What is the management approach for paroxysmal supraventricular tachycardia (SVT)?

Management of Paroxysmal Supraventricular Tachycardia

Begin with vagal maneuvers in the supine position, immediately followed by intravenous adenosine if unsuccessful, and proceed to synchronized cardioversion for hemodynamically unstable patients or when pharmacological therapy fails. 1

Acute Management Algorithm

Step 1: Assess Hemodynamic Stability

• Hemodynamically unstable patients (hypotension, altered mental status, acute heart failure, ongoing chest pain) require immediate synchronized cardioversion as first-line therapy. 1
• Stable patients proceed through the stepwise approach below. 1

Step 2: Vagal Maneuvers (First-Line for Stable Patients)

• Perform in supine position to maximize effectiveness. 1
• Modified Valsalva maneuver: Patient bears down against closed glottis for 10-30 seconds, generating at least 30-40 mm Hg intrathoracic pressure, with 43% acute conversion rate. 1, 2
• Carotid sinus massage: Apply steady pressure over right or left carotid sinus for 5-10 seconds only after confirming absence of carotid bruit by auscultation. 1
• Cold stimulus (diving reflex): Apply ice-cold wet towel to face as alternative vagal maneuver. 1
• Switching between vagal maneuver techniques achieves overall success rate of 27.7%. 1, 3
• Never apply pressure to the eyeball - this practice is dangerous and abandoned. 1, 3

Step 3: Intravenous Adenosine (First-Line Pharmacotherapy)

• Adenosine terminates AVNRT in 91-95% of patients and is the recommended first-line drug for hemodynamically stable patients. 1, 2
• Adenosine also serves diagnostic function by unmasking atrial activity in flutter or atrial tachycardia. 1
• Critical caveat: Have electrical cardioversion immediately available, as adenosine may precipitate atrial fibrillation that conducts rapidly down accessory pathways, potentially causing ventricular fibrillation. 1
• Minor, brief side effects (<1 minute duration) occur in approximately 30% of patients. 1

Step 4: Second-Line Pharmacotherapy (If Adenosine Fails)

• Intravenous calcium channel blockers (diltiazem or verapamil) are reasonable for hemodynamically stable patients with Class IIa recommendation, achieving 80-98% conversion rates. 1, 3
• Intravenous beta-blockers are reasonable alternatives with Class IIa recommendation, though less effective than calcium channel blockers. 1, 3
• Critical contraindication: 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, 3

Step 5: Synchronized Cardioversion (Refractory Cases)

• Perform synchronized cardioversion when pharmacological therapy fails or is contraindicated in hemodynamically stable patients (Class I recommendation). 1
• Highly effective for terminating all forms of SVT. 1

Special Consideration: Pre-Excited Atrial Fibrillation

• Hemodynamically unstable: Immediate synchronized cardioversion (Class I). 1, 3
• Hemodynamically stable: Ibutilide or intravenous procainamide (Class I recommendation). 1, 3
• Absolutely avoid AV nodal blocking agents (adenosine, calcium channel blockers, beta-blockers, digoxin) as they may cause life-threatening ventricular rates. 1, 3

Long-Term Management

Definitive Treatment: Catheter Ablation

• Catheter ablation is first-line therapy for recurrent symptomatic PSVT, offering potential cure without chronic medication need. 3, 2, 4
• Single procedure success rates of 94.3-98.5% with low complication rates. 2
• Particularly recommended for patients with Wolff-Parkinson-White syndrome. 4

Chronic Pharmacological Suppression (Alternative to Ablation)

• Oral beta-blockers, diltiazem, or verapamil are first-line for ongoing management in patients without ventricular pre-excitation. 3
• These agents reduce frequency and duration of SVT episodes. 3
• For patients without structural heart disease who decline ablation: Flecainide or propafenone are reasonable alternatives. 3, 5, 6
• Flecainide dosing: Start 50 mg every 12 hours for PSVT, may increase by 50 mg twice daily every 4 days to maximum 300 mg/day. 5
• Propafenone reduces attack rates in paroxysmal supraventricular arrhythmias, with 47-67% of patients remaining attack-free. 6

Patient Self-Management Education

• Teach proper vagal maneuver techniques for self-termination of future episodes. 3
• Valsalva maneuver performed supine is most effective patient-initiated intervention. 3

Critical Pitfalls to Avoid

• Obtain 12-lead ECG immediately to distinguish SVT from ventricular tachycardia, which may masquerade as narrow-complex tachycardia on single-lead monitoring. 7
• Never use AV nodal blockers without first excluding pre-excitation pattern or accessory pathway conduction. 1, 3
• Avoid flecainide in patients with structural heart disease, recent myocardial infarction, or chronic atrial fibrillation due to proarrhythmic risk. 5
• Do not initiate or uptitrate antiarrhythmics too rapidly - allow 3-5 days to reach steady state before dose adjustments. 5
• Carotid massage carries stroke risk if performed without first excluding carotid bruits. 1, 3