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ECG Basics

  1. Basics of ECG Dr Subroto Mandal, MD, DM, DC Associate Professor, Cardiology
  4. With EKGs we can identify Arrhythmias Myocardial ischemia and infarction Pericarditis Chamber hypertrophy Electrolyte disturbances (i.e. hyperkalemia, hypokalemia) Drug toxicity (i.e. digoxin and drugs which prolong the QT interval)
  6. EKG Leads which measure the difference in electrical potential between two points 1. Bipolar Leads: Two different points on the body 2. Unipolar Leads: One point on the body and a virtual reference point with zero electrical potential, located in the center of the heart
  7. EKG Leads The standard EKG has 12 leads: 3 Standard Limb Leads 3 Augmented Limb Leads 6 Precordial Leads
  8. Standard Limb Leads
  9. Standard Limb Leads
  10. Augmented Limb Leads
  11. All Limb Leads
  12. Precordial Leads
  13. Precordial Leads
  14. Right Sided & Posterior Chest Leads
  15. Arrangement of Leads on the EKG
  16. Anatomic Groups (Septum)
  17. Anatomic Groups (Anterior Wall)
  18. Anatomic Groups (Lateral Wall)
  19. Anatomic Groups (Inferior Wall)
  20. Anatomic Groups (Summary)
  21. RULE 6 The R wave must grow from V1 to at least V4 The S wave must grow from V1 to at least V3 and disappear in V6
  22. P Pulmonale P Mitrale
  23. QRS in LVH & RVH
  24. Conditions with Tall R in V1
  25. Right Atrial and Ventricular Hypertrophy
  27. Variable Shapes Of ST Segment Elevations in AMI Goldberger AL. Goldberger: Clinical Electrocardiography: A Simplified Approach. 7th ed: Mosby Elsevier; 2006.
  28. T wave
  29. QT Interval
  30. Determining the Heart Rate Rule of 300/1500 10 Second Rule
  31. Rule of 300 Count the number of “big boxes” between two QRS complexes, and divide this into 300. (smaller boxes with 1500) for regular rhythms.
  32. What is the heart rate? (300 / 6) = 50 bpm
  33. What is the heart rate? (300 / ~ 4) = ~ 75 bpm
  34. What is the heart rate? (300 / 1.5) = 200 bpm
  35. The Rule of 300 It may be easiest to memorize the following table: 50 6 60 5 75 4 100 3 150 2 300 1 Rate No of big boxes
  36. 10 Second Rule EKGs record 10 seconds of rhythm per page, Count the number of beats present on the EKG Multiply by 6 For irregular rhythms.
  37. What is the heart rate? 33 x 6 = 198 bpm
  38. Calculation of Heart Rate
  39. The QRS Axis The QRS axis represents overall direction of the heart’s electrical activity. Abnormalities hint at: Ventricular enlargement Conduction blocks (i.e. hemiblocks)
  40. The QRS Axis Normal QRS axis from -30 ° to +90 ° . -30 ° to -90 ° is referred to as a left axis deviation (LAD) +90 ° to +180 ° is referred to as a right axis deviation (RAD)
  41. Determining the Axis The Quadrant Approach The Equiphasic Approach
  42. Determining the Axis Predominantly Positive Predominantly Negative Equiphasic
  43. Quadrant Approach: Example 1 Negative in I, positive in aVF  RAD
  44. Quadrant Approach: Example 2 Positive in I, negative in aVF  Predominantly positive in II  Normal Axis (non-pathologic LAD)
  45. The Equiphasic Approach 1. Most equiphasic QRS complex. 2. Identified Lead lies 90° away from the lead 3. QRS in this second lead is positive or Negative
  46. QRS Axis = -30 degrees
  47.                                                                      QRS Axis = +90 degrees-KH
  49. Equiphasic Approach Equiphasic in aVF  Predominantly positive in I  QRS axis ≈ 0°
  50. Thank You
  51. BRADYARRYTHMIA Dr Subroto Mandal, MD, DM, DC Associate Professor, Cardiology
  52. Sinus Bradycardia
  53. Junctional Rhythm
  54. Mobitz type 1 (Wenckebach Phenomenon)
  55. Third Degree Heart Block 3rd degree AV block with a left ventricular escape rhythm, 'B' the right ventricular pacemaker rhythm is shown.
  56. The nonconducted PAC's set up a long pause which is terminated by ventricular escapes; Wider QRS morphology of the escape beats indicating their ventricular origin. AV Dissociation
  57. AV Dissociation Due to Accelerated ventricular rhythm
  58. Thank You
  59. Ventricular Conduction Normal Signal moves rapidly through the ventricles Abnormal Signal moves slowly through the ventricles
  61. Left Ventricular Hypertrophy
  62. Bundle Branch Blocks
  63. Normal Impulse Conduction Sinoatrial node AV node Bundle of His Bundle Branches Purkinje fibers
  65. RBBB
  85. PERICARDIAL EFFUSION-Electrical alterans
  87. HYPOTHERMIA- Giant Osborne waves

