The document provides information on how to read and interpret electrocardiograms (ECGs). It discusses the positioning of the 12 leads on the body and what each lead represents in terms of electrical activity. It then outlines the normal characteristics seen on an ECG, including measurements like the PR interval and QRS width. Ten rules for determining a normal ECG tracing are listed. The document also reviews how to calculate heart rate from an ECG and defines left and right axis deviation. In summary, it serves as a guide for interpreting the various components and measurements of a standard 12-lead ECG.

1. How to read and interpret ECG
DR Ihab Suliman
MBBS ECFMG MRCP(UK) ABcv MRCP
spec (End and DM) CBNC FESC
Abstract committee grader for ESC
Confe 2019

3. Lead Position
• A typical ECG report shows the cardiac cycle from 12
different vantage points (I, II, III, aVR, aVL, aVF, V1-V6), like
viewing the event electrically from 12 different locations (like
a 3D perspective).BUT only 10 electrodes are used.
• Lead I represents activity that is going from the right arm to
the left arm
• Lead II represents activity that is going from the right arm to
the left leg
• Lead III represents activity that is going from the left arm to
the left leg
• aVL is placed on the left arm (or shoulder)
• aVF is placed on the left leg (or hip)
• aVR is placed on the right arm (or shoulder)
• V1- 4th intercostal space to the right of sternum
• V2- 4th intercostal space to the left of sternum
• V3- halfway between V2 and V4
• V4- 5th intercostal space in the left mid-clavicular line
• V5- 5th intercostal space in the left anterior axillary line
• V6- 5th intercostal space in the left mid axillary line

4. Normal ECG

5. Young lady staff on diet, felt atypical CP.

6. 50 years old male , atypical CP, Normal ECG

7. 41 years old male anxious. Sinus Tachycardia

8. • NSR.
• Sinus tachycardia
• Normal ECG

13. The 10 rules for a normal ECG
I II III aVR aVL aVF V1 V2 V3 V4 V5 V6
.2

14. Rule 1
PR
interval
Millivolts
Milliseconds
0 200 400 600
-0.5
0
0.5
1.0
P
R
T
Q
S
PR interval should be 120 to
200 milliseconds or 3 to 5 little
squares

15. Rule 2
Millivolts
Milliseconds
0 200 400 600
-0.5
0
0.5
1.0
QRS
P
R
T
Q
S
The width of the QRS complex
should not exceed 110 ms, less
than 3 little squares

16. Rule 3
I II III aVR aVL aVF
The QRS complex should be
dominantly upright in leads I and II

17. Rule 4
I II III aVR aVL aVF
QRS and T waves tend to have the
same general direction in the limb
leads

18. Rule 5
P
Q
T
S
All waves are negative in lead aVR

19. Rule 6
V1
V2
V3
V4
V5
V6
The R wave in the precordial leads must grow from V1 to at least V4

20. I II III aVR aVL aVF V1 V2 V3 V4 V5 V6
Rule 7
The ST segment should start isoelectric except in V1 and
V2 where it may be elevated

21. Rule 8
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

22. Rule 9
I II III aVR aVL aVF V1 V2 V3 V4 V5 V6
There should be no Q wave or only a small q less than
0.04 seconds in width in I, II, V2 to V6

23. Rule 10
I II III aVR aVL aVF V1 V2 V3 V4 V5 V6
The T wave must be upright in I, II, V2 to V6

24. What is the heart rate?
•(300 / 6) = 50 bpm
•www.uptodate.com

25. What is the heart rate?
•(300 / ~ 4) = ~ 75 bpm
•www.uptodate.com

26. What is the heart rate?
•(300 / 1.5) = 200 bpm

27. 10 Second Rule
As most EKGs record 10 seconds of rhythm per page,
one can simply count the number of beats present on the
EKG and multiply by 6 to get the number of beats per 60
seconds.
This method works well for irregular rhythms.

28. What is the heart rate?
•33 x 6 = 198 bpm
•The Alan E. Lindsay ECG Learning Center ; http://medstat.med.utah.edu/kw/ecg/

29.  Left axis deviation - negative QRS in lead AVF
 Right axis deviation - negative QRS in lead I
 Severe Right axis deviation negative QRS in BOTH
lead I and AVF
Quick & Easy AXIS DETERMINATION
AVF
AVF
AVF
AVF
AVF
AVF
I
I
I
I
I
I

30. The QRS Axis
By near-consensus, the normal
QRS axis is defined as ranging
from -30° to +90°.
-30° to -90° is referred to as a left
axis deviation (LAD)
+90° to +180° is referred to as a
right axis deviation (RAD)

31. Determining the Axis
Predominantly
Positive
Predominantly
Negative
Equiphasic

32. The Quadrant Approach
1. Examine the QRS complex in leads I and aVF to determine if they
are predominantly positive or predominantly negative. The
combination should place the axis into one of the 4 quadrants
below.

33. Quadrant Approach: Example 1
Negative in I, positive in aVF  RAD
The Alan E. Lindsay ECG
Learning Center
http://medstat.med.utah.ed
u/kw/ecg/

34. Quadrant Approach: Example 2
Positive in I, negative in aVF  Predominantly positive in II 
Normal Axis (non-pathologic LAD)
The Alan E. Lindsay ECG
Learning Center
http://medstat.med.utah.ed
u/kw/ecg/

35. Thank U Very Much