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1. 1. 12-LeadElectrocardiography a comprehensive course sson2 Le Adam Thompson, EMT-P, A.S.
3. 3. The 6-Step Method• 1. Rate & Rhythm• 2. Axis Determination• 3. Intervals• 4. Morphology• 5. STE-Mimics• 6. Ischemia, Injury, & Infarct
4. 4. Lesson Two• Frontal Axis determination tutorial• Precordial Axis rotation• Pathologies that cause axis deviation
5. 5. Objectives• Learn how to determine the frontal axis.• Distinguish between the different causes of axis deviation.• Learn how to identify rotation of the precordial axis.
6. 6. Axis Determination• Critical Skill!• Use the hexaxial reference system for the frontal plane.• Identify clockwise or counterclockwise rotation of R-wave progression.
7. 7. Pathologies Frontal Plane Axis Precordial Axis ERAD Right Axis Pathological Early Transition Late Transition Deviation Left Axis Counterclockwise Clockwise -90° to 180° Deviation Rotation Rotation 90° to 180° -30° to -90°• Ventricular • May be normal • Pregnancy • Posterior wall • SometimesRhythm • LPFB • LAFB infarction Normal,• Paced Rhythm • RVH especially in • Pulmonary • WPW• Dextrocardia • RBBB women disease • Pulmonary • Anterior MI• Electrolyte • RVH diseasederangement • LVH • RBBB • LBBB • LAFB • WPW • Hyperkalemia • LBBB • Dextrocardia • Q-waves, MI • Lung Disease •Venrticular Rhythm
8. 8. Willem Einthoven Won the Nobel Prize in Physiology orMedicine in 1924 for inventing the stringgalvanometer which was the first EKG.
9. 9. Einthoven’s Triangle• Electrically, leads I, II, & III form an equilateral triangle.• Einthoven’s Law I + (-II) + III = 0
10. 10. Einthoven’s Law• How it works• Lead I – The R wave is about 7 1/2 mm tall. – The S wave is about 2 1/2 mm deep. – Subtract the S wave from the R wave • you come up with 5 mm.
11. 11. Einthoven’s Law• Lead I = 5mm• Lead II – It’s essentially a monophasic QS complex. – About -10 mm.
12. 12. Einthoven’s Law• Lead I = 5mm• Lead II = -10mm• Lead III – R wave that is about 1 mm high. – The S wave is about 16 mm deep. – Subtract the S wave from the R wave. – -15 mm.
14. 14. Einthoven’s Law• Lead I = 5mm• Lead II = -10mm• Lead III = -15mm – Plug the numbers in. • I + (-II) + III = 0 • 5 + 10 -15 = 0
15. 15. Einthoven’s LawThe equilateral triangle
16. 16. Electrical Axis What is the heart’s electrical axis? Mean vector Cardiac vector 4 1 3 3 2 2The first area to depolarize (1) is the interventricular septum
17. 17. Electrical Axis What is the heart’s electrical axis? Mean vector Cardiac vector 4 1 3 3 2 2Next, the area around the left and right ventricular apex (2) depolarizes from a endocardial-to-epicardial direction (inside-out).
18. 18. Electrical Axis What is the heart’s electrical axis? Mean vector Cardiac vector 4 1 3 3 2 2Finally, the lateral walls of the left and right ventricledepolarize (3) and last the high lateral wall of the left ventricle (4).
19. 19. Electrical Axis What is the heart’s electrical axis? Mean vector Cardiac vector 4 1 3 3 2 2The big arrow is the heart’s mean (average) electricalvector. If you averaged the millions of cardiac vectors, you would get the “mean vector”.
20. 20. Mean Electrical Vector + + A B A + BMean vector moves towards positive electrode = positive QRSMean vector moves away from positive electrode = negative QRSMean vector is perpendicular to positive electrode = equiphasic QRS
21. 21. Mean Electrical VectorRed arrow is heart’smean electrical vector
22. 22. Mean Electrical VectorLead I views the heart’sVector similar to theimage on the left.Leads II & III do the samefrom their angles.
23. 23. Einthoven’s Triangle =
24. 24. Hexaxial Reference SystemThe arrows and leadnames are placed on Ithe side of thepositive electrode. III II
25. 25. Hexaxial Reference System The augmented leads provide the other 3 leads of the hexaxial reference system.
26. 26. Hexaxial Reference System
27. 27. Hexaxial Reference SystemaVR aVL + I = aVF III II
28. 28. Hexaxial Reference System
29. 29. Hexaxial Reference System QuickTime™ and a mpeg4 decompressor are needed to see this picture.
