First part of Basics of ECG in Children

1. BASICS OF PAEDIATRIC ECG
Ehab Zahran
Part I

2. What it looks like
when I’m reading an ECG
vs What’s actually happening

3. A 12-year-old boy presents to the
A&E department following a
syncopal episode in the middle of
a football game. The parents
report that he appeared pale and
remained unresponsive for 1min.
He recalls that he had some chest
discomfort but does not remember
the rest of the event. A 12-lead
ECG was obtained.

4. Let’s read the ECG

5. Objectives
 Normal ECG:
- Rate
- Rhythm
- Axis
- PR interval
- QRS duration
- QTc interval
 SVT
 LQTS
 Heart block
 RBBB / LBBB
 RVH / LVH
 Vtach / VF
 Electrolyte disturbance
 Brugada syndrome
 Cardiomyopathies

6. ECG complex relates to the electrical activity of the heart,
not muscular contraction.

7. Definitions
Wave: a positive or negative deflection from baseline

8. Definitions
Interval: The time between two specific ECG events
= Wave + Segment

9. Definitions
Segment: a portion of the baseline

10. Definitions
Complex: The combination of multiple waves grouped together
= Multiple waves without segment

11. ECG LEAD PLACEMENT - CHILD

12. ECG LEAD PLACEMENT - NEWBORN

13. ECG interpretation checklist
Step 4 QT – ST – T
Step 3 QRS complex
Step 2 P wave – PR interval
Step 1 Rhythm – Rate – Axis

14. Standardization

15. Standardization

16. Standardization
Small square = 1 mm = 0.04 s
Big square = 5 small boxes = 0.2 s
5 big squares = 1 s
30 big squares = 6 s
300 big squares = 1 min

17. Rhythm
Look at P wave:
- Upright? - Constant?
- Appears before every QRS? - Followed by QRS every
time?
- Look all the same?

18. Rhythm
Sinus arrhythmia

19. Heart rate

20. Heart rate

21. Heart rate

22. Heart rate
One ECG strip = 10 seconds
HR = Number of R waves x 6

23. Heart rate
Calculate HR

24. Heart rate
Calculate HR

25. Heart rate
Calculate HR

26. Heart rate
Calculate HR

27. Axis
Denotes overall direction of the electrical activity of the heart
– represents the major vector of ventricular activation

28. Axis interpretation

29. Axis interpretation

30. Axis deviation causes
RAD LAD
RVH LVH
PS AS
ASD TA
TOF AVSD
WPW WPW
RBBB Cardiomyopathy
Normal variation Normal variation

31. Right axis deviation (RAD)
o RVH
o PS
o ASD
o TOF
o RBBB
o WPW
o Normal variation

32. Left axis deviation (LAD)
o LVH
o AS
o AVSD
o Cardiomyopathy
o WPW
o Normal variation

33. P wave
P wave = 3 small squares

34. P wave – The abnormal
Prolonged
Myocarditis
Certain CHD
Hyperkalaemia
Digitalis toxicity
Short WPWS
GSD
Variable Second degree HB

35. PR interval
Beginning of P -> Beginning of QRS

36. QRS complex
Beginning of Q -> End of S

37. QRS complex – The abnormal
Prolonged Bundle branch blocks
WPWS
Ventricular arrhythmias
High Ventricular hypertrophy
WPWS
Low
Pericarditis
Myocarditis
Hypothyroidism
Normal newborns

38. ST segment
End of S -> Beginning of T

39. ST segment – The abnormal

40. QT interval
Beginning of Q -> End of T
[<0.45 s]
<6 months < 0.49 s

41. QT interval

42. Corrected QT “QTc”
• The corrected QT interval (QTc) estimates the QT interval at a standard
heart rate of 60 bpm.
• This allows comparison of QT values over time at different heart rates
and improves detection of patients at increased risk of arrhythmias.

43. Corrected QT “QTc”
QT = 12 small boxes = 12 x 0.04 = 0.48
RR = 17 small boxes = 17 x 0.04 = 0.68
QTc = 0.48 / square root of 0.68 = 0.58
= Prolonged QT [Normal up to 0.45 sec]
* Causes : Electrolyte abnormalities, Myocarditis, Medications, Head injury.
* Symptoms : Palpitations, Chest pain, SOB, Dizziness, Syncope, Cardiac arrest.

44. T wave
Normally negative in aVR & V1

45. T wave: The abnormal
Tall, peaked Hyperkalaemia
LVH
Flat
Normal newborns
Hypokalaemia
Hypothyroidism
Myocarditis
Inverted Raised ICP

46. Normal values for age

47. A 12-year-old boy presents to the
A&E department following a
syncopal episode in the middle of
a football game. The parents
report that he appeared pale and
remained unresponsive for 1min.
He recalls that he had some chest
discomfort but does not remember
the rest of the event. A 12-lead
ECG was obtained.

48. Let’s read the ECG

49. *ID Check
Name
DOB

50. Standardization
Rhythm
Rate
Axis
P wave
PR interval
QRS
ST
QT -> QTc

51. SUMMARY

53. Take-home Message

54. 10 Rules of
a Normal ECG
1. P wave always positive in I & II, and negative in aVR
2. All waves are negative in lead aVR
3. QRS & T waves have same direction in limb leads
4. QRS should be dominantly upright in leads I & II
5. R wave grows from V1 to at least V4
6. ST segment isoelectric except in V1 & V2 where it
may be elevated
7. T wave in V1 inverts after 7 days till 7 years
8. In I & II + V2 to V6 P wave is upright
9. In I & II + V2 to V6 T wave is upright
10. In I & II + V2 to V6 No Q wave (or small Q)

55. References