Right bundle branch block (RBBB)
In RBBB, the right bundle branch no longer conducts electricity. Therefore, as the electrical impulse leaves the His bundle, it enters left bundle branch only, and is carried to the left ventricle. Then, from the left ventricle, the electrical impulse finally makes its way to the right ventricle. As a result, the two ventricles no longer receive the electrical impulse simultaneously. First the left ventricle receives the electrical impulse, then the right.Left Bundle Branch Block
Figure 4 - Left Bundle Branch Block (LBBB)In LBBB, the opposite occurs. Here, the left bundle branch no longer conducts electricity. The electrical impulse thus enters right bundle branch, and is carried to the right ventricle (first panel). From there, it finally spreads to the left ventricle (second panel). Once again, the two ventricles no longer receive the electrical impulse simultaneously. First the right ventricle receives the electrical impulse, then the left.
With either type of BBB, therefore, the electrical signal spreads across the ventricles sequentially, as opposed to simultaneously. This sequential spread of the impulse (i.e., first the right ventricle, then the left – or vice versa) means that it takes longer for the impulse to reach throughout the ventricles.
