EKG Atlas-LAFB

Criteria of left anterior fascicular block

II. QRS vector shows left axis deviation (LAD) in frontal plane > -30 degrees.

III. QRS morphology

• Limb leads
  1. qR in leads I and aVL.
  2. rS in leads II, III, and aVF.
  3. R peaks in aVL before aVR.
• Precordial leads
  1. Delayed R wave transition.
  2. Persistent S wave in V5-V6
  3. Normal QRS morphology if precordial leads are recorded 2-3 interspaces higher.
• Orthogonal leads
  1. qR in lead X
  2. rS in lead Y