1. Introduction to Pediatric ECGs
Thomas R. Burklow, MD
Asst C, Pediatric Cardiology
Walter Reed Army Medical Center
Pediatric ECGs

2. Electrophysiology and Anatomy
SA Node 
Pediatric ECGs

3. Mechanics of tracing Small box = 1 x 1 mm Large box = 5 x 5 mm
Paper speed (horizontal boxes)
Standard = 25 mm/sec
Voltage calibration (vertical boxes)
Standard = 10 mm/mV (2 big boxes)
Half standard = 5 mm/mV (1 big box)
May have 10/5: standard for chest leads, half-standard for precordial leads
NOTE THE CALIBRATION!!
Pediatric ECGs

4. ECG basics: grid paper
Pediatric ECGs

5. Basic electrocardiogram
Pediatric ECGs

6. Interpretation Be systematic!! Rhythm Rate Axis Intervals
Atrial enlargement
Ventricular hypertrophy
ST/T wave evaluation
Pediatric ECGs

7. Rhythm Sinus rhythm Subsidiary pacemaker Tachyarrhythmia
Bradyarrhythmia
Atrioventricular block
Pediatric ECGs

8. Normal sinus rhythm P wave before every QRS QRS following every P wave
Normal P wave axis
Normal PR interval is NOT required
Pediatric ECGs

9. P wave axis Atrial depolarization occurs from SA node
Wave passes right to left, top to bottom
Positive deflections in leads I (right to left) and aVF (top to bottom)
Normal P wave axis = 0-90 degrees
Abnormal axis implies ectopic pacemaker
Coronary sinus or “low right atrial” rhythm is common benign finding, especially in teens
Positive in lead I, negative in aVF
Pediatric ECGs

10. Rate Measured in beats per minute 60 / RR interval (in seconds)
300 / number of “big boxes” between consecutive QRS complexes
1500 / number of “little boxes” between consecutive QRS complexes
Pediatric ECGs

11. Heart rate Known time interval
Beats in 6 seconds (30 “big boxes”) x 10
Beats in 3 seconds (15 “big boxes”) x 20
Pediatric ECGs

12. Heart rate Rate approximation Rate estimate: 300 - 150 - 75 - 60 - 50
Easy to memorize
No calculator needed
Pediatric ECGs

13. Normal resting heart rates
Newborn: bpm
2 years: bpm
4 years: bpm
> 6 years: bpm
Adult: bpm
Pediatric ECGs

14. Axis Hexaxial reference system Horizontal reference system
Bipolar limb leads
I, II, III
Augmented unipolar leads
aVR, aVL, aVF
Horizontal reference system
Precordial leads
V1 - V7
Right sided leads (e.g. rV3)
Pediatric ECGs

15. Reference systems
Pediatric ECGs

16. Axis determination Successive approximation Equal amplitudes
Locate quadrant with leads I and aVF
Narrow down by using leads within quadrant
Use most equiphasic lead
Axis is perpendicular to that lead, in the quadrant previously identified
Equal amplitudes
If two leads with equal net QRS amplitudes exist, the mean axis lies midway between the axis of these two leads
Pediatric ECGs

17. Quadrant determination
Normal axis
Left axis
“Boston”
Right axis
Extreme R/L axis
“Seattle”
Pediatric ECGs

18. Successive approximation
Pediatric ECGs

19. Axis determination Amplitude vector Add net R-S in lead I, R-S in aVF
Plot in mm on grid (lead I horizontal, lead aVF vertical)
Draw vector from origin to net amplitude
Angle of vector = axis
Pediatric ECGs

20. Right axis deviation Axis > 100 degrees
“Normal for age”: rightward axis > 100 degrees, but within normal limits for age (e.g. 2 week old with axis of +140)
Suggestive of RVH
Pediatric ECGs

21. Left axis deviation Axis < -5 degrees Q waves in leads I and aVL
Conduction abnormality
Associated with atrioventricular septal defect
No correlation with LVH
Occurs in 5% of normal population
Pediatric ECGs

22. Causes of left axis deviation
Normal variant
AV septal defect (including primum ASD)
Perimembranous inlet VSD
Tricuspid atresia
Single ventricle
Double outlet right ventricle
Noonan syndrome
Left anterior hemiblock after MI
Pediatric ECGs

23. PR Interval
Onset of atrial contraction to onset of ventricular contraction (measures cumulative time of depolarization through atria, AV node, and His-Purkinje system)
Varies between leads
Increases with age
Decreases with heart rate
Pediatric ECGs

24. Long PR interval = First degree AV block Drugs
Atrial surgery (scar tissue)
Acute rheumatic fever (minor Jones criteria)
Kawasaki disease
Pediatric ECGs

25. Short PR interval Etiologies Wolff-Parkinson-White
Glycogen storage disease type IIa (Pompe’s)
Fabry disease
GM1 gangliosidosis
Friedrich’s ataxia
Duchenne’s muscular dystrophy
Pediatric ECGs

