What are the guidelines for managing tachycardia?

Guidelines for Managing Tachycardia

The management of tachycardia should follow a structured approach based on hemodynamic stability, with immediate synchronized cardioversion for unstable patients and a stepwise pharmacological approach for stable patients. 1, 2

Initial Assessment and Classification

Hemodynamic Stability Assessment

• Hemodynamically unstable: Hypotension, altered mental status, signs of shock, chest pain, heart failure
  • Immediate synchronized cardioversion is recommended regardless of tachycardia type 1, 2

QRS Complex Width

• Narrow QRS complex tachycardia (<120 ms): Likely supraventricular origin
• Wide QRS complex tachycardia (≥120 ms): May be ventricular tachycardia or SVT with aberrancy

Management Algorithm for Hemodynamically Stable Narrow QRS Tachycardia

First-Line Interventions

1. Vagal Maneuvers (Class I, Level B-R) 1, 2

   • Valsalva maneuver: Patient bears down against closed glottis for 10-30 seconds in supine position
   • Carotid sinus massage: Apply steady pressure over carotid sinus for 5-10 seconds (after confirming absence of bruit)
   • Success rate of combined techniques: approximately 28% 1

2. Adenosine IV (Class I, Level B-R) 1, 2

   • Initial dose: 6 mg rapid IV push followed by saline flush
   • If ineffective: 12 mg IV push, may repeat once if needed
   • Terminates approximately 95% of AVNRT cases
   • Contraindicated in severe bronchial asthma
   • Have resuscitation equipment available

Second-Line Interventions

1. IV Calcium Channel Blockers (Class IIa, Level B-R) 1, 2

   • Diltiazem or verapamil for hemodynamically stable patients
   • Avoid in patients with pre-excited AF, hypotension, or heart failure

2. IV Beta Blockers (Class IIa, Level B-R) 1, 2

   • Metoprolol or esmolol for hemodynamically stable patients
   • Avoid in patients with pre-excited AF, severe bronchospasm, or decompensated heart failure

3. Synchronized Cardioversion (Class I, Level B-NR) 1

   • Recommended when pharmacological therapy fails or is contraindicated
   • Sedate patient if hemodynamically stable

Management of Wide QRS Complex Tachycardia

Hemodynamically Stable Wide QRS Tachycardia

1. If SVT with aberrancy is confirmed: Follow narrow QRS algorithm
2. If ventricular tachycardia or uncertain mechanism: 1, 2
   • IV procainamide or sotalol (Class I recommendation)
   • IV amiodarone is acceptable, preferred in patients with impaired LV function
   • Avoid AV nodal blocking agents (adenosine, calcium channel blockers, beta blockers) if pre-excited AF is suspected

Special Considerations

• Pre-excited AF: Avoid AV nodal blockers as they can increase conduction through accessory pathway and precipitate ventricular fibrillation 2
• Digitalis toxicity-induced VT: Specific antidotes may be required 1

Long-Term Management

Pharmacological Options

• Beta blockers: First-line for long-term management 2
• Calcium channel blockers: Alternative if beta blockers contraindicated 2
• Class IC agents (flecainide, propafenone): For patients without structural heart disease 2
• Amiodarone: For refractory cases, but has significant side effect profile 2

Definitive Treatment

• Catheter ablation: Recommended for recurrent, symptomatic SVT 2
  • Success rates >95% for most SVT mechanisms
  • Can be considered first-line therapy to avoid lifelong medication

Common Pitfalls to Avoid

1. Misdiagnosis of wide QRS tachycardia as SVT when it's VT
2. Simultaneous use of IV calcium channel blockers and beta blockers can cause profound hypotension
3. Using AV nodal blockers in pre-excited AF can accelerate ventricular rate
4. Delaying cardioversion in patients with hemodynamic compromise
5. Failure to recognize tachycardia-induced cardiomyopathy in persistent tachycardia

By following this structured approach to tachycardia management, clinicians can effectively diagnose and treat various tachyarrhythmias while minimizing complications and improving patient outcomes.