Left Axis Deviation

Causes of left axis deviation
  • Advanced age
  • LVH
  • Obesity
  • Emphysema
  • Inferior MI (loss of inferior forces)
  • Left anterior fascicular block (LAFB); diagnostic criteria:
    • left axis deviation > - 45 degrees
    • leads I and aVL ­ but start with a narrow Q (qR)
    • leads II, III, aVF  but start with a small r (rS)
    • QRS may be slightly widened but < 0.12s