1. BASIC ECG WORKSHOP
FOR PARAMEDIC
Dr. Rashidi Ahmad
MD USM, MMED USM, FADUSM
Lecturer/Emergentist
Dept. of Emergency Medicine
School of Medical Sciences
USM Health Campus
Kelantan, Peninsular of Malaysia

2. What is an ECG?
• An ECG is a method of measuring,
displaying and recording the electrical
activity of a heart
• Electrical stimuli is amplified to create a
“rhythm strip” by a machine that
consistently produces representations of
the heart’s electrical activity

3. 1st ECG machine - 1920

4. Indications
• ECG is used as a baseline and screening test for
CAD, cardiomyopathies, or left ventricular
hypertrophy
• Preoperatively, TRO silent coronary artery
disease.
• To detect metabolic alterations
• To evaluate patients with chest pain and in the
management of patients with suspected or known
ACS.
• To demonstrate ECG abnormalities in patients
with myocardial, valvular, and congenital heart
disease will eventually demonstrate.
• To evaluate rhythm disorders

7. EKG Precordial Leads

9. Vertical and horizontal perspective
of the ECG Leads
Leads Anatomical
II, III, aVF Inferior surface of
heart
V1 to V4 Anterior surface of
heart
I, aVL, V5, and V6 Lateral surface of heart
V1 and aVR Right atrium

10. • Electrical impulse traveling directly
towards the electrode produces an
upright (“positive”) deflection relative to
the isoelectric baseline

18. Components of a NSR

19. How to Read an EKG Strip

21. Electrocardiographic diagnosis
• Rate of waves
• Rhythm of waves
• Sequence of the waves in one cardiac cycle
• Presence or absence of waves within each
cardiac cycle
• Duration of the waves
• Distance between waves in one cardiac cycle
• Configuration of waves

22. Sequence of reading ECG
• Identify P, QRS and T
• Rate
• Rhythm
• P wave
• PR interval
• QRS complex
• ST segment
• T wave
• QT interval
• U wave
• Morphological changes

23. Identify P, QRS and T

25. Rate determination
• Method I - Times Ten
- Simplest, quickest, most commonly
used technique that is particularly useful
if the rhythm is irregular.
• Method II – 1500 or 300 Method
- Use only if cardiac rhythm is regular.
• If P & QRS are independent – calculate atrial
rate & ventricular rate separately

26. Determine the rate

29. Rhythm
Regular, irregular, irregularly irregular

31. P wave
• P waves usually precede
each QRS complex
• < 3 small squares in
duration
• < 2.5 small squares in
amplitude
• Commonly biphasic in
lead V1
• Best seen in leads II

32. I II III aVR aVL aVF V1 V2 V3 V4 V5 V6
The P waves should be upright in I, II, and V2 to V6
& negative in lead aVR

33. More P waves than QRS complex
P waves entirely absent

34. QRS complex without P wave in front of them
Abnormal P wave configuration

37. PR interval

38. 1.0 R
PR
interval
0.5
T
PR interval should be
Millivolts
P 0.12-0.20s or 3 to 5 little
Q
0 squares
-0.5 S
0 200 400 600
Milliseconds

42. QRS Complex

43. 1.0 R
0.5 The width of the QRS
Millivolts
T
P
complex should not exceed
0
Q 0.12s or less than 3 little
squares
-0.5 S
QRS
0 200 400 600
Milliseconds

44. I II III aVR aVL aVF
The QRS complex should be
dominantly upright in leads I
and II

45. I II III aVR aVL aVF V1 V2 V3 V4 V5 V6
Non-pathological Q waves: < 2 small squares deep, < 1 small
square wide, < 25% of the amplitude of the corresponding R wave
There should be no Q wave or only a small q in I, II, V2 to V6

46. V6
V5
V4
V3
V2
V1
The height of the R wave: variable & increases progressively
across the precordial leads; < 27 mm in leads V5 and V6
The R wave in lead V6,is often smaller than the R wave in V5

47. S wave
• S wave - Deepest in the right precordial leads
• Decreases in amplitude across the precordium,
and is often absent in leads V5 and V6
• The depth of the S wave should not exceed 30
mm in a normal individual

50. Which one are normal, RBB,
LBB?

56. ST Segment
• Normal ST Segment is flat
(isoelectric)
• Elevation or depression of ST
segment by 1 mm or more,
measured 0.08 s (or 2 small
squares) past the J point is
ABNORMAL

57. J point or a point up to 40 msec (one small square) beyond the J point
were the favoured points of measurement.

58. I II III aVR aVL aVF V1 V2 V3 V4 V5 V6
The ST segment should start isoelectric except
in V1 and V2 where it may be elevated

61. “Non-specific T and ST changes”
• T-wave flattening:
• T-wave inversion:
• ST-segment scooping:
•ST-segment depression

63. T wave
• Asymmetrical: first half
has a more gradual
slope than second half
• < than 2/3 of R
amplitude
• T wave amplitude
rarely exceeds 10 mm

64. I II III aVR aVL aVF
T and QRS tend to have the
same general direction in
the limb leads

65. I II III aVR aVL aVF V1 V2 V3 V4 V5 V6
The T wave must be upright in I, II, V2 to V6

66. Hyperacute T wave
- Earliest change of AMI
- Lasting only 5- 30 minutes from onset of pain

68. QT interval
• QT interval decreases when heart rate
increases
• QT interval should be 0.35- 0.45 s, and
should not be more than half of the interval
between adjacent R waves (R-R interval).

70. U wave
• Normal U waves are small, round, symmetrical
and positive in lead II, with amplitude < 2 mm
(amplitude is usually < 1/3 T wave amplitude in
same lead)
• U wave direction is the same as T wave
direction in that lead
• More prominent at slow heart rates and usually
best seen in the right precordial leads.

72. Summary

73. Sequence of reading ECG
• Identify P, QRS and T
• Rate
• Rhythm
• P wave
• PR interval
• QRS complex
• ST segment
• T wave
• QT interval
• U wave
• Morphological changes

74. Electrocardiographic diagnosis
• Rate of waves
• Rhythm of waves
• Sequence of the waves in one cardiac cycle
• Presence or absence of waves within each
cardiac cycle
• Duration of the waves
• Distance between waves in one cardiac cycle
• Configuration of waves

75. Dr. Rashidi Ahmad
MD USM, MMED USM, FADUSM
Pensyarah/Pakar Perubatan kecemasan
Pusat Pengajian Sains Perubatan
USM Kampus Kesihatan, Malaysia
shidee_ahmad@yahoo.com
+609 7663244