This document discusses cardiac axis and axis deviation in electrocardiograms (ECGs). It defines the normal cardiac axis as between -30 to 90 degrees. It describes left axis deviation as less than -30 degrees and right axis deviation as greater than 90 degrees. Common causes of left axis deviation include left ventricular hypertrophy, inferior myocardial infarction, and left anterior fascicular block. Common causes of right axis deviation include right ventricular hypertrophy, lateral or apical myocardial infarction, and chronic lung disease.

1. AXIS

2. The
average
direction of
electrical forces
in the frontal
plane (limb leads)
+/-180degrees
Lead 1
0degrees
measured from the zero
reference point (lead 1)

3. http://www.ecgteacher.com/index.php
/axis-a-chambers/the-cardiac-axis
Normal QRS/Cardiac Axis
QRS: -30 to 90 degrees

4. Recognising Axis Deviation
http://www.ecgteacher.com/index.php/axis-a-cham

5. Lead I is a left-sided
lead, and as aVF is
perpendicular to lead I,
it can be considered a
right-sided lead.
Quick Look Test 1 & aVF

6. Limb leads
Lead 1 = zero
Quick Look Test Limb
Leads

7. All about the…
Less than -30 degrees
= Left Axis Deviation
-30 to 90 degrees
QRS
Greater than 90 degrees = Right
Axis Deviation
= Normal

8. Right Ventricular
Lateral and apical MI
Hypertrophy (RVH) — most common
Left Posterior Fascicular Block (LPFB) — diagnosis of exclusion
Chronic lung disease, e.g. COPD
Acute Right Heart Strain, e.g. acute lung disease such as pulmonary embolus
Right Axis Deviation…RAD
Normal in infants and children
Hyperkalemia
Dextrocardia – rare +++

9. Left Ventricular
Hypertrophy (LVH) — most common
Inferior MI
Left Anterior Fascicular Block (LAFB) — diagnosis of exclusion
Ventricular pre-excitation (WPW)
Left Axis Deviation…LAD
LBBB
paced beats
Primum ASD — rSR’ pattern

10. 180 to -90 degrees
rare
VT
Extreme Axis Deviation
Right Ventricular Hypertrophy (RVH)
Hyperkalemia
Apical MI

11. Rule of thumb: the heart axis
(QRS) rotates towards
hypertropy and away from
infarction

12. For more info and with thanks…
http://lifeinthefastlane.com/ecg-library/basics/axis/
http://www.ecgteacher.com/