3.2.0 Left Bundle Branch Block (LBBB)

Left bundle branch block (LBBB) occurs when impulse transmission through the left bundle branch is slowed or blocked and activation of the interventricular septum and the left ventricle occur via impulses that cross over from the right ventricle. The causes of left bundle branch block are listed here.

Note that as with right bundle branch block, LBBB may be functional, occurring in response to abrupt changes in cycle length. It may also occur in the absence of an obvious cause. However, this occurs much less frequently than does right bundle branch block