The document provides a detailed overview of the cardiac cycle, its physiological properties, and the principles of electrocardiography (ECG). It describes the electrical and mechanical phases of the cardiac cycle, components of ECG, and how to interpret the data it provides regarding heart function. Additionally, it outlines the types of ECG monitoring, lead configurations, and methods for calculating heart rate.

1. NORMAL
ECG
Prepared by
Mahmoud Taha Abd El-kafy
Under supervision of
Prof.dr/Warda Youssif
Dr/ Youssria Abd Elsalam

2. OBJECTIVES
Discuss the composition of the
cardiac cycle &cardiac properties
Describe how impulse conduction
works in the heart
Identify how leads and planes
function.

3. OBJECTIVES (CONT.)
Identify types of ECG
monitoring.
Describe the components of an
electrocardiogram complex
along with their significance.
Identify how to calculate the rate
and rhythm of an ECG recording.

4. OUTLINES:
Cardiac cycle &cardiac properties.
Intrinsic conduction system.
Types of ECG.
ECG Leads.
ECG paper.
Characteristics of normal ECG tracing.
Heart Rate Calculation.
Normal axis of the heart

5. CARDIAC CYCLE
The cardiac cycle is composed of both
the electrical activity due to
automaticity and the mechanical
(muscular) response known as
contraction.
Generation and transmission of
electrical impulses depend on
automaticity, excitability, conductivity,
and contractility of cardiac cells.

6. ELECTROPHYSIOLOGIC
PROPERTIES OF THE
HEART
Automaticity:
can generate an electric
impulse on its own
Excitability:
Non-pacemaker cells can
respond to impulse and
depolarize

7. ELECTROPHYSIOLOGIC
PROPERTIES OF THE
HEART (CONT.)
Conductivity:
Can transmit impulse from cell
membrane to cell membrane
Contractility:
Cardiac muscle cells can shorten fiber
length in response to electrical
stimulation, creating sufficient pressure
to propel blood forward (Mechanical
activity)

8. CARDIAC
CYCLE(CONT.)
The electrical activity can be divided
into two phases called depolarization
and repolarization. The mechanical
response is divided into diastole and
systole.
Depolarization is the active phase of
electrical activity. Repolarization is the
resting phase during which electrical
activity is minimal.

9. •Phase of the cardiac cycle
when the myocardium contracts
is termed systole.
Phase of the cardiac cycle when
myocardium is relaxed is
termed diastole.

10. WHAT IS AN ECG?
Records electrical activity of the heart
Gives us information about cardiac
rhythm, ischaemia/infarction and some
generalised disorders (e.g. electrolyte
imbalance)
4 limb and 6 chest electrodes = 12 lead
ECG
Each lead gives a different viewpoint of
electrical activity in the heart

11. ECG

12. USES OF ECG
TRACING
To detect:
Ischemia/infarction
Arrhythmias
Ventricular and atrial enlargements
Conduction defects
Pericarditis
Effects of some drugs and electrolytes
(Digoxen &potassium).

13. NORMAL CONDUCTION
SYSTEM

16. SA node:
Rate: 60 to 100 bpm
AV node:
Rate: 40-60 bpm
Bundle of His:
Rate: 40-60 bpm
Purkinje Fibers:
Rate: 20-40 bpm

17. TYPES OF ECG
The two types of ECG
recording are the 12-lead ECG
and single-lead ECG,
commonly known as a rhythm
strip. Both types give valuable
information about heart
function.

18. 12 LEAD ECG

19. ECG (A
RHYTHM STRIP)

20. ECG LEADS
Standard Limb Leads

21. AUGMENTED LEADS
AVR looks from right shoulder into
the middle
AVL looks from left shoulder into
the middle
AVF looks from the left feet to the
middle

22. Red
Yellow
Green
Black
Right Arm
Left Arm
Left Leg
Right Leg

23. Limb Leads

24. PRECARDIAL
LEADS

25. PRECARDIAL
LEADS

26. View from Chest and Limb
Leads

27. LEAD PLACEMENTS
V1 - 4th ICS, Right sternal border
V2 - 4th ICS, Left sternal border
V3 - Midway between V2 and V4
V4 - 5th ICS, Mid clavicle
V5 - Anterior aspect of axilla, same line as V4
V6 - Mid axilla, same line a V4
4 limb leads.

28. ECG PAPER

29. ECG PAPER

30. The EKG is recorded on ruled paper. The smallest
divisions are one millimeter squares

31. The height and depth of a wave is measured in
millimeters and represents a measure of voltage

32. The horizontal axis represents time

33. One small box = 0.04
seconds
One large box = 5 small
boxes = 0.2 seconds
5 large boxes = 1 second

36. P WAVE
It represents atrial depolrization
Location:
precedes the QRS complex.
Amplitude:
2-3 mm high.

37. P WAVE
Duration:
0.06 to 0.12 second (1.5 to3
small blocks).
Configuration:
rounded and upright.
Deflection:
positive

38. P WAVE

39. PR INTERVAL
 Start of P wave to start of QRS
 Normal = 0.12-0.2s (3-5 small squares)

40. QRS COMPLEX
Represents ventricular
depolarization.
Measured from the beginning of
the Q (or R) wave to the end of the
S wave.
Should be <0.12s duration(less
than 3 small boxes).

