What are the management options for Supraventricular Tachycardia (SVT)?

Management of Supraventricular Tachycardia (SVT)

For acute SVT management, perform the modified Valsalva maneuver in the supine position with immediate leg elevation as first-line treatment, followed by adenosine 6 mg rapid IV bolus if vagal maneuvers fail, and proceed to synchronized cardioversion for hemodynamically unstable patients. 1, 2, 3

Acute Management Algorithm

Step 1: Initial Assessment and Vagal Maneuvers

Hemodynamically stable patients should receive vagal maneuvers as the immediate first-line intervention. 1, 3

• The modified Valsalva maneuver is superior to standard Valsalva and carotid sinus massage, with a 43.7% success rate versus 24.2% for standard Valsalva and only 9.1% for carotid massage. 4, 5 The technique involves the patient bearing down against a closed glottis for 10-30 seconds (equivalent to 30-40 mmHg pressure) while supine, then immediately lying flat with legs raised. 1, 2, 3

• Carotid sinus massage should only be performed after confirming absence of carotid bruits by auscultation, applying steady pressure over the right or left carotid sinus for 5-10 seconds. 1, 3

• The diving reflex (applying ice-cold wet towel to the face) is an alternative vagal maneuver. 1, 3

• Never apply pressure to the eyeball—this practice is dangerous and has been abandoned. 1, 3

• Switching between vagal maneuver techniques increases overall success to approximately 27.7%. 1, 3

Step 2: Pharmacological Management for Stable Patients

If vagal maneuvers fail, adenosine is the first-line medication with 90-95% effectiveness. 1, 2, 3

• Administer 6 mg rapid IV bolus followed immediately by saline flush. 1, 2
• If ineffective, give up to two subsequent 12 mg doses. 1
• Adenosine is safe during pregnancy due to its short half-life. 1, 2

For patients who fail adenosine or when adenosine is contraindicated, use IV calcium channel blockers or beta blockers. 1, 3

• IV diltiazem or verapamil are particularly effective for converting AVNRT to sinus rhythm (Class IIa recommendation). 1, 3
• IV beta blockers have an excellent safety profile but are less effective than calcium channel blockers. 1, 3
• Critical caveat: Avoid calcium channel blockers and beta blockers in patients with suspected pre-excited atrial fibrillation, ventricular tachycardia, or systolic heart failure, as these may cause hemodynamic instability or ventricular fibrillation. 1, 3

Step 3: Cardioversion

Synchronized cardioversion is mandatory for hemodynamically unstable patients when vagal maneuvers and adenosine fail or are not feasible (Class I recommendation). 1, 3

• Synchronized cardioversion is also indicated for hemodynamically stable patients when pharmacological therapy fails or is contraindicated. 1, 3
• Cardioversion can be performed safely at all stages of pregnancy if necessary. 2

Special Consideration: Pre-Excited Atrial Fibrillation

For patients with pre-excitation (Wolff-Parkinson-White syndrome), avoid all AV nodal blocking agents (adenosine, verapamil, diltiazem, beta blockers), as they may accelerate ventricular rate and precipitate ventricular fibrillation. 3

• For hemodynamically stable pre-excited AF, use IV ibutilide or procainamide (Class I recommendation). 2, 3
• For hemodynamically unstable pre-excited AF, proceed directly to synchronized cardioversion. 3

Long-Term Management

Pharmacological Prevention

Beta blockers are the first-line option for long-term prevention of recurrent SVT. 2, 3

• Calcium channel blockers (diltiazem or verapamil) are reasonable alternatives to beta blockers. 2, 3
• These agents reduce the frequency and duration of SVT episodes. 3

For patients without structural heart disease who are not candidates for ablation, flecainide or propafenone are reasonable alternatives. 3, 6, 7

• Critical warning: Flecainide should never be used in patients with structural heart disease, ventricular dysfunction, or recent myocardial infarction due to significant proarrhythmic risk, including a 13% incidence of proarrhythmic events in sustained VT patients and potential fatal outcomes. 1, 6
• Flecainide is FDA-approved only for prevention of PSVT in patients without structural heart disease. 6
• Propafenone reduced SVT recurrence in clinical trials, with 47-53% of patients remaining attack-free versus 13-16% on placebo. 7

Definitive Treatment: Catheter Ablation

Catheter ablation is the definitive curative option and should be considered first-line for patients with recurrent symptomatic SVT. 2, 3, 8

• Ablation is particularly indicated for patients with frequent symptomatic episodes, poor medication tolerance or ineffectiveness, or patient preference for non-pharmacological treatment. 2, 3
• Catheter ablation has high success rates with low complication frequency, providing cure without need for chronic medication. 3, 8
• The decision should consider episode frequency and duration, symptom severity, and occupational requirements. 3

Patient Education

All patients should be taught proper vagal maneuver techniques for self-management of future episodes. 2, 3

• Instruct patients to perform the modified Valsalva maneuver in a supine position by forcefully exhaling against a closed airway for 10-30 seconds, then immediately lying flat with legs raised. 2, 3
• Patients should understand when to seek emergency care (persistent symptoms, hemodynamic instability). 3

Critical Diagnostic Consideration

Always obtain a 12-lead ECG to differentiate tachycardia mechanisms before initiating treatment. 2, 3

• It is essential to distinguish SVT with aberrancy from ventricular tachycardia before treatment, as misdiagnosis can lead to inappropriate and potentially harmful therapy. 2, 3
• Look specifically for evidence of pre-excitation (delta waves, short PR interval) to avoid dangerous AV nodal blocking agents. 3