What is the management approach for a child presenting with supraventricular tachycardia (SVT)?

Management of Supraventricular Tachycardia in Children

For pediatric SVT, initiate vagal maneuvers immediately in hemodynamically stable patients, followed by adenosine at 150-250 mcg/kg (higher than adult dosing), and proceed directly to synchronized cardioversion for any hemodynamically unstable child. 1

Acute Management Algorithm

Step 1: Assess Hemodynamic Stability

• Hemodynamically unstable (hypotension, poor perfusion, altered mental status): Proceed immediately to synchronized cardioversion 2
• Hemodynamically stable: Begin with vagal maneuvers 3

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

• Perform with patient in supine position 3
• Valsalva maneuver: Have child bear down against closed glottis for 10-30 seconds (equivalent to 30-40 mm Hg pressure) 1, 3
• Ice-cold stimulus: Apply ice-cold wet towel to face (diving reflex) - particularly effective in infants 1, 3
• Carotid sinus massage: Only after confirming absence of bruit; apply steady pressure for 5-10 seconds 1, 3
• Success rate approximately 27.7% when switching between techniques 3

Step 3: Adenosine (If Vagal Maneuvers Fail)

• Dosing in children requires higher weight-based doses than adults: 150-250 mcg/kg 1
• Effectiveness rate: 91-95% 3
• Critical caveat: Infants have significantly lower response rates to first adenosine dose compared to older children 2
• Young age is associated with increased odds of adenosine-refractory SVT 2
• Have cardioversion equipment immediately available as adenosine may precipitate atrial fibrillation 1

Step 4: Refractory or Unstable Cases

• Synchronized cardioversion is the definitive treatment for hemodynamically unstable patients or those refractory to adenosine 1, 2
• Cardioversion is rarely needed but highly effective when required 2
• Medical management with antiarrhythmics may have a role before cardioversion in select unstable patients 2

Critical Medication Considerations by Age

Infants (<1 year)

• Digoxin and propranolol have similar efficacy for SVT without pre-excitation 1
• Absolutely avoid digoxin if pre-excitation is present - associated with sudden cardiac death and ventricular fibrillation in infancy 1
• Amiodarone, sotalol, propafenone, or flecainide can be used for refractory SVT 1
• Verapamil is contraindicated in neonates and infants due to high risk of electromechanical dissociation 4

Older Children (>5 years) and Adolescents

• Beta-blocker therapy is most often the initial pharmacological therapy 1
• Verapamil may be used with same restrictions as adults (avoid in wide QRS complex tachycardia or significant hemodynamic compromise) 4
• Flecainide is not first-line due to rare but serious adverse events even in structurally normal hearts 1

Mechanism-Specific Considerations

Accessory Pathway-Mediated Tachycardia (>70% of infant SVT)

• Accounts for >70% of SVT in infants, decreasing to ~55% in adolescents 1
• Never use AV nodal blocking agents (verapamil, diltiazem, beta-blockers) if pre-excitation suspected - may accelerate ventricular rate and cause ventricular fibrillation 3
• Cardiac arrest may be the initial manifestation of pre-excitation even without prior symptoms 1

Pre-excited Atrial Fibrillation

• Synchronized cardioversion for hemodynamically unstable patients 1
• Ibutilide or IV procainamide for hemodynamically stable patients 1
• Avoid all AV nodal blocking agents 3

Long-Term Management Considerations

Prophylactic Therapy in Infants

• Advisable because recognition of tachycardia is often delayed until symptoms develop 4
• Spontaneous cessation expected in most neonates/infants during first year of life 4
• Attempt withdrawal of drug treatment around end of first year 4

Older Children

• Spontaneous cessation is rare 4
• Catheter ablation can be successfully performed with acute success rates comparable to adults, providing potential cure without chronic medication 1, 4
• Success rates highest in left-sided accessory pathways 1
• Should only be performed with clear indication as long-term effects on growing myocardium remain unknown 4

Common Pitfalls to Avoid

• Never apply pressure to eyeball - dangerous and abandoned practice 3
• Do not use flecainide as first-line in children despite effectiveness 1
• Recognize age-dependent adenosine response: Only 1 of 17 infant episodes responded to first adenosine dose in one study 2
• Ensure proper ECG diagnosis before treatment to distinguish SVT from ventricular tachycardia 3
• Risk stratification with 24-hour monitoring or exercise testing should be considered for children with pre-excitation to assess persistence 1