Basic simple approach of how to read ECG

1. Basics of ECG
interpretation
BY
USAMA ELSAYED
Lecturer of anesthesia and
intensive care

2. Objectives
 Why ECG?
 How to monitor ECG
 Physiology of pulse conduction
 Interpretation

3. WHY?
Chest pain
Heart failure
Collapse / syncope
Shock / hypotension
Palpitations
Cardiac arrest
preoperative

4. GOLDEN RULE
Look at the patient
not just the paper

5. How ?
 3-lead monitoring
 12-lead monitoring
 ‘Quick-look’ paddles
 Hands-free adhesive pads

6. 12 lead monitoring
6 chest electrodes Called V1-6
4 limb electrodes
Right arm Ride
Left arm Your
Left leg Green
Right leg Bike

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

10. Impulse Conduction & the ECG

11. ECG Paper

13. ECG Leads

14. ECG waves components
 P wave = atrial depolarisation
 QRS = ventricular depolarisation
 T = repolarisation of the ventricles

15. ECG interpretation
 History
 QRS Rhythm
 QRS Rate
 QRS Width
 QRS Axis
 P Wave
 P & QRS Relation
 Ischemic changes

16. History
 Again: treat the patient not the paper
 Check
o Name and age
o Time and date
o Indication (chest pain or routine pre op)
o Any previous or subsequent ECGs (Is it
part of a serial ECG sequence?)

17. IIII
QRS Rhythm

18. QRS Rhythm
 Sinus Rhythm
Cardiac impulse originates from the sinus
node. Every QRS must be preceded by P
wave ????
Sinus not normal sinus ??

19. 2- QRS
RATE
* At standard paper speed of 25 mm sec-1, 5 large squares = 1 second* At standard paper speed of 25 mm sec-1, 5 large squares = 1 second

20. QRS Width
 The width of the QRS complex should
be less than 0.12 seconds (3 small
squares)
 suggests a ventricular conduction
problem usually right or left bundle
branch block (RBBB or LBBB)

21. QRS
WIDTH

22. LBBB

23. RBBB

24. 02/20/15
Dr Gamal Abbas
NOV 2007 24

25. 02/20/15
Dr Gamal Abbas
NOV 2007 25

26. QRS Height
RVH: V1 R/S ratio >1 or V6 S/R ratio >1.
LVH: S in V1 or V2 + R in V5 or V6 ≥ 35 mm

27. The QRS Axis
 Represents the overall direction of the heart’s activity
 Axis of –30 to +90 degrees is normal

28. The QRS Axis
 Left axis deviation(LAD)
o Inferior MI
o LVH
o Left anterior hemiblock

29. The QRS Axis
 Right axis deviation(RAD)
o RVH
o Anterolateral MI
o Left posterior hemiblock

30. P Wave

31. P Wave
Atrial activity
Positive in II
Negative in aVR
Height
A tall P wave (over 2.5mm) can be called P
pulmonale
As in right atrial enlargement
o Pul. Htn
o TS
o PS

32. P Wave
 Length
> 2.5 small squares and a bifid shape is
called P mitrale
Left atrial hypertrophy
o Mitral valve disease
o LVH

33. P & QRS Relationship
 2 Questions
o Is every P followed by QRS?
o PR Interval

34. The PR interval
 measured between the start of the P
wave to the start of the QRS complex.
 time between depolarisation of the atria
and ventricular depolarisation.
 3- 5 small squares(0.12 - 0.2 sec)

35. Relation between atrial and ventricular
activity
 Heart Block: First Degree
first degree ht block

36. Möbitz Type I (Wenckebach) Block
Möbitz Type II Block
Relation between atrial and ventricular activity

37. Heart Block: Third Degree
Relation between atrial and ventricular activity

38. The ST segment , T and Q
wave (Ischrmic changes)
 ST segment Sit on the isoelectric
line
 Abnormal if there is planar (i.e.
flat) elevation or depression of
the ST segment

40. The ST segment , T and Q
wave (Ischrmic changes)
Baseline

41. The ST segment , T and Q
wave (Ischrmic changes)
Width of Q wave is 0.04 secs

43.  Peaked T wave as
in hyper kalemid

45. I and
AVL
II, III and AVF
V3 & v4
V1 & v2
V5 & v6
Where the positive electrode is
positioned, determines what
part of the heart is seen!

46. A Normal 12 Lead ECG

48. Putting it ALL together

49. Anterolateral myocardial infarction

50. Inferior myocardial infarctionInferior myocardial infarction

51. Posterior myocardial infarctionPosterior myocardial infarction

52. Practice
 QRS rhythm
 QRS rate
 QRS Width
 P wave
 P & QRS relationship
 Ischemic changes

53. Let’s Practice

54. Practice
Supraventricular Tachycardia
Atrial Fibrillation
Atrial Flutter ( 2/1 )
Sinus Bradycardia

55. Practice
First degree heart block
Second degree heart block (Mobits type I)
Third degree heart block
Second degree heart block (Mobits type II)

56. Practice
Anterior MI with lateral
involvement
ST elevations V2, V3, V4
ST elevations II, AVL, V5

57. Practice
Anteroseptal MI
ST elevations V1, V2, V3, V4

58. Practice
Inferior MI
ST elevation II,III AVF

59. Practice
Inferior lateral MI
ST elevations II, III, AVF
ST elevations V5

60. Practice
•Acute inferior MI
•Lateral ischemia

61. Normal

62. RBB w/inferior MI

63. Atrial fibrillation

64. Normal

65. Ventricular tachycardia

66. Normal

67. Right bundle branch block.

68. Lateral MI
Reciprocal changes

69. Common Dangerous
Rhythms
Asystol
P wave Asystol
Course Ventricular Fibrillations
Fine Ventricular Fibrillations
Criteria of ventricular fibrillations
* Bizarre irregular waveform * No recognisable QRS complexes
* Random frequency and amplitude

70. Common Dangerous Rhythms
(Ventricular)
Ventricular Tachycardia
Torsade De Pointes

71. Any questions

72. Remember
Practice makes
perfect.