What is the treatment for narrow complex tachycardia?

Treatment of Narrow Complex Tachycardia

The treatment of narrow complex tachycardia should follow a stepwise approach starting with vagal maneuvers, followed by adenosine, then calcium channel blockers or beta blockers, and finally synchronized cardioversion for hemodynamically unstable patients or when pharmacological therapy fails. 1

Initial Assessment and Hemodynamic Stability

The treatment approach depends primarily on the patient's hemodynamic stability:

• Hemodynamically unstable patients (hypotension, altered mental status, chest pain, heart failure):

  • Immediate synchronized cardioversion is indicated 1
  • Do not delay cardioversion to attempt medications or vagal maneuvers in unstable patients 2

• Hemodynamically stable patients:

  • Follow the stepwise approach detailed below

Treatment Algorithm for Hemodynamically Stable Patients

First-Line: Vagal Maneuvers

• Success rate approximately 27.7% 3
• Techniques (performed in supine position):
  • Modified Valsalva maneuver: bearing down against closed glottis for 10-30 seconds (equivalent to 30-40 mmHg pressure) 1
  • Carotid sinus massage: apply steady pressure over right or left carotid sinus for 5-10 seconds (after confirming absence of carotid bruit) 1
  • Cold stimulus to face: applying ice-cold wet towel to face 1, 2
  • Quick backward lying maneuver: quickly lying backward from a seated position 4

Second-Line: Adenosine

• Highly effective with approximately 95% success rate in AVNRT 1
• Dosing:
  • Initial dose: 6 mg IV rapid push followed by saline flush
  • If ineffective after 1-2 minutes: 12 mg IV rapid push
  • Can repeat 12 mg dose once more if needed
• Acts as both diagnostic and therapeutic agent 1, 5
• Transient side effects may include dyspnea, chest pain, flushing, and headache 5

Third-Line: Calcium Channel Blockers or Beta Blockers

• Calcium channel blockers:

  • IV diltiazem or verapamil are particularly effective 1
  • Contraindicated in patients with pre-excited atrial fibrillation, ventricular tachycardia, significant LV dysfunction, or high-grade AV block 2

• Beta blockers:

  • IV metoprolol or esmolol can be effective 1, 2
  • Use with caution in patients with asthma, COPD, or heart failure 2

Fourth-Line: Synchronized Cardioversion

• Indicated when pharmacological therapy fails or is contraindicated 1
• Highly effective in terminating SVT 1
• Requires appropriate sedation in conscious patients

Special Considerations

Recurrent Episodes

• For long-term management of recurrent episodes, consider:
  • Oral beta blockers, diltiazem, or verapamil as first-line therapy 2
  • Flecainide or propafenone as second-line options (avoid in structural heart disease) 2, 6
  • Referral for catheter ablation (success rates 94-98%) 2

Pitfalls to Avoid

1. Misdiagnosis: Ensure the rhythm is truly a narrow complex tachycardia (QRS <0.12 seconds) 7
2. Inappropriate medication use:
   • Avoid verapamil or diltiazem in patients with suspected pre-excitation syndromes or ventricular tachycardia 1, 2
   • Avoid dihydropyridine calcium channel blockers (e.g., nifedipine) 2
3. Delayed cardioversion in hemodynamically unstable patients 2
4. Carotid massage without first checking for carotid bruits 1
5. Eyeball pressure is dangerous and should never be used 1

Follow-up

• Refer to cardiology or electrophysiology within 1-2 weeks after initial presentation 2
• Consider catheter ablation as definitive treatment, especially for recurrent episodes 2

By following this stepwise approach, most narrow complex tachycardias can be effectively terminated with minimal risk to the patient, with the treatment strategy tailored based on hemodynamic stability and response to initial interventions.