What is electrical axis
The sum total of all vectors generated by action
potentials of individual ventricular myocytes.
What can a deviated axis indicate?
Infarct, Hypertrophy, Conduction delay, Pregnancy, COPD, Obesity
Isoelectric means
Lead that is exactly the
same distance + as it is -
How many isoelectric leads does each EKG have?
1
- in I, - in aVF
Extreme right axis deviation
+ in I, - in aVF
Left axis deviation
- in I, + in aVF
Right axis deviation
+ in I, + in aVF
Normal axis
A normal axis is from
-30 to 110
What axis may be pathological or physiological?
Left
A left axis deviation with a positive QRS in lead II is
Physiological
A left axis deviation with a negative QRS in lead II is
Pathological
The isoelectric lead will always have
The smallest QRS complex
List causes of right axis deviation
- Normal in adolescents and children
- Right ventricular hypertrophy
- Left posterior hemiblock
- Dextrocardia –mirror image
- Ectopic ventricular beats and rhythm
- RBBB
- Emphysema
- Lt MI
Causes of left axis deviation
- Left anterior hemiblock (LAH)
- Ectopic ventricular beats and rhythms
- Pregnancy
- Ascites
- Abdominal tumors
- Left ventricular hypertrophy
- Rt MI
The most frequent cause of left axis deviation is
Left anterior hemiblock
