Lateral precordials: V5–V6

V5–V6 sit over the lateral left ventricle, facing the main depolarization, so they show a tall R with a small preceding septal q (a qR complex).

• V5–V6: a qR complex, a small septal q, then a dominant R; the S wave is nearly gone by V6.
• The septal q is normal when it is narrow (< 40 ms) and shallow (< 25% of the R).
• The T wave is upright.