ECG

Electrocardiography displays the electrical activity of the heart. It does not provide any information about the mechanical or functional activities of the heart, but valuable information can be collected based on the changes in the various segments and waves.

Steps

  1. Measure heart rate
  2. Check regularity (R-R distance)
  3. Calculate electrical axis (leads I and AVF)
  4. Examine P wave
    1. Are they regular? Same polarity? P waves are followed by QRS?
    1. Abnormalities:
      1. P-mitrale (increased duration)
      2. P-pulmonale (increased amplitude)
      3. P-cardiale (bifid)
  5. PR interval (0.12-0.2s or 3-5 small boxes)
    1. <0.12s WPW
    2. >0.2s AV block
  6. QRS complex
    1. Narrow (<0.12s, or 3 small boxes)
    2. Broad (>0.12s)
    3. Tall R wave may indicate hypertrophy
  7. ST segment
    1. Elevated means STEMI
    2. Depressed means ischemia
    3. "Boat shaped" depression in digoxin usage
  8. T-wave (should be upright in all leads except aVR and V1)
    1. Inversion means ischemia

AV blocks

  • 1st degree: prolonged
  • 2nd degree:
    • Mobitz I (progressively prolongs, then stops)
    • Mobitz II (some Ps don’t get through)
  • 3rd degree: P and QRS are not matching

Bundle branch block

  • RBBB (v1,2,3 RsR)
  • LBBB (v4,5,6 RsR)

Miscellaneous

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