axis
The heart's electrical axis refers to the general direction of the heart's depolarization
wavefront (or mean electrical vector) in the frontal plane. Usually oriented in the
direction of the right shoulder to left foot, which is associated with left inferior
quadrant hexaxial reference system, although 30o to +90 o is considered normal.
• Left axis deviation (-30o to-90o) may indicate left anterior fascicular block or Q
waves of inferior myocardial infarction.
• Right axis deviation (+90 o to +180 o) may indicate left posterior fascicular block, Q
waves from the upper lateral myocardial infarction, or ventricular-right pitch.
• In case of right bundle branch block, right or left deviation may indicate bifasciculus
block.