1. Determining AXIS: 12 Lead ECG's
Using the Hexaxial Diagram to find the degree of Axis Deviation
This technique is a little hard to learn
but it is very accurate (+ or – 100 to 150)
Emily Koch, RN, BSN, ACNPc
Clinician III
4 East UVA Health System

2. Basics of 12 Lead ECG's Determining AXIS
To determine the axis a scale must be used such as the one at the left. Each physician uses a slightly different degree as the upper limit of normal, but typically degrees.

3. Basics of 12 Lead ECG's Determining AXIS
First you must find the most equiphasic QRS complex in the six limb leads. This is done by adding and subtracting the number of squares each QRS complex has above the baseline and below the baseline in each lead.

4. Basics of 12 Lead ECG's Determining AXIS
Locate the lead perpendicular to the lead with the most isoelectric QRS. If the perpendicular lead has a positive QRS, orient the axis to the positive pole of this lead. If it is negative then orient it to the negative Pole of this lead.

5. Basics of 12 Lead ECG's Determining AXIS
If there is a lead with a QRS that is taller than the lead perpendicular to the most isoelectric, the axis is the mean of the two.
Remember: If the tallest
lead has a positive QRS,
orient the axis to the
positive pole of this lead. If it is negative then
orient it to the negative
pole.

7. Causes of Abnormal Axis
Left Axis Deviation = An axis between -30 and -90
May be normal in the elderly and very obese
Due to high diaphragm during pregnancy, ascites, or ABD tumors
Left Anterior Hemiblock
Left Bundle Branch Block
WPW Syndrome
Congenital Lesions
Right Vent. Pacer or ectopic rhythms
Emphysema

8. Causes of Abnormal Axis
Right Axis Deviation = An axis between +120 and +180
Can be normal variant
Right Vent. Hypertrophy
Right Bundle Branch Block
Left Posterior Hemiblock
Left Ventricular ectopic rhythms
Some right Vent. Ectopic rhythms
WPW Syndrome

9. Causes of Abnormal Axis
Extreme Right Axis Deviation = An axis between - 90 and +180
Ventricular ectopic rhythms
Right Vent. Paced rhythms
Less commonly seen in patients with cardiomyopathies and in those with multiple MI's

10. Normal ECG Most isoelectric is aVL.
II is perpendicular and has mostly positive QRS. It also has the tallest QRS.
Axis is 60 degrees and NORMAL

11. Determine Axis Answer: aVR is most isoelectric
III is perpendicular and has tallest QRS
QRS is III is mostly negative so axis is oriented to negative pole of lead III
Axis is -60 degrees. LEFT axis deviation