41. QRS COMPLEX
Q wave – first negative
deflection
R wave – first positive
deflection after a P wave
S wave – negative deflection
following an R wave

42. QRS COMPLEX

43. ST SEGMENT
The isoelectric segment
following depolarization and
preceding ventricular
repolarization
From the end of the QRS to the
beginning of the T wave

44. ST SEGMENT
Elevation or depression of the ST
segment by 0.1 mV from the baseline
is abnormal

45. T WAVE
Represents ventricular recovery or
repolarization
T follows the QRS complex and is
usually the same direction as the
QRS complex. If QRS is
predominantly negative an inverted T
wave is not necessarily abnormal

46. T WAVE
Location: follows the S wave.
Amplitude: 0.5 mm in leads
I,II,III,& UP to 10 mm in the
pericardial leads.
Configuration: typically round
and smooth.

47. T WAVE

48. U wave
Represents late ventricular
repolarization
QT interval
Represents the total time required
for ventricular depolarization and
repolarization.
Measured from the beginning of the
QRS complex to the end of the T
wave

49. QT INTERVAL
Duration: varies according to
age, gender and heart rate,
usually lasts from 0.36 to
0.44 second (9 to 11 small
boxes.
The faster the heart rate, the
shorter the QT interval.

50. QT INTERVAL

51. NORMAL SINUS RHYTHM
Originates in the sinoatrial node
(SA)
Rhythm: atrial/ventricular
regular
Rate: atrial/ventricular rates 60
to 100 bpm
P Waves: present, consistent
configuration

52. NORMAL SINUS
RHYTHM (CONT.)
One P wave before every QRS
PR interval: 0.12 to 0.20
second and constant
QRS duration: 0.04 to 0.10
second (1 to 3 small blocks)
and constant

54. NORMAL ECG

55. The standard EKG is composed of 12
separate leads

56. If you observe this same object from six different
reference points, you will recognize the car

57. To obtain the limb leads, electrodes are
placed on the right and left arms and the left
leg forming a triangle (Einthoven’s)

58. Each side of the triangle formed by the three
electrodes, represents a lead (I, II, III) using
different electrode pairs for each lead

59. By pushing these three leads to the center of the triangle,
there are three intersecting lines of reference

60. Another lead is the AVR lead. The AVR lead
uses the right arm as positive and all other limb
electrodes as a (common ) grand (negative).

61. The remaining two limb leads are AVL and AVF
and are obtained in a similar manner

62. The AVR, AVL, and AVF leads intersect at different angles
and produce three other intersecting lines of reference

63. All six leads, I, II, III, AVR, AVL and AVF, meet to form
six neatly inter-secting reference lines which lie in a
flat plane on the patient’s chest.

64. Each limb lead records from a different angle, thus
each lead (I, II, II, AVR, AVL, and AVF) is a different
view of the same cardiac activity

65. If you observe this same object from six different
reference points, you will recognize the car

66. To obtain the six chest leads, positive electrode is placed
at six different positions around the chest

67. The chest leads are projected through the AV Node towards the
patient’s back which is the negative end of each chest lead

68. Leads V1 and V2 are placed over the right side of the
heart, while V5 and V6 are over the left side of the heart.

69. Leads V3 and V4 are located over the
interventricular septum

70. To demonstrate the direction of electrical
activity, we use a “vector”

71. We can use small vectors to demonstrate ventricular depolarization
which begins in the endocardium (inner lining) and proceeds
through the ventricular wall

72. The Mean QRS Vector normal points downward and
to the patient’s left side

73. With the sphere in mind, consider lead I (left arm with
the positive electrode, right arm with the negative)

74. If the QRS complex is negative in lead I (Vector toward
the right), this is Right Axis Deviation

75. In lead AVF if the QRS is mainly positive one the
tracing, then the Mean QRS Vector points downward

76. In AVF if the QRS is negative, the Vector points
upward into the negative half of the sphere

77. If the QRS is positive in lead I and also positive in
AVF, the Vector points downward and to the
patient’s left (normal range)

78. If the QRS is positive in lead I, and negative in AVF,
that places the Vector in the upper left quadrant

79. Now by looking at the QRS complex in I and AVF you
can locate the Mean QRS Vector

80. HEART RATE
CALCULATION
Two methods can be used to calculate
the heart rate:
10-times method:
Used especially if the rhythm is
irregular. Count the number of P
waves in a 6-second strip (30 large
blocks) then multiply the number of
P waves by 10 to get the atrial rate.

81. To calculate ventricular rate count R
wave in a 6-second strip then
multiply this number by 10.

82. RULE OF 300
This method only works for regular
rhythms.
Take the number of “big boxes”
between neighboring QRS
complexes, and divide this into
300. The result will be
approximately equal to the rate.

83. COUNT THE
RATE HERE?

84. QUESTIONS

85. PRACTICE
EXERCISE

87. for attention
for attention