Refers to the direction of movement of depolarization
- Look in leads I and AVF
- I-left, AVF-right
- both up = Normal axis
- both down = Extreme right axis deviation
- Lup/Rdown = Left axis deviation
- Rup/Ldown = Right axis deviation
- Specific axis degrees: determine type of deviation, choose most iso-electric line and go to that line on the circle chart. Go 90 degrees into the good quadrant (the one you know you're in) and that will tell you the exact degrees.