This document provides an overview of basic ECG interpretation and nursing management. It begins with the anatomy and physiology of the cardiovascular system, including the heart chambers, valves, vessels and conduction system. It then covers electrophysiology, describing the cardiac cycle, waveforms and intervals on an ECG. The document provides steps for analyzing rhythm strips and discusses various sinus arrhythmias like sinus tachycardia, bradycardia, arrhythmia and arrest.

1. Basic ECG Interpretation and Nursing
Management Course
Presented by:
Rami AL-Khateeb

2. Outline
• Anatomy and Physiology of Cardiovascular
System
• Conduction System
• Electrophysiology of the heart
• Waveforms, intervals, segments, and
Complexes
• Analyzing a rhythm strip
• Sinus arrhythmias

3. Anatomy and Physiology of Cardiovascular
System

4. Introduction
• The primary function of the heart is to pump
blood throughout the body.
• Blood transports oxygen and nutrients and
has other important functions.

5. Introduction (Cont.)
• The vascular system consists of the arteries,
capillaries, and veins through which the heart
pumps blood throughout the body.

6. The Heart
• Cone shaped muscular
organ-10cm long.
• Weighs 220gm in
female and 310gm in
males.
• Position-Lies in
thoracic cavity behind
mediastinum and
between the lungs.

7. Heart Anatomy

9. Location of Heart in Thorax

10. Layers of Heart

11. Heart Chambers

12. Heart Chambers (Cont.)

13. Heart Chambers (Cont.)

14. Heart Valves (Cont.)

15. Heart Valves (Cont.)

16. Heart Valves (Cont.)

17. Heart Valves (Cont.)

18. Heart Valves

19. Heart Valves (Cont.)

20. The great vessels (Cont.)

21. The Conduction System
The Conduction System
• The cardiac conduction system is a group of
specialized cardiac muscle cells in the walls of
the heart that send signals to the heart muscle
causing it to contract.

22. The Conduction System (Cont.)
The main components of the cardiac conduction
system are:
• SA node
• AV node
• Bundle of HIS
• Bundle branches
• Purkinje fibers

23. The Conduction System (Cont.)

24. Electrical Activity of Myocardium
1) atrial depolarization
begins
2) atrial depolarization
complete (atria
contracted)
3) ventricles begin to
depolarize at
apex; atria
repolarize (atria
relaxed)
4) ventricular
depolarization
complete
(ventricles
contracted)
5) ventricles begin to
repolarize at apex
6) ventricular
repolarization
complete
(ventricles
relaxed)

25. Cardiac Innervation

26. Coronary Circulation (Cont.)

28. Cardiovascular Blood Flow

29. Cardiac cycle (Cont.)

30. Quiz

31. Quiz Answer
1. Right Coronary
2. Left Anterior Descending
3. Left Circumflex
4. Superior Vena Cava
5. Inferior Vena Cava
6. Aorta
7. Pulmonary Artery
8. Pulmonary Vein
9. Right Atrium
10. Right Ventricle
11. Left Atrium
12. Left Ventricle
13. Papillary Muscles
14. Chordae Tendineae
15. Tricuspid Valve
16. Mitral Valve
17. Pulmonary Valve
Aortic Valve (Not pictured

32. Electrophysiology
• The heart is composed of cardiac muscle
(myocardium),which is made up of thousands
of cardiac cells.
• Stimulation of one cardiac cell initiates
stimulation of adjacent cells and ultimately
leads to cell contraction.

33. Electrophysiology
• There are two basic cardiac cell groups:
• The pacemaker cells: specialized cells of the
electrical conduction system responsible for
generation of electrical impulses.
•
• The myocardial (mechanical) cells: consist of
contractile protein filaments called actin and
myosin. When these cells are stimulated, the
filaments shorten and slide together, causing
myocardial cell contraction.

34. Electrophysiology
• Cardiac cells characteristics:
• Automaticity : the ability of the pacemaker cells to
generate their own electrical impulses spontaneously; this
characteristic is specific to the pacemaker cells.
• Excitability :the ability of the cardiac cells to respond to an
impulse; this characteristic is shared by all cardiac cells. .
• Conductivity :the ability of cardiac cells to receive an
electrical impulse and transmit it to other cardiac cells; this
characteristic is shared by all cardiac cells.
• Contractility : the ability of the myocardial cells to short­en
and cause muscle contraction; this characteristic is specific
to myocardial cells.

