ECG

1. ECG
BASIC GUIDELINES
&
TATIO

2. ORIENTATION OF
THE 12-LEAD ECG
Types of Leads
1.Bipolar limb
leads
2.Augmented limb
leads
3.“Unipolar” (+)
chest leads

3. 1. Bipolar limb leads (frontal
plane)
(RA = right arm; LA = left arm, LL = left
leg)
- Lead I: RA (- pole) to LA (+ pole) (Right -to- Left
direction)
-Lead II: RA (-) to LL (+) (mostly Superior -to- Inferior
direction)
-Lead III: LA (-) to LL (+) (mostly Superior -to-
Inferior
direction)

4. 1. Bipolar limb leads (frontal
plane)
(RA = right arm; LA = left arm, LL = left
leg)

5. 2. Augmented limb leads (frontal plane)
(RA = right arm; LA = left arm, LL = left leg)
Homeobook.com
-Lead aVR: RA (+) to [LA & LL] (-) (mostly
Rightward direction)
-Lead aVL: LA (+) to [RA & LL] (-) (mostly
Leftward direction)
-Lead aVF: LL (+) to [RA & LA] (-) (Inferior
direction)

6. 2. Augmented limb leads (frontal plane)
(RA = right arm; LAHo
=meo
lb
eook
f.c
tom
arm, LL = left

7. 3. “Unipolar” (+) chest leads
(horizontal plane):
-Leads V1, V2, V3: (mostly Posterior
-to-
Anterior direction)
-Leads V4, V5, V6: (mostly Right -to-
Left direction)

8. 3. “Unipolar” (+) chest leads (horizontal plane)

9. LIMB LEAD PLACEMENT

10. CHEST LEAD PLACEMENT
Precordial lead placement V1: 4th
intercostal space (IS)
adjacent to right sternal border
V2: 4th IS adjacent to left sternal
border
V3: Halfway between V2 and V4
V4: 5th IS, midclavicular line V5:
horizontal to V4; anterior axillary
line
V6: horizontal to V4-5; midaxillary
line
(Note: in women, the precordial
leads should be placed on the breast
surface not under the breast to
insure proper lead placement)

11. ECG
PAPER

12. Cardiac Conduction System

13. Normal ECG

14. ECG --
WAVE

15. P -
WAVE
P wave: sequential depolarization of
the right and left atria

16. P -
WAVE•The impulse is originating at the SA node
•It spreads over the atria in an usual
direction.
•There is no defect of conduction.
•The strength of conduction, mass of atrial
musculature, nutritions are normal.
•Duration 0.12 sec(3 small squares)
•Amplitude 0.25 mv(2.5 small square)
•Upright in all leads except VR
•Inverted – dextro cardia

17. P – WAVE
MORPHOLOGY
The P wave in general should not be more than 1 box wide or 1
box tall. If it exceeds these, it generally means that either or
both atria is enlarged (hypertrophied). The best lead to look at
the P wave is V1. In lead V1, the following characteristics
indicate pathology:
•Positive deflection greater than 1 box wide or 1 box in height
--> right atrial hypertrophy
•If P wave is inverted SA node fails to initiate the impulse.
•If P wave is absent in atrial fibrillation – nodal rhythm, sino
atrial block and hyperkalaemia
•If P wave is hidden – in rapid tachycardia

18. Q –
WAVE
Q wave and represents depolarisation in
the septum

19. Negative deflection which preceeds R wave
•Caused by the activity of septum.
•Small negative wave & often inconspicious detection.
•Absent in infants suffering from congenital patency
of the septum.
•Prominent Q wave indicates old infarction.
•Q wave in lead III and aVR should be ignore
•Abnormal Q wave- MI, ischemia, bundle branch
block, left ventricular hypertrophy
•A Q wave is significant if it is greater than 1 box
wide or greater than 1/3 the amplitude of the QRS
complex.
Q –
WAVE

20. Negative deflection which preceeds R wave
•Caused by the activity of septum.
•Small negative wave & often inconspicious detection.
•Absent in infants suffering from congenital patency
of the septum.
•Prominent Q wave indicates old infarction.
•Q wave in lead III and aVR should be ignore
•Abnormal Q wave- MI, ischemia, bundle branch
block, left ventricular hypertrophy
•A Q wave is significant if it is greater than 1 box
wide or greater than 1/3 the amplitude of the QRS
complex.
Q – WAVE MORPHOLOGY

21. R –
WAVE
R - waves indicate the changing direction of the
electrical stimulus as it passes through the
heart's conduction system.

