What are the key differences between adult and pediatric electrocardiogram (EKG) values?

Key Differences Between Adult and Pediatric EKG Values

The most significant differences between adult and pediatric EKG values involve QRS duration, axis deviation, heart rate, and normal variants that change throughout childhood development. 1

QRS Axis Differences

• In neonates, the normal QRS axis ranges between 60° and 190° (termed "extreme right axis" when between 90° and 190°) 1
• By ages 1-5 years, the axis shifts leftward to between 10° and 110° 1
• Between 5-8 years, the normal QRS axis may extend to 140° 1
• Between 8-16 years, the normal QRS axis extends to 120° 1
• In adults, the normal QRS axis is between 30° and 90° 1, 2

QRS Duration Differences

• Complete RBBB criteria:

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

• Incomplete RBBB criteria:

  • Adults: QRS duration between 110-120 ms 1
  • Children 4-16 years: QRS duration between 90-100 ms 1
  • Children <8 years: QRS duration between 86-90 ms 1

• Complete LBBB criteria:

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

• Incomplete LBBB criteria:

  • Adults: QRS duration between 110-119 ms 1
  • Children 8-16 years: QRS duration between 90-100 ms 1
  • Children <8 years: QRS duration between 80-90 ms 1

• Nonspecific intraventricular conduction disturbance:

  • Adults: QRS duration >110 ms 1
  • Children 8-16 years: QRS duration >90 ms 1
  • Children <8 years: QRS duration >80 ms 1

Normal Variants in Pediatric EKGs

• In children, an rSr' pattern in V1 and V2 with normal QRS duration is a normal variant, unlike in adults where it may suggest pathology 1
• Q-waves may have higher amplitudes in pediatric lateral leads (V5-V6) compared to adults 3
• Incomplete RBBB pattern may be present in the absence of heart disease in children, particularly when lead V1 is recorded higher than normal position 1

Diastolic Function Assessment

• Adult standards for diastolic dysfunction are often inappropriately applied to pediatric patients 1
• In neonates and infants, the pattern of Doppler mitral E/A is highly variable, and inversion may be physiological 1
• At high neonatal heart rates, E/A fusion is quite frequent 1

Clinical Implications

• Leftward QRS-axis shifts in children may indicate congenital defects with underdevelopment of the right ventricle (e.g., tricuspid atresia) or abnormal conduction system location 1
• Failure to account for age-related differences in EKG interpretation can lead to misdiagnosis of pathology in normal pediatric patients 2, 4
• Maturational changes over early childhood years result in differences in normal heart rates, interval durations, and ventricular dominance 4

Common Pitfalls in Interpretation

• Applying adult criteria to pediatric EKGs without age adjustment 4
• Misinterpreting normal rSr' pattern in V1/V2 as pathological in children 1
• Failing to recognize that T-wave inversion in right precordial leads is normal in children 5
• Overdiagnosis of conduction abnormalities by using adult criteria for QRS duration 1

Understanding these key differences is essential for accurate EKG interpretation in pediatric patients, as normal parameters evolve significantly from birth through adolescence before reaching adult values 6.