What is the treatment approach for tachycardia in the Emergency Department (ED)?

Treatment Approach for Tachycardia in the Emergency Department

The treatment of tachycardia in the ED should follow a structured algorithm based on hemodynamic stability, with immediate synchronized cardioversion for unstable patients and targeted pharmacological therapy for stable patients based on the specific type of tachycardia. 1

Initial Assessment and Stabilization

• Assess for signs of hemodynamic instability:

  • Systolic BP ≤90 mmHg
  • Altered mental status
  • Ischemic chest discomfort
  • Acute heart failure
  • Signs of shock 1, 2

• Immediate interventions:

  • Provide supplemental oxygen if hypoxemic or showing increased work of breathing
  • Attach cardiac monitor
  • Establish IV access
  • Obtain 12-lead ECG (if available and doesn't delay treatment for unstable patients) 1

Management Algorithm Based on Stability

For Hemodynamically Unstable Patients

1. Proceed immediately to synchronized cardioversion regardless of tachycardia type 1, 2
   • Initial energy:
     • 100-200J for atrial fibrillation (biphasic)
     • 50-100J for SVT and atrial flutter
     • 100J for monomorphic VT 1
   • Provide sedation if patient is conscious and time permits, but do not delay cardioversion in extremely unstable patients 1
   • Increase energy in stepwise fashion if initial shock fails 1

For Hemodynamically Stable Patients

Step 1: Determine if QRS is narrow (<0.12 sec) or wide (≥0.12 sec) 2, 3

For Narrow Complex Tachycardias:

1. Try vagal maneuvers (carotid sinus massage, Valsalva) 2, 4
2. Adenosine (if regular rhythm): 6mg rapid IV bolus, may repeat with 12mg if ineffective 2, 4
3. Rate control medications if adenosine fails:
   • Calcium channel blockers: Diltiazem 15-20mg IV over 2 minutes 2, 5
     • Contraindicated in heart failure, hypotension, or pre-excitation syndromes 5
   • Beta-blockers: Metoprolol 5mg IV over 2-5 minutes, may repeat up to 3 doses 2, 6
     • Use with caution in heart failure, bronchospastic disease 6
   • For atrial fibrillation with heart failure: Consider digoxin or amiodarone 1, 2

For Wide Complex Tachycardias:

1. Regular monomorphic VT:

   • Without heart failure/AMI: Procainamide 20-50 mg/min until arrhythmia suppressed (max 17 mg/kg) 1, 2, 7
   • With heart failure/AMI: Amiodarone 150mg IV over 10 minutes, followed by infusion 1, 2
   • Alternative: Lidocaine 1-3 mg/kg IV 2

2. Polymorphic VT:

   • With long QT: Magnesium IV, pacing, and beta-blockers 1
   • Without long QT: Beta-blockers if ischemic 1

3. Undifferentiated wide complex tachycardia:

   • Consider adenosine to help diagnose the underlying rhythm 1
   • AVOID verapamil or diltiazem as they can cause hemodynamic collapse if the rhythm is VT 2, 5

Special Considerations

• Sinus tachycardia: Identify and treat underlying cause (fever, anemia, hypotension, etc.) rather than treating the tachycardia directly 1

• Atrial fibrillation:

  • Rate control: Beta-blockers or diltiazem
  • Rhythm control: Ibutilide, dofetilide, flecainide, or amiodarone 1, 2

• Maintain electrolyte balance:

  • Keep potassium >4.0 mEq/L
  • Keep magnesium >2.0 mg/dL 2

• For refractory cases:

  • Consider underlying causes (electrolyte abnormalities, ischemia, drug toxicity)
  • Consider urgent coronary revascularization if evidence of acute ischemia 2, 8

Pitfalls and Caveats

• Never give verapamil or diltiazem for wide-complex tachycardias of uncertain origin, as they can cause hemodynamic collapse in VT 2, 5

• Heart rate <150 bpm with symptoms is more likely due to underlying condition rather than the tachycardia itself 1

• In patients with poor cardiac function, "normalizing" heart rate can be detrimental as cardiac output may be dependent on the rapid rate 1

• Electrical cardioversion has the highest efficacy for terminating stable monomorphic VT compared to pharmacological options 7

• Mortality is significantly higher when VT occurs during acute myocardial infarction 8

• For incessant atrial tachycardia, be aware of potential development of tachycardiomyopathy 9