1. ECGG Interpretation
Najib Ul Haq
coyright 2004 Anna Story

2. ECG ECG Basics Normal Sinus Rhythm How to Analyze a Rhythm
Heart Arrhythmias
Diagnosing a Myocardial Infarction
Advanced 12-Lead Interpretation

3. Normal Cardiac Current Flow

4. Basics of Current movement
Current Electrode
Electrode Current

5. Normal ECG

6. Normal Impulse Conduction
Sinoatrial node
AV node
Bundle of His
Bundle Branches
Purkinje fibers

7. Impulse Conduction & the ECG
Sinoatrial node
AV node
Bundle of His
Bundle Branches
Purkinje fibers

8. Atrial depolarization
The PR Interval
Atrial depolarization +
Delay in AV junction
(AV node/Bundle of His)
(Delay allows time for the atria to contract before the ventricles contract)

9. The “PQRST” P wave - Atrial depolarization
QRS - Ventricular depolarization
T wave - Ventricular repolarization

10. Normal ECG

11. Normal ECG

12. Einthoven’s Triangle Lead I - + Lead III Lead II
extends from the right to the left arm
Lead III
extends from the left arm to the left foot
Lead II
extends from the right arm to the left foot

13. Diagnosing MI
To diagnose a myocardial infarction you need to go beyond looking at a rhythm strip and obtain a 12-Lead ECG.
12-Lead ECG
Rhythm Strip

14. The 12-Lead ECG
The 12-Lead ECG sees the heart from 12 different views.
Therefore, the 12-Lead ECG helps you see what is happening in different portions of the heart.
The rhythm strip is only 1 of these 12 views.

15. The 12-Leads The 12-leads include: 3 Limb leads (I, II, III)
3 Augmented leads (aVR, aVL, aVF)
6 Precordial leads (V1- V6)

16. Normal ECG

17. Views of the Heart Lateral portion of the heart
Some leads get a good view of the:
Anterior portion of the heart
Inferior portion of the heart

18. ST Elevation
One way to diagnose an acute MI is to look for elevation of the ST segment.

19. A Normal 12 Lead ECG
2004 Anna Story

20. ST Elevation (cont)
Elevation of the ST segment (greater than 1 small box) in 2 leads is consistent with a myocardial infarction.

21. Left Main Coronary Artery
Branches quickly into the LAD & LCX. Involves almost 2/3 of the heart muscle primarily anterior
Right Coronary Artery (RCA) The RCA supplies blood to the bottom (inferior) portion and part of the back (posterior) portion of the left ventricle The posterior portion of the septum is also supplied with blood from the RCA.
SA Node 55%
AV Node 90%
AV Blocks
Left Anterior Descending Branch (LAD) The LAD supplies blood to the front (anterior) portion of the left ventricle, apical including most of the anterior portion of the septum separating the ventricles.
Bundle Branch Block, AMI, CHF
Left Circumflux Branch (LCX) The LCX supplies blood to the left side (lateral) portion and the back (posterior) portion of the left ventricle.
SA Node 45%
AV Node 10%
Lateral & posterior MI

22. MI Locations Lateral portion of the heart
Anterior portion of the heart
Lateral portion of the heart
Inferior portion of the heart
Look again at this picture of the heart.

23. MI Locations Lateral portion of the heart
Anterior portion of the heart
Lateral portion of the heart
Inferior portion of the heart
Look again at this picture of the heart.

24. Anterior View of the Heart
The anterior portion of the heart is best viewed using leads V1- V4.

25. Anterior MI
Remember the anterior portion of the heart is best viewed using leads V1- V4.
Limb Leads
Augmented Leads
Precordial Leads

26. View of Anterior Heart Wall
Anterior Wall MI
View of Anterior Heart Wall
Leads V3, V4
Looks at anterior heart wall
Looks from the left anterior chest

27. Lateral MI
So what leads do you think the lateral portion of the heart is best viewed?
Leads I, aVL, and V5- V6
Limb Leads
Augmented Leads
Precordial Leads

28. View of Lateral Heart Wall
Lateral Wall MI
View of Lateral Heart Wall
Leads I and aVL
Looks at lateral heart wall
Looks from the left arm toward heart
*Sometimes known as High Lateral*

29. Inferior MI Now how about the inferior portion of the heart?
Leads II, III and aVF
Limb Leads
Augmented Leads
Precordial Leads

30. View of Inferior Heart Wall
Inferior Wall MI
View of Inferior Heart Wall
Leads II, III, aVF
Looks at inferior heart wall
Looks from the left leg up

31. Putting it all Together
Now, where do you think this person is having a myocardial infarction?

32. Inferior Wall MI
This is an inferior MI. Note the ST elevation in leads II, III and aVF.

33. Inferior Wall MI
This is an inferior MI. Note the ST elevation in leads II, III and aVF.

34. Inferior Wall MI

35. Putting it all Together
How about now?

36. Anterolateral MI
This person’s MI involves both the anterior wall (V2-V4) and the lateral wall (V5-V6, I, and aVL)!

37. Thank You