How do I manage SVT (supraventricular tachycardia)?

Management of Supraventricular Tachycardia (SVT)

For hemodynamically unstable SVT, perform immediate synchronized cardioversion; for stable patients, start with vagal maneuvers followed by intravenous adenosine as first-line therapy. 1

Acute Management Algorithm

Step 1: Assess Hemodynamic Stability

Hemodynamically Unstable (hypotension, altered mental status, signs of shock, chest pain, acute heart failure):

• Perform immediate synchronized cardioversion without delay 1
• If the patient is conscious but hypotensive, provide sedation before cardioversion 1
• Adenosine may be considered first only if the tachycardia is regular with narrow QRS complex 1
• Cardioversion successfully restores sinus rhythm in nearly all patients with hemodynamically unstable SVT 1

Step 2: Management of Hemodynamically Stable SVT

First-Line Therapy:

• Vagal maneuvers should be attempted initially 1, 2
  • Modified Valsalva maneuver: patient bears down against closed glottis for 10-30 seconds (equivalent to 30-40 mm Hg pressure), with 43% effectiveness 1, 2
  • Carotid sinus massage: apply steady pressure over carotid sinus for 5-10 seconds after confirming absence of bruit (avoid in elderly or those with carotid disease) 1
  • Ice-cold wet towel to face (diving reflex) 1
  • Switching between techniques increases overall success to 27.7% 1

Second-Line Therapy:

• Adenosine is the recommended pharmacologic agent for acute treatment of stable SVT 1
  • Terminates SVT in 90-95% of patients 1, 2
  • Brief side effects occur in approximately 30% of patients but last less than 1 minute 1
  • Have electrical cardioversion immediately available, as adenosine may precipitate atrial fibrillation that could conduct rapidly 1

Third-Line Pharmacologic Options (if adenosine fails or is contraindicated):

• Intravenous diltiazem or verapamil are effective alternatives 1

  • Terminate SVT in 64-98% of patients 1
  • Slow infusion over 20 minutes may reduce hypotension risk 1
  • Critical caveat: Do NOT use if ventricular tachycardia or pre-excited atrial fibrillation is possible, as these can cause hemodynamic collapse or ventricular fibrillation 1
  • Avoid in patients with suspected systolic heart failure 1

• Intravenous beta blockers are reasonable alternatives 1

  • Less effective than diltiazem for terminating SVT but have excellent safety profile 1
  • Particularly useful in patients who cannot tolerate calcium channel blockers 1

Fourth-Line:

• Synchronized cardioversion if pharmacologic therapy is ineffective or contraindicated 1
  • Success rate of 80-98% when combined with appropriate drug therapy 1
  • Perform after adequate sedation or anesthesia in stable patients 1

Ongoing/Long-Term Management

First-Line Options:

• Catheter ablation is useful for diagnosis and definitive treatment of SVT 1

  • Single procedure success rates of 94.3-98.5% 2
  • Recommended as first-line therapy to prevent recurrence 2
  • Should be considered for all patients with symptomatic recurrent SVT 1

• Oral beta blockers, diltiazem, or verapamil for ongoing management in patients without ventricular pre-excitation 1

  • Appropriate for patients who decline ablation or are not candidates 1

Second-Line Pharmacologic Options:

• Flecainide or propafenone are reasonable for patients without structural heart disease or ischemic heart disease 1

  • Only in patients who prefer not to undergo catheter ablation 1

• Sotalol may be reasonable when first-line agents fail 1

• Dofetilide may be considered when beta blockers, calcium channel blockers, flecainide, and propafenone are ineffective or contraindicated 1

Patient Education:

• All patients should be educated on performing vagal maneuvers for self-management of SVT episodes 1
• Refer all patients treated for SVT to a heart rhythm specialist 3

Critical Pitfalls to Avoid

• Never use calcium channel blockers (verapamil, diltiazem) if there is any possibility of ventricular tachycardia or pre-excited atrial fibrillation, as this can precipitate ventricular fibrillation and hemodynamic collapse 1
• Avoid eyeball pressure as a vagal maneuver—this technique is potentially dangerous and has been abandoned 1
• Do not use digoxin acutely for SVT termination; it is only considered for ongoing management in select cases 1
• Be prepared for recurrent SVT immediately after cardioversion or adenosine, as atrial or ventricular premature complexes may reinitiate tachycardia—have antiarrhythmic drugs ready 1
• Ensure intravenous access and resuscitation equipment are available before administering adenosine, as it may precipitate brief asystole or atrial fibrillation 1