ECG Criteria 2

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  1. How is axis determined in RBBB?
    Look at the initial 60-80 ms (should be normal unless LAFB or LPFB is present)
  2. What is the duration of LBBB and RBBB?
    120 ms (greater than or equal to)
  3. What are the five criteria for RBBB?
    1. duration 120 ms or greater; 2. R' in V1 or V2 (R' > R); 3. delayed onset of intrinsicoid deflection (beginning of QRS to peak of R > 0.05 seconds in V1 and V2; 4. secondary ST/T wave changes in V1 and V2; 5. wide slurred S in I, V5, and V6
  4. Does RBBB interfere with the diagnosis of MI or LVH?
  5. What are the criteria for incomplete RBBB?
    RBBB morphology with QRS duration between 90-120 ms
  6. What is the QRS axis in LAFB?

    -45 --> -90 degrees

    100 --> 180 degrees
  7. Why is there left axis deviation in LAFB?
    The impulse reaches the LV via the LPF (inserts in the inferoseptal wall); initial impulse is downward and rightward (r wave inferiorly) then the wave heads leftward and upwards (deep S inferiorly, large R left leads); takes 20 ms longer (QRS widening and delayed R peak in AVL)
  8. Is the septum depolarized R-->L or L--> R?

    L--> R

    The left bundle arborizes earliest, therefore impulses reach the left side of the septum first
  9. What are the criteria for LAFB?
    Axis -45 --> -90 degrees; qR in I and AVL; rS in III; QRS duration 80-100 ms; no other causes of LAD
  10. What are the "other" causes of LAD in LAFB?
    LVH, inferior MI, emphysema, ostium primum ASD, LBBB
  11. What false positive diagnosis can result from LAFB?

    Which false negative?
    LVH based on voltage criteria in I and avL

    Inferior MI
  12. What part of the heart is activated by the left anterior fascicle?
    anterior and lateral walls of the LV
  13. What are the criteria for LPFB?
    RAD, QRS duration 80-100 ms, no other factors causing RAD
  14. What are the "other" causes of RAD in LPFB?
    RVH, verticle heart, emphysema, lateral wall MI, dextrocardia, lead reversal, WPW
  15. Why is there right axis deviation in LPFB?
    The impulse reaches the LV via the LAF (inserts in the upper, lateral wall); initial impulse is upward and leftward (endo --> epi) (r waves in left leads and q waves inferiorly); the wave then heads downward and rightward (tall R waves inferiorly and deep S waves in I and avL); takes 20 ms longer (wider QRS) and reaches the inferior leads late (delayed R peak in AVF)
  16. Why is isolated LAFB more common than isolated LPFB?
    The LPF is shorter, thicker, and received blood from two arteries (RCA and LAD)
  17. What are the 5 criteria for LBBB?
    1. QRS > 120 ms; 2. delayed onset of intrinsicoid deflection in leads I, V5, V6; 3. broad monophasic R waves in I, V5, V6; 4. secondary ST / T wave changes; 5. rS or QS in right precordial leads
  18. How do you determine axis in LBBB?
    you cannot
  19. Can LVH and LBBB be coded simultaneously?
  20. What is the criteria for incomplete LBBB?
    LBBB morphology with QRS duration 90-120 seconds
  21. What is the diagnosis?  QRS > 110 ms without LBBB or RBBB morphology?
    Nonspecific intraventricular conduction disturbance
  22. ECG definition of ischemia?


    ST depression, T waves usually inverted, no q waves

    ST segment elevation; no q waves

    abnormal Q waves, ST elevated or depressed; T waves inverted, normal, or upright and symmetrically peaked
  23. What is the ST elevation criteria in the leads V1-V3?

    All the others?
    2 mm 

    1 mm
  24. What Q waves are abnormal in V1-V3?

    The other leads (except AVR)
    any q wave

    > 30 ms, > 1 mm depth in 2 contiguous leads
  25. What is the definition of acute MI?

    Recent MI?

    Age Indeterminant?
    Abnormal Q waves, ST elevation; hyperacute T waves very early

    Abnormal Q waves, isoelectric ST segments, ischemic (usually inverted) T waves

    Abnormal Q waves, isoelectric ST segments, normal T waves
  26. Anterolateral MI, recent or acute:
    Abnormal Q waves with significant ST elevation in leads V4-V6
  27. Anteroseptal MI:

    Lateral MI:


    I and avL

    II, III, avF
  28. Posterior MI, age recent or acute

    Age indeterminate or old
    R wave in V1 > 40 ms with R/S > 1 and significant ST depression

    without ST depression
  29. Normal variant, early repol
    ST segment elevation at the J point, Concave upward, distinct notch and slur of the downstroke of the R wave, no ST depression
  30. Nonspecific ST and/or T wave abnormalities
    < 1 mm ST depression or elevation, and/or T wave flat or slightly inverted
  31. ST and/or T wave suggesting ischemia
    ST: horizontal or downsloping ST segments with or without T wave inversion

    T: Biphasic T waves with or without ST depression; symmetrically or deeply inverted T waves
  32. ST and/or T waves suggesting injury
    ST segment elevation; T waves invert before ST segments resolve; ST depression in the noninfarct leads is common
  33. Prolonged QT interval
    QTC > 440 ms or > 50% of the RR
  34. In which lead is the QT segment measured?
    Longest QT interval with a distinct T wave termination
  35. Prominent U wave
    > 1.5 mm
  36. How is ST segment elevation produced?
    MI causes destruction of the dielectric property of the cell membrane which allows free motion of ions.  This depresses the baseline; the ST segments are actually not moved because during early repolarization there is not much movement of ions
  37. What rhythms can result from digitalis toxicity?
    Atrial tachycardia with block, AF with complete heart block, 2nd or 3rd degree AV block, 3rd degree AV block with accelerated junctional rhythm or AIVR, SVT with alternating bundle branch block
  38. What electrolyte abnormalities exacerbate dig toxicity?
    hypokalemia, hypomagnesemia, hypercalcemia
Card Set
ECG Criteria 2
These are from O'Keefe ECG book
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