What is the treatment for Supraventricular Tachycardia (SVT)?

Treatment of Supraventricular Tachycardia (SVT)

The modified Valsalva maneuver is the most effective first-line treatment for hemodynamically stable SVT, followed by adenosine as second-line therapy, with synchronized cardioversion reserved for unstable patients. 1, 2, 3

Treatment Algorithm for SVT

Hemodynamically Stable Patients

1. First-line: Vagal Maneuvers

   • Modified Valsalva maneuver is superior with a success rate 3.62 times higher than carotid sinus massage 2, 3
   • Technique: Patient performs Valsalva strain (bearing down) in semi-recumbent position, then immediately lies flat with legs elevated
   • Standard Valsalva maneuver and carotid sinus massage are alternatives but less effective 1, 3

2. Second-line: Adenosine

   • Initial dose: 6 mg rapid IV push
   • Success rate approximately 91% in terminating AVNRT 1
   • Has diagnostic value by helping identify the underlying mechanism
   • Class I, Level B-R recommendation 1

3. Third-line: IV Calcium Channel Blockers or Beta Blockers

   • IV verapamil (5-10 mg over 2 min)
   • IV metoprolol (2.5-5 mg over 2 min)
   • Class IIa, Level C-LD recommendation 1

4. Fourth-line: Synchronized Cardioversion

   • Used when medications fail to convert rhythm
   • Class I, Level B-NR recommendation 1

Hemodynamically Unstable Patients

• Immediate synchronized electrical cardioversion
• Class I, Level B-NR recommendation 1, 4

Long-term Management Options

1. Oral Medications

   • Calcium channel blockers: Verapamil (240-480 mg/day) or diltiazem
   • Beta blockers: Metoprolol
   • Class I, Level B-R recommendation 1
   • Flecainide for prevention of paroxysmal SVT in patients without structural heart disease 5

2. Catheter Ablation

   • Curative option for most SVT mechanisms 6
   • Should be considered after initial management and specialist referral

Important Contraindications and Precautions

• Avoid beta blockers in patients with severe bronchospastic pulmonary disease 1
• Avoid calcium channel blockers in patients with ventricular dysfunction, severe sinus node dysfunction, or AV block 1
• Avoid flecainide and propafenone in patients with structural heart disease or coronary artery disease 1, 5
  • Flecainide carries a boxed warning for proarrhythmic effects
  • Should not be used in patients with recent myocardial infarction 5

Special Populations

• Pregnant patients: Follow same algorithm starting with vagal maneuvers; adenosine is safe as second-line; for cardioversion, place electrode pads to direct energy away from uterus 1
• Infants and children <1 year: Avoid verapamil due to risk of cardiovascular collapse; avoid digoxin if pre-excitation is suspected 1
• Patients with Wolff-Parkinson-White syndrome and atrial fibrillation: Use IV procainamide if stable; immediate cardioversion if unstable 4

Diagnostic Considerations

• Regular ECG and Holter monitoring assessment is necessary for all patients 1
• Evaluate for accessory pathways, especially Wolff-Parkinson-White syndrome 1
• Compare ECG during tachycardia with sinus rhythm to determine the underlying mechanism 6

Common Pitfalls to Avoid

1. Using standard Valsalva instead of modified Valsalva (modified is significantly more effective) 2, 3
2. Using flecainide in patients with structural heart disease (can cause fatal arrhythmias) 5
3. Delaying cardioversion in hemodynamically unstable patients 1, 4
4. Failing to refer patients for specialist evaluation after initial management 6
5. Not recognizing SVT with aberrancy versus ventricular tachycardia