35. Electrophysiology
• The constant movement of ions across the
cardiac cell membrane continuously changes
the electrical charge inside the cell, resulting
in periods of stimulation (depolarization) and
periods of rest (repolarization).

36. Electrophysiology

37. Electrophysiology
The conduction system
consists of:
• Sino­ atrial (SA) node
• Interatrial tract
(Bachmann's bundle)
• Internodal tracts,
• Atrioventricular (AV)
node
• Bundle of His
• Right and left bundle
branches
• Purkinje fibers.

38. Electrophysiology
• The SA node is
located in the wall
of the upper right
atri­um near the
inlet of the
superior vena cava.
• Discharge impulses
at a rate of 60 to
100 beats/minute.

39. Electrophysiology
The AV node has
three main
functions:
• Slow conduction
• Backup pacemaker.
• Block some of the
impulses from
being conducted to
the ventricles.

40. Electrophysiology
The bundle of
His divides:
• Right bundle
branch
• Left bundle
branch.

41. Electrophysiology
The right bundle
conducts impulse
to right ventricle
The left bundle
divides into :
• Anterior fascicle
• Posterior fascicle.

42. Electrophysiology
• The Purkinje
fibers carry the
impulse the
ventricles.

43. Electrophysiology

44. Waveforms and current flow

45. Waveforms and current flow

46. Refractory Period
• It is a period
of time for
which the
cardiac cells
may unable
to respond,
to a
stimulus.

47. ECG graph paper

48. Waveforms, intervals, segments, and
Complexes
P wave
• The first deflection of the cardiac
cycle, caused by depolarization of the
atria.
• Smooth and rounded.
• The amplitude shouldn't exceed 2.5
mm
• Duration shouldn't be greater than
0.10 second.
• The P wave is normally positive in
lead II.

49. Waveforms, intervals, segments, and
Complexes

50. Waveforms, intervals, segments, and
Complexes
• PR interval
• Measured from
the beginning of
the P wave to the
beginning of the
QRS complex.
• The normal
duration is
0.12 to 0.20 sec.

51. Waveforms, intervals, segments, and
Complexes

52. Waveforms, intervals, segments, and
Complexes
QRS complex
• represents the
conduction from the
bundle of His
throughout the
ventricles
• The QRS complex is
the largest complex.
• The point where the
QRS complex ends is
called the J point.
• The normal QRS
complex duration
0.10 second or less.
• ≥ 0.12 is Abnormal

53. Waveforms, intervals, segments, and
Complexes

54. Waveforms, intervals, segments, and
Complexes

55. Waveforms, intervals, segments, and
Complexes
ST segment
• The ST segment begins
with the end of the QR8
complex and ends with
the onset of the T wave.
• The normal ST segment is
flat (isoelectric).
• The point marking the
end of the QRS complex
and the beginning of the
ST segment is called the J
point.

56. Waveforms, intervals, segments, and
Complexes

57. Waveforms, intervals, segments, and
Complexes

58. Waveforms, intervals, segments, and
Complexes
T wave
• Represents
ventricular
repoarization.
• Slopes upward
from the ST
segment and
ends when the
waveform
returns to
baseline
• Amplitude less
than 5 mm.

59. Waveforms, intervals, segments, and
Complexes

60. Waveforms, intervals, segments, and
Complexes

61. Waveforms, intervals, segments, and
Complexes

62. Waveforms, intervals, segments, and
Complexes
QT Interval
• The QT interval is measured
from the beginning of the
QRS complex to the end of
the T wave.
• The normal QT interval
should be less than half the
distance between two
consecutive R waves when
the rhythm is regular.
• The QT interval can be
measured more accurately if
it's corrected for heart rate
(QT rate corrected, or QTc).

63. Waveforms, intervals, segments, and
Complexes

64. Waveforms, intervals, segments, and
Complexes
• U wave
• Normal U waves are
small, rounded, and
symmetrical; positive in
lead II.
• Usually less than 2 mm
in amplitude (always
smaller than the
preceding T wave).
• Some causes:
Hypokalemia
Cardiomyopathy
Digitalis, Quinidine, and
Procainamide.

