What is the workup and treatment for a pediatric patient complaining of palpable tachycardia (fast heartbeat)?

Workup for Pediatric Patient with Palpable Tachycardia

Begin by immediately assessing hemodynamic stability—if the child shows signs of shock, altered mental status, or cardiovascular compromise, proceed directly to synchronized cardioversion at 0.5-1 J/kg rather than pursuing diagnostic workup. 1

Immediate Stabilization and Initial Assessment

For hemodynamically stable patients, the priority is obtaining a 12-lead ECG while simultaneously establishing monitoring and IV access. 1, 2

• Maintain patent airway and administer supplemental oxygen if hypoxemia is present, as this commonly drives tachycardia 1
• Attach cardiac monitor/defibrillator to continuously monitor rhythm 1
• Establish IV or intraosseous (IO) access as soon as possible 1
• Monitor blood pressure and pulse oximetry continuously 1
• Obtain a 12-lead ECG immediately—this is the single most important diagnostic test and should not be delayed 1, 2

Critical Diagnostic Workup

ECG Analysis

The 12-lead ECG determines your entire management pathway by answering three key questions 1, 2:

• QRS duration: Narrow (<0.09 seconds) versus wide (>0.09 seconds) complex tachycardia 3
• P-wave morphology and relationship to QRS: Helps distinguish sinus tachycardia from SVT 3
• Presence of pre-excitation (delta waves suggesting Wolff-Parkinson-White syndrome): This requires immediate cardiology referral 2

Identify Underlying Causes

Before attributing symptoms to a primary arrhythmia, systematically evaluate for secondary causes 2, 4:

• Fever and infection: Common pediatric triggers 4
• Dehydration and hypovolemia: Check mucous membranes, capillary refill, urine output 4
• Anemia: Assess for pallor, obtain hemoglobin 2
• Hypoxemia: Check oxygen saturation 1
• Pain and anxiety: Often overlooked in children 4
• Medications or drug toxicity: Obtain detailed medication history 4
• Hyperthyroidism: Consider in persistent unexplained tachycardia 2

Additional Diagnostic Studies

Obtain an echocardiogram to exclude structural heart disease, including hypertrophic cardiomyopathy, dilated cardiomyopathy, valvular abnormalities, and coronary artery anomalies 2

Management Based on ECG Findings

Narrow-Complex Tachycardia (<0.09 seconds)

Differentiate sinus tachycardia from supraventricular tachycardia (SVT) using the 12-lead ECG and clinical context 3, 1:

If Sinus Tachycardia:

• Treat the underlying cause, not the heart rate itself 2, 4
• The upper limit of physiologic sinus tachycardia is approximately 220 minus the patient's age 2
• No specific antiarrhythmic therapy is indicated for physiologic sinus tachycardia 2

Critical pitfall: When cardiac function is poor, cardiac output may be dependent on a rapid heart rate—"normalizing" the heart rate in compensatory tachycardia can be detrimental 2

If Supraventricular Tachycardia:

Attempt vagal maneuvers first (Class IIa recommendation) unless the patient is hemodynamically unstable or this will delay definitive treatment 3, 1:

• In infants and young children: Apply ice to the face without occluding the airway 3
• In older children: Carotid sinus massage or Valsalva maneuvers (have the child blow through a narrow straw) 3

If vagal maneuvers fail and IV/IO access is available, adenosine is the drug of choice (Class I recommendation) 3, 1:

• Initial dose: 0.1 mg/kg rapid IV/IO bolus (maximum first dose 6 mg) 1
• Second dose: 0.2 mg/kg rapid bolus (maximum second dose 12 mg) 1
• Note: Children require higher doses than adults (150-250 mcg/kg) 3

If adenosine fails or SVT recurs, consider synchronized cardioversion (0.5-1 J/kg, increasing to 2 J/kg if needed) 1

For refractory cases, consider amiodarone 5 mg/kg IV/IO over 20-60 minutes OR procainamide 15 mg/kg IV/IO over 30-60 minutes 1

Wide-Complex Tachycardia (>0.09 seconds)

Wide-complex tachycardia requires immediate cardiology consultation and often represents ventricular tachycardia or SVT with aberrancy 3, 2

Mandatory Cardiology Referral Criteria

Immediate referral to pediatric cardiology is required for 2:

• Pre-excitation (Wolff-Parkinson-White syndrome) on ECG 2
• Syncope during tachycardia or with exercise 2
• Wide complex tachycardia of unknown origin 2
• Documented sustained SVT 2

Consultation with an expert in pediatric arrhythmias is strongly recommended before treating hemodynamically stable children, as all arrhythmia therapies have potential for serious adverse effects 3, 1

Long-Term Considerations

Recognize that persistent tachycardia (weeks to months) with fast ventricular response can cause tachycardia-mediated cardiomyopathy, which is reversible but requires careful long-term follow-up even after recovery 2

Risk stratification with ambulatory 24-hour monitoring or treadmill exercise testing is often considered for children with pre-excitation to assess persistence 3

Common Pitfalls to Avoid

• Never use digoxin in the presence of pre-excitation, as its use in infancy has been associated with sudden cardiac death or ventricular fibrillation 3
• Avoid rate-controlling medications in patients with accessory pathways (WPW syndrome), as this can accelerate conduction through the accessory pathway 4
• Do not attribute all tachycardia to anxiety or panic disorder—diagnosis is often delayed because of this misdiagnosis 5
• Monitor continuously during treatment to evaluate the effect of interventions 1