ECG Interpretation, Manual for medical student

1. ECG
Interpretation
Dr AliReza Bahmani
Emergency Medicine Specialist
(ZAUMS)

3. “Type a quote here.”
–Johnny Appleseed

8. STEP ONE
. ID Name/ Date /Time / Speed / Calibration

9. The correct paper speed should
be 25 mm/ second
.

10. Calibration : Standard gain is
1 mV to 10 mm

11. STEP TWORhythm :
1. Regular Or Irregular
Irregular :
Irregular regular : atrial flutter
Irregular irregular : atrial fibrillation and MAT
2. Sinus Or Non sinus :
Sinus :
If Sinus Wave Rate ˂60 Bradycardia
If Sinus Wave Rate 60-120 Norm
If Sinus Wave Rate ˃ 100 Tachycardia

12. Regular Or Irregular

13. Sinus Or Non sinus

14. STEP THREE
Rate Regular

15. Irregular Rhythms:
• With Irregular Rhythms (such as Atrial Fibrillation)
always note the general
(average) ventricular rate (QRS’s per 6-sec. strip ✕ 10)
or take the patient’s
pulse.

17. Example #

18. STEP FOUR
Axis

22. STEP FIVE
P Morphology

25. STEP SIX
PR Interval
and
PR Segment

26. PR INTERVAL:
Normally between 0.12 and 0.20 seconds.
PR Interval < 0.12 s (Wolff Parkinson White
Syndrome (WPW))
PR Interval > 0.2 s Heart Blocks

27. PR Interval < 0.12 s
Wolff Parkinson White Syndrome (WPW)

28. PR Interval > 0.2 s Heart Block

31. PR Segments
on the ECG is their change from the isoelectric
line – elevation or depression
. PR segment depression can be a signal for
pericarditis or atrial infarction

34. STEP SEVEN
QRS Morphology

35. Duration less than or equal to 0.10 seconds
Upper limit of normal amplitude is 2.5 - 3.0 mv
Small septal Q waves in I, aVL, V5 and V6 (duration
less than or equal to 0.04 seconds; amplitude less than
1/3 of the amplitude of the R wave in the same lead).
Positive deflection with a large, upright R in leads I, II,
V4 - V6 and a negative deflection with a large, deep S
in aVR, V1 and V2
Poceeding from V1 to V6, the R waves get taller while
the S waves get smaller. At V3 or V4, these waves are
usually equal.

36. QRS WIDTH
Bundle Branch Blocks (BBBs)
QRS duration of greater than 0.12 seconds
right bundle branch block,
left bundle branch block,
QRS duration between 0.10- 0.12 seconds
Left anterior hemiblock
Left posterior hemiblock
Ventricular arrhythmias

38. LAHB
LPHB

40. QRS Amplitude or Voltage

41. Low QRS Voltage

43. High QRS Voltage
LVH
Sokolow-Lyon Criteria: Add the S wave in V1
plus the R wave in V5 or V6. If the sum is greater
than 35 mm, LVH is present.
The typical pattern with LVH includes
deviation of the ST segment in the opposite
direction of the QRS complex (discordance),
and a typical T wave inversion pattern is
present, as seen in the image here:

45. RVH
R/S ratio of greater than 1 in lead V1
R wave in lead V1 is greater than 7 millimeters
Strain pattern occurs when the right ventricular
wall is quite thick, and the pressure is high, as
well.
Strain causes ST segment depression and
asymmetric T wave inversions in leads V1 to V3.

48. Electrical alternans is an electrocardiographic
phenomenon of alternation of QRS complex
amplitude or axis between beats and a possible
wandering base-line. It is seen in cardiac tamponade
and severe pericardial effusion

49. STEP EIGHT
ST Segment
isoelectric, slanting upwards to the T wave in the
normal ECG
can be slightly elevated (up to 2.0 mm in some
precordial leads)
never normally depressed greater than 0.5 mm in any
lead
ST segment depression or ST segment elevation
can indicate cardiac pathology

50. ST segments deviation
1. Benign early repolarization (BER)
2. Ventricular hypertrophy
3. Left Bundle branch block
4. Pericarditis
5. Myocardial infarctions
Strain pattern

51. Normal ST segment
elevation (BER)
this occurs in leads with large S waves (e.g., V1-3), and
the normal configuration is concave upward.
ST segment elevation with concave upward
appearance may also be seen in other leads; this is
often called benign early repolarization, although it's a
term with little physiologic meaning

63. Convex or straight upward ST segment
elevation (e.g., leads II, III, aVF) is abnormal and
suggests transmural injury or infarction

66. ST segment depression is always an abnormal
finding, although often nonspecific

67. ST segment depression is often characterized
as "upsloping", "horizontal", or "downsloping“

72. T wave
T wave deflection should be in the same direction as the
QRS complex in at least 5 of the 6 limb leads
Normally rounded and asymmetrical, with a more gradual
ascent than descent
Should be upright in leads V2 - V6, inverted in aVR
If the T wave appears symmetric, cardiac pathology such
as ischemia may be present.
The height of the T wave should not exceed 5 mm in limb
leads and more than 10 mm in precordial leads

75. QT interval
Durations normally less than or equal to 0.40
seconds for males and 0.44 seconds for females
A quick way to distinguish a prolonged QT
interval is to examine if the T wave ends beyond
the halfway point between the RR interval.

77. Dysrhythmia
Interpretation

81. Example

82. Second Degree Heart
Block Type I

83. Second Degree Heart
Block Type II

84. Third Degree Heart Block

85. Ventricular Fibrillation

86. Ventricular Tachycardia

87. Ventricular Tachycardia
Monomorphic

88. Ventricular Tachycardia
Polymorphic

89. Ventricular Tachycardia
Torsade de Pointes

90. Wolff-Parkinson-White
Syndrome

91. Normal Sinus Rhythm

92. Junctional Tachycardia

93. Bundle Branch Block

94. Atrial Fibrillation

95. Multifocal Atrial
Tachycardia

96. Sinus Arrhythmia
Heart rate frequently increases with inspiration,
decreasing with expiration

97. Sinus Arrest

98. Sinoatrial Block

100. Accelerated Junctional
Rhythm

101. Accelerated Idioventricular
Rhythm

103. 2nd Degree AV Block
(Mobitz Type I)

104. 2nd Degree AV Block
(Mobitz Type II)

105. 3rd Degree AV Block

108. STEP NINTH
ISCHEMIA

109. Differences Between Ischemia, Injury and
Infarction
Ischemia: Reduction of myocardial oxygen for less
than 20 minutes. The damage is reversible. In the
electrocardiogram, ischemia produces changes in
T wave.
Injury: Persistence of oxygen deficiency (more than
20 min). Damage is still reversible. Injury is
characterized by ST segment abnormalities.
Infarction: Persistence of oxygen deficiency for
more than two hours. Damage is irreversible.
Infarction is characterized by pathological Q
waves on the Electrocardiogram.

110. Sub endocardial Ischemia
Subendocardial injury is usually caused by a partial
occlusion of a coronary artery
Subendocardial injury causes ST segment
depression in more than one EKG lead.
Subepicardial or Transmural Injury Patern
When a total occlusion of a coronary artery occurs, a
transmural injury appears , This means that the entire
myocardium in the area is affected.
produces ST segment elevation in leads near the
affected regions

148. STEP TEN
Miscellaneous
Pulmonary Embolism
Electrolytes
Digitalis

149. ARVD

151. HCM

153. LVH Strain

154. LV Aneurysm

155. Modified Sgarbossa

156. Pericarditis

157. Right Bundle Branch Block

158. Wellens