65. Waveforms, intervals, segments, and
Complexes

66. Quiz

67. Quiz

68. Quiz

69. Quiz

70. Quiz

71. Quiz

72. ECG Monitoring

73. ECG Monitoring

74. ECG Monitoring

75. ECG Monitoring

76. ECG Monitoring

77. Analyzing a rhythm strip
There are five basic steps to be followed in
analyzing a rhythm strip:

78. Analyzing a rhythm strip
Step 1:
Determine the regularity (rhythm) of the R waves
• Measure from R wave to R wave across the rhythm
strip, marking any variation in R-wave regularity.
• If the rhythm varies by 0.12 second (3 squares) or
more between the shortest and longest R-wave, the
rhythm is irregular.
• If the rhythm doesn't vary or varies by less than 0.12
second, the rhythm is considered regular.

79. Analyzing a rhythm strip

80. Analyzing a rhythm strip
Step 2:
Calculate the heart rate
• This measurement will always refer to the
ventricular rate unless the atrial and ventricular
rates differ.
• The ventricular rate is usually determined by
looking at a 6-second rhythm strip.
• Methods of HR calculation differ according to
the regularity or irregularity of the rhythm

81. Analyzing a rhythm strip
Regular rhythms
• Two methods can be used:
• Rapid rate calculation : Count the number of R
waves in a 6-second strip and multiply by 10.
• Precise rate calculation - Count the number of
small squares between two consecutive R
waves,divide the number of small squares
between the two consecutive R waves into
1,500.

82. Analyzing a rhythm strip

83. Analyzing a rhythm strip
Irregular rhythms
• Only rapid rate calculation is used.
• Count the number of R waves in a 6- second
strip and multiple by 10, or count the number
of R waves in a 3-second strip and multiply by
20.

84. Analyzing a rhythm strip

85. Analyzing a rhythm strip
Note that:
• When rhythm strips have premature beats,
the premature beats aren't included in the
calculation of the rate.
• When rhythm strips have more than one
rhythm on a 6-second strip, rates must be
calculated for each rhythm

86. Analyzing a rhythm strip

87. Analyzing a rhythm strip
Step 3:
Identify and examine P waves
• Analyze the P waves - one P wave should
precede each QRS complex.
• All P waves should be identical (or near
identical) in size, shape, and position.

88. Analyzing a rhythm strip

89. Analyzing a rhythm strip
Step 4:
Measure the PR interval
• Measure from the beginning of the P wave as it
leaves base-line to the beginning of the QRS
complex.
• Count the number of squares contained in this
interval and multiply by 0.04 second.

90. Analyzing a rhythm strip

91. Analyzing a rhythm strip
Step 5:
Measure the QRS complex
• Measure from the beginning of the QRS
complex as it leaves baseline until the end of
the QRS complex when the ST segment
begins.
• Count the number of squares in this
measurement and multiply by 0.04 second.

92. Analyzing a rhythm strip

93. Analyzing a rhythm strip
Five basic steps to analyze a rhythm strip:
• Step 1: Determine the regularity (rhythm) of
the R waves
• Step 2: Calculate the heart rate
• Step 3: Identify and examine P waves
• Step 4: Measure the PR interval
• Step 5: Measure the QRS complex

94. Quiz

95. Quiz

96. Quiz

97. Quiz

98. Quiz

99. Quiz

100. Quiz

101. Sinus arrhythmias
Sinus arrhythmias results from disturbances in impulse
discharge from the sinus node.
• The sinus node retains its role as pacemaker but the
impulses are:
• Too fast (sinus tachycardia)
• Too slow (sinus bradycardia)
• Irregular impulses (sinus arrhythmia)
• Fails to initiate an impulse (sinus arrest)
• The impulses initiated are blocked as they exit the
sinoatrial (SA) node (sinus exit block)

102. Sinus arrhythmias

103. Sinus arrhythmias
• Normal sinus rhythm
Characteristics:
• Heart rate between 60 and 100 b/min.
• The P waves are normal in size, shape, and
direction; positive in lead II.
• One P wave preceding each QRS complex.
• The duration of the PR interval and the QRS
complex is each within normal limits.
Treatment:
???????????