26. QRS Duration Beginning of Q wave to end of S wave
Use a lead where a Q wave is visible
Normal = (may be up to 0.09 in adolescents)
> 0.12 = bundle branch block
: evaluate morphology
Pediatric ECGs

27. RSR’ Morphology Seen in right precordial leads: V1, rV3
Common: occurs in 7% of kids
R and R’ both small and of short duration
S wave larger than R and R’
R’ is less than 10 mm (15 mm in infants)
Abnormal RSR’ may reflect RBBB or RVH (volume overload type)
Pediatric ECGs

28. QT Interval
Onset of ventricular depolarization (Q wave) to end of ventricular repolarization (T wave)
Do NOT include U waves
Varies inversely with heart rate
Best leads: II, V5, V6
QTC (Bazett’s formula) = QT/square root RR
Normal < 0.44 sec
May be as high as 0.45 sec in adol/adult females
May be as high as 0.49 sec in newborns (to 6 mo.)
QT ruler
Pediatric ECGs

29. QT Abnormalities Short QT Long QT - Congenital Long QT - Acquired
Digoxin
Hypercalcemia
Long QT - Congenital
Jervell-Lange-Nielsen
AR, deafness
Romano-Ward
AD, normal hearing
Long QT - Acquired
Metabolic
Hypocalcemia
Hypomagnesemia
Malnutrition (anorexia)
Drugs
Ia and III antiarrhythmics
Phenothiazines
TCA
CNS trauma
Myocardial
Ischemia
Myocarditis
Pediatric ECGs

30. Atrial enlargement Right atrial enlargement Left atrial enlargement
P wave amplitude > 2.5 mm in II
Deep negative deflection in first 0.04 seconds in chest leads
Left atrial enlargement
Terminal portion of P wave
Negative deflection in V1 beyond 0.04 sec
Duration of negative deflection > 0.04 sec
Total duration > 0.10 sec
Pediatric ECGs

31. Atrial enlargement
Pediatric ECGs

32. Right ventricular hypertrophy
Mild
R’ > 15 mm (< 1 year) or > 10 mm (> 1 year)
Abnormal RSR’ of normal to slightly prolonged duration in right chest leads
Moderate
Definite right axis deviation (non-RBBB)
rR’ or pure R in right chest leads
Significant S in left chest leads
Pediatric ECGs

33. Right ventricular hypertrophy
Severe
Marked RAD
qR pattern V3R or V1
Tall pure R wave > 15 mm (any age) in right chest
Upright T wave > 3-5 days of age
Very tall R wave with ST depression and T wave inversion in V1 (“strain”)
Deep S wave V6
Pediatric ECGs

34. Left ventricular hypertrophy
Criteria
LAD for age (more useful in neonates/infants)
R in V5/V6 or I, II, III, aVF, aVL above normal
S in V1/V2 above normal
Abnormal R/S ratio (R/S in V1/V2 below normal)
Deep/wide q wave in V5/V6 above fmm
Tall symmetric T waves = “LV diastolic overload”
With LVH, inverted T waves in I/aVF = “strain”
Pediatric ECGs

35. Combined ventricular hypertrophy
Criteria
Positive voltage criteria for LVH and RVH
In absence of BBB, preexcitation
Positive voltage criteria for LVH or RVH with relatively large voltages for the other ventricle
Large equiphasic QRS complexes in > 2 limb leads and midprecordial (V2 - V5) leads
“Katz-Wachtel” phenomenon
Pediatric ECGs

36. QRS morphologies Normal RBBB Preexcitation (“delta wave”) IV block
Pediatric ECGs

37. Conduction disturbances: RBBB
Prolongation in terminal phase of QRS (“terminal slurring”
Delayed conduction through RBB prolongs depolarization of RV
Slurring is to the right and anterior
RAD
QRS above ULN for age
Wide/slurred S in I, V5, V6
Terminal slurred R’ in aVR and V1, V2, V3r
ST segment shift, T wave inversion (in adults)
Pediatric ECGs

38. RBBB

39. Bundle branch block RBBB: Etiologies LBBB ASD/PAPVR
Right ventriculotomy
Ebstein’s
Coarctation (< 6 months)
LBBB
Rare in children
Seen in adults with ischemic and hypertensive heart disease
Pediatric ECGs

40. Intraventricular block
Slowing throughout QRS complex
Etiologies
Metabolic disorders (hyperkalemia)
Myocardial ischemia (CPR, quinidine toxicity)
Diffuse myocardial disease
Pediatric ECGs

41. Wolff-Parkinson-White
“Preexcitation”: initial slurring of QRS
Accessory conduction pathway
Premature depolarization of part of the myocardium
Slow conduction  delta wave
Criteria:
Short PR interval for age
Delta wave
Wide QRS for age
Pediatric ECGs

42. Preexcitation syndromes
Lown-Ganong-Levine
Short PR interval
Normal QRS duration
Fibers bypass upper AV node, but conduct normally
Mahaim fiber
Normal PR interval
Long QRS duration
Delta wave
Fiber bypasses His bundle, enters RV myocardium
Pediatric ECGs