Axis Determination: Method 1
1. Check lead I (0 degrees)
  1. QRS positive (predominately up)
    1. Vector points to patient's Left
    2. Correlates with right half of axis circle
  2. QRS negative (predominately down)
    1. Vector points to patient's Right
    2. Correlates with left half of axis circle
2. Check lead aVF (90 degrees)
  1. QRS positive (predominately up)
    1. Vector points to bottom half of axis circle
  2. QRS negative (predominately down)
    1. Vector points to upper half of axis circle
3. Interpretation
  1. Indeterminate: Extreme Right Axis Deviation
    1. Lead I: Negative QRS
    2. Lead aVF: Negative QRS
  2. Right Axis Deviation
    1. Lead I: Negative QRS
    2. Lead aVF: Positive QRS
  3. Normal range
    1. Lead I: Positive QRS
    2. Lead aVF: Positive QRS
  4. Left Axis Deviation
    1. Lead I: Positive QRS
    2. Lead aVF: Negative QRS
Axis Determination: Method 2
1. Select Isoelectric lead from limb and augmented leads
  1. Isoelectric lead averages to baseline
  2. Positive deflection equals negative deflection
2. Identify isoelectric lead on axis circle
3. Choose lead that is perpendicular to isoelectric lead
4. Use Lead I and aVF to determine quadrant
5. Read perpendicular lead's degrees off axis circle

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This page was written by Scott Moses, MD. This page was last revised before 5/10/08, prior to consistent tracking of revision date. This page was last published on 5/10/2008. Please send comments and questions to the editor. Contact information may be found on the page About the Family Practice Notebook. These pages are best viewed with Microsoft Internet Explorer 6.0.