Surgical Critical Care: Tachyarrhythmia

Sinus Tachycardia (ST)

• EKG Pattern:
  • Heart Rate > 100 bpm
  • Normal P Waves Preceding Every QRS Complex
• Compared to SVT:
  • Most Likely Secondary to Underlying Cause (Pain/Stressor)
  • Progressively Increases Rate
  • HR Usually Not Very High < 150 bpm
  • Typically See Separate P & T Waves
  • Generally Asymptomatic
  • May See Moderate Rate Variability
• Treatment: Treat Underlying Cause
  • Indications for β-Blocker Treatment:
    • Acute Coronary Syndrome
    • Symptomatic Inappropriate (No Explanation) Sinus Tachycardia

Atrial Flutter

• EKG Pattern:
  • Rapid Regular Atrial Depolarizations (“Saw Tooth” Pattern) – About 300 bpm
  • Not All P Waves Produce a Ventricular Contraction
  • Regular Ventricular Rate – About 150 bpm
• Treatment: Similar to Atrial Fibrillation

Multifocal Atrial Tachycardia (MAT)

• EKG Pattern:
  • “Chaotic” Variable P Waves with ≥ 3 Different Morphologies (Different Sites of Origin)
  • Heart Rate > 100 bpm
• Strongly Associated with Pulmonary Disease (COPD Most Common)
• Also Seen in Cardiac Disease, Hypokalemia or Hypomagnesemia
• Treatment:
  • First Step: Correct Hypomagnesemia & Hypokalemia
  • If Serum Magnesium Normal: Give Empiric Magnesium
    • MgSO4 Bolus 2 g, Then Infuse 6 g Over 6 Hours
  • If Fails: Metoprolol
    • Severe Bronchospasm: Verapamil

Supraventricular Tachycardia (SVT)/Paroxysmal Supraventricular Tachycardia (PSVT)

• EKG Pattern:
  • Heart Rate > 100 bpm
  • Narrow QRS Complex (< 120 ms)
• Compared to Sinus Tachycardia:
  • Often Has No Identified Underlying Cause
  • Sudden Onset
  • HR Usually Very High > 150 bpm
  • Typically See Combined P & T Waves
  • Generally Symptomatic
  • Often Has Limited Rate Variability
• Types:
  • Atrioventricular Nodal Reentrant Tachycardia (AVNRT) (60% – Most Common)
  • Atrioventricular Reentrant Tachycardia (AVRT) (30%)
  • Sinoatrial Nodal Reentry Tachycardia (SNART)
  • Focal Atrial Tachycardia
  • Junctional Ectopic Tachycardia
• Treatment:
  • Stable:
    • Initial: Vagal Maneuvers (Carotid Massage & Valsalva Maneuver)
      • 12-18% Success
    • If Fails: Adenosine
  • Unstable: Synchronized Cardioversion

Wolff-Parkinson-White Syndrome (WPW)

• EKG Pattern:
  • Pre-Excitation “Delta Waves” (Slurring Slow Risk of the Initial QRS Complex)
  • Short PR Interval (< 120 ms)
  • Prolonged QRS Complex
• Accessory Pathway Through the Bundle of Kent
• May Cause Recurrent SVT
• Treatment:
  • Stable: Procainamide
    • Avoid Drugs that Block AV Node (β-Blockers, CCB & Digoxin) – Can Cause Conversion to VT/VF
  • Unstable: Synchronized Cardioversion

Ventricular Tachycardia (VT)

• EKG Pattern:
  • Heart Rate > 100 bpm
  • Wide QRS Complex (≥ 120 ms)
  • No Fixed Relationship of P Wave & QRS Complex
• If Sustained (> 30 Seconds) There Can Be an Immediate Threat to Life
• Treatment:
  • Stable: Amiodarone
  • Unstable: Synchronized Cardioversion

Torsades de Pointes

• EKG Pattern:
  • Polymorphic Ventricular Tachycardia
  • QRS Complexes Appear to Be “Twisting Around the Isoelectric Points”
• Associated with Prolonged QT Intervals
• Can Convert to Ventricular Fibrillation
• Treatment: IV Magnesium
  • MgSO4 Bolus 2 g, Then Infuse 2-4 mg/min

Ventricular Fibrillation (VF)

• EKG Pattern:
  • Sudden Chaotic Irregular Deflections
  • No Identifiable P Waves, QRS Complexes or T Waves
  • Rate 150-500 bpm
• Non-Perfusing Rhythm
• Fatal if Not Corrected
• Treatment:
  • Initial: Start CPR & Give Oxygen
  • Every 2 Minutes:
    • Check Rhythm
    • Defibrillation
    • Alternate Epinephrine & Amiodarone Every Other 2 Minutes