Exam

# Right Axis Deviation

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Right Axis Deviation, Extreme Right Axis Deviation, Right Superior QRS Axis

• Definitions
1. Extreme Right Axis Deviation (right superior axis, -90 to 180)
1. Negative net QRS voltage in lead I
2. Negative net QRS voltage in lead avF
3. On clock face, represents the 9:00 to 12:00 position
2. Right Axis Deviation
1. Deviation into lead III axis (+90 to -90 degrees)
2. Negative net QRS voltage in lead I
3. Positive net QRS voltage in lead avF
4. On clock face, represents the 6:00 to 9:00 position
• Interpretation
• Based on most isoelectric lead
1. Images
2. Approach
1. See QRS Axis
2. Lead with most symmetric voltage (as much positive QRS voltage as negative QRS voltage)
3. Choose lead that is perpendicular to isoelectric lead and that leads axis is the same as the QRS Axis
3. Extreme Right Axis Deviation (-90 to -180, negative in lead I and negative in lead avF)
1. Most Isoelectric I (avF is perpendicular): -90 (12:00)
2. Most Isoelectric avL (II is perpendicular): -120 (11:00)
3. Most Isoelectric III (avR is perpendicular): -150 (10:00)
4. Most Isoelectric avF (I is perpendicular): -180 (9:00)
4. Right Axis Deviation (+180 to +90, negative in lead I and positive in lead avF)
1. Most Isoelectric avF (I is perpendicular): +180 (9:00)
2. Most Isoelectric II (avL is perpendicular): +150 (8:00)
3. Most Isoelectric avR (III is perpendicular): +120 (7:00)
4. Most Isoelectric I (avF is perpendicular): +90 (6:00)
• Causes
• References
1. Mattu (2020) Crit Dec Emerg Med 34(4): 18