Management of Supraventricular Tachycardia (SVT)
The management of SVT should follow a stepwise approach starting with vagal maneuvers, progressing to adenosine, other pharmacological agents, and finally catheter ablation for definitive treatment, with modified Valsalva maneuver being the most effective initial intervention. 1
Initial Assessment and Management
Hemodynamically Unstable Patients
- Immediate synchronized cardioversion is indicated for hemodynamically unstable patients (Class I, Level B-NR) 1
- Do not delay cardioversion to administer medications in unstable patients 1
Hemodynamically Stable Patients
Vagal Maneuvers (First-Line) (Class I, Level B-R) 1
- Modified Valsalva maneuver (MVM) is superior with success rates of 43.7% compared to 24.2% for standard Valsalva and 9.1% for carotid sinus massage 2
- Technique: Have patient perform strain in seated position, then immediately lie backward for enhanced vagal stimulation 3
- Other options: standard Valsalva, carotid sinus massage, facial application of ice-cold wet towel 1
- Caution: Do not attempt vagal maneuvers in hypotensive patients 1
Adenosine (Second-Line) (Class I, Level B-R) 1
- Use when vagal maneuvers fail (91% success rate)
- Acts as both diagnostic and therapeutic agent
- Safe in pregnancy due to short half-life 1
IV Calcium Channel Blockers or Beta Blockers (Class IIa, Level B-R) 1
- Options include diltiazem, verapamil, metoprolol, or esmolol
- Caution: IV calcium channel blockers are contraindicated in suspected pre-excited AF or VT 1
Synchronized Cardioversion
- Indicated when pharmacological therapy fails or is contraindicated (Class I, Level B-NR) 1
Long-term Management
Pharmacological Prevention
Oral medications (Class I, Level B-R) 1:
- Beta blockers
- Calcium channel blockers
- Class IC antiarrhythmics (flecainide, propafenone) in patients without structural heart disease
- Ivabradine (2.5-7.5 mg twice daily) (Class IIa, Level B-R)
Important medication considerations:
- Flecainide: Indicated for PSVT prevention in patients without structural heart disease 4
- Propafenone: Effective for PSVT with 47% of patients remaining attack-free compared to 16% with placebo 5
- Amiodarone: Consider for short-term use when alternatives aren't viable, but monitor for thyroid disorders 1
- Contraindication: Flecainide and propafenone are contraindicated in patients with structural heart disease due to proarrhythmic risk 1, 4
Definitive Treatment
- Catheter ablation (Class I, Level B-NR) 1
- Recommended for recurrent symptomatic SVT
- Success rates of 94-98%
- Provides potential cure without need for chronic medications
- Consider as first-line therapy in appropriate candidates
Special Populations
Pregnancy
- Use lowest recommended medication doses
- Avoid medications in first trimester if possible
- Adenosine is safe due to short half-life 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 termination of episodes
- Explain warning signs requiring medical attention
- Discuss medication side effects and importance of adherence 1
Potential Complications and Pitfalls
Sustained high heart rates (≥200 bpm) can lead to:
- Hemodynamic deterioration
- Tachycardia-induced cardiomyopathy
- Sudden symptom development 1
Proarrhythmic effects:
Follow-up
- Refer patients to cardiology or electrophysiology within 1-2 weeks after initial presentation
- Monitor patients on medication therapy for side effects and efficacy
- Consider catheter ablation for definitive treatment of recurrent symptomatic SVT 1