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- 1. 12-LeadElectrocardiography a comprehensive course xis T he A Adam Thompson, EMT-P, A.S.
- 2. Resources• http://www.blaufuss.org/ECGviewer/indexFrame2.html• ems12lead.com/
- 3. The 6-Step Method• 1. Rate & Rhythm• 2. Axis Determination• 3. Intervals• 4. Morphology• 5. STE-Mimics• 6. Ischemia, Injury, & Infarct
- 4. 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.
- 5. Axis Determination• Critical Skill!• Use the hexaxial reference system for the frontal plane.• Identify clockwise or counterclockwise rotation of R-wave progression.
- 6. 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 disease • RBBB women • Pulmonary • Anterior MI• Electrolyte • RVH diseasederangement • LVH • RBBB • LBBB • LAFB • WPW • Hyperkalemia • LBBB • Dextrocardia • Q-waves, MI • Lung Disease •Venrticular Rhythm
- 7. Willem Einthoven Won the Nobel Prize in Physiology orMedicine in 1924 for inventing the stringgalvanometer which was the first EKG.
- 8. Einthoven’s Triangle• Electrically, leads I, II, & III form an equilateral triangle.• Einthoven’s Law I + (-II) + III = 0
- 9. 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.
- 10. Einthoven’s Law• Lead I = 5mm• Lead II – It’s essentially a monophasic QS complex. – About -10 mm.
- 11. 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.
- 12. Einthoven’s Law• Lead I = 5mm• Lead II = -10mm• Lead III = -15mm
- 13. Einthoven’s Law• Lead I = 5mm• Lead II = -10mm• Lead III = -15mm – Plug the numbers in. • I + (-II) + III = 0 • 5 + 10 -15 = 0
- 14. Einthoven’s LawThe equilateral triangle
- 15. 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
- 16. 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).
- 17. 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).
- 18. 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”.
- 19. 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
- 20. Mean Electrical VectorRed arrow is heart’smean electrical vector
- 21. Mean Electrical VectorLead I views the heart’sVector similar to theimage on the left.Leads II & III do the samefrom their angles.
- 22. Einthoven’s Triangle =
- 23. Hexaxial Reference SystemThe arrows and leadnames are placed on Ithe side of thepositive electrode. III II
- 24. Hexaxial Reference System The augmented leads provide the other 3 leads of the hexaxial reference system.
- 25. Hexaxial Reference System
- 26. Hexaxial Reference System - aVF- II - III- 90° -60° aVR aVL aVR+ - 120° + - 30° aVL - 150° I I-+/-180° 0° I+ 30° aVL- 150° aVR- 120° 90° 60°III II aVF III+ II+ aVF+
- 27. Hexaxial Reference System aVF - II- - 90° III- - 60° - 120° aVR+ aVL+ - 30° - 150° 0° I- I+ +/- 180° 30° - aVL 150° aVR- 60° 120° III+ 90° II+ aVF+
- 28. The Hexaxial Method Axis Determination Thompson 66We –only need to concentrate on the first six leadsECG 13 ECG – 14
- 29. Hexaxial MethodThe Hexaxial Method 5 Easy StepsStep 1: Determine the equiphasic lead.Step 2: Find that lead on the diagram.Step 3: Find the perpendicular lead.Step 4: Determine if it is positive or negative.Step 5: Find your Axis. The Hexaxial Method will determine the mean Q
- 30. The Hexaxial Method Axis Determination Thompson 66Step 13 Find the equiphasic lead aVF- ECG – 1: II- - 90° III- - 60° - 120° aVR + - aVL+ 30° - 150° I- 0° I+ +/- 180° 30° aVL- 150° aVR- 60° 120° 90°Step 4: Is the perpendicular lead ECG – 14 III+ II+ aVF+ positive or negative?
- 31. Hexaxial Reference System Find the most equiphasic lead
- 32. Hexaxial Reference System + + A B A + B• When the mean axis is perpendicular to the positive electrode, the QRS is equiphasic.
- 33. Hexaxial Reference System aVF- II- - 90° III- - 60° - 120° aVR + - aVL+ 30° - 150° I- 0° I+ +/- 180° 30° aVL- 150° aVR- 60° 120° 90° III+ II+ aVF+
- 34. 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.
- 35. Axis Deviation• So what is a normal axis?• Why does it matter if an axis is deviated?
- 36. Normal Axis • The normal quadrant for the QRS axis is the Southeast quadrant. • From 0° to 90°
- 37. Left Axis Deviation • From -90° to 0° • This is considered the Northeast quadrant.
- 38. 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
- 39. 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.
- 40. Extreme Right Axis Deviation • Called ERAD • From -90° to -180° • QRS in I, II, & III are negative • Probably ventricular – Idioventricular – Paced rhythm
- 41. 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
- 42. Hexaxial Reference System aVF- II- - 90° III- - 60° - 120° aVR + - aVL+ 30° - 150° I- 0° I+ +/- 180° 30° aVL- 150° aVR- 60° 120° 90° III+ II+ aVF+
- 43. 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
- 44. on T Pathologies Hexaxial Method -90° 5 Easy StepsStep 1: Determine the equiphasic lead. ERAD LADStep 2: Find that lead on the diagram. 180° 0°Step 3: Find the perpendicular lead. RAD NormalStep 4: Determine if it is positive or negative.Step 5: Find your Axis. 90° The Hexaxial Method will determine the mean QRS axis in the frontal plane.
- 45. Fascicles• Right Bundle Branch – 1 Fascicle• Left Bundle Branch – 2 Fascicles • Left Anterior • Left Posterior
- 46. Fascicular Blocks Left PosteriorFascicular Block Left Anterior Fascicular Block
- 47. 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
- 48. END

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