Skip to content

Pediatric ECG Interpretation Basics

Learning Objectives

Core Knowledge & Clinical Reasoning

  • [ ] Apply age-appropriate normal values for heart rate, axis, and intervals
  • [ ] Recognize the normal evolution of pediatric ECG from newborn to adolescent
  • [ ] Identify critical abnormalities requiring urgent action (WPW, LQTS, complete heart block)
  • [ ] Systematically interpret a pediatric ECG using a structured approach

Systems-Based Practice

  • [ ] Determine when to obtain an ECG in pediatric patients
  • [ ] Recognize when ECG findings require urgent cardiology consultation

Key Concept

Pediatric ECG normal values are AGE-DEPENDENT An adult-read ECG will often be "abnormal" in children - know the pediatric norms

Heart Rate by Age

Age Normal Range (bpm) Concern if < Concern if >
Newborn 100-180 80 200
1-12 months 100-170 80 180
1-3 years 90-150 70 160
3-5 years 80-140 60 140
5-10 years 70-120 55 130
>10 years 60-100 50 120

QRS Axis by Age

Age Normal Axis
Newborn-1 month +60 to +180° (RVD normal)
1-6 months +30 to +120°
6 months-adult 0 to +90°

Rightward axis is NORMAL in newborns due to RV dominance in utero

PR Interval by Age

Age Normal PR (sec)
Newborn 0.08-0.12
Infant 0.08-0.14
Child 0.10-0.16
Adolescent 0.12-0.20

QTc (Corrected QT)

Value Interpretation
<440 ms Normal
440-460 ms Borderline
>460 ms Prolonged - evaluate for LQTS
>500 ms High risk - urgent evaluation

QTc = QT / √RR (Bazett formula)

Normal Pediatric ECG Features

T-Wave Evolution

  • Birth-7 days: Upright T waves in V1 (normal)
  • >7 days-adolescence: T waves INVERTED in V1-V3 (normal "juvenile pattern")
  • Adolescence/adult: T waves upright in V1-V2

Upright T wave in V1 after 7 days of age = RVH until proven otherwise

Right Ventricular Dominance

  • Normal in newborns/infants
  • Tall R waves in V1, deep S in V6
  • Gradually shifts to LV dominance by age 6 months

Systematic ECG Interpretation

The 10-Step Approach

  1. Rate: Count R-R intervals, use age-appropriate norms
  2. Rhythm: Regular? P before every QRS? QRS after every P?
  3. Axis: Use leads I and aVF quadrant method
  4. P waves: Present? Morphology? (RAE, LAE)
  5. PR interval: Age-appropriate? AV block?
  6. QRS duration: Narrow or wide?
  7. QRS morphology: Hypertrophy pattern? Bundle branch block?
  8. ST segments: Elevation? Depression?
  9. T waves: Appropriate for age? Inverted where shouldn't be?
  10. QTc: Calculate and assess

Critical Findings - Know These

Wolff-Parkinson-White (WPW)

  • Triad: Short PR + Delta wave + Wide QRS
  • Risk: SVT, rarely sudden death (AF with rapid conduction)
  • Action: Cardiology referral

Long QT Syndrome (LQTS)

  • QTc >460 ms (suspect if >450)
  • QTc >500 ms = High risk
  • Action: Urgent cardiology referral, avoid QT-prolonging drugs

Complete Heart Block

  • P waves and QRS completely dissociated
  • **Ventricular rate slow (40-60)
  • Action: Urgent - may need pacing

Severe Hyperkalemia

  • Peaked T waves → Widened QRS → Sine wave
  • Action: STAT potassium, cardiac monitoring, treatment

ST Elevation (Rare in Children)

  • Pericarditis: Diffuse ST elevation + PR depression
  • MI (rare): Focal ST elevation in coronary distribution
  • Action: Urgent evaluation

Common ECG Patterns

Right Ventricular Hypertrophy (RVH)

  • Tall R in V1 (beyond age-appropriate)
  • Right axis deviation
  • T wave changes in right precordial leads
  • Consider: PS, TOF, pulmonary hypertension

Left Ventricular Hypertrophy (LVH)

  • Deep S in V1 + Tall R in V5/V6
  • Voltage criteria age-dependent
  • Strain pattern (ST-T changes)
  • Consider: AS, coarctation, HCM, hypertension

Right Atrial Enlargement (RAE)

  • Tall, peaked P waves (>3 mm) in lead II
  • "P pulmonale"

Left Atrial Enlargement (LAE)

  • Wide, notched P waves (>0.10 sec) in lead II
  • "P mitrale"

ECG by Clinical Scenario

Murmur Evaluation

  • Look for: Chamber enlargement, axis deviation

Syncope Evaluation

  • Look for: WPW, LQTS, Brugada, HCM pattern, heart block

Chest Pain

  • Look for: ST changes (pericarditis, ischemia), arrhythmia

Palpitations

  • Look for: WPW, ectopy, SVT if captured

Pre-Sports Participation

  • Look for: WPW, LQTS, HCM pattern, Brugada

Board Pearls

Pearl: Rightward axis is NORMAL in newborns

RAD in a newborn ≠ pathology

Pearl: Upright T in V1 after day 7 = RVH

Should be inverted ("juvenile T wave pattern")

Pearl: QTc >460 ms = evaluate for LQTS

Especially with syncope or family history SCD

Pearl: Short PR + Delta wave + Wide QRS = WPW

Risk of SVT and rarely sudden death

Pearl: Always use AGE-APPROPRIATE normal values

Adult normals don't apply to children

Self-Assessment

Q1: A 2-week-old has an ECG showing upright T waves in V1. Is this normal?

Answer **Answer**: NO - this suggests RVH **Rationale**: After 7 days of life, T waves should be inverted in V1 (and often V1-V3) as part of the normal "juvenile T wave pattern." Upright T waves in V1 after the first week suggest RVH and warrant echocardiography.

Q2: A 15-year-old athlete has a screening ECG showing PR interval of 0.08 seconds with slurred upstroke of QRS. What is the diagnosis?

Answer **Answer**: Wolff-Parkinson-White (WPW) syndrome **Rationale**: Short PR (<0.12 sec) with delta wave (slurred QRS upstroke) is diagnostic of WPW. This requires cardiology evaluation for risk stratification.

Q3: What QTc value requires urgent evaluation?

Answer **Answer**: QTc >500 ms requires urgent evaluation; >460 ms warrants further assessment **Rationale**: QTc >500 ms is associated with significantly increased risk of torsades de pointes and sudden death, especially in setting of syncope or family history.

Key Guidelines

2023 AHA/ACC Scientific Statement: Electrocardiographic Screening in Young Athletes Circulation. 2023 Pediatric ECG interpretation and athlete screening guidance

HRS/EHRA/APHRS Expert Consensus on Inherited Arrhythmia Syndromes (2017) Heart Rhythm. 2017;14:e555-e607 ECG criteria for channelopathies

References

  • O'Connor M, et al. Circulation. 2024
  • Schwartz PJ, et al. Circulation. 2009;120:1761-1767
  • Park MK. Pediatric Cardiology for Practitioners, 7th ed.