104. Sinus arrhythmias

105. Sinus arrhythmias
• Sinus tachycardia
Characteristics:
• HR (100 – 180) b/min.
• P waves are normal in size, shape, and direction;
and positive in lead II, with one P wave preceding
each QRS complex.
• PR duration is normal.
• It is the normal response of increase body's
demand.
• Sinus tachycardia begins and ends gradually.

106. Sinus arrhythmias
• Causes:
• Excitement,Exertion, exercise,Fever,
Infections,Hypoxia,Hypovolemia,Hypotension,Hy
perthyroidism,Pain,Anxiety,Myocardial ischemia,
Drugs (epinephrine, norepinephrine, dopamine,
dobutamine,…)
• Treatment:
• In healthy individuals doesn't require aggressive
treatment.
• Treatment should be directed to correcting the
underlying cause of the arrhythmia.

107. Sinus arrhythmias

108. Sinus arrhythmias
• Sinus bradycardia
• Characteristics:
• HR (40 – 60) b/min.
• The P waves are normal in size, shape, and
direction; positive in lead II, with one P wave
preceding each QRS complex.
• PR duration is normal.
• Sinus bradycardia is the normal response of the
heart to relaxation or sleeping.

109. Sinus arrhythmias
Causes:
• Acute MI,Vagal stimulation,Sleep apnea
syndrome,Hypothyroidism,Hypothermia,
Sleep,Hyperkalemia,Increased intracranial pressure,
Drugs (digitalis, calcium channel blockers, and beta
blockers).
Treatment:
• Doesn't require treatment unless the patient becomes
symptomatic
• If sinus bradycardia persists, the treatment of choice is
atropine, 0.5 mg.

110. Sinus arrhythmias

111. Sinus arrhythmias
Sinus arrhythmia
Characteristics:
• Sinus arrhythmia is a rhythm that originates in the sinus node and discharges
impulses irregularly
• HR may be normal (60 - 100 b/min), but is commonly associated with sinus
bradycardia.
• The P waves are normal in size, shape, and direction; and positive in lead II, with
one P wave preceding each QRS complex
• The duration of the PR interval and the QRS complex is each within normal limits.
• Sinus arrhythmia is a normal phenomenon and is commonly associated with the
phases of respiration.
• Sinus arrhythmia is an extremely common finding among children and young
adults.
Treatment:
• Sinus arrhythmia in healthy individuals usually doesn't require treatment.

112. Sinus arrhythmias

113. Sinus arrhythmias
Sinus arrest
• characterized by a sudden pause in the sinus rhythm in which one or more beats is
missing.
• The P waves in the underlying rhythm will be normal in size, shape, and direction
and positive in lead II with one P wave preceding each QRS complex.
• PR duration is normal .
• Sinus arrest is caused by a failure of the SA node to initiate an impulse and is
therefore a disorder of automaticity.
• This failure in the automaticity of the SA node upsets the timing of the sinus node
discharge, and the underlying rhythm won't resume on time after the pause

114. Sinus arrhythmias

115. Sinus arrhythmias
Sinus exit block
• characterized by a sudden pause in the sinus rhythm in which one
or more beats is missing.
• The P waves in the underlying rhythm will be normal in size, shape,
and direction and positive in lead II with one P wave preceding each
QRS complex.
• PR duration is normal .
• Sinus exit block, an electrical impulse is initiated by the SA node,
but is blocked as it exits the sinus node, preventing conduction of
the impulse to the atria. Thus, SA exit block is a disorder of
conductivity.
• Because the regularity of the sinus node discharge isn't interrupted
(just blocked), the underlying rhythm will resume on time after
the pause.

116. Sinus arrhythmias

117. Quiz

118. Quiz

119. Quiz

120. Quiz

121. Quiz

122. Quiz

123. Quiz

124. Quiz

125. Quiz

126. References
• ECG Workout (Exercises in arrhythmia
Interpretation), Jane Huff, 5th Edition (2006).
• Thelans Critical Care Nursing, Diagnosis and
Management Linda D. Urden 4th
Edition (2002).

127. Thanks