What are the treatment options for supraventricular tachycardia (SVT)?

Treatment of Supraventricular Tachycardia

For acute SVT management, perform vagal maneuvers first (modified Valsalva maneuver is most effective), followed by intravenous adenosine if vagal maneuvers fail, and proceed to synchronized cardioversion for hemodynamically unstable patients or when pharmacological therapy is ineffective. 1, 2

Acute Management Algorithm

Step 1: Vagal Maneuvers (First-Line)

• Modified Valsalva maneuver is superior to all other vagal techniques, with a 43.7% initial success rate and 28.1% sustained rhythm at 5 minutes, compared to standard Valsalva (24.2% initial, 6.1% sustained) and carotid sinus massage (9.1% initial, 3% sustained). 3, 4
• Perform with patient in supine position: have patient bear down against closed glottis for 10-30 seconds (equivalent to 30-40 mm Hg intrathoracic pressure). 1, 2
• Alternative vagal maneuvers include carotid sinus massage (only after confirming absence of bruit by auscultation, apply steady pressure for 5-10 seconds) or applying ice-cold wet towel to face (diving reflex). 1, 2
• Never apply pressure to the eyeball—this practice is dangerous and abandoned. 1, 2

Step 2: Adenosine (First-Line Pharmacotherapy)

• Administer intravenous adenosine if vagal maneuvers fail, with 91-95% effectiveness for terminating AVNRT and orthodromic AVRT. 1, 2, 5
• Have synchronized cardioversion immediately available, as adenosine may precipitate atrial fibrillation with rapid ventricular conduction or even ventricular fibrillation. 1
• Minor side effects occur in approximately 30% of patients but last less than 1 minute. 1

Step 3: Alternative Pharmacotherapy (If Adenosine Fails or Contraindicated)

• Intravenous diltiazem or verapamil are highly effective for converting AVNRT to sinus rhythm in hemodynamically stable patients (Class IIa recommendation). 1, 2
• Intravenous beta-blockers are reasonable but less effective than calcium channel blockers (Class IIa recommendation). 1, 2
• Critical caveat: Avoid AV nodal blocking agents (verapamil, diltiazem, beta-blockers) in patients with suspected pre-excitation or Wolff-Parkinson-White syndrome, as they may accelerate ventricular rate and precipitate ventricular fibrillation. 1, 2

Step 4: Synchronized Cardioversion

• Perform immediate synchronized cardioversion for any hemodynamically unstable patient (Class I recommendation). 1, 2
• Also use synchronized cardioversion in hemodynamically stable patients when pharmacological therapy fails or is contraindicated (Class I recommendation). 1

Special Situation: Pre-Excited Atrial Fibrillation

• For hemodynamically unstable patients with pre-excited AF: immediate synchronized cardioversion (Class I recommendation). 1, 2
• For hemodynamically stable patients with pre-excited AF: use ibutilide or intravenous procainamide (Class I recommendation). 1, 2
• Absolutely avoid AV nodal blocking agents (adenosine, verapamil, diltiazem, beta-blockers) as they can cause life-threatening ventricular fibrillation. 1, 2

Long-Term Management

Definitive Treatment: Catheter Ablation

• Catheter ablation is the most effective therapy to prevent recurrent PSVT, with single-procedure success rates of 94.3-98.5% and should be considered first-line definitive treatment. 2, 5
• Offers potential cure without need for chronic pharmacological therapy with low complication rates. 2, 5
• Decision should consider frequency/duration of episodes, severity of symptoms, patient preference, and occupational requirements. 2

Chronic Pharmacological Therapy (If Ablation Declined or Not Candidate)

• Oral beta-blockers, diltiazem, or verapamil are first-line for ongoing management in patients without ventricular pre-excitation. 2
• These agents reduce frequency and duration of SVT episodes. 2
• For patients without structural heart disease who are not ablation candidates: flecainide or propafenone are reasonable alternatives. 2, 6
• Critical warning about flecainide: Reserved only for patients without structural heart disease, recent myocardial infarction, or chronic atrial fibrillation due to proarrhythmic risk (13-26% in high-risk patients, with 0.5-10% mortality in early studies). 6

Patient Education

• Teach all patients proper modified Valsalva technique for self-management of future episodes: forcefully exhale against closed airway for 10-30 seconds while supine. 2
• Educate on recognition of symptoms requiring emergency care (hemodynamic instability, prolonged episodes). 2