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QRS Axis
Aka: QRS Axis, EKG Axis, Electrocardiogram Axis
- Interpretation: Axis Determination (Method 1)
- Images: Main

- Check lead I (0 degrees)
- QRS positive (predominately up)
- Vector points to patient's Left
- Correlates with right half of axis circle
- QRS negative (predominately down)
- Vector points to patient's Right
- Correlates with left half of axis circle
- Check lead aVF (90 degrees)
- QRS positive (predominately up)
- Vector points to bottom half of axis circle
- QRS negative (predominately down)
- Vector points to upper half of axis circle
- Interpretation
- Indeterminate: Extreme Right Axis Deviation
- Lead I: Negative QRS
- Lead aVF: Negative QRS
- Right Axis Deviation
- Lead I: Negative QRS
- Lead aVF: Positive QRS
- Normal range
- Lead I: Positive QRS
- Lead aVF: Positive QRS
- Left Axis Deviation
- Lead I: Positive QRS
- Lead aVF: Negative QRS
- Interpretation: Axis Determination (Method 2)
- Select Isoelectric lead from limb and augmented leads
- Isoelectric lead averages to baseline
- Positive deflection equals negative deflection
- Identify isoelectric lead on axis circle
- Lead with most symmetric voltage (as much positive QRS voltage as negative QRS voltage)
- Choose lead that is perpendicular to isoelectric lead
- Use Lead I and aVF to determine quadrant
- Read perpendicular lead's degrees off axis circle
- Extreme Right Axis Deviation (-90 to -180, negative in lead I and negative in lead avF)
- Most Isoelectric I (avF is perpendicular): -90 (12:00)
- Most Isoelectric avL (II is perpendicular): -120 (11:00)
- Most Isoelectric III (avR is perpendicular): -150 (10:00)
- Most Isoelectric avF (I is perpendicular): -180 (9:00)
- Right Axis Deviation (+180 to +90, negative in lead I and positive in lead avF)
- Most Isoelectric avF (I is perpendicular): +180 (9:00)
- Most Isoelectric II (avL is perpendicular): +150 (8:00)
- Most Isoelectric avR (III is perpendicular): +120 (7:00)
- Most Isoelectric I (avF is perpendicular): +90 (6:00)
- Left Axis Deviation (-90 to -30, positive in lead I and negative in lead avF)
- Most Isoelectric I (avF is perpendicular): -90 (12:00)
- Most Isoelectric avR (III is perpendicular): -60 (1:00)
- Most Isoelectric II (avL is perpendicular): -30 (2:00)
- Normal Axis (+90 to -30, positive in lead I and positive in lead avF)
- Most Isoelectric avF (I is perpendicular): 0 (3:00)
- Most Isoelectric III (avR is perpendicular): +30 (4:00)
- Most Isoelectric avL (II is perpendicular): +60 (5:00)
- Most Isoelectric I (avF is perpendicular): +90 (6:00)