What are normal ECG (electrocardiogram) changes in children?

Normal ECG Changes in Children

The normal pediatric ECG differs significantly from adult ECGs and changes throughout childhood, with the most dramatic changes occurring in the first year of life and continuing gradually until late adolescence. 1

Age-Specific Normal ECG Parameters

QRS Axis

• Neonates (0-30 days):

  • Normal axis between +60° and +190° ("extreme right axis" between +90° and +190°) 1
  • Gradually shifts leftward throughout childhood

• Children 1-5 years: Normal axis between +10° and +110° 1

• Children 5-8 years: Normal axis may extend to +140° 1

• Children 8-16 years: Normal axis extends to +120° 1

QRS Duration

• Children <4 years: Normal QRS duration <90 ms 1
• Children 4-16 years: Normal QRS duration <100 ms 1
• Adults: Normal QRS duration <120 ms 1

Heart Rate

• 0-1 days: 93-154 bpm (mean 123) 1
• 1-3 days: 91-159 bpm (mean 123) 1
• 3-7 days: 90-166 bpm (mean 129) 1
• 7-30 days: 107-182 bpm (mean 149) 1
• 1-3 months: 121-179 bpm (mean 150) 1

PR Interval

• Neonates and infants (0-30 days): 0.07-0.14 seconds 1
• 1-3 months: 0.07-0.13 seconds 1

Normal Variants in Pediatric ECGs

RSR' Pattern

• An rsr' pattern in leads V1 and V2 with normal QRS duration is a normal variant in children 1
• This should not be confused with incomplete RBBB

Incomplete RBBB

• In children, incomplete RBBB may be diagnosed when:
  • QRS duration between 90-100 ms (ages 4-16 years)
  • QRS duration between 86-90 ms (ages <4 years)
  • Terminal rightward deflection <40 ms but ≥20 ms 1
• May be present in the absence of heart disease, particularly when lead V1 is recorded higher than or to the right of normal position 1

T-Wave Patterns

• Negative T-waves in right precordial leads are normal in young children 2
• T-wave inversion in V1-V3 is a normal finding in children and adolescents

Important Considerations for Interpretation

Age-Specific Reference Values

• Always refer to age-specific reference values when interpreting pediatric ECGs 1, 3
• Up to 20% of pediatric ECGs obtained in acute settings may have clinically significant abnormal findings 4

Common Pitfalls in Interpretation

• Misdiagnosing normal variants as pathology:

  • Mistaking normal rsr' pattern for RBBB
  • Interpreting normal right axis deviation in infants as pathological
  • Considering normal T-wave inversions in right precordial leads as ischemic changes

• Overlooking age-specific criteria:

  • Applying adult criteria for intervals and durations to pediatric ECGs
  • Failing to account for normal rightward axis in neonates and young children

When to Refer to Pediatric Cardiology

• ECG findings that don't match age-appropriate norms
• Persistent left axis deviation in infancy (may indicate congenital heart defects) 1
• Abnormal QRS duration for age
• Abnormal QT interval for age
• Arrhythmias or conduction abnormalities

Technology Considerations

• Digital ECG systems may affect newborn ECGs more significantly than those of older children or adults 1
• Standard 12-lead ECGs should be obtained, with additional leads (V3R, V4R, V7) sometimes providing valuable information for congenital heart lesions 1

Understanding these normal age-related changes is crucial for accurate interpretation of pediatric ECGs and avoiding unnecessary referrals or interventions while ensuring appropriate identification of truly pathological findings.