30. 30. Hexaxial Reference System• Lead I cuts through body horizontally• aVF cuts through body vertically• II, III, aVF are inferior• III & aVL are reciprocal
31. 31. Hexaxial Reference System How to use it
32. 32. Hexaxial Reference System Find the most equiphasic lead
33. 33. Hexaxial Reference System Find the most equiphasic lead
34. 34. Hexaxial Reference System + + A B A + B• When the mean axis is perpendicular to the positive electrode, the QRS is equiphasic.
37. 37. Hexaxial Reference SystemLook at aVF, is it positive or negative?
38. 38. Hexaxial Reference SystemSince aVF is positive,look at the measurenext to the side withthe up arrow.Axis is about +90°
39. 39. Hexaxial Reference System About +90°
40. 40. Axis Determination• Is that too much work?• You’re first time is always the hardest.• The more you do this, the easier it is to do.• Eventually, you won’t need any diagrams.
41. 41. Axis Determination Lets practice…
42. 42. Axis DeterminationFind the most equiphasic lead.
43. 43. Axis Determination Looks like Lead II…
44. 44. Axis Determination Lead aVF
45. 45. Axis DeterminationWhich lead isperpendicular toaVF?
46. 46. Axis DeterminationWhich lead isperpendicular toaVF?
47. 47. Axis DeterminationIs Lead I positive or negative?
49. 49. Axis Deviation• So what is a normal axis?• Why does it matter if an axis is deviated?
50. 50. Normal Axis • The normal quadrant for the QRS axis is the Southeast quadrant. • From 0° to 90°
51. 51. Left Axis Deviation • From -90° to 90° • This is considered the Northeast quadrant.
52. 52. Left Axis Deviation • From 0° to -30° • This is considered physiological left axis deviation • Pathological axis deviation is from -30° to -90° • Most common cause is left anterior fascicular block
53. 53. Right Axis Deviation • From 90° to -180° • Negative QRS in Lead I • Positive QRS in aVF – Possible Left Posterior Fascicular Block – Q-Waves from lateral MI – Right Ventricular Hypertrophy – Pulmonary Disease.
54. 54. Extreme Right Axis Deviation • Called ERAD • From -90° to -180° • QRS in I, II, & III are negative • Probably ventricular – Idioventricular – Paced rhythm
55. 55. Cheat Sheet Normal Physiologic Pathologic Right Axis Extreme Indeterminate Axis Left Left Right Axis Axis 0° to 90° 0° to -30° -30° to -90° 90° to 180° -90° to 180° ?Lead ILead IILead III
56. 56. PracticeLook at leads I, II, & III
57. 57. Cheat Sheet Normal Physiologic Pathologic Right Axis Extreme Indeterminate Axis Left Left Right Axis Axis 0° to 90° 0° to -30° -30° to -90° 90° to 180° -90° to 180° ?Lead ILead IILead III
58. 58. PracticeNormal Axis
59. 59. PracticeNormal Axis
60. 60. PracticeWhich lead is equiphasic?
61. 61. PracticeWhich lead is equiphasic?
62. 62. Practice • Lead aVL is equiphasic • Lead II is perpendicular to aVL • Lead II is positive
64. 64. Quadrant Method• Much easier to do.• Faster and more practical for rapid interpretation.• Does not give you a very close estimate.
67. 67. Quadrant Method aVF - Negative Positive-I QRS in QRS in I+ Lead I Lead I aVF +
68. 68. PracticeLets take a look
69. 69. Quadrant Method aVF --I I+ aVF +
70. 70. Quadrant Method aVF - Negative QRS Complex in aVF-I I+ Positive QRS Complex in aVF aVF +
71. 71. PracticeLets take a look
72. 72. Quadrant Method aVF --I I+ aVF +
73. 73. Quadrant Method aVF --I I+ aVF +
76. 76. Frontal Axis Modern 12-Lead monitors do a pretty good job estimating the QRS Axis.
77. 77. Frontal Axis
78. 78. Precordial Axis• Sometimes called Z axis• Clockwise or Counterclockwise rotation
80. 80. Precordial Axis 4 1 3 3 • The main impulse travels 2 2 down then to the left.Mean vectorCardiac vector
81. 81. Precordial Axis 4 1 3 3 2 2 V1 V2 V3 V6Mean vector V4 V5Cardiac vector
82. 82. Precordial Axis - +Lets pretend the impulse is a delivery truck thathas a positive front end and a negative backend.
83. 83. Precordial Axis
84. 84. Precordial AxisV1 V2 V3 V4 V5 V6
85. 85. Precordial Axis +V1 V2 V3 V4 V5 V6
86. 86. Precordial Axis +V1 V2 V3 V4 V5 V6
87. 87. Precordial Axis - +V1 V2 V3 V4 V5 V6
88. 88. Precordial Axis - +V1 V2 V3 V4 V5 V6
89. 89. Precordial Axis - +V1 V2 V3 V4 V5 V6
90. 90. Precordial Axis - +V1 V2 V3 V4 V5 V6
91. 91. Prec ordial Axis - +V1 V2 V3 V4 V5 V6
92. 92. Precordial Axis- +V1 V2 V3 V4 V5 V6
93. 93. Precordial Axis• The normal transition zone is between V3 and V4.• V1 should be predominately negative.• V6 should be mostly positive.