22. R –
WAVER is most constant & conspicuous wave having the
tallest amplitude.
•First positive deflection during ventricular
depolarisation.
•Follows immediately upon Q wave.
•In abnormal conditions of ventricles, the shape, size,
duration of R & S altered.
•R wave in aVL must not be > 13mm
•R wave in aVF must not be > 20mm
•Minimum voltage: Atleast one R wave should be >
8mm
•Maximum voltage : The tallest R should not be > 27mm

23. S –
WAVE
S wave represents depolarization in the Purkinje
fibres.

24. S is next downward deflection to R.
•In lead I, R is mainly caused by right ventricle and S due
to left ventricle.
•In lead III, it is just reverse.
•For instance, in bundle branch heart block their
duration is prolonged beyond 0.1sec. & their relative
amplitude varies.
•Deepest S wave shouldnot be > 30mm
•Sum of tallest R wave and deepest S wave should not be
> 40mm
•Abnormal R and S wave suggest ventricular
hypertrophy, posterior MI, WPW syndrome,
dextrocardia+
S –
WAVE

25. •Steady progression from V1 to V6. (R wave).
•At V1 it is predominantly downwards.(S wave)
•From V2 to V6 it progresses to upwards.
•Duration: should be 0.08 - 0.10 sec (2 - 2.5 boxes).
LOW VOLTAGE:
•QRS complex < 5 small square in most of the leads:
pericardial effusion, myxoedema, emphysema, obesity,
HIGH VOLTAGE:
•Ventricular hypertrophy
•Abnormal QRS suggest: incomplete budle branch block
and WPW syndrome
QRS - MORPHOLOGY

26. T –
WAVE
Both ventricles repolarise before the
cycle repeats

27. T –
WAVE
Represents: ventricular repolarization.
•Always upright in leads I and II
•Always inverted in aVR
•Lead V1 normally upright (may be inverted in
20%)
•Lead V2 normally upright( may be inverted in
5
%)
•If upright in V1 and inverted in V2 : abnormal
•Must be upright in leads V3 and V6

28. T – WAVE MORPHOLOGY
T wave Morphology
*Abnormal T wave in shape, size, direction, duration,
reaction to exercise in leads I & II are of great prognostic
significance – myocardial damage with cardiac hypoxia.
*Ischemia: when T waves are in an opposite direction
(inverted), it may indicate that ischemia is present,
especially when it occurs in a pattern as previously
described for ST segment changes.
*Hyperkalemia: associated with tall peaked T waves, flat P
waves, and wide QRS complexes
*Hypokalemia: associated with flat T waves, U waves, U
waves taller than T waves

29. U –
WAVE
The U wave occurs when the ECG machine picks up
repolarisation of the Purkinje fibres.
electrolyte imbalances (potassium) but, again, this is
not very common.

30. This upright wave, when present, follows
the T wave. What it represents is not
certain.
U Wave Morphology
•The presence of U waves may indicate
hypokalemia.
U –
WAVE

31. This is the junction between the QRS complex
and the ST segment.
J – Point

32. •Sinus rhythm PP- RR are equal.
•They are used to calculate the heart
rate.
•PP is atrial rate& RR is the
ventricular rate.
CALCULATION
•Y = 1500/X beats/min.
•X = PP or RR interval.
P-P & R-R
INTERVAL

33. Measures from the beginning of P wave to the
beginning of QRS complex. It represents the total
amount of time required for depolarization of atria
( p wave) as well as the time required for the impulse
to travel slowly through the AV junction, through the
bundle branches, & just upto the point of QRS.
•Normally 0.13 to 0.16 sec.should not exceed 0.2 sec.
P-R
INTERVAL

34. NORMAL
INTERVAL
P-R interval = 0.12 - 0.20 sec (3 - 5 small squares)
QRS width = 0.08 - 0.12 sec (2 - 3 small squares)
Q-T interval 0.35 - 0.43 sec
* The PR interval should really be referred to as the PQ
interval; however it is commonly refeH
ro
rm
eeo
dboo
ak.
scom
the PR

35. REGIONS OF
HEART

36. CLINICAL
CONDITIONS

37. ISCHAEMIC
HEART
DISEASE

38. Acute inferior myocardial infarction

39. Acute anterior myocardial infarction

40. Acute posterior myocardial infarction

41. old inferior myocardial infarction
A 53 year old man with Ischaemic
Heart Disease

42. Acute inferior myocardial infarction
in presence of LBBB

43. HYPERTROPH
Y
PATTERNS

44. Left ventricular and left atrial
hypertrophy - aortic stenosis

45. Left ventricular and left atrial
hypertrophy - aortic stenosis

46. Mitral Stenosis

47. Right atrial hypertrophy

48. Left ventricular hypertrophy in the
presence of left anterior hemiblock

49. Left ventricular hypertrophy in the
presence of left anterior hemiblock

50. Atrioventricula
r (AV) block

51. First degree AV block

52. First degree AV block

53. 2 to 1 Atrioventricular block

54. Complete Heart Block
A 70 year old man with exercise
intolerance

55. Complete heart block and
atrial fibrillation
An 82 year old lady with dizzy
spells

56. bundle
branch

57. Right Bundle Branch Block

58. Left anterior hemiblock

59. Left anterior hemiblock

60. Left bundle branch block

61. 'Trifascicular' block
A 90 year old lady with
syncope

62. Supraventricula
r rhythms

63. Sinus bradycardia
A 55 year old man with 4 hours of
"crushing" chest pain.

64. Sinus tachycardia

65. Atrial Bigeminy

66. Atrial Premature Beat
A 48 year old man with thumping
sensations in his chest

67. Atrial fibrillation with rapid
ventricularresponse
A 76 year old man with
breathlessness.

68. Atrial fibrillation with pre-
existingLBBB
A 60 year old woman with
hypertension.

69. Atrial Flutter
A 68 year old lady on digoxin complaining
of lethargy.

70. Atrial flutter with 2:1 AV
conduction

71. Wolff-Parkinson-White syndrome
with atrial fibrillation

72. Wolff-Parkinson-White syndrome
with atrial fibrillation
A 47 year old man with a long history of
palpitations and, lately, blackouts.

73. VENTRICULAR
RHYTHMS

74. Ventricular premature beats

75. Ventricular premature beats

76. Ventricular bigeminy

77. Idioventricular escape rhythm
in Complete Heart Block

78. Idioventricular escape rhythm
in Complete Heart Block

79. Ventricular tachycardia with clear
AV dissociation

80. Ventricular tachycardia with clear
AV dissociation

81. Ventricular tachycardia with
subtle AV dissociation

82. Ventricular tachycardia with
subtle AV dissociation

83. Torsade de pointes ventricular
tachycardia

84. Polymorphic Ventricular
Tachycardia with an ICD

85. Polymorphic Ventricular
Tachycardia with an ICD

86. Ventricular
Fibrillation
A 60 year old man with 2 hours of "crushing"
chest pain suddenly collapses

87. PACEMAKER
S

88. Ventricular
pacemaker
A 72 year old man with a permanent
pacemaker.

89. Dual Chamber Pacemaker
with an ICD

90. Dual Chamber Pacemaker
with an ICD

91. Wolff
Parkinson
White
syndrome

92. WPW syndrome - left lateral
pathway

93. WPW syndrome - anteroseptal
pathway

94. Wolff-Parkinson-White syndrome
with atrial fibrillation

95. MISCELLANEOU
S

96. Implantable Cardioverter
Defibrillator

97. Implantable Cardioverter
Defibrillator
Implantable cardioverter defibrillator
Most of this 12-lead recording is polymorphic ventricular tachycardia but, in
the rhythm strip, the large deflection (arrowed) is the defibrillator
discharging.
Following the defibrillation a dual chamber pacemaker can be seen.
OK so I cheated a little with this one as the odds of catching this on a 12-
lead ECG recording are very slim indeed. This is a reconstructed 12-lead
recording from an electrophysiology study testing the device after
placement.
A 36 year old lady with recurrent blackouts.

98. Electrical Alternans -
pericardialeffusio
n

99. Long QT interval Romano-Ward
Syndrome

100. Lown-Ganong-Levine
Syndrome
A 50 year old man with bouts of
tachycardia.
A 50 year old man with bouts of
tachycardia.

101. Acute pulmonary embolus

102. Acute pulmonary embolus
A 40 year old woman with
pleuritic chest pain and
breathlessness.

103. Hyperkalaemia

104. Hyperkalaemia
A 58 year old man on
haemodialysis presents with
profound weakness after a
weekend fishing trip.

105. Hypokalaemia

106. Hypokalaemia
A 22 year old lady with prolonged
vomiting

107. Piggy-back heart transplant

108. Digitalis
effect
A 64 year old lady on
digoxin

109. ECG
THANK
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