What is the management of Paroxysmal Supraventricular Tachycardia (PSVT)?

Management of Paroxysmal Supraventricular Tachycardia (PSVT)

The definitive management of PSVT follows a stepwise approach, with adenosine being the first-line pharmacological treatment for hemodynamically stable patients, while immediate synchronized cardioversion is indicated for unstable patients. 1

Initial Assessment and Acute Management

Hemodynamically Unstable Patients

• Immediate synchronized DC cardioversion is the treatment of choice 2, 1
• No delay for medication trials should occur in unstable patients

Hemodynamically Stable Patients

1. Vagal maneuvers (first step)

   • Modified Valsalva maneuver (most effective vagal technique)
   • Carotid sinus massage (use with caution in elderly)
   • Success rate approximately 27.7% 1

2. Adenosine (if vagal maneuvers fail)

   • First-line pharmacological agent
   • Dosing: 6 mg rapid IV push, followed by 12 mg if needed
   • Success rate approximately 91-95% 1
   • Advantages: rapid onset, short half-life
   • Cautions:
     • Use with caution in severe asthma
     • May require higher doses in patients on theophylline
     • Effects potentiated by dipyridamole
     • May produce VF in patients with coronary artery disease 2, 1

3. Calcium channel blockers (if adenosine fails or is contraindicated)

   • Verapamil or diltiazem
   • Mechanism: Inhibits calcium influx through slow channels in cardiac conduction system 3
   • Verapamil slows AV conduction and interrupts reentry at the AV node 3

4. Beta blockers (alternative to calcium channel blockers)

   • Metoprolol or atenolol
   • Therapeutic dose range: 25-200 mg twice daily for metoprolol 1

5. Synchronized cardioversion (if medications fail)

   • Highly effective for terminating PSVT 1

Special Diagnostic Considerations

• ECG response to treatment can aid diagnosis:
  • Termination with P wave after last QRS favors AVRT or AVNRT
  • Termination with QRS complex favors atrial tachycardia
  • Continuation with AV block suggests atrial tachycardia or flutter 2

Long-term Management Options

Pharmacological Management

1. First-line options:

   • Oral beta blockers
   • Diltiazem or verapamil 1

2. Second-line options (for patients without structural heart disease):

   • Flecainide or propafenone
   • Contraindicated in structural heart disease or coronary artery disease 1, 4

3. Third-line options (for refractory cases):

   • Class III antiarrhythmics (sotalol, dofetilide, amiodarone)
   • Amiodarone reserved as last option due to side effects 1

Definitive Treatment

• Catheter ablation is recommended as the definitive treatment
  • Success rates of 94-98% 1, 5
  • Provides potential cure without need for chronic medications
  • Referral to cardiology/electrophysiology within 1-2 weeks after initial presentation 1

"Pill-in-the-pocket" Approach

• For infrequent, well-tolerated episodes
• Patient self-administers oral beta blockers, diltiazem, or verapamil at onset of symptoms 1

Special Populations

Pregnancy

• Adenosine is safe due to short half-life
• Use lowest effective medication doses
• Avoid medications in first trimester if possible 1

End-stage Renal Disease

• Monitor for electrolyte abnormalities
• Be aware of dialysis-related fluid shifts triggering arrhythmias 1

Patient Education

• Teach proper vagal maneuver techniques for home use
• Warn about signs/symptoms requiring medical attention 1
• Explain risk of recurrence (approximately 4% after ED discharge) 6

Common Pitfalls to Avoid

1. Failing to differentiate SVT with aberrancy from ventricular tachycardia
2. Using dihydropyridine calcium channel blockers (like nifedipine) which should be avoided
3. Using flecainide or propafenone in patients with structural heart disease
4. Delaying cardioversion in hemodynamically unstable patients
5. Using adenosine in patients with severe bronchial asthma