ECG made easy

1. ECG INTERPRETATION
Part 2

2. ECG INTERPRETATION
Part 2

4. Coronal plane (Limb Leads)
1. Bipolar leads - l , l l , l l l
2.Unipolar leads - aVL,Avr aVF
Transverse plane
V1 — V6 (Chest Leads)
10 electrodes

5. LIMB LEADS

6. Augmented limb
leads

9. How to READ??

10. Standardization

11. Calibrate to 10mm/mV
Rate at 25mm/s

12. Rhythm
 “Constant Ps & Rs interval”.
 Every QRS must be preceded by a P
wave.

13. Heart rate
Regular:
300/RRbig or 1500/RR
For irregular Rhythm: 15 cm scale
number of R waves in a 6-second (30 big
square) X 10.

14. AXIS
Neonate & infant: 90-150
child: 60-120
elder: “>12 years” 30-90

15. Left leaves
Right reaches

17. ECG INTERPRETATION
PART 2
 WAVES
 INTERVALS
 CHAMBER HYPERTROPHY

18. Waves
Physiological waves:
P-wave:
Best seen in Lead II
Normally 2-3 small squares (0.08-0.12
sec) duration & height
“Simple 2.5X2.5”.

21. Height
 A tall P wave (over
2.5mm) can be
called P pulmonale
 Occurs due to right
atrial hypertrophy

22. Length
 A P wave with a
length >0.08
seconds (2 small
squares) and a bifid
shape is called P
mitrale
 It is caused by left
atrial hypertrophy

23. QRS-waves
 Q - First downward
 R - first upward
 R’ - 2nd
upward
 S - first downward after 1st
upward
 QS

24. QRS-waves

26. QRS-waves
Duration: <3 small squares ( 0.12 secs )
Amplitude: Variable <2.0 mV or 4 big sq
Q wave: <3 small squares depth in “right
leads” V1 , v2

27. QRS
Progression:
A. Right to left: From mainly S in V1 to
mainly R in V6
B. Age: From RV dominance in neonates
to LV dominance after age of 3 years.

28. R wave Progression

29. QRS
 Narrow QRS
 Broad QRS
 RSR’
 LVH vs RVH
 Delta slurring

30. T wave
 Repolarization begins in the last area of the
heart to have been depolarized, and then
travels backward, in a direction opposite that
of the wave of depolarization
 both an approaching wave of depolarization
and a receding wave of repolarization
generate a positive deflection on the EKG,

32. T-wave:
 V6 T - always upright. ( If inverted indicate
LVH )
 The amplitude, of T wave is one third to two
thirds that of the corresponding R wave
 V1 it is inverted from age of 1 week up to
puberty “16 years”; upright after birth & after
puberty.

33. T wave
 Tall T wave
 Flat (< 0.5 mm negative )
 Inverted (> 0.5 mm negative )

35. Pathological waves
1. Delta-wave
2. J-wave (Osborne wave)
3. R’ -wave
4. U-wave

37. ???

40. Interval /segment

41. Interval / segment

42. Intervals
PR Interval
Normally, 2-5 small squares (average
0.08-0.2 sec)
 Long PR >5
 Short PR <2

43. Q-T Interval
 The duration of the QT interval is
proportionate to the heart rate.

44. Q-T Interval
Count the number of small squares, then multiply by
0.04 seconds, that the QT in seconds.
Bazett Formula.
QTc = QT/square root of RR
“RR: are the small squares between 2 R waves”
Crude normal value: 0.35-0.45 at rate between 60-
100

45. Short Q-T:
Hypercalcemia
Long Q-T:
 5 Hypos “Thermia, Thyroidism, Calcemia,
Magnisemia & Kalemia”
 2 Syndromes: Romano–Ward & Jervell and
Lange–Nielson “+Deafness”
 Drugs: e.g. Tricyclic Antidepressant

46. S-T segment
Elevated ST segment:
Pericarditis / MI
Depressed ST segment:
 Ischemia ( Angina )
 Hypokalemia.

47. Chamber size
 RAE vs LAE
 RVH vs LVH

48. Chamber size
Right Atrial Enlargement:
Tall P- wave “P pulmonale”
( >3 small squares )
Lead II & V2

49. Left Atrial Enlargement:
Wide P- wave “P mitrale”
>3 small squares (> 0.12 sec)
Lead II & V6

51. RVH vs LVH

52. R wave Progression

53. Right Ventricular
Hypertrophy
 In lead V1, the R wave is larger than the
S wave.
 In lead V6, the S wave is larger than the
R wave
 With Right axis deviation

54. Left Ventricular
Hypertrophy
 R wave in V5 + S wave in > 35 mm.
R in V5 is 26mm, S in V1 in
15mm.
The sum is 41 mm

55. Bi-Ventricular
Hypertrophy
Sum of RS in V3 & V4 > 60

60. ECG INTERPRETATION
PART 3
 Arrythmias
 Heart block
 Myocardial infarction

61. Acute myocardial infarction
Three stages:
1. T wave peaking followed by T wave
inversion
2. ST segment elevation
3. Appearance of new Q waves

62. 3 stages

63. Pathologic Q wave
 The Q wave must be greater than 0.04
seconds in duration.
 The depth of the Q wave must be at least one
third the height of the R wave in the same
QRS complex.
Lead AVR should not be considered when
assessing possible infarction.

65.  T wave inversion --- not diagnostic
 ST segment elevation is a reliable sign
 Appearance of new Q waves indicates
irreversible myocardial cell death has
occurred
Reciprocal Changes --- at lead distant from an
infarct ( ST segment depression )

68.  Inferior infarction- inferior leads
 Lateral infarction - the left lateral leads
 Anterior infarction - Any of the
precordial leads (V1 through V6)
 Posterior infarction- reciprocal changes
in the anterior leads, especially V1.

69. Arrythmia

70. Sinus arrythmia