Editor's Notes

  1. Atrial depolarisation Electrically both atria act almost as one. They have relatively little muscle and generate a single, small P wave. P wave amplitude rarely exceeds two and a half small squares (0.25 mV). The duration of the P wave should not exceed three small squares (0.12 s). The wave of depolarisation is directed inferiorly and towards the left, and thus the P wave tends to be upright in leads I and II and inverted in lead aVR. Sinus P waves are usually most prominently seen in leads II and V1. A negative P wave in lead I may be due to incorrect recording of the electrocardiogram (that is, with transposition of the left and right arm electrodes), dextrocardia, or abnormal atrial rhythms. Normal P waves may have a slight notch, particularly in the precordial (chest) leads. Bifid P waves result from slight asynchrony between right and left atrial depolarisation. A pronounced notch with a peak­to­peak interval of > 1 mm (0.04 s) is usually pathological, and is seen in association with a left atrial abnormality—for example, in mitral stenosis.
  2. The R wave in lead V6 is smaller than the R wave in V5, since the V6 electrode is further from the left ventricle. The depth of the S wave, generally, should not exceed 30 mm in a normal individual (although > 30 mm are occasionally recorded in normal young male adults) In another website it is also shown that small q wave seen in leads III and aVF Normal q-waves reflect normal septal activation (beginning on the LV septum); they are narrow (<0.04s duration) and small (<25% the amplitude of the R wave). They are often seen in leads I and aVL when the QRS axis is to the left of +60o, and in leads II, III, aVF when the QRS axis is to the right of +60o. Septal q waves should not be confused with the pathologic Q waves of myocardial infarction (
  3. Sokolow + Lyon (Am Heart J, 1949;37:161) S V1+ R V5 or V6 > 35 mm Cornell criteria (Circulation, 1987;3: 565-72) SV3 + R avl > 28 mm in men SV3 + R avl > 20 mm in women Framingham criteria (Circulation,1990; 81:815-820) R avl > 11mm, R V4-6 > 25mm S V1-3 > 25 mm S V1 or V2 + R V5 or V6 > 35 mm R I + S III > 25 mm Romhilt + Estes (Am Heart J, 1986:75:752-58) Point score system
  4. ST segment depression is always an abnormal finding, although often nonspecific (
  5. As a general rule, T wave amplitude corresponds with the amplitude of the preceding R wave, though the tallest T waves are seen in leads V3 and V4. Tall T waves may be seen in acute myocardial ischaemia and are a feature of hyperkalaemia.
  6. Poor Man's Guide to upper limits of QT: For HR = 70 bpm, QT<0.40 sec; for every 10 bpm increase above 70 subtract 0.02 sec, and for every 10 bpm decrease below 70 add 0.02 sec. For example: QT < 0.38 @ 80 bpm QT < 0.42 @ 60 bpm