What is the appropriate management of a patient with supraventricular tachycardia (SVT)?

Management of Supraventricular Tachycardia

Begin with immediate hemodynamic assessment: if the patient is unstable (hypotension, altered mental status, chest pain, shock, or acute heart failure), proceed directly to synchronized cardioversion after sedation; if stable, initiate vagal maneuvers followed by adenosine if unsuccessful. 1, 2

Hemodynamically Unstable SVT

• Perform immediate synchronized cardioversion after administering sedation if the patient is conscious but hypotensive—this restores sinus rhythm in nearly 100% of hemodynamically unstable patients. 1, 2
• Do not delay cardioversion to attempt vagal maneuvers or pharmacologic therapy when the patient exhibits hypotension, acutely altered mental status, signs of shock, ischemic chest pain, or acute heart failure symptoms. 1
• Have defibrillation equipment immediately available and ensure adequate sedation/anesthesia before the procedure. 1, 2

Hemodynamically Stable SVT: Stepwise Approach

Step 1: Vagal Maneuvers (Class I Recommendation)

• Start with the modified Valsalva maneuver: have the patient bear down against a closed glottis for 10–30 seconds at approximately 30–40 mm Hg intrathoracic pressure, which achieves conversion in roughly 43% of attempts. 2, 3
• If unsuccessful, proceed to carotid sinus massage: apply steady pressure over the carotid sinus for 5–10 seconds after confirming absence of carotid bruit—avoid this in elderly patients or those with known carotid disease. 2, 3
• Consider facial cooling (diving reflex) by applying an ice-cold wet towel to the face as an additional vagal technique. 2
• Rotating among different vagal maneuvers increases overall conversion success to approximately 27.7%. 2, 4

Critical pitfall: Never use eyeball pressure as a vagal maneuver—it is dangerous and has been abandoned from clinical practice. 2, 3

Step 2: Adenosine (First-Line Pharmacologic, Class I)

• Administer intravenous adenosine if vagal maneuvers fail—it terminates SVT in 90–95% of patients with AVNRT or AVRT. 1, 2, 5
• Give as a rapid bolus via proximal IV followed immediately by a saline flush, with continuous ECG recording during administration to distinguish drug failure from successful termination with immediate reinitiation. 1
• Transient side effects (flushing, chest discomfort, dyspnea) occur in approximately 30% of patients but resolve within one minute due to adenosine's very short half-life. 1, 2

Critical pitfall: Defibrillation equipment must be immediately available because adenosine can precipitate rapid atrial fibrillation requiring electrical cardioversion. 2

Step 3: Calcium Channel Blockers (Class IIa, Second-Line)

• Use intravenous diltiazem or verapamil if adenosine fails or is contraindicated—these agents convert SVT in 64–98% of hemodynamically stable patients. 1, 2, 3
• Administer as a slow infusion over up to 20 minutes to reduce the risk of hypotension. 1, 2
• Verapamil specifically achieves conversion in 60–80% of episodes within 10 minutes according to FDA labeling. 2

Critical pitfalls:

• Never administer calcium channel blockers if ventricular tachycardia or pre-excited atrial fibrillation is possible—this can precipitate ventricular fibrillation and hemodynamic collapse. 1, 2, 3
• Do not use in patients with suspected systolic heart failure, as diltiazem prolongs AV nodal conduction and has negative inotropic effects. 1, 6
• Avoid concurrent administration of IV calcium channel blockers with IV beta-blockers due to synergistic hypotensive and bradycardic effects. 2

Step 4: Beta-Blockers (Class IIa, Alternative Second-Line)

• Consider intravenous beta-blockers as reasonable alternatives when calcium channel blockers are not tolerated or contraindicated—they have an excellent safety profile but are slightly less effective than calcium channel blockers. 1, 2, 3

Step 5: Synchronized Cardioversion for Refractory Stable SVT

• Perform synchronized cardioversion with appropriate sedation/anesthesia when pharmacologic therapy is ineffective or contraindicated in hemodynamically stable patients—this achieves an 80–98% success rate. 1, 2

Long-Term Management After Conversion

Immediate Post-Conversion Assessment

• Obtain a 12-lead ECG immediately after conversion to identify pre-excitation patterns (delta waves) or other baseline abnormalities that reveal the SVT mechanism—this is critical because calcium channel blockers and beta-blockers become contraindicated in patients with pre-excitation. 4, 3
• Observe patients for approximately 4 hours with continuous cardiac monitoring after successful conversion to detect immediate recurrence. 3

Risk Stratification by Episode Frequency

• For infrequent episodes (1–2 per year): teach vagal maneuvers (modified Valsalva, carotid massage, facial cooling) as the primary self-management strategy. 4
• For frequent episodes (>2 per year): initiate oral beta-blockers, diltiazem, or verapamil as first-line suppressive therapy (Class I recommendation)—these medications work by slowing AV nodal conduction. 4, 3

Definitive Treatment: Catheter Ablation

• Refer for electrophysiologic study with catheter ablation as the preferred long-term management for all patients with recurrent symptomatic SVT—single-procedure success rates range from 94.3% to 98.5%. 2, 4, 5
• Catheter ablation should be considered first-line therapy, particularly for patients with atrioventricular nodal reentrant tachycardia due to the very low risk of AV block. 7

Medical Management for Patients Declining or Unsuitable for Ablation

• Oral beta-blockers, diltiazem, or verapamil are appropriate first-line long-term options for patients without ventricular pre-excitation. 2, 4, 3
• In patients without structural heart disease or ischemic heart disease who prefer medical therapy, flecainide or propafenone are reasonable choices—flecainide is initiated at 50 mg every 12 hours and may be increased in increments of 50 mg twice daily every four days, with a maximum dose of 300 mg/day for paroxysmal supraventricular arrhythmias. 2, 8
• Sotalol may be used when first-line agents fail, and dofetilide is an option when beta-blockers, calcium channel blockers, flecainide, and propafenone are ineffective or contraindicated. 2

Critical pitfall: Avoid calcium channel blockers and beta-blockers in patients with pre-excitation on ECG, severe conduction abnormalities, sinus node dysfunction, decompensated systolic heart failure, or hypotension. 4

Patient Education

• Teach all patients how to perform vagal maneuvers (modified Valsalva, carotid massage, facial cooling) for self-management of SVT episodes and ensure they can demonstrate proper technique. 2, 4
• Provide specific trigger avoidance counseling, including avoidance of caffeine, alcohol, stress, and fatigue. 4

Follow-Up Strategy

• Schedule cardiology follow-up within 2–4 weeks to review ECG findings, assess response to suppressive therapy, and discuss definitive management options including catheter ablation. 4
• Monitor for breakthrough episodes, medication side effects, and development of new conduction abnormalities. 4