ventricular tachycardia showing a "twisting" QRS axis. It arises from a prolonged QT interval (>500 ms).
• Causes (Prolonged QT):
  • Drugs: Antiarrhythmics (Class IA, III), Antipsychotics (haloperidol), Antibiotics (macrolides), Antifungals.
  • 📌 Mnemonic (ABCDE): AntiArrhythmics, AntiBiotics, antiCychotics, antiDepressants, antiEmetics.
  • Electrolytes: ↓K+, ↓Mg++, ↓Ca++.
  • Congenital Long QT Syndromes.
• Presentation: Syncope, palpitations; can degrade to ventricular fibrillation.

• Treatment:
  • 1st Line: IV Magnesium Sulfate.
  • Withdraw offending drugs & correct electrolytes.
  • Consider temporary pacing if unstable.

⭐ IV Magnesium Sulfate is the immediate therapy for Torsades de Pointes, effective even with normal serum magnesium levels as it stabilizes the cardiac membrane.

Management - Shock or Medicate?

Primary question: Is the patient stable or unstable? Unstable signs include hypotension, altered mental status, shock, ischemic chest pain, or acute heart failure.

• Stable Monomorphic VT: IV amiodarone, procainamide, or sotalol.
• Stable Polymorphic VT:
  • Normal QT: Treat ischemia, correct electrolytes. IV amiodarone, β-blockers.
  • Prolonged QT (Torsades de Pointes): IV magnesium sulfate.

⭐ For stable, wide-complex tachycardia, IV amiodarone is the preferred first-line antiarrhythmic agent.

High-Yield Points - ⚡ Biggest Takeaways

• Ventricular tachycardia (VT): A run of ≥3 consecutive PVCs. Treat stable VT with antiarrhythmics like amiodarone; treat unstable VT with synchronized cardioversion.
• Ventricular fibrillation (VF): A lethal arrhythmia causing immediate cardiac arrest. Management is emergent defibrillation (unsynchronized shock) and CPR.
• Torsades de Pointes: A polymorphic VT associated with a prolonged QT interval. The first-line treatment is IV magnesium sulfate.
• Capture and fusion beats are pathognomonic for VT.