Cardiology Question 12 Instructor

What are the causes of left axis deviation (LAD) on ECG?

  1. Left anterior hemiblock
  2. Inferior myocardial infarction
  3. RV apical pacing & middle cardiac vein pacing
  4. WPW / pre-excitation / bypass tract
  5. Pulmonary Emphysema
  6. Hyperkalemia
  7. Ventricular ectopic rhythms
  8. Mechanical shifts: Expiration, high diaphragm from pregnancy, ascites, abdominal tumors, etc.
  9. Endocardial cushion defects, some other acyanotic and cyanotic congenital lesions
  10. Normal variation

Note 1: LVH is not a cause. Left axis deviation is associated with LBBB but LBBB is not a cause of LAD.

Note 2: LAD is does not invariably accompany LVH. Significant LAD suggest presence of myocardial disease in the LV apart from pure hypertrophy.

Marriott 8th ed. 1987 p. 50-55

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