What is the treatment for paroxysmal supraventricular tachycardia (SVT)?

Treatment for Paroxysmal Supraventricular Tachycardia

For acute paroxysmal SVT in hemodynamically stable patients, begin with vagal maneuvers (specifically the modified Valsalva maneuver in supine position with legs raised), followed immediately by adenosine 6 mg rapid IV bolus if vagal maneuvers fail, and reserve synchronized cardioversion for hemodynamically unstable patients. 1, 2

Acute Management Algorithm

Step 1: Immediate Assessment and ECG

• Obtain a 12-lead ECG immediately to confirm SVT and distinguish it from ventricular tachycardia before initiating any treatment 2
• Assess hemodynamic stability (blood pressure, mental status, signs of shock) 1

Step 2: Hemodynamically Unstable Patients

• Proceed directly to synchronized cardioversion as a Class I intervention 1
• This is the definitive treatment for any patient showing signs of hemodynamic compromise 1

Step 3: Hemodynamically Stable Patients - Vagal Maneuvers First

The modified Valsalva maneuver is the most effective vagal technique with the highest success rate among all vagal maneuvers 3:

• Have the patient lie supine and bear down against a closed glottis for 10-30 seconds, then immediately lie flat with legs raised 2
• This technique has a 43% effectiveness rate and is superior to carotid sinus massage 4, 3

Alternative vagal maneuvers if modified Valsalva fails 1:

• Apply ice-cold wet towel to the face (diving reflex) 1
• Carotid sinus massage (only after confirming absence of carotid bruits) 1

Critical pitfall to avoid: Never apply pressure to the eyeball—this practice is dangerous and has been abandoned 1

Step 4: Pharmacological Management When Vagal Maneuvers Fail

Adenosine is the first-line medication with 91-95% effectiveness 1, 2, 4:

• Initial dose: 6 mg rapid IV bolus followed immediately by saline flush 2
• Adenosine is safe even during pregnancy due to its short half-life 2

If adenosine fails or is contraindicated, use IV calcium channel blockers 1:

• IV diltiazem or verapamil are highly effective for converting AVNRT to sinus rhythm (Class IIa recommendation) 1
• Verapamil works by inhibiting calcium influx through slow channels, slowing AV conduction and interrupting reentry at the AV node 5
• Peak therapeutic effects occur within 3-5 minutes after bolus injection 5

Beta-blockers are a Class IIa alternative but are less effective than calcium channel blockers 1

Critical Warning: Pre-excitation Syndromes

If pre-excitation (Wolff-Parkinson-White) is suspected, AVOID all AV nodal blocking agents (verapamil, diltiazem, beta-blockers, adenosine) as they may accelerate ventricular rate and precipitate ventricular fibrillation 1, 2:

• For hemodynamically stable pre-excited AF: use ibutilide or IV procainamide (Class I recommendation) 1, 2
• For hemodynamically unstable pre-excited AF: proceed directly to synchronized cardioversion 1

Long-Term Management for Recurrent Episodes

First-Line Pharmacological Prevention

Oral beta-blockers, diltiazem, or verapamil are the first-line options for ongoing management in patients with recurring SVT without ventricular pre-excitation 1, 2:

• These agents reduce the frequency and duration of SVT episodes 1
• Beta-blockers are specifically recommended as the first-line option by the American College of Cardiology 2

Alternative Pharmacological Options

For patients without structural heart disease who are not candidates for ablation, flecainide or propafenone are reasonable alternatives 1:

• Propafenone reduced attack rates significantly in clinical trials, with 47-53% of patients remaining attack-free compared to 13-16% on placebo 6
• These agents should only be used in patients without structural heart disease 1

Definitive Curative Treatment

Catheter ablation is the most effective therapy to prevent recurrent PSVT and should be offered as first-line definitive treatment 4:

• Single procedure success rates: 94.3-98.5% 4
• Provides potential cure without need for chronic pharmacological therapy 1, 2
• High success rates with low frequency of serious complications 1

Consider ablation for 1:

• Frequent symptomatic episodes
• Poor tolerance or ineffectiveness of medications
• Patient preference for non-pharmacological approach
• Occupational requirements (e.g., pilots, commercial drivers)

Patient Self-Management Education

Teach all patients proper vagal maneuver techniques for self-termination of future episodes 1, 2:

• Modified Valsalva maneuver technique (forcefully exhaling against closed airway for 10-30 seconds in supine position, then lying flat with legs raised) 1, 2
• Ice-cold wet towel application to face 1

Common pitfall: Switching between different vagal maneuver techniques has only a 27.7% success rate, so proper technique with the modified Valsalva is more important than trying multiple different maneuvers 1