94. 94. Precordial AxisLets take a look at a 12-lead
95. 95. Precordial AxisIs V1 mostly negative?
96. 96. Precordial AxisIs V6 mostly positive?
97. 97. Precordial AxisWhere is the transition?
98. 98. Precordial AxisThe Precordial Axis is Normal
99. 99. Precordial Axis V1 V2 V3 V4 V5 V6Now picture the precordial leads in this pattern.
100. 100. Precordial Axis V1 V2 V3 V4 V5 V6Normal transition
101. 101. Precordial Axis V1 V2 V3 V4 V5 V6Early transition = Counterclockwise Rotation
102. 102. Precordial Axis V1 V2 V3 V4 V5 V6Late transition = Clockwise Rotation
103. 103. Precordial Axis
104. 104. Precordial AxisEarly Transition - Counterclockwise Rotation
105. 105. Precordial AxisEarly Transition - Counterclockwise Rotation
106. 106. Precordial Axis Another Example
107. 107. Precordial AxisLate Transition - Clockwise Rotation
108. 108. Pathologies Frontal Plane Axis Precordial Axis ERAD Right Axis Pathological Early Transition Late Transition Deviation Left Axis Counterclockwise Clockwise -90° to 180° Deviation Rotation Rotation 90° to 180° -30° to -90°• Ventricular • May be normal • Pregnancy • Posterior wall • SometimesRhythm • LPFB • LAFB infarction Normal,• Paced Rhythm • Pulmonary • WPW • RVH especially in• Dextrocardia • RBBB women disease • Pulmonary • Anterior MI• Electrolyte • RVH diseasederangement • LVH • RBBB • LBBB • LAFB • WPW • Hyperkalemia • LBBB • Dextrocardia • Q-waves, MI • Lung Disease •Venrticular Rhythm
109. 109. Fascicles• Right Bundle Branch – 1 Fascicle• Left Bundle Branch – 2 Fascicles • Left Anterior • Left Posterior
110. 110. Fascicular Blocks Left PosteriorFascicular Block Left Anterior Fascicular Block
111. 111. Fascicular Block• Bifascicular Block – Right Bundle Branch Block (RBBB) with either: • Left Anterior Fascicular Block (LAFB) • Left Posterior Fascicular Block (LPFB) – Only one fascicle remaining• Trifascicular Block – RBBB with LAFB/LPFB and 1st degree AV Block – May degrade into lethal arrhythmia rapidly
112. 112. Practice
113. 113. PracticeIdentify the rate & regularity
114. 114. PracticeIdentify the rate & regularity
115. 115. PracticeIdentify the rate & regularity
116. 116. PracticeIdentify the rate & regularity 1 2 3
117. 117. PracticeIdentify the rate & regularity 1 2 3 300 ÷ 3 = 100
118. 118. HR ≈ 100 PracticeIdentify the rhythm
119. 119. HR ≈ 100 PracticeIdentify the rhythm
120. 120. HR ≈ 100 PracticeIdentify the rhythm
121. 121. HR ≈ 100 Normal Sinus PracticeNormal Sinus Rhythm
122. 122. HR ≈ 100 Normal SinusPracticeFrontal Axis?
123. 123. HR ≈ 100 Normal SinusPracticeFrontal Axis?
124. 124. HR ≈ 100 Normal SinusPracticeFrontal Axis?
125. 125. Practice • Equiphasic lead is aVF. • Find lead perpendicular to aVF
126. 126. Practice • Equiphasic lead is aVF. • Find lead perpendicular to aVF
127. 127. HR ≈ 100 Normal SinusPracticeFrontal Axis?
128. 128. Practice • Lead I is positive • Frontal axis is about 0°
129. 129. Practice • Lead I is positive • Frontal axis is about 0° • That is in normal quadrant.
130. 130. HR ≈ 100 Normal Sinus Frontal axis is normal PracticeFrontal Axis = Normal, about 0°
131. 131. HR ≈ 100 Normal Sinus Frontal axis is normal PracticePrecordial Axis
132. 132. HR ≈ 100 Normal Sinus Frontal axis is normal PracticeEarly Transition, Counterclockwise Rotation
133. 133. PracticeLets try another
134. 134. Practice
135. 135. PracticeDetermine Rate & Rhythm
136. 136. HR ≈ 75 Normal Sinus PracticeDetermine Rate & Rhythm
137. 137. HR ≈ 75 Normal Sinus PracticeDetermine Frontal Axis