What is the treatment for supraventricular tachycardia (SVT)?

Treatment of Supraventricular Tachycardia (SVT)

The first-line treatment for SVT should begin with vagal maneuvers, followed by adenosine in hemodynamically stable patients, and synchronized cardioversion for unstable patients or when other methods fail. 1

Acute Management Algorithm

Step 1: Assess Hemodynamic Stability

• Determine if the patient is hemodynamically stable or unstable (hypotension, altered mental status, signs of shock, chest pain, or acute heart failure) 1

Step 2: For Hemodynamically Stable Patients

1. Vagal Maneuvers (First-Line)

   • Perform with patient in supine position 1
   • Modified Valsalva Maneuver is the most effective vagal maneuver with higher conversion rates than standard techniques 2, 3
     • Patient bears down against closed glottis for 10-30 seconds (equivalent to 30-40 mmHg pressure) 1
   • Carotid sinus massage (after confirming absence of carotid bruit)
     • Apply steady pressure over right or left carotid sinus for 5-10 seconds 1
   • Cold stimulus to face (ice-cold wet towel) can also be effective 1
   • Overall success rate of vagal maneuvers is approximately 27.7% 1
   • Caution: Applying pressure to eyeball is dangerous and should not be performed 1

2. Adenosine (If vagal maneuvers fail)

   • Highly effective (90-95% success rate) for terminating AVNRT and orthodromic AVRT 1, 4
   • Acts as both diagnostic and therapeutic agent 1
   • Brief side effects (<1 minute) occur in approximately 30% of patients 1, 4
   • Caution: May precipitate atrial fibrillation; have electrical cardioversion equipment available 1

3. Intravenous Calcium Channel Blockers or Beta Blockers (If adenosine fails)

   • Diltiazem or verapamil are particularly effective for AVNRT 1
   • Success rates of 80-98% for conversion to sinus rhythm 1
   • Caution: Avoid in patients with suspected VT, pre-excited AF, or systolic heart failure 1
   • Beta blockers have excellent safety profile but may be less effective than calcium channel blockers 1

4. Oral Medications (When IV access unavailable)

   • Oral beta blockers, diltiazem, or verapamil may be reasonable 1
   • Can be administered in conjunction with vagal maneuvers 1

5. Intravenous Amiodarone (When other therapies ineffective or contraindicated)

   • May be considered for refractory cases 1
   • Short-term IV administration doesn't cause long-term toxicity 1

Step 3: For Hemodynamically Unstable Patients

• Immediate Synchronized Cardioversion 1
  • Highly effective for terminating SVT 1
  • Should be performed promptly when patient shows signs of hemodynamic compromise 1
  • For stable patients, provide adequate sedation or anesthesia first 1

Special Considerations for Pre-excited AF

• Immediate synchronized cardioversion for hemodynamically unstable patients 1
• For stable patients with pre-excited AF, ibutilide or IV procainamide are recommended 1
• Caution: Avoid AV nodal blocking agents (diltiazem, verapamil, beta blockers) in patients with pre-excitation as they may enhance conduction over accessory pathway 1

Long-term Management

• Catheter ablation is the most effective therapy to prevent recurrent SVT with success rates of 94.3-98.5% 3
• Pharmacological options for patients who decline ablation or are not candidates:
  • Oral beta blockers, diltiazem, or verapamil 1
  • Flecainide or propafenone for patients without structural heart disease 1, 5
  • Caution: Flecainide can cause proarrhythmic effects, especially in patients with structural heart disease or recent myocardial infarction 5
  • Sotalol, dofetilide, or amiodarone may be considered when other options fail 1

Common Pitfalls and Caveats

• Always confirm the rhythm is SVT and not ventricular tachycardia before treatment 1
• Ensure absence of pre-excited AF before administering AV nodal blocking agents 1
• Adenosine may cause brief but uncomfortable side effects (chest discomfort, dyspnea, flushing) 4
• Patients may have premature beats after conversion that can trigger recurrence of SVT 1
• Flecainide can cause new or worsened arrhythmias, especially in patients with coronary artery disease 5
• Eyeball pressure is dangerous and should never be used as a vagal maneuver 1