The lead most commonly used to assess BBB morphology is which lead?

The lead most commonly used to assess BBB morphology is which lead?

• A. V1
• B. V2
• C. V3
• D. V4

Answer: (A)

Focusing on how a bundle branch block changes the pattern of depolarization, the lead over the right ventricle provides the clearest snapshot of the block’s effect. In right bundle branch block, the right ventricle is activated late, so the tracing in the right-precordial lead shows the classic rsR' pattern—with a small initial R, a terminal R' that is tall and wide. That distinctive pattern in this lead makes it the most informative for recognizing BBB morphology. In left bundle branch block, the changes are more evident in the left-sided leads, while the right-precordial lead often shows a QS or rS pattern, reinforcing that V1 is the go-to lead for identifying the presence and type of BBB. So, the lead you’d most rely on to assess BBB morphology is the right-precordial lead.

Focusing on how a bundle branch block changes the pattern of depolarization, the lead over the right ventricle provides the clearest snapshot of the block’s effect. In right bundle branch block, the right ventricle is activated late, so the tracing in the right-precordial lead shows the classic rsR' pattern—with a small initial R, a terminal R' that is tall and wide. That distinctive pattern in this lead makes it the most informative for recognizing BBB morphology. In left bundle branch block, the changes are more evident in the left-sided leads, while the right-precordial lead often shows a QS or rS pattern, reinforcing that V1 is the go-to lead for identifying the presence and type of BBB. So, the lead you’d most rely on to assess BBB morphology is the right